- Efficient conversion of microcrystalline cellulose to 1,2-alkanediols over supported Ni catalysts
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Nickel supported on a variety of supports was evaluated in the batchwise hydrogenolysis of high-crystalline cellulose under hydrothermal conditions. The supports examined included Al2O3, kieselguhr, TiO 2, SiO2, activated carbon (AC), ZnO, ZrO2 and MgO. All tested catalysts can effectively convert cellulose while the choice of supports plays a critical role in the product distribution and selectivity. The Ni catalysts favour the formation of industrially attractive 1,2-alkanediols such as 1,2-propanediol, ethylene glycol, 1,2-butanediol and 1,2-hexanediol. It was found that the bifunctional ZnO-supported Ni catalysts displayed superior activities and the best result was obtained on 20% Ni/ZnO which exhibited complete conversion of cellulose with up to 70.4% total glycol yields. The mechanism of the reaction involved was tentatively proposed by identifying the products formed. The Royal Society of Chemistry 2012.
- Wang, Xicheng,Meng, Lingqian,Wu, Feng,Jiang, Yijun,Wang, Lei,Mu, Xindong
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- Cu-Mg-Zr/SiO2 catalyst for the selective hydrogenation of ethylene carbonate to methanol and ethylene glycol
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A Cux-Mgy-Zrz/SiO2 catalyst with a total metal loading of 60 wt% prepared by a deposition-precipitation method was applied for the selective hydrogenation of ethylene carbonate to methanol and ethylene glycol in a fixed-bed reactor. As a result, the Cu8-Mg1-Zr0.47/SiO2 catalyst furnished 99% ethylene carbonate conversion with 85% selectivity to methanol and 99% selectivity to ethylene glycol under the optimized reaction conditions. Moreover, the Cu8-Mg1-Zr0.47/SiO2 catalyst also showed a good lifetime and neither the activity nor the selectivity decreased the during 208 h test. The reaction was found to depend sensitively on the Cu particle size, the surface acidity and the catalyst surface composition. The synergistic effect of balanced Cu0 and Cu+ sites was considered to play a critical role in attaining high yields of methanol and ethylene glycol. Boric oxide also had a positive effect on the hydrogenation of ethylene carbonate, affording higher selectivity to methanol under much milder conditions.
- Tian, Jingxia,Chen, Wei,Wu, Peng,Zhu, Zhirong,Li, Xiaohong
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- Hydrogenation of dimethyl oxalate to ethylene glycol over Cu/KIT-6 catalysts
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Copper supported on KIT-6 mesoporous silica was preparedviaammonia evaporation (AE) method and applied for the catalytic hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). The high specific surface area and interconnected mesoporous channels of the support facilitated the dispersion of copper species. The effect of AE temperature and copper loading on the structure of catalysts and induced change in hydrogenation performance were studied in detail. The results showed that both parameters influenced the overall and/or intrinsic activity. The hydrogenation of DMO to EG was proposed to proceedviathe synergy between Cu0and Cu+sites and catalysts with high surface Cu0/Cu+ratio exhibited high intrinsic activity in the investigated range.
- Yu, Xinbin,Burkholder, Michael,Karakalos, Stavros G.,Tate, Gregory L.,Monnier, John R.,Gupton, B. Frank,Williams, Christopher T.
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- Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes
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Catalytic hydrogenation of cyclic carbonates to diols and methanol was achieved using a molecular catalyst based on earth-abundant manganese. The complex [Mn(CO)2(Br)[HN(C2H4PiPr2)2] 1 comprising commercially available MACHO ligand is an effective pre-catalyst operating under relatively mild conditions (T=120 °C, p(H2)=30–60 bar). Upon activation with NaOtBu, the formation of coordinatively unsaturated complex [Mn(CO)2[N(C2H4PiPr2)2)] 5 was spectroscopically verified, which confirmed a kinetically competent intermediate. With the pre-activated complex, turnover numbers up to 620 and 400 were achieved for the formation of the diol and methanol, respectively. Stoichiometric reactions under catalytically relevant conditions provide insight into the stepwise reduction form the CO2 level in carbonates to methanol as final product.
- Kaithal, Akash,H?lscher, Markus,Leitner, Walter
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- One-pot synthesized core/shell structured zeolite@copper catalysts for selective hydrogenation of ethylene carbonate to methanol and ethylene glycol
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Copper-based catalysts, with highly dispersed and stabilized Cu nanoparticles, intensified mass transfer and a well-balanced Cu0/Cu+ ratio at low Cu loadings, are highly desirable for the selective hydrogenation of ethylene carbonate to ethylene glycol and methanol, an efficient indirect route of CO2 utilization. A hierarchically core/shell-structured Silicalite-1@Cu composite was developed via a base-assisted chemoselective host-guest interaction between the silicon species of MFI-type Silicalite-1 and external Cu salt source. In situ generated mesoporosity and strong Cu-silicate interaction made the uniform Cu NPs firmly immobilized and highly dispersed outside the core S-1 crystals. The S-1@Cu hybrid possessed the co-existing Cu0/Cu+ active species with a suitable ratio, and served as a highly active, selective and robust catalyst for selective ethylene carbonate hydrogenation, providing a lifetime >350 h together with >99% ethylene carbonate conversion, >99% ethylene glycol yield, and more importantly 93% methanol yield at a relatively low Cu loading of 21.4 wt%.
- Ding, Yu,Tian, Jingxia,Chen, Wei,Guan, Yejun,Xu, Hao,Li, Xiaohong,Wu, Haihong,Wu, Peng
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- Highly efficient conversion of carbon dioxide catalyzed by polyethylene glycol-functionalized basic ionic liquids
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A series of polyethylene glycol (PEG)-functionalized basic ionic liquids (ILs) were developed for efficient CO2 conversion into organic carbonates under mild conditions. In particular, BrTBDPEG150TBDBr was proven to be a highly efficient and recyclable catalyst for the synthesis of cyclic carbonates without utilization of any organic solvents or additives. This is presumably due to the activation of epoxide assisted by hydrogen bonding and activation of CO2 by the ether linkage in the PEG backbone or through the formation of carbamate species with the secondary amino group in the IL cation on the basis of in situ FT-IR study under CO2 pressure. In addition, the subsequent transesterification of cyclic carbonate e.g. ethylene carbonate (EC) with methanol to dimethyl carbonate (DMC) can also be effectively catalyzed by BrTBDPEG150TBDBr, thanks to the activation of methanol by the secondary and tertiary nitrogen in the IL to easily form CH 3O-, realizing a so-called "one-pot two-stage" access to DMC from CO2 without separation of cyclic carbonate by using one kind of single component catalyst. Therefore, this protocol represents a highly efficient and environmentally friendly example for catalytic conversion of CO2 into value-added chemicals such as DMC by employing PEG-functionalized basic ILs as catalysts.
- Yang, Zhen-Zhen,Zhao, Ya-Nan,He, Liang-Nian,Gao, Jian,Yin, Zhong-Shu
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- Aqueous phase reforming of glycerol using doped graphenes as metal-free catalysts
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Boron-doped graphene obtained by pyrolysis at 900°C of the boric acid ester of alginate was found to be the most active graphene among a series of doped and co-doped graphenes to promote the aqueous phase reforming of glycerol at 250°C. This reaction is of interest in the context of valorization of the aqueous wastes of carbohydrate syrups. Control experiments adding to undoped graphene 1 wt% of triphenylborane, tris(pentafluorophenyl)borane or bis(pinacolyl)diborane as models of possible boron atom types present in B-doped graphene, and boric acid that could be present in a residual amount after pyrolysis, show in all cases an increase in the catalytic activity of graphene. B-doped graphene has also activity for glucose aqueous phase reforming. B-doped graphene undergoes deactivation upon reuse, probably due to B leaching. The results show that graphenes are promising metal-free catalysts for aqueous phase reforming and are alternatives to those containing platinum.
- Esteve-Adell, Iván,Crapart, Bertrand,Primo, Ana,Serp, Philippe,Garcia, Hermenegildo
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- Mechanistic aspects of the oxidative functionalization of ethane and ethanol by platinum(II) salts in aqueous medium. Role of platinum(II)-olefin and platinum(IV) - alkyl intermediates
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The relative rate of C-H bond activation by the Pt(II) ion decreased in the order H-CH2CH3 > H-CH2CH2OH > H-CH(OH)CH3.The platinum(II)-ethylene complex, -, 1, was the key intermediate in the oxidation of ethane, ethanol, and diethyl ether to 1,2-ethanediol by platinum(II) in aqueous medium.In particular, the intermediacy of 1 in the oxidation of ethanol to 1,2-ethanediol and 2-chloroethanol was verified through labeling studies.In D2O, 1, upon oxidation with one of a number of oxidants, converted to 2-, 2. 2 in turn decomposed to a mixture of 1,2-ethanediol and 2-chloroethanol on heating.The rate conversion of 1 was a function of pH, the anions present, and the oxidant used.While the conversion of 1 to 2 involved a nucleophilic attack by water (or hydroxide ion), such a step was not observed in the absence of an oxidant.In basic D2O, the sequential replacement of Cl- by OD- in 1 occurred to successively form -, - and -.The process was reversed upon acidification.The species 2-, 3, appeared to be the source for the small quantities of hydroxy- and/or chloroacetaldehyde formed during the oxidation of 1. 3 was synthesized independently by the reaction of acetaldehyde with a mixture of PtCl42-, and PtCl62- in aqueous medium.When 1 was oxidized by Cl2 in CD3OD solution, the principal product was 2- 4, when a small amount of water was present, and CD3OCH2CH2OCD3 in the absence of water. Keywords: Platinum complex; C-H activation; Oxidation; Ethane; Ethylene; Ethanol
- Hutson, Alan C.,Lin, Minren,Basickes, Naomi,Sen, Ayusman
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- Efficient one-pot production of 1,2-propanediol and ethylene glycol from microalgae (Chlorococcum sp.) in water
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The catalytic valorization of microalgae, a sustainable feedstock to alleviate dependence on fossil fuel and offset greenhouse gases emissions, is of great significance for production of biofuels and value-added chemicals from aquatic plants. Here, an interesting catalytic process is reported to convert microalgae (Chlorococcum sp.) into 1,2-propanediol (1,2-PDO) and ethylene glycol (EG) in water over nickel-based catalysts. The influences of reaction temperature, initial H2 pressure and reaction time on the product distribution were systematically investigated by using a batch reactor. Under optimal reaction conditions (at 250 °C for 3 h with 6.0 MPa of H2 pressure), microalgae were directly and efficiently converted over a Ni-MgO-ZnO catalyst and the total yield of polyols was up to 41.5%. The excellent catalytic activity was attributed to the smaller size and better dispersion of Ni particles on the MgO-ZnO supporter based on the characterization results as well as its tolerance to nitrogen-containing compounds. Besides, the reaction pathway was proposed based on the formation of reaction intermediates and the results of model compound conversion.
- Miao,Zhu,Wang,Tan,Wang,Liu,Kong,Sun
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- Hydrogenolysis of glycerol over supported bimetallic Ni/Cu catalysts with and without external hydrogen addition in a fixed-bed flow reactor
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The role of high hydrogen pressure in the hydrogenolysis of glycerol to 1,2-propanediol has been studied extensively. Given the peculiar properties of hydrogen such as its inflammability and explosibility, the hydrogenolysis of glycerol without external hydrogen addition seems a more advantageous option. This study focuses on the conversion of glycerol to 1,2-propanediol over different supported bimetallic Ni/Cu catalysts in a fixed-bed flow reactor, using in situ hydrogen production and external hydrogen. Among the catalysts prepared, Ni/Cu/TiO2 catalyst was observed to efficiently catalyze the hydrogenolysis of glycerol to 1,2-propanediol under N2 pressure using 2-propanol as hydrogen source. This was due to the high Cu dispersion and Ni/Cu atomic ratio on the catalyst surface. However, the experimental results indicated that the effect of catalyst acid sites on glycerol hydrogenolysis was more noticeable when the reaction was performed under H2 pressure. The metal active sites of the catalyst played a significant role in the hydrogen production and also affected the glycerol hydrogenolysis with hydrogen produced from 2-propanol catalytic transfer hydrogenation (CTH) and glycerol aqueous phase reforming (APR). The stability study revealed that the Ni/Cu/TiO2 catalyst underwent serious deactivation during the hydrogenolysis of glycerol. The characterization results showed that the metal leaching and metal particles sintering were responsible for the catalyst deactivation when the glycerol hydrogenolysis was conducted using water as a solvent. However, the activity loss for reactions performed using 2-propanol as a solvent was mainly related to the metal particles sintering and the presence of adsorbed species on the catalyst surface.
- Cai, Fufeng,Pan, Donghui,Ibrahim, Jessica Juweriah,Zhang, Jun,Xiao, Guomin
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- Catalytic conversion of glucose and cellobiose to ethylene glycol over Ni-WO3/SBA-15 catalysts
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Hydrogenolysis of glucose and cellobiose, used as the model feedstocks, over Ni-WO3/SBA-15 catalysts has been investigated to probe the influencing factors for the conversion of cellulose to ethylene glycol (EG). The conversion of glucose and cellobiose to EG showed different dependencies on reaction temperature; a lower reaction temperature was needed for the former. Additionally, the surface atomic ratio of W to Ni on the Ni-WO3/SBA-15 catalysts was the key factor for the product distribution. Both glucose and cellobiose had their own optimum W-Ni ratio for the production of EG, and the ratio of W to Ni for glucose was slightly lower than that of cellobiose. On the other hand, the Ni-WO3/SBA-15 catalysts were thoroughly characterized by N2 adsorption-desorption, X-ray diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results indicated that the reducibility of Ni-WO3/SBA-15 catalysts with high Ni loading was more similar to that of pure NiO. More importantly, the change of surface atomic content of Ni and W of Ni-WO3 catalysts with various Ni loadings resulted from the surface W species of the catalysts being gradually covered by Ni species with the increase of Ni loading.
- Cao, Yueling,Wang, Junwei,Kang, Maoqing,Zhu, Yulei
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- Glycerol hydrogenolysis promoted by supported palladium catalysts
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Catalytic hydrogenolysis, with high conversion and selectivity, promoted by supported palladium substrates in isopropanol and dioxane at a low H 2 pressure (0.5MPa), is reported for the first time. The catalysts, characterized by using BET isotherms, transmission electron microscopy (TEM), temperature-programmed reduction (TPR), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were obtained by coprecipitation and impregnation techniques. The coprecipitation method allows catalysts with a metal-metal or a metal-support interaction to be obtained, which enhances the catalytic performance for both the conversion of glycerol and the selectivity to 1,2-propanediol. Analogous reactions carried out with catalysts prepared by using impregnation are less efficient. A study of the solvent and temperature effect is also presented. The obtained results allow the hydrogenolysis mechanism to be inferred; this involves both the direct replacement of the carbon-bonded OH group by an incoming hydrogen or the formation of hydroxyacetone as an intermediate, which subsequently undergoes a hydrogenation process to give 1,2-propanediol. Finally, catalytic tests on a large-scale reaction at a higher H2 pressure and recycling of the samples were carried out with the better performing catalysts (Pd/CoO and Pd/Fe 2O3 prepared by using coprecipitation) to verify possible industrial achievements.
- Musolino, Maria Grazia,Scarpino, Luciano Antonio,Mauriello, Francesco,Pietropaolo, Rosario
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- Influence of support on the performance of copper catalysts for the effective hydrogenation of ethylene carbonate to synthesize ethylene glycol and methanol
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Hydrogenation of ethylene carbonate (EC) is an attractive and promising approach for indirect hydrogenation of CO2 to co-produce ethylene glycol (EG) and methanol (MeOH). In this work, thermodynamics of EC hydrogenation was firstly calculated, and the results disclosed that EC hydrogenation is exothermic (ΔrHθm = -71.59 kJ mol-1) and thermodynamically favorable (ΔrGθm = -25.62 kJ mol-1). The mesoporous silica supported copper catalysts were successfully prepared by facile ammonia evaporation method using KIT-6, MCM-41 and SBA-15 as support materials. The as-prepared Cu/KIT-6, Cu/MCM-41 and Cu/SBA-15 were thoroughly characterized by N2 physisorption, ICP-AES, N2O titration, FT-IR, XRD, H2-TPR, TEM, XPS and XAES. It was found that copper nanoparticles were well dispersed on these supports. Interestingly, a larger metallic Cu surface area with higher dispersion was obtained on SBA-15 when compared with KIT-6 and MCM-41. Furthermore, Cu0 and Cu+ species in various ratios were verified to co-exist on the surfaces of the three catalysts, which originated from CuO and copper phyllosilicate, respectively. The catalytic performances showed that Cu/SBA-15 exhibited a superior catalytic activity with a TON of 22.0 and 11.4 (mol mol-1) towards EG and MeOH, respectively. Importantly, 100% of EC conversion, 94.7% of EG yield and 62.3% of MeOH yield were achieved within a short reaction time of 4 h over Cu/SBA-15 under optimized conditions. The synergetic effect between Cu0 and Cu+ species, in which it was proposed that Cu0 species dissociated H2, while Cu+ species absorbed the carbonyl group of EC, was responsible for the higher catalytic activity of Cu/SBA-15.
- Li, Fengjiao,Wang, Liguo,Han, Xiao,He, Peng,Cao, Yan,Li, Huiquan
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- Effect of Calcination Temperature on the Textural Properties and Catalytic Behavior of the Al2O3 Doped Mesoporous Monometallic Cu Catalysts in Dimethyl Oxalate Hydrogenation
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Abstract: Al2O3 doped mesoporous monometallic Cu catalysts were successfully synthesized though the self-assembly Cu species derived from the oxalate precursor undergoing thermal decomposing. The evolutions of microstructures, physicochemical and surface properties of the CuAl catalysts have been systematically characterized focusing on the effect of the calcination temperature during catalyst preparation. It is found that the textural and surface properties of the CuAl catalysts were profoundly affected by the calcination temperature, further determining the resultant catalytic behavior in dimethyl oxalate (DMO) hydrogenation. Particularly, the CuAl-500 possessing the maximum surface Cu+ sites and proper surface acid features exhibits?100.0% DMO conversion and 98.0% ethylene glycol (EG) selectivity in presence of the adequate active Cu0 sites, which is superior to that of the other catalysts under the identical reaction conditions. And no activity loss occurred for more than 200?h demonstrated of the outstanding stability of the CuAl-500 catalyst. Moreover, the synergistic effect between surface Cu+ and Cu0 sites should be responsible for DMO selective hydrogenation. Additionally, the strengthened chemical interaction between Cu and Al species endows the catalysts outstanding stability by suppressing the dispersive Cu NPs agglomeration during DMO hydrogenation. Graphic Abstract: [Figure not available: see fulltext.]
- Kong, Xiangpeng,Wu, Yuehuan,Yuan, Peihong,Wang, Man,Wu, Peng,Ding, Lifeng,Wang, Ruihong,Chen, Jiangang
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- Identifying the components of the solid–electrolyte interphase in Li-ion batteries
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The importance of the solid–electrolyte interphase (SEI) for reversible operation of Li-ion batteries has been well established, but the understanding of its chemistry remains incomplete. The current consensus on the identity of the major organic SEI component is that it consists of lithium ethylene di-carbonate (LEDC), which is thought to have high Li-ion conductivity, but low electronic conductivity (to protect the Li/C electrode). Here, we report on the synthesis and structural and spectroscopic characterizations of authentic LEDC and lithium ethylene mono-carbonate (LEMC). Direct comparisons of the SEI grown on graphite anodes suggest that LEMC, instead of LEDC, is likely to be the major SEI component. Single-crystal X-ray diffraction studies on LEMC and lithium methyl carbonate (LMC) reveal unusual layered structures and Li+ coordination environments. LEMC has Li+ conductivities of >1 × 10?6 S cm?1, while LEDC is almost an ionic insulator. The complex interconversions and equilibria of LMC, LEMC and LEDC in dimethyl sulfoxide solutions are also investigated.
- Wang, Luning,Menakath, Anjali,Han, Fudong,Wang, Yi,Zavalij, Peter Y.,Gaskell, Karen J.,Borodin, Oleg,Iuga, Dinu,Brown, Steven P.,Wang, Chunsheng,Xu, Kang,Eichhorn, Bryan W.
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- Design and preparation of hydrated MgAl supported Cu catalysts with high alkalinity by MOCVD for the hydrogenolysis of cellulose
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The unhydrated and hydrated MgAl supported Cu catalysts were successfully prepared by metal-organic chemical vapor deposition (MOCVD) method. The structure properties of metal-organic precursor, supports and catalysts were determined by 1H NMR, FTIR, XRD, N2 physisorption, TEM, N2O titration, and CO2-TPD. The hydration of support had a significant effect on the structure of the final catalysts. The hydrated Mg3Al1 support was benefited to the adsorption and deposition of CuII(hfac)2, resulting in the decrease of the reduction decomposition temperature. Due to the restoration of the layered structure, the 5%Cu/H-Mg3Al1 catalyst had a low BET surface area and pore volume. However, it exhibited higher base sites density and got better performance for cellulose hydrogenolysis compared to the 5%Cu/Mg3Al1 catalyst, which suggested that the hydration before reaction was superior to that during reaction for the catalytic performance, due to the competition between water and products (alcohols with strong adsorption) during reaction, resulting in a decrease in the concentration of in-situ formed surface OH? and the amount of base sites. It was noteworthy that unobvious change in phases of the 5%Cu/H-Mg3Al1 catalyst was observed before and after reaction, which provided a promising way to establish the relationship between structure and catalytic performance.
- Xiao, Zihui
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- Ruthenium-catalysed hydrogenation of esters using tripodal phosphine ligands
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The synthesis of a new tripodal phosphine ligand, N(CH2PEt 2)3, N-TriPhosEt is reported, and the use of tripodal ligands of this type, N(CH2PR2)3 (R = Ph, Et), in conjunction with ruthenium for the catalysed hydrogenation of dimethyl oxalate (DMO) is reported and contrasted with catalysis using the MeC(CH2PPh2)3 (TriPhosPh) ligand. A different order of reaction with respect to the DMO substrate is found, and the rate is slower. A study of the kinetics and mechanism of the hydrogenation of DMO with Ru(acac)3/TriPhosPh is described, along with the effect of different additives to the system. The performance of Ru(acac) 3/TriPhosPh/Zn system with unactivated ester substrates is probed and found to proceed significantly slower. Finally, based upon experimental observations, a mechanism is proposed for ester hydrogenation using ruthenium catalysts with tripodal phosphine ligands.
- Hanton, Martin J.,Tin, Sergey,Boardman, Brian J.,Miller, Philip
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- 1,3-Dimethylimidazolium-2-carboxylate: A zwitterionic salt for the efficient synthesis of vicinal diols from cyclic carbonates
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The development of efficient, cheap and recyclable catalysts for reactions under mild reaction conditions is a very attractive topic in green chemistry. Herein, a series of basic ionic liquids (ILs) were investigated as catalysts for the synthesis of vicinal diols via the hydrolysis of cyclic carbonates in order to improve this kind of synthetic process. The effects of the IL structure, the molar ratio of cyclic carbonate to water, and various reaction parameters on the catalytic performance were investigated in detail. It was found that 1,3-dimethylimidazolium-2-carboxylate, a simple halogen-free zwitterionic catalyst, showed high activity (a space-time yield of 1086 h-1) and excellent selectivity for the preparation of ethylene glycol via the hydrolysis of ethylene carbonate. The catalyst could be reused over six times without obvious loss of catalytic activity. Also, it was applicable to a variety of cyclic carbonates for the production of their corresponding vicinal diols with high yields and selectivities. A possible catalytic cycle for this kind of catalytic process was proposed based on the experimental results, NMR spectroscopy and theoretical calculations. This reaction protocol opens a new possibility for chemical synthesis as a substitution for traditional base or basic ILs. This journal is the Partner Organisations 2014.
- Sun, Jian,Yao, Xiaoqian,Cheng, Weiguo,Zhang, Suojiang
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- Anion-specific binding to n-hexadecyl phosphorylcholine micelles
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Hexadecyl phosphorylcholine (HPC) micelles incorporate anions rather than cations in the interfacial region, giving an anionoid micelle with a negative zeta potential. Hydronium ion incorporation in the micellar pseudophase parallels the increase in the n
- Priebe, Jacks P.,Souza, Bruno S.,Micke, Gustavo A.,Costa, Ana C.O.,Fiedler, Haidi D.,Bunton, Clifford A.,Nome, Faruk
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- Studies on mechanism for homogeneous catalytic hydration of ethylene oxide: Effects of pH window and esterification
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Selective hydration of ethylene oxide (EO) was investigated with several inorganic salt systems as homogeneous catalysts. By optimizing reaction conditions, the highest monoethylene glycol (MEG) selectivity of 98% was obtained with >99% EO conversion at a water/EO molar ratio = 10. The effects of pH value and anion addition-esterification on MEG selectivity were systematically studied, and a comprehensive mechanism was proposed based on the results. The conclusion should be useful in developing high performance catalysts for the manufacture of MEG by EO hydration at a low water/EO ratio. Crown Copyright
- Yang, Zhi-Jian,Ren, Nan,Zhang, Ya-Hong,Tang, Yi
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- The synthesis of highly reactive, multi-functional α,β-epoxy- and α-acetoxy-nitrosamines
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The synthesis of the reactive acetates, trans-3-acetoxy-2-hydroxy-N-nitrosomorpholine 3 and N-(1-acetoxy-2-hydroxyethyl)-N-nitrosoethanolamine 12, of two α-hydroxynitrosamines has been accomplished through the ring opening of the corresponding epoxides, NEMOR and 10 which were prepared by dimethyldioxirane oxidation of the vinyl nitrosamines.
- Park, Misun,Gu, Feng,Loeppky, Richard N.
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- Efficient Photoelectrochemical Conversion of Methane into Ethylene Glycol by WO3 Nanobar Arrays
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Photoelectrochemical (PEC) conversion of methane (CH4) has been extensively explored for the production of value-added chemicals, yet remains a great challenge in high selectivity toward C2+ products. Herein, we report the optimization of the reactivity of hydroxyl radicals (.OH) on WO3 via facet tuning to achieve efficient ethylene glycol production from PEC CH4 conversion. A combination of materials simulation and radicals trapping test provides insight into the reactivity of .OH on different facets of WO3, showing the highest reactivity of surface-bound .OH on {010} facets. As such, the WO3 with the highest {010} facet ratio exhibits a superior PEC CH4 conversion efficiency, reaching an ethylene glycol production rate of 0.47 μmol cm?2 h?1. Based on in situ characterization, the methanol, which could be attacked by reactive .OH to form hydroxymethyl radicals, is confirmed to be the main intermediate for the production of ethylene glycol. Our finding is expected to provide new insight for the design of active and selective catalysts toward PEC CH4 conversion.
- Ma, Jun,Mao, Keke,Low, Jingxiang,Wang, Zihao,Xi, Dawei,Zhang, Wenqing,Ju, Huanxin,Qi, Zeming,Long, Ran,Wu, Xiaojun,Song, Li,Xiong, Yujie
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- Catalytic conversion of cellulose to ethylene glycol over tungsten phosphide catalysts
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Tungsten phosphide (WP) showed good activity in the selective conversion of cellulose to ethylene glycol (EG). At a H2 initial pressure of 6 MPa and temperature of 245 °C, EG yield reached 25.4 mol over 20WP/AC (activated carbon) and 46.0 mol over 2Ni-20WP/AC, which demonstrated a remarkable synergy between Ni and WP.
- Zhao, Guanhong,Zheng, Mingyuan,Wang, Aiqin,Zhang, Tao
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- Physical and chemical studies of tungsten carbide catalysts: Effects of Ni promotion and sulphonated carbon
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Ni promoted tungsten carbides have been shown to be an effective catalyst for cellulose conversion reaction. With the use of both in situ and ex situ techniques an investigation into the physical and chemical aspects of the Ni-promoted tungsten carbide catalyst supported on activated carbon either in pure form or functionalized with sulfuric acid was conducted. In situ XRD analysis performed during the carburization process showed that non-promoted samples formed a mixture of nanosized W2C, WC1-x and WC carbide phases. In the case of Ni promoted catalysts, in situ XRD, XANES, XPS and TEM analysis revealed that Ni aids in lowering the carburization temperature by 50 °C but also assisted in the deposition of polymeric carbon onto the catalyst surface which reduced cellulose conversion. However, the results indicate beneficial effects caused by the high carbon coverage by stopping the W2C to WC carbide phase transition. Thus, carburization of Ni promoted samples produced only W2C phase, which is stable up to 800°C. The functionalization of activated-carbon with -SO3H not only increases the hydrolysis of cellulose but also lead to a greater dispersion of Ni over the catalyst. The resulting improvement in the interaction between Ni/W/C increases the cellulose transformation in a one-pot synthesis towards the production of ethylene glycol.
- Rodella, Cristiane B.,Barrett, Dean H.,Moya, Silvia F.,Figueroa, Santiago J.A.,Pimenta, Maria T. B.,Curvelo, Antonio Aprígio S.,Teixeira Da Silva, Victor
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- Decomposition reactions of (hydroxyalkyl) nitrosoureas and related compounds: Possible relationship to carcinogenicity
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(Hydroxyalkyl)nitrosoureas and the related cyclic carbamates N-nitrosooxazolidones are potent carcinogens. The decompositions of four such compounds, 1-nitroso-1-(2-hydroxyethyl)urea, 3-nitrosooxazolid-2-one, 1-nitroso-1-(2-hydroxypropyl)urea, and 5-methyl-3-nitrosooxazolid-2-one, in aqueous buffers at physiological pH were studied to determine if any obvious differences in decomposition pathways could account for the variety of tumors obtined from these four compounds. The products predicted by the literature mechanisms of nitrosourea and nitrosooxazolidone decompositions (which were derived from experiments at pH 10-12) were indeed the products formed, including glycols, active carbonyl compounds, epoxides, and, from the oxazolidones, cyclic carbonates. Furthermore, it was shown that in pH 6.4-7.4 buffer epoxides were stable reaction products. However, in the presence of hepatocytes, most of the epoxide was converted to glycol. The analytical methods developed were then applied to the analysis of the decomposition products of some related dialkylnitrosoureas, and similar results were obtained. The formation of chemically reactive secondary products and the possible relevance of these results to carcinogenesis studies are discussed.
- Singer
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- Enhanced catalytic performance for SiO2-TiO2 binary oxide supported Cu-based catalyst in the hydrogenation of dimethyloxalate
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Copper based catalyst with Si-Ti binary-oxide support is synthesized via a facile ammonia evaporation method for selective hydrogenation of dimethyloxalate (DMO) to ethylene glycol (EG). 100% conversion of DMO and 90% selectivity to EG could be obtained over the Cu/SiO2-TiO2 catalyst at high liquid hourly space velocity (LHSV). Catalytic stability is greatly enhanced when the Si-Ti binary oxide is used as support because of the intimate interaction between copper species and the support. The improved catalytic performance compared to the unitary oxide-supported catalysts SiO2 and TiO2 could be attributed to the highly dispersed copper species stabilized by the binary support. Also, the electron transfer from TiO 2 to Cu-species is found to play an important role in improving the surface charge density of the metallic copper, which is helpful to improve the catalytic activity.
- Wen, Chao,Yin, Anyuan,Cui, Yuanyuan,Yang, Xinli,Dai, Wei-Lin,Fan, Kangnian
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- Hydrogenation of carbon monoxide by homogeneous ruthenium-rhenium bimetallic catalysts: effects of rhenium carbonyl as a promoter for ethylene glycol formation
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The activity of the ruthenium-halide catalyst for ethylene glycol formation from CO/H2 is enhanced by a rhenium carbonyl compound.The activity of the Ru-Re bimetallic catalyst is dependent upon the ratio of Re/Ru atoms and the ratio of moles of halide to atoms of Re.The activities of Ru-Re-alkali metal iodide catalysts increased with increasing ionic radius of alkali metal.
- Tanaka, Masahide,Kiso, Yoshihisa,Saeki, Kenji
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- A New Aspect of the Pressure Effect in Syngas Conversion to Ethylene Glycol
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Pressure effect in syngas conversion to ethylene glycol (EG) is understood in terms of respective partial pressures of hydrogen (PH2) and carbon monoxide (PCO).A new mechanism is proposed to explain an etraordinary effect of PH2 on the selectivity to EG.
- Masuda, Takashi,Murata, Kazuhisa,Matsuda, Akio
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- An effective and stable Ni2P/TiO2 catalyst for the hydrogenation of dimethyl oxalate to methyl glycolate
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An effective and stable bifunctional Ni2P/TiO2 catalyst was proposed for gas-phase hydrogenation of dimethyl oxalate to corresponding alcohols. A 93.0% conversion of DMO with a selectivity of 88.0% to methyl glycolate was observed under 210 °C. Moreover, the catalyst showed an excellent stability which can be performed for 3600 h under the reaction conditions of 230 °C, 3 MPa H2 and the weight space velocity of 0.1 h?1.
- Chen, Hongmei,Tan, Jingjing,Zhu, Yulei,Li, Yongwang
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- Chiral Polyol Synthesis Catalyzed by a Thermostable Transketolase Immobilized on Layered Double Hydroxides in Ionic liquids
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In this work we set out to study the activity of a thermostable Transketolase (TK) from Geobacillus stearothermophilus (TKgst) in an ionic liquid as cosolvent, which has never been investigated before with this enzyme. 1-Butyl-3-methylimidazolium chloride ([BMIm][Cl]) in the range 30-50% in water maintained the total activity of TKgst and increased the reaction rate in the presence of pentoses as acceptor substrates, particularly d-ribose. To improve the synthetic process, TKgst was immobilized on an inorganic support, layered double hydroxides (LDHs), with excellent immobilization yield and catalytic activity using a simple, eco-compatible, efficient coprecipitation procedure. The biohybrid MgAl@TKgst was tested in 30% [BMIm][Cl] for the synthesis of a rare, very costly commercially available sugar, d-sedoheptulose, which was obtained in one step from d-ribose with an isolated yield of 82%. This biohybrid was reusable over four cycles with no loss of enzymatic activity. The particular activity of free and immobilized TKgst in [BMIm][Cl] holds promise to extend the applications of TKgst in other ionic liquids and unusual media in biocatalysis.
- Ali, Ghina,Moreau, Thomas,Forano, Claude,Mousty, Christine,Prevot, Vanessa,Charmantray, Franck,Hecquet, Laurence
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- HOMOGENEOUS CATALYTIC HYDROGENATION OF DICARBOXYLIC ACID ESTERS. II
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Hydrogenation of dimethyl oxalate in the presence of Ru(CO)2(CH3COO)2(PBu3)2 gives methyl glycolate and subsequently ethylene glycol.The formation of the glycol is favoured by hydroxylated solvents.
- Matteoli, Ugo,Menchi, Gloria,Bianchi, Mario,Piacenti, Franco
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- Selective Hydrogenolysis of Glycerol to Propylene Glycol on Supported Pd Catalysts: Promoting Effects of ZnO and Mechanistic Assessment of Active PdZn Alloy Surfaces
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Pd catalysts have received increasing attention for selective hydrogenolysis of glycerol to propylene glycol because of their good hydrothermal stability and high selectivity for cleavage of C-O bonds over C-C bonds. Addition of Zn can facilitate glycerol hydrogenolysis to propylene glycol on Pd surface, but the promoting role of Zn, stability of the resulting active PdZn alloys and reaction mechanism remain largely unexplored. Here, we synthesized monoclinic zirconia-supported PdZn (PdZn/m-ZrO2) catalysts via an incipient wetness impregnation method. Glycerol hydrogenolysis turnover rates (normalized per surface Pd atom measured by H2 chemisorption) and propylene glycol selectivity on these PdZn/m-ZrO2 catalysts depended sensitively on their Zn/Pd molar ratios, and Zn leaching from the PdZn alloy phases led to deactivation of PdZn/m-ZrO2. Such deactivation was efficiently inhibited when physical mixtures of Pd/m-ZrO2 and ZnO were directly used in glycerol hydrogenolysis, leading to in situ formation of PdZn alloy layers on Pd surfaces with excellent stability and recyclability. Dependence of turnover rates on glycerol and H2 concentrations, combined with the primary kinetic isotope effects (kH/kD = 2.6 at 493 K), reveals the kinetically relevant step of glycerol hydrogenolysis involving the α-C-H cleavage in 2,3-dihydroxypropanoxide intermediate to glyceraldehyde on PdZn alloys and Pd. Measured rate constants show that the transition state of α-C-H cleavage is more stable because of the stronger oxophilicity of Zn on PdZn alloys than on Pd, which thus facilitates α-C-H cleavage of the Zn-bound intermediate by adjacent Pd on PdZn alloys. Such synergy between Zn and Pd sites accounts for the observed superiority of PdZn alloys to Pd in glycerol hydrogenolysis. (Chemical Equation Presented).
- Sun, Qianhui,Wang, Shuai,Liu, Haichao
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- A boron-doped carbon aerogel-supported Cu catalyst for the selective hydrogenation of dimethyl oxalate
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Carbon aerogels (CA) were applied in the synthesis of Cu/CA catalysts by the impregnation method and the catalysts with boron-doped CA supports were systematically characterized and evaluated in the hydrogenation of dimethyl oxalate (DMO). The Cu/xB-CA catalyst with 25 wt% copper showed 100% DMO conversion and the highest ethylene glycol (EG) or methyl glycolate (MG) selectivity of 70% at 230 °C as well as a lifetime of over 150 h. The characterization results disclosed the reason the performance of the catalysts could be tuned facilely by changing the amount of boron doping, which effectively influenced the interrelation between copper and CA, acidity and alkalinity of catalysts and Cu dispersion. Both the original carbon aerogels and that promoted with little B could provide larger surface areas and high dispersion of the metal. The species, size of copper particles and the ratio of Cu+/(Cu+ + Cu0) could be regulated by boron doping, thus adjusting the type of hydrogenation products.
- Lu, Xiaodong,Lu, Xiaodong,Wang, Guofu,Yang, Yu,Kong, Xiangpeng,Chen, Jiangang
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- Vapour phase hydrogenolysis of glycerol over nano Ru/SBA-15 catalysts on the effect of preparatory routes and metal precursors
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The effect of preparation method and metal precursor of ruthenium employed during the preparation of Ru/SBA-15 catalysts were investigated. The catalytic functionalities are evaluated during the vapour phase hydrogenolysis of glycerol to 1,2-propyleneglyc
- Pavankumar, Vanama,Srikanth, Chakravartula S.,Rao, Anipindi Nageswara,Chary, Komandur V. R.
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- Synergistic effect between Pd and Re on Pd-Re/SBA-15 catalysts and their catalytic behavior in glycerol hydrogenolysis
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Pd-Re/SBA-15 catalysts were prepared by the impregnation method. The influence of the interaction between Pd and Re in the Pd-Re catalysts on glycerol hydrogenolysis was investigated. Pd and Re had interaction which was confirmed by H2-TPR, XPS and EXAFS. In the Pd-Re catalysts, Re showed a higher oxidation state compared with that of the mono-component Re catalyst. The mechanically mixed Pd + Re catalysts showed a lower glycerol conversion than that of the bi-component Pd-Re catalysts, which suggested that the interaction of Pd and Re was very important in glycerol hydrogenolysis.
- Li, Yuming,Liu, Huimin,Ma, Lan,He, Dehua
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- The kinetics of glycerol hydrodeoxygenation to 1,2-propanediol over Cu/ZrO2 in the aqueous phase
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The kinetics of glycerol hydrodeoxygenation to 1,2-propanediol via the selective cleavage of the primary C-O bond was systematically studied in the aqueous phase over a co-precipitated Cu/ZrO2 catalyst. Unsupported pure metallic Cu was used as reference catalyst. Batch experiments were performed in an autoclave by varying the reaction temperature (175–225 °C), H2 partial pressure (25–35 bar) and initial glycerol concentration (2–8 wt%). The Cu/ZrO2 catalyst was found to be highly selective to 1,2propanediol (up to 95%), and ethylene glycol was obtained as major by-product from parallel C–]C bond hydrogenolysis. The apparent activation energies amounting to 106 and 105 kJ mol-1 for Cu/ZrO2 and pure metallic Cu, respectively, of the hydrodeoxygenation pathway provide further evidence for metallic Cu acting as the active site. Kinetic analysis of the rate of glycerol consumption yielded a zero-order dependence on the concentration of glycerol suggesting an essentially almost full coverage of adsorbed glycerol as most strongly bound organic adsorbate. In contrast, a first-order dependence on hydrogen concentration was observed. Hydrogen is assumed to be not only required for the fast hydrogenation of the intermediate acetol, but also for the removal of adsorbed atomic oxygen originating from water dissociation to create empty sites for dissociative glycerol adsorption. Thus, the active Cu sites are assumed to be fully adsorbate-covered under reaction conditions.
- Gabrysch, Thomas,Muhler, Martin,Peng, Baoxiang
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- Platinum on carbonaceous supports for glycerol hydrogenolysis: Support effect
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Metal vapor synthesis (MVS) technique was applied to generate Pt-nanoparticles of different size (1.3 nm and 2.5 nm) deposited onto carbonaceous supports, mainly characterized by a different surface area. The supported catalysts were employed in the glycerol hydrogenolysis reaction carried out under basic reaction conditions at 433 and 453 K to obtain 1,2-propanediol as the main liquid product. Comparison of the composition of the liquid- and gas-phase products obtained by the different catalysts showed a clear dependence of aqueous-phase reforming, water-gas shift reaction activity as well as 1,2-propanediol chemoselectivity on the degree of Pt-sintering occurring on different carbon supports. High-resolution transmission electron microscopic and X-ray powder diffraction studies carried out on as-synthesized and recovered heterogeneous catalysts provided clear evidences that a high surface area carbon support, such as Ketjen Black EC-600JD, notably retards nanoparticle aggregation.
- Oberhauser, Werner,Evangelisti, Claudio,Jumde, Ravindra P.,Psaro, Rinaldo,Vizza, Francesco,Bevilacqua, Manuela,Filippi, Jonathan,Machado, Bruno F.,Serp, Philippe
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- Size effects of Pt-Re bimetallic catalysts for glycerol hydrogenolysis
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A series of Pt-Re/CNTs catalysts with different particle sizes have been synthesized and applied in glycerol hydrogenolysis to elucidate the size effects. The trend of turnover frequency (TOF) for these different sized Pt-Re/CNTs catalysts follows a volcanic curve, in which the TOF for Pt-Re/CNTs catalyst with particle size of 1.9 nm is ca. 7.5 times higher than that of 4.9 nm. X-ray photoelectron spectroscopy analysis revealed that the surface Pt/Re ratio decreased with the decrease of particle size. The enrichment of surface rhenium species on smaller particles probably led to the increase in the surface acidity, which could be one reason for the enhanced activity over smaller sized Pt-Re/CNTs catalysts. However, too small sized Pt-Re/CNTs catalyst (e.g., 1.5 nm) suffered from severe coking, resulting in the lower activity. Moreover, the hydrogenolysis of different substrates (glycerol, 1,2-propanediol and 1,3-propanediol) over different sized Pt-Re/CNTs catalysts was also investigated. It was revealed that the reactivity declined in the following order: glycerol > 1,3-propanediol > 1,2-propanediol, and the cleavage of secondary C-O bond was favored over larger sized Pt-Re/CNTs catalyst. Based on these results, a possible reaction pathway depending on Pt-Re particle size was proposed.
- Deng, Chenghao,Duan, Xuezhi,Zhou, Jinghong,Chen, De,Zhou, Xinggui,Yuan, Weikang
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- Effect of surface hydroxyl group of ultra-small silica on the chemical states of copper catalyst for dimethyl oxalate hydrogenation
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Cu/SiO2 catalyst prepared by ammonia evaporation method was reported to perform a great catalytic activity and selectivity in dimethyl oxalate (DMO) hydrogenation, which is one of the key steps in ethylene glycol (EG) synthesis from syngas. In recent years, significant advances have achieved on the nature of active sites and catalytic mechanism. However, the fabrication of Cu/SiO2 catalyst with controllable copper species remains challenging. Here, we reported a facile and effective approach to manipulate the surface hydroxyls of silica, which was revealed to be important factor for the formation of active species. An excellent linear correlation between surface hydroxyl groups of silica and the amount of Cu+ species was demonstrated, indicating that the formation of copper phyllosilicate can be kinetically favoured with increasing surface hydroxyls during preparation. Furthermore, as the copper phyllosilicate formation is enhanced, the specific surface area is significantly increased and the polymerization of copper hydroxide may be slow down, resulting in a highly improved dispersion of metallic copper as well. The enlarged surface areas of Cu0 and Cu+ species greatly enhanced the catalytic performance of Cu/SiO2 in DMO hydrogenation to EG. These understandings on the relationship between surface hydroxyl groups and chemical states of copper catalyst may lead to new possibilities in rational design of catalysts.
- Wang, Yue,Yang, Wenlong,Yao, Dawei,Wang, Shengping,Xu, Yan,Zhao, Yujun,Ma, Xinbin
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- Effect of Zn doping on the hydrogenolysis of glycerol over ZnNiAl catalyst
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Nickel based catalyst is of interest in the industrial catalytic processes, and it is always modified by doping a second element to improve its catalytic properties. Understanding the role of dopant is extremely helpful in tailoring the active centers. In this work, Zn could induce a significant improvement of the catalytic performance of NiAl for the hydrogenolysis of glycerol. The Zn doped ZnNiAl catalysts exhibited high activity and the improved selectivity to 1,2-propanediol, it was about 2 times higher than the original ones. The ZnNi alloy formed in ZnNiAl was responsible for the noticeable catalytic performance. They preferred to coordinate with the end hydroxyl group of glycerol, promoted the cleavage of CO bond in glycerol, and resulted in the dominant formation of 1,2-propanediol. The findings described here will provide a useful knowledge for rational design of nickel-based catalysts, as well as reveal a new reaction model for the hydrogenolysis of glycerol.
- Li, Xiaoru,Zhang, Chao,Cheng, Haiyang,He, Limin,Lin, Weiwei,Yu, Yancun,Zhao, Fengyu
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- Structured Pd-Au/Cu-fiber catalyst for gas-phase hydrogenolysis of dimethyl oxalate to ethylene glycol
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Galvanic co-deposition of 0.5 wt% Au and 0.1 wt% Pd on a microfibrous-structure using 8 μm Cu-fibers delivers a Pd-Au/Cu-fiber catalyst, which is highly active, selective and stable for the hydrogenolysis of dimethyl oxalate to ethylene glycol. Au and Pd synergistically promote the hydrogenolysis activity of Cu+ sites, while Au also critically stabilizes Cu+ sites to prevent deep reductive deactivation.
- Zhang, Li,Han, Lupeng,Zhao, Guofeng,Chai, Ruijuan,Zhang, Qiaofei,Liu, Ye,Lu, Yong
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- Efficient hydrogenation of dimethyl oxalate to ethylene glycol: Via nickel stabilized copper catalysts
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CuNi/SiO2 nanocatalysts with Ni-stabilized Cu nanoparticles of around 10 nm were synthesized. After H2 reduction, the catalysts with grain size of around 25 nm showed very high performance in the catalytic hydrogenation of dimethyl oxalate to ethylene glycol under mild reaction conditions. The composition and structure of these nanocatalysts were characterized. This study showed that Ni played a key role in stabilizing Cu against deactivation. To meet the requirements of industrial application, the optimal CuNi/SiO2 nanocatalyst was tested under continuous reaction for over 2000 hours. The conversion and product selectivity were maintained at 99% and above 95%, respectively.
- Zhu, Junhua,Ye, Yingchun,Tang, Yi,Chen, Liangfeng,Tang, Kangjian
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p. 111415 - 111420
(2016)
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- Promoting effect of Ru on Ir-ReOx/SiO2 catalyst in hydrogenolysis of glycerol
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Ru-added Ir-ReOx/SiO2 catalysts worked as efficient catalysts for the selective hydrogenolysis of glycerol to 1,3-propanediol and 1-propanol. 0.9 wt% Ru-added Ir-ReOx/SiO2 catalyst demonstrated high activity for
- Tamura, Masazumi,Amada, Yasushi,Liu, Sibao,Yuan, Zhenle,Nakagawa, Yoshinao,Tomishige, Keiichi
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- Influence of Ni species on the structural evolution of Cu/SiO2 catalyst for the chemoselective hydrogenation of dimethyl oxalate
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A novel family of heterogeneous Cu-Ni/SiO2 catalysts with appropriate metal ratios displayed outstanding selectivity to methyl glycolate (96%) and to ethylene glycol (98%) in the chemoselective gas-phase hydrogenation of dimethyloxalate. The chemical states of nickel species were found to have a strong influence on the structural evolution of the catalysts and correspondent catalytic behaviors. The selectivity to the two products could be tuned by modulating the chemical states of nickel species. It is shown that oxidative nickel species are helpful in improving the dispersion of copper species because of the enrichment of copper on the surface of the nickel species, thus enhancing the catalytic activity and selectivity to ethylene glycol. The selectivity to methyl glycolate could be greatly improved by the Cu-Ni bimetallic catalyst. An 83% yield of methyl glycolate and a 98% yield of ethylene glycol could be obtained over the bimetallic Cu-Ni catalyst and the NiO-modified catalyst, respectively.
- Yin, Anyuan,Wen, Chao,Guo, Xiaoyang,Dai, Wei-Lin,Fan, Kangnian
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- Investigation of Activated-Carbon-Supported Copper Catalysts with Unique Catalytic Performance in the Hydrogenation of Dimethyl Oxalate to Methyl Glycolate
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Copper-based activated-carbon (AC)-supported catalysts were synthesized by a facile ammonia evaporation-impregnation method. Unlike the conventional Cu/SiO2 catalyst, which showed highly catalytic selectivity towards ethylene glycol (EG) or EtOH, Cu/AC catalysts display unique selectivity to methyl glycolate (MG). The catalytic performance relies on the high content of surface Cu+ species and the relatively large copper particles with moderate hydrogenation activity.
- Cui, Yuanyuan,Wang, Bin,Wen, Chao,Chen, Xi,Dai, Wei-Lin
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- Ce promoted Cu/γ-Al2O3 catalysts for the enhanced selectivity of 1,2-propanediol from catalytic hydrogenolysis of glucose
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Ce promoted Cu/γ-Al2O3 catalysts were prepared with varying amounts of Cu (x = 0–10 wt%) and Ce (y = 0–15 wt%). The prepared catalysts were characterized and tested for the conversion of aqueous glucose (5 wt%) to 1,2-propanediol in a batch reactor. 10%Ce-8%Cu/γ-Al2O3 showed the complete conversion of glucose with 62.7% selectivity of 1,2-propanediol and total glycols (1,2-propanediol, ethylene glycol & 1,2-butanediol) of 81% at milder reaction conditions. Cu facilitated the hydrogenation activity and Ce loading optimize the acid/base sites of Cu/γ-Al2O3 which obtain high selectivity of 1, 2-propanediol. Catalyst reusability is reported.
- Balachandran Kirali, Arun Arunima,Marimuthu, Banu,Sreekantan, Sreejith
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- Utilizing in situ spectroscopic tools to monitor ketal deprotection processes
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The use of protection groups to shield a functional group during a synthesis is employed throughout many reactions and organic syntheses. The role of a protection group can be vital to the success of a reaction, as well as increase reaction yield and selectivity. Although much work has been done to investigate the addition of a protection group, the removal of the protection group is just as important – however, there is a lack of methods employed within the literature for monitoring the removal of a protection group in real time. In this work, the process of removing, or deprotecting, a ketal protecting group is investigated. Process analytical technology tools are incorporated for in situ analysis of the deprotection reaction of a small molecule model compound. Specifically, Raman spectroscopy and Fourier transform infrared spectroscopy show that characteristic bands can be used to track the decrease of the reactant and the increase of the expected products over time. To the best of our knowledge, this is the first report of process analytical technology being used to monitor a ketal deprotection reaction in real time. This information can be capitalized on in the future for understanding and optimizing pharmaceutically-relevant deprotection processes and downstream reactions.
- Ralbovsky, Nicole M.,Lomont, Justin P.,Ruccolo, Serge,Konietzko, Janelle,McHugh, Patrick M.,Wang, Sheng-Ching,Mangion, Ian,Smith, Joseph P.
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- Stable ethanol synthesis via dimethyl oxalate hydrogenation over the bifunctional rhenium-copper nanostructures: Influence of support
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Addition of oxophilc rhenium to decorate small copper nanoparticles has been validated to be an efficient method to prepare a low-copper catalyst for the direct synthesis of ethanol via dimethyl oxalate (DMO) hydrogenation process, and herein we investigated the impact of supports on the catalytic performance of ReCu catalysts. A series of materials including activated carbon (AC), Al2O3, SiO2, TiO2 and ZrO2 were utilized as the support and as prepared Re2Cu5 catalysts were evaluated. The results exhibited that the Re2Cu5/ZrO2 catalyst possesses the highest DMO hydrogenation activity and ethanol yield (~93%), which may be due to its lowest Cu0/Cu+ ratio (0.13), smallest Cu particle size (~0.84 nm) a relative high reduction degree (59%). The CO adsorption behavior characterized by in situ IR spectroscopy showed that a strong metal-support interaction creates an electron deficient environment of Cu nanoparticle, resulting in a lower Cu0/Cu+ ratio that enhances the activation of C[dbnd]O bond in the DMO molecular.
- Chen, Xingkun,Ding, Yunjie,Du, Zhongnan,Li, Zheng,Lin, Ronghe,Wang, Shiyi,Wang, Xuepeng,Zhu, Hejun
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p. 241 - 252
(2022/02/22)
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- Selectively chemo-catalytic hydrogenolysis of cellulose to EG and EtOH over porous SiO2 supported tungsten catalysts
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Cellulosic ethanol produced from lignocellulose biomass can alleviate the shortage of conventional fossil energy supply and reduce global CO2 emissions. Wherein, hydrogenolysis of cellulose to ethanol is a new method for the synthesis of fuel ethanol, which could theoretically utilizes all carbon atoms in glucose in the direct retro-aldol condensation (RAC) reaction to produce ethanol, and can potentially break through the technical bottleneck of biological methods. Herein, we show that the benefits of the mesoporous structure of tungsten-based catalysts can be leveraged to influence the selective hydrogenolysis of cellulose into C2 products. Comparing the performance of different pore size SiO2 supported tungsten catalysts and detailed characterizations revealed that the mesoporous structure of supports can affect the morphology, crystal sizes, and surface chemistry of the catalysts, which presented a combined effect on the hydrogenolysis reaction. Whereby, 51.5 wt% ethylene glycol (EG) was obtained from the direct hydrogenolysis of cellulose over Ru-WOx/SiO2 (500 ?) catalyst under 513 K, and 40.5 wt% ethanol (EtOH) was obtained from the direct hydrogenolysis of cellulose over Ir-WOx/SiO2 (500 ?) catalyst under 553 K, respectively.
- Fan, Maohong,Mu, Shifang,Sun, Qi,Wang, Haiyong,Wang, Xiaolong,Wang, Yan,Weng, Yujing,Zhang, Mingwei,Zhang, Yulong
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- Method for preparing ethylene glycol through photocatalytic conversion of methanol
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The invention relates to a method for preparing ethylene glycol through photocatalytic conversion of methanol, and relates to ethylene glycol and photocatalysts. According to the method, methanol is taken as a raw material and is directly converted into ethylene glycol and H2 at room temperature under the action of a solid photocatalyst; and the method comprises the following reaction processes: adding methanol and a catalyst into a pressure-resistant glass container, carrying out normal-temperature visible light or ultraviolet light illumination stirring reaction, and reacting for a certain time to obtain ethylene glycol and H2. According to the invention, the method has universality and can be expanded to other photocatalytic systems, and the light quantum yield of the main product ethylene glycol is 2.5 times or more than 2.5 times of the light quantum yield of the main product ethylene glycol under the same wavelength reported by current literatures and patents.
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Paragraph 0026; 0028-0058
(2021/06/26)
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- CO2atmosphere enables efficient catalytic hydration of ethylene oxide by ionic liquids/organic bases at low water/epoxide ratios
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The development of an efficient and low-cost strategy for the production of monoethylene glycol (MEG) through hydration of ethylene oxide (EO) at low H2O/EO molar ratios is an important industrial challenge. We have established that by using CO2as the reaction atmosphere, hydration of EO can be achieved at a low H2O/EO ratio of 1.5?:?1 along with high yields (88-94%) and selectivities (91-97%) of MEG catalyzed by binary catalysts of ionic liquids and organic bases. The results are significantly better than those of experiments conducted under an atmosphere of N2. Isotope labeling experiments revealed that CO2had altered the reaction pathway and participated in the reaction, in which cycloaddition of EO with CO2occurred first followed by the hydrolysis of ethylene carbonate (EC) to generate MEG and recover CO2. The ionic liquids and organic bases synergistically catalyzed the one-pot two-step reaction. DFT calculations confirmed that this route is more kinetically favorable compared to the pathway of direct epoxide hydration.
- Ding, Tong,Gao, Guohua,Xia, Fei,Yuan, Huixia,Zha, Jinyin,Zhang, Dawei,Zhang, Jingshun
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supporting information
p. 3386 - 3391
(2021/05/25)
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- Nanotitania catalyzes the chemoselective hydration and alkoxylation of epoxides
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Glycols and ethoxy– and propoxy–alcohols are fundamental chemicals in industry, with annual productions of millions of tons, still manufactured in many cases with corrosive and unrecoverable catalysts such as KOH, amines and BF3?OEt2. Here we show that commercially available, inexpensive, non–toxic, solid and recyclable nanotitania catalyzes the hydration and alkoxylation of epoxides, with water and primary and secondary alcohols but not with phenols, carboxylic acids and tertiary alcohols. In this way, the chemoselective synthesis of different glycols and 1,4–dioxanones, and the implementation of nanotitania for the production in–flow of glycols and alkoxylated alcohols, has been achieved. Mechanistic studies support the key role of vacancies in the nano–oxide catalyst.
- Ballesteros–Soberanas, Jordi,Leyva–Pérez, Antonio,Martínez–Castelló, Aarón,Oliver–Meseguer, Judit,Tejeda–Serrano, María
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- Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions
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The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging. In this study, acidic poly(ionic liquid)s with swelling ability (SAPILs) were designed and synthesized via the free radical copolymerization of ionic liquid monomers, sodium p-styrenesulfonate, and crosslinkers, followed by acidification. The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength. The thermogravimetric analysis results in the temperature range of 300–345 °C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H) (245 °C). Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional (3D) honeycomb structure in water, which was ascribed to the swelling-induced self-assembly of the molecules. Moreover, we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol, and determined that their catalytic activity was much higher than that of homogeneous acid catalysts. The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures. Depending on the reaction mixture, the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it, which suggested the high enrichment ability of SAPILs for cyclohexyl acetate. The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate, which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.
- Chen, Bihua,Deng, Xi,Ding, Tong,Gao, Guohua,Ma, Sanguan,Ni, Bing,Wang, Xin,Zhang, Dawei,Zhang, Yongya
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p. 297 - 309
(2020/07/25)
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- Nano composite ion exchange resin catalyst and application thereof
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The invention relates to a catalytic hydration reaction of alkylene oxide and a nano composite ion exchange resin catalyst thereof. The preparation process of the nano composite ion exchange resin catalyst comprises copolymerization of a nano material, a monomer and a cross-linking agent, a functionalization reaction of a copolymer and an ion exchange reaction. The nano composite ion exchange resin catalyst has the following structural general formula: P-NR1R2R3M, wherein P is a nano composite resin matrix, R1, R2 and R3 are all fatty groups or aromatic groups CxHy, x is any integer from1 to 10, y is any integer from 3 to 21, and M is an anion and selected from the group consisting of bicarbonate ions, hydroxide ions, bisulfite ions, carboxylate ions, citrate ions, heteropoly acid ions, trifluoromethanesulfonate, p-toluenesulfonate, benzenesulfonate, methanesulfonate, tetrafluoroborate or hexafluorophosphate. The catalyst can be applied to organic reactions such as catalytichydration of alkylene oxide.
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Paragraph 0093-0113
(2021/01/29)
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- Sterically controlling 2-carboxylated imidazolium salts for one-step efficient hydration of epoxides into 1,2-diols
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In order to overcome the disadvantages of excessive water and many byproducts in the conventional process of epoxide hydration into 1,2-diols, 2-carboxylated imidazolium salts were first adopted as efficient catalysts for one-step hydration of epoxides into 1,2-diols. By regulating the cation chain lengths, different steric structures of 2-carboxylated imidazolium salts with chain lengths from C1 to C4 were prepared. The salt with the shortest substituent chain (DMIC) exhibited better thermal stability and catalytic performance for hydration, achieving nearly 100% ethylene oxide (EO) conversion and 100% ethylene glycol (EG) selectivity at 120 °C, 0.5 h with just 5 times molar ratio of H2O to EO. Such a tendency is further confirmed and explained by both XPS analysis and DFT calculations. Compared with other salts with longer chains, DMIC has stronger interaction of CO2?anions and imidazolium cations, exhibiting a lower tendency to release CO2?and form HO-CO2?, which can nucleophilically attack and synergistically activate ring-opening of epoxides with imidazolium cations. The strong huge sterically dynamic structure ring-opening transition state slows down the side reaction, and both cations and anions stabilized the transition state imidazolium-EG-HO-CO2?, both of which could avoid excessive hydration into byproducts, explaining the high 1,2-diol yield. Based on this, the cation-anion synergistic mechanism is then proposed.
- Cheng, Weiguo,Dong, Li,Fu, Mengqian,Su, Qian,Tan, Xin,Yao, Xiaoqian,Ying, Ting,Zhang, Suojiang
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supporting information
p. 2992 - 3000
(2021/05/07)
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- Hydrogen-Catalyzed Acid Transformation for the Hydration of Alkenes and Epoxy Alkanes over Co-N Frustrated Lewis Pair Surfaces
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Hydrogen (H2) is widely used as a reductant for many hydrogenation reactions; however, it has not been recognized as a catalyst for the acid transformation of active sites on solid surface. Here, we report the H2-promoted hydration of alkenes (such as styrenes and cyclic alkenes) and epoxy alkanes over single-atom Co-dispersed nitrogen-doped carbon (Co-NC) via a transformation mechanism of acid-base sites. Specifically, the specific catalytic activity and selectivity of Co-NC are superior to those of classical solid acids (acidic zeolites and resins) per micromole of acid, whereas the hydration catalysis does not take place under a nitrogen atmosphere. Detailed investigations indicate that H2 can be heterolyzed on the Co-N bond to form Hδ-Co-N-Hδ+ and then be converted into OHδ-Co-N-Hδ+ accompanied by H2 generation via a H2O-mediated path, which significantly reduces the activation energy for hydration reactions. This work not only provides a novel catalytic method for hydration reactions but also removes the conceptual barriers between hydrogenation and acid catalysis.
- Deng, Qiang,Deng, Shuguang,Gao, Ruijie,Li, Xiang,Tsang, Shik Chi Edman,Wang, Jun,Zeng, Zheling,Zou, Ji-Jun
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p. 21294 - 21301
(2021/12/17)
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- Well-defined Cp*Co(III)-catalyzed Hydrogenation of Carbonates and Polycarbonates
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We herein report the catalytic hydrogenation of carbonates and polycarbonates into their corresponding diols/alcohols using well-defined, air-stable, high-valent cobalt complexes. Several novel Cp*Co(III) complexes bearing N,O-chelation were isolated for the first time and structurally characterized by various spectroscopic techniques including single crystal X-ray crystallography. These novel Co(III) complexes have shown excellent catalytic activity to produce value added diols/alcohols from carbonate and polycarbonates through hydrogenation using molecular hydrogen as sole reductant or iPrOH as transfer hydrogenation source. To demonstrate the developed methodology's practical applicability, we have recycled the bisphenol A monomer from compact disc (CD) through hydrogenation under the established reaction conditions using phosphine-free, earth-abundant, air- and moisture-stable high-valent cobalt catalysts.
- Dahiya, Pardeep,Gangwar, Manoj Kumar,Sundararaju, Basker
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p. 934 - 939
(2020/12/15)
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- Urea-Functionalized Swelling Poly(ionic liquid)s as Efficient Catalysts for the Transesterification and Hydrolysis of Ethylene Carbonate
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Urea-functionalized poly(ionic liquid)s (PILs) were synthesized through polymerization of urea tethered imidazolium ionic liquid monomers (urea-IL) with sodium acrylate, and N,N′-methylenebisacrylamide (MBA) as a crosslinker. Close-packed and interconnected pores (1–4 (Formula presented.)) under swollen state could be observed from the cryogenic scanning electron microscopy (cryo-SEM) images. The promising catalytic activity of the PILs was illustrated for the transesterification reaction of ethylene carbonate with methanol. High activity and selectivity could be achieved by using poly(urea-IL)-n catalysts, which was similar to that of corresponding homogeneous ionic liquid catalysts. The urea tethered imidazolium in PILs acted as hydrogen-bonding donor to activate ethylene carbonate and intermediate 2-hydroxyethyl methyl carbonate (HEMC) for enhancing catalytic activity. The swelling ability of urea-functionalized PILs in methanol enabled active urea sites accessible for substrates. However, the complete conversion of ethylene carbonate was limited by reversible reaction between ethylene carbonate and HEMC. A possible synergistic activation mechanism for the transesterification reaction was proposed and supported by NMR titrations. The catalyst can be reused and recycled five times with stable activity. Furthermore, urea-functionalized swelling PILs also exhibited high catalytic activity for the hydrolysis of ethylene carbonate.
- Hu, Hao,Wang, Xin,Chen, Bihua,Gao, Guohua
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p. 3945 - 3952
(2021/07/31)
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- Influence of La-doping on the CuO/ZrO2catalysts with different Cu contents for hydrogenation of dimethyl oxalate to ethylene glycol
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Herein, Cu/ZrO2catalysts containing different Cu contents with or without La-doping were used for the selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Effects of La addition and the optimal Cu content were thoroughly investigated. It was found that the Cu0/Cu+pairs located at interfacial sites for CuO/ZrO2catalysts with different Cu contents played an important role in the hydrogenation of DMO to EG. Interestingly, the La-doping could make the copper dispersion increase obviously. Besides, it greatly inhibited the crystal phase transformation from tetragonal to monoclinic zirconia regardless of being calcined at 750 °C. Meanwhile, the incorporation of La promoted the activation of hydrogen although resulting in a small increase in acidic/basic sites over the catalyst surface, which led to a higher conversion of DMO while the selectivity of EG decreased slightly. As a result, 97.2% selectivity of EG, which corresponds to 100% conversion of DMO, was achieved over the La-doped CuO/ZrO2catalyst with 33 wt% Cu content, which was also stable for more than 168 h on stream. This results revealed that the strong interaction between La promoters and Cu species was another type of important active site with high catalytic efficiency in addition to the Cu0/Cu+site of La-doped CuO/ZrO2?catalyst.
- Ding, Jian,Guo, Xiaohui,Liu, Huimin,Wang, Meihui,Wang, Yaxiong,Wang, Zhenfeng,Yu, Gewen
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p. 18102 - 18113
(2021/10/12)
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- One-step bulk fabrication of a CaO/carbon heterogeneous catalyst from calcium citrate for rapid synthesis of dimethyl carbonate (DMC) by transesterification of ethylene carbonate (EC)
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Dimethyl carbonate (DMC) is well known as an extremely industrially valuable substance. The demand for high-efficiency synthesis of DMC has greatly driven the exploration of novel catalysts and their low-cost preparation methods. Herein, a novel method for the rapid batch preparation of CaO/carbon catalysts using calcium citrate (CaCi) was provided, and these catalysts were used to catalyze the transesterification reaction of methanol and ethylene carbonate (EC) to synthesize DMC and ethylene glycol (EG). Accordingly, the structure and properties of the catalysts were characterized using XRD, FTIR, N2adsorption-desorption, TG, TG-IR, CO2-TPD, XPS, SEM, TEM and ICP-OES techniques. Meanwhile, the effect of various process conditions such as carbonization temperature, reaction temperature, reaction time and catalyst amount has been extensively evaluated. Under the optimal process parameters, the conversion of EC and the selectivity of DMC and EG were 81.2, 99.3 and 99.5%, while the turnover number (TON) and turnover frequency (TOF) were 54.1 and 162 h?1, respectively. Furthermore, kinetic analysis was carried out, and the value ofk(reaction rate constant) was ≈0.159 mol L?1min?1. The reusability was also investigated.
- Wei, Qiang,Zhang, Gang,Yao, Jie,Chen, Xuejun,Wang, Gongying,Yang, Xiangui
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supporting information
p. 5540 - 5550
(2021/04/06)
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- PROCESS FOR THE SYNTHESIS OF ETHYLENE GLYCOL
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The invention relates to a process for the production of ethylene glycol from CO2, comprising the steps of : i) Reducing CO2 to CO; ii) Reacting the CO produced in step i) with an amine to form an oxamide or an oxamate or with an alcohol to form an oxalate; and iii) Reducing the oxamide, oxamate or oxalate formed in step ii) to form ethylene glycol, a process for the production of an oxamide, oxamate or oxalate and a process for the production of polyethylene terephthalate.
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Page/Page column 53-54
(2021/10/11)
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- Product Control and Insight into Conversion of C6 Aldose Toward C2, C4 and C6 Alditols in One-Pot Retro-Aldol Condensation and Hydrogenation Processes
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Alcohols have a wide range of applicability, and their functions vary with the carbon numbers. C6 and C4 alditols are alternative of sweetener, as well as significant pharmaceutical and chemical intermediates, which are mainly obtained through the fermentation of microorganism currently. Similarly, as a bulk chemical, C2 alditol plays a decisive role in chemical synthesis. However, among them, few works have been focused on the chemical production of C4 alditol yet due to its difficult accumulation. In this paper, under a static and semi-flowing procedure, we have achieved the product control during the conversion of C6 aldose toward C6 alditol, C4 alditol and C2 alditol, respectively. About C4 alditol yield of 20 % and C4 plus C6 alditols yield of 60 % are acquired in the one-pot conversion via a cascade retro-aldol condensation and hydrogenation process. Furthermore, in the semi-flowing condition, the yield of ethylene glycol is up to 73 % thanks to its low instantaneous concentration.
- Gao, Lou,Hou, Wenrong,Hui, Yingshuang,Tang, Yi,Zhan, Yulu,Zhang, Yahong
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p. 560 - 566
(2021/06/25)
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- Synthesis of a high surface area and highly dispersed Cu-O-Si complex oxide used for the low-temperature hydrogenation of dimethyl oxalate to ethylene glycol
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A highly dispersed Cu-O-Si composite oxide framework catalyst with high surface area (619 m2/g) and very small particle size (~3 nm) has been synthesized using an improved precipitation method, which showed high catalytic activity toward the hydrogenation of dimethyl oxalate (DMO) (99.9% conversion of DMO and 96.7% selectivity for ethylene glycol) even at low temperature (175 °C). In addition, its chemical stability was significantly enhanced due to the formation of a Cu-O-Si composite structure and the low reaction temperature, and the catalyst did not show any significant inactivation during the stability test over 140 h.
- Zhao, Yu,Kan, Xian,Yun, Hongfei,Wang, Dongliang,Li, Ning,Li, Guixian,Shen, Jianyi
-
-
- Aqueous phase hydrogenolysis of renewable glycerol to 1, 2-propanediol over bimetallic highly stable and efficient Ni-Cu/Al2O3 catalyst
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The effect of Cu and Ni supported over mesoporous alumina catalyst was investigated for hydrogenolysis of glycerol in the aqueous phase to produce 1, 2-Propanediol (1, 2-PD). Nanocrystalline Cu and Ni supported catalysts were prepared by the hydrothermal method, and were characterized by XRD, SEM, TEM, BET, ICP-AES, TPR, and XPS. The effect of reaction parameters like temperature, pressure, and time were studied in detail. In this work, it was found that the Cu-nanoparticles are the critical factor for the selective production of 1, 2-PD. Mesoporous alumina support played an important role for the Cu and Ni oxide particles. The acid and metal function both played an important role in getting higher selectivity of 1, 2-PD. The reaction condition of 200 °C, 50 bar, and catalyst to feed ratio of 0.1 displayed the best performance using NiCuAl-1 (5%Ni, 62%Cu, and 33%Al) catalyst with glycerol conversion of 67.1% and 1, 2-PD selectivity of 90.1%. The catalyst was recycled five times for checking its catalytic behavior on the conversion and selectivity, and it was found that the catalyst did not change its activity during the recycle test, confirming the true heterogeneous nature of the catalyst.
- Ali, Syed Saif,Andola, Suresh Chandra,Bal, Rajaram,Bhandari, Sonu,Jha, Mukund Kumar,Pandey, Ankit,Poddar, Mukesh Kumar,Sahani, Govind Kumar
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- Citric acid modified Ni3P as a catalyst for aqueous phase reforming and hydrogenolysis of glycerol to 1,2-PDO
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Citric acid (CA) modified Ni3P catalysts with small particle sizes were prepared by H2 temperature-programmed reduction (H2-TPR) of the precursors, which were prepared by co-precipitation with Ni(NO3)2·6H2O and (NH4)2HPO4, using citric acid as the chelating agent and calcining under a N2 atmosphere. The catalytic activity of the prepared catalysts was tested in the aqueous phase reforming (APR) and hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). The effects of the CA/Ni molar ratio and reaction conditions (temperature, pressure, and time) on APR and hydrogenolysis of glycerol were investigated. The CA(1)-Ni3P catalyst exhibited the best performance at 220 °C, 0.5 MPa N2, and 8 h with 74.6% glycerol conversion and 43.2% selectivity of 1,2-PDO. The prepared CA(x)-Ni3P catalysts were characterized by XRD, N2 adsorption, Raman spectroscopy, CO-chemisorption and TEM. The addition of CA significantly enhanced the dispersion of Ni species in the precursors and enlarged the surface area of the catalyst. The residual carbonaceous species after calcination in N2 prevented the aggregation of Ni3P particles and promoted the reduction of the precursors. Compared with the unmodified Ni3P and CA(x)-Ni3P calcined in air, the CA(x)-Ni3P calcined in N2 with a smaller average particle size exhibited higher catalytic activities.
- Hu, Tianyu,Liu, Bingyu,Liu, Shan,Liu, Ying-Ya,Sun, Zhichao,Wang, Anjie,Wang, Yao,Yu, Zhiquan
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p. 21725 - 21731
(2021/12/13)
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- Highly selective hydrogenation of diesters to ethylene glycol and ethanol on aluminum-promoted CuAl/SiO2 catalysts
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A highly selective CuAl/SiO2 catalyst was prepared for the hydrogenation of dimethyl oxalate (DMO) and ethylene carbonate (EC) to ethanol and ethylene glycol (EG), respectively. Aluminum modified silica sol was used to prepare CuAl/SiO2 catalysts by a hydrothermal method. The catalytic performance of the CuAl/SiO2 catalysts with varying aluminum content was investigated at the conditions of 553 K and 2.5 MPa for DMO hydrogenation, while 453 K and 3 MPa for EC hydrogenation. The results showed that the Cu1.0Al/SiO2 catalyst exhibited the highest selectivity of ethanol (~94 %) in the DMO hydrogenation, while the Cu0.5Al/SiO2 catalyst exhibited the highest selectivity of EG (~95 %) and methanol (65 %) in the EC hydrogenation. Characterizations (e.g., TPD, TPR and XANES) indicated that the moderate aluminum modification on SiO2 in the form of [tbnd]Si–OH–Al bond could not only tune the support acidity to polarize the C[dbnd]O bond of esters, but also intrinsically facilitate the dispersion of Cu active species to activate H2, which thus facilitated the selective hydrogenation reaction to EG, ethanol and methanol.
- Shu, Guoqiang,Ma, Kui,Tang, Siyang,Liu, Changjun,Yue, Hairong,Liang, Bin
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p. 173 - 180
(2020/01/13)
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- Gas Phase Glycerol Valorization over Ceria Nanostructures with Well-Defined Morphologies
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Glycerol solutions were vaporized and reacted over ceria catalysts with different morphologies to investigate the relationship of product distribution to the surface facets exposed, particularly, the yield of bio-renewable methanol. Ceria was prepared with cubic, rodlike, and polyhedral morphologies via hydrothermal synthesis by altering the concentration of the precipitating agent or synthesis temperature. Glycerol conversion was found to be low over the ceria with a cubic morphology, and this was ascribed to both a low surface area and relatively high acidity. Density functional theory calculations also showed that the (100) surface is likely to be hydroxylated under reaction conditions which could limit the availability of basic sites. Methanol space-time-yields over the polyhedral ceria samples were more than four times that for the cubic material at 400 °C, where 201 g of methanol was produced per hour per kilogram of the catalyst. Under comparable glycerol conversions, we show that the rodlike and polyhedral catalysts produce a major intermediate to methanol, hydroxyacetone (HA), with a selectivity of ca. 45%, but that over the cubic sample, this was found to be 15%. This equates to a 13-fold increase in the space-time-yield of HA over the polyhedral samples compared to the cubes at 320 °C. The implications of this difference are discussed with respect to the reaction mechanism, suggesting that a different mechanism dominates over the cubic catalysts to that for rodlike and polyhedral catalysts. The strong association between exposed surface facets of ceria to high methanol yields is an important consideration for future catalyst design in this area.
- Smith, Louise R.,Sainna, Mala A.,Douthwaite, Mark,Davies, Thomas E.,Dummer, Nicholas F.,Willock, David J.,Knight, David W.,Catlow, C. Richard A.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 4893 - 4907
(2021/05/04)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
- -
-
Paragraph 0111
(2021/03/19)
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- Preparation method of dialkyl carbonate
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The invention relates to a preparation method of dialkyl carbonate. The method comprises the following steps: by using cyclic carbonate and monohydric alcohol as raw materials, carrying out transesterification under the catalysis of triazole onium ionic liquid to obtain the dialkyl carbonate. According to the brand-new method for preparing the dialkyl carbonate, the cyclic carbonate and the monohydric alcohol are catalyzed by using the triazolium ionic liquid to be subjected to transesterification to obtain the dialkyl carbonate, and the dialkyl carbonate prepared by using the method has relatively high selectivity and conversion rate; and the selectivity of the obtained dialkyl carbonate can reach 99.5%. Compared with a method for preparing dialkyl carbonate in the prior art, the triazolium ionic liquid catalyst used in the invention has the advantages of high catalytic efficiency, high stability, no need of other solvents or cocatalysts, mild reaction conditions and the like, and has high industrial application value.
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-
Paragraph 0051-0079
(2021/05/01)
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- Method for direct conversion of carbon dioxide to dialkyl carbonates using ethylene oxide as feedstock
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A method for co-production of high purity dimethyl carbonate and mono-ethylene glycol by applying a reactor, such as a membrane reactor and/or an adsorbent-catalytic reactor by capturing and reacting carbon dioxide with methanol and ethylene oxide. Carbon dioxide may be recovered from primary sources (utilities and industrial processes) by a membrane or solid adsorbent, and subsequently converted to an intermediate hydroxy-ethyl-methyl carbonate by reacting with ethylene oxide and methanol. For high-purity carbon dioxide (obtained by carbon capture technologies or from an ethanol fermentation process), the membrane reactor is replaced with a catalytic reactor for direct conversion of carbon dioxide to hydroxy-ethyl-methyl carbonate by reacting with ethylene oxide and methanol. The hydro-ethyl-methyl carbonate is further reacted with methanol for conversion to dimethyl carbonate. A combination of heterogeneous and homogeneous catalysts is implemented for an effective conversion of carbon dioxide. An integrated reactive distillation process using side reactors is used for facilitating catalytic reaction for production of high purity dimethyl carbonate.
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Page/Page column 17-20
(2021/03/11)
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- PROCESS FOR PREPARING ALKYLENE GLYCOL MIXTURE FROM A CARBOHYDRATE SOURCE WITH DECREASED SELECTIVITY FOR POLYOL SIDE PRODUCTS
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The invention relates to a process for preparing a mixture of alkylene glycols (e.g. ethylene glycol and/or propylene glycol) from a carbohydrate source by catalytic conversion with hydrogen. More specifically, the catalytic hydrogenolysis process of the invention has a decreased selectivity for larger polyols like sorbitol and erythritol, which larger polyols are obtained generally as a side product in catalytic hydrogenolysis, when viewed in comparison to the selectivity for small alkylene glycols (like ethylene glycol and propylene glycol). This is achieved by ensuring the carbohydrate feed is rich in sucrose.
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Page/Page column 7-9
(2021/08/27)
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- High-Pressure CO Electroreduction at Silver Produces Ethanol and Propanol
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Reducing CO2 to long-chain carbon products is attractive considering such products are typically more valuable than shorter ones. However, the best electrocatalyst for making such products from CO2, copper, lacks selectivity. By stud
- Corbett, Paul J.,Koper, Marc T. M.,Raaijman, Stefan J.,Schellekens, Maarten P.
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supporting information
p. 21732 - 21736
(2021/08/26)
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- Efficient photodegradation of 2-chloro-4-nitrophenol over Fe-doped BiOCl nanosheets with oxygen vacancy
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Photodegradation of organic pollutants emerged as a promising route for environmental remediation. Due to abundant localized electrons, oxygen vacancies (OVs) over BiOCl could promote the adsorption of organic pollutants and activation of oxygen to produce more reactive oxygen species (ROS) during the photocatalytic reaction. Considering the high oxidation potential (E0 = 1.8-2.7 V vs. NHE) of the hydroxyl radicals (OH), we introduced Fe dopant in the OV-associated BiOCl system (Fe-BOC) to build Fenton-like catalysts, which converted the H2O2 generated in the photoreaction to produce more OH for the photodegradation of 2-chloro-4-nitrophenol. Experimental results revealed that the concentration of H2O2 in the undoped BiOCl (BOC) photoreaction system was higher, while much more OH was detected in Fe-BOC, indicating that the Fenton-like reaction occurred for the conversion of H2O2 into OH over Fe-BOC. In addition, the better charge separation of Fe-BOC could motivate more surface e- for O2 activation into O2-. Thus, the more reactive oxygen species (OH and O2-) produced over Fe-BOC resulted in 3.1 times higher photocatalytic activity in contrast to that of BOC.
- Liu, Xiangming,Wu, Haoyuan,Xu, Hua,Yang, Xinmin,Ye, Jinhua
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p. 5119 - 5124
(2021/08/16)
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- SYSTEM AND PROCESS FOR CO-PRODUCING DIMETHYL CARBONATE AND ETHYLENE GLYCOL
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A system and a process for co-producing dimethyl carbonate and ethylene glycol. The system comprises an interconnected ethylene carbonate preparation unit and an ethylene carbonate alcoholysis unit. The ethylene carbonate preparation unit comprises a fixed bed reactor and a light-component stripping column connected to each other. The fixed bed reactor is filled with a supported ionic liquid catalyst. The process comprises the steps of: reacting carbon dioxide and ethylene oxide as raw materials in the fixed bed reactor to produce ethylene carbonate, purifying the ethylene carbonate and then mixing it with an alcoholysis reaction catalyst, and reacting the mixture with methanol in a reactive distillation tower, producing dimethyl carbonate and ethylene glycol. The process increases the conversion rate of ethylene oxide and avoids the need for a process of separating conventional homogeneous catalysts from ethylene carbonate, thereby reducing process energy consumption and simplifying process procedures.
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Page/Page column 4-6
(2021/10/30)
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- Enhanced one-pot selective conversion of cellulose to ethylene glycol over NaZSM-5 supported metal catalysts
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The mesopores interconnected with microporous NaZSM-5 was synthesised by sol-gel method. Reactions involving cellulose using different bimetallic and trimetallic combinations of nickel, aluminium, and tungsten metals supported on NaZSM-5 have been carried out. Different weight percentages (wt%) of Al, Ni, and W were loaded onto the NaZSM-5 support via a wet impregnation method. The prepared catalysts were characterized using PXRD, FE-SEM, HR-TEM, BET, and XPS studies to investigate the presence of mesopores, the textural properties, the metal loading, and the active oxidation states. The catalytic activities of the xAl-yNi-zW/NaZSM-5 (where x, y, and z are the wt% values of Al, Ni, and W, respectively) supported catalysts were studied during the one-pot conversion of cellulose into ethylene glycol at 220 °C and with a pressure of 70 bar H2 (at the reaction temperature) in water (as a solvent). The 5%Al-8%Ni-25%W/NaZSM-5 catalyst exhibited the highest cellulose conversion of 100%, with an ethylene glycol yield as high as 89% (C mol%) under moderate reaction conditions being reported for the first time. Al3+ in the catalyst hydrolyzed cellulose, and W5+ species acted as acid centres that facilitated the retro-aldol condensation reaction and eventually led to an increased EG yield in the presence of Ni. The catalyst was moderately stable after four consecutive runs for 6 h at 220 °C and at a H2 reaction pressure of 70 bar, though a 12 h reaction resulted in the highest EG yield. The high yields under moderate reaction conditions promise an energy-efficient and economically feasible process.
- Arunima Kirali, Arun,Marimuthu, Banu,Sreekantan, Sreejith
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supporting information
p. 19244 - 19254
(2021/11/09)
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- Promotional effect of indium on Cu/SiO2catalysts for the hydrogenation of dimethyl oxalate to ethylene glycol
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The synthesis of ethylene glycol (EG) through hydrogenation of syngas-derived dimethyl oxalate (DMO) has been a promising method because syngas can be obtained from plentiful resources such as coal, natural gas, biomass,etc.In this work, we fabricated several indium-promoted Cu/SiO2catalysts by a one-pot hydrolysis precipitation (HP) method for the DMO-to-EG reaction. The textural and physiochemical properties of the catalysts were revealed using multiple characterization methods. The intimate contact of Cu and In enhances the reduction of indium oxide and the formation of CuIn alloy. The introduction of indium also markedly improves the copper dispersion and formation of Cu0active sites, which improve the activation of H2. The plentiful interface of Cu+-CuIn alloy prompts the conversion of the carbonyl group adsorbed on the Cu+sites with the dissociated hydrogen on the vicinal CuIn alloy, which is confirmed by the higher TOF (Cu+) and the lower apparent activation energy (Ea) on the Cu1In/SiO2catalyst. Both CuIn alloy and Cu0species have a synergistic effect with Cu+, endowing the Cu1In/SiO2catalyst with a higher EG yield (96%) in comparison with the Cu/SiO2catalyst without doping.
- Huang, Huijiang,Kong, Lingxin,Ma, Xinbin,Wang, Hui,Wang, Shengping,Wang, Xiaofei,Xu, Yuxi,Zhao, Yujun
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p. 6854 - 6865
(2021/10/25)
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- Superior CNT-supported bimetallic RuCu catalyst for the highly selective hydrogenolysis of glycerol to 1,2-propanediol
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Selective hydrogenation of glycerol to 1,2-propanediol (1,2-PD) is a promising route for sustainable production of platform chemicals. Herein, a bimetallic RuCu catalyst supported on multiwall carbon nanotubes (RuCu/MWCNT) is reported that shows superior catalytic performance leading to 93.4% 1,2-PD selectivity under mild reactions conditions.
- Albert, Jakob,Bukowski, Anna,Fiedler, Bodo,Sherbi, Magdy,Velichkova, Hristiana,Wesner, Anne,Wisniewski, Valea Kim
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p. 6649 - 6653
(2021/10/25)
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- Capturing ethylene glycol with dimethyl carbonate towards depolymerisation of polyethylene terephthalate at ambient temperature
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Depolymerisation of polyethylene terephthalate (PET) via alkali metal alkoxide catalysed methanolysis efficiently proceeded at ambient temperature by capturing ethylene glycol (EG) with dimethyl carbonate (DMC), which biased the equilibrium toward dimethy
- Nakajima, Yumiko,Sato, Junichi,Tanaka, Shinji
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supporting information
p. 9412 - 9416
(2021/12/09)
-
- AEROBIC ELECTROCATALYTIC OXIDATION OF HYDROCARBONS
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This invention is directed to a method of oxygenating hydrocarbons with molecular oxygen, O2, as oxidant under electrochemical reducing conditions, using polyoxometalate compounds containing copper such as Q10 [Gu4(H2O)2(B-α-PW9O)2] or Q12{ [Cu(H2O)]3[(A-α- PW9O34)2(NO3)-] } or solvates thereof as catalysts, wherein Q are each independently selected from alkali metal cations, alkaline earth metal cations, transition metal cations, NH4+,H+ or any combination thereof.
- -
-
Paragraph 0074
(2022/01/04)
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- A new solution route for the synthesis of CuFeO2 and Mg-doped CuFeO2 as catalysts for dye degradation and CO2 conversion
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In this study, CuFeO2 and Mg-doped CuFeO2 powders are synthesized by using a novel chemical solution route under an ambient atmosphere. By regulating the pH of the reaction solution, on the basis of Pourbaix diagrams, and the stoichiometric ratio of copper to iron ions, delafossite CuFeO2 powders are formed at 363 K in an aqueous solution. Mg-doped CuFeO2 powders are also synthesized by using the same chemical route with the trace addition of Mg(II) ions. From the powder X-ray diffraction results, all diffraction peaks are of the delafossite structure with dominated 3R phase and few 2H phase. X-ray photoelectron spectroscopy measurements show that the chemical environments of the Cu and Fe ions are consistent with the binding energies of Cu(I) and Fe(III) in the delafossite structure of CuFeO2. The UV–vis spectra show that the CuFeO2 and Mg-doped CuFeO2 powders are both able to absorb light with wavelengths ranging from 300 to 700 nm. The calculated optical band gaps of the CuFeO2 and Mg-doped CuFeO2 powders are 1.35 and 1.5 eV, respectively. With regard to the application of the powders in the photodegradation of 50 ppm methylene blue, the results suggest that at an incident light irradiation of AM 1.5G, the photodegradation efficiency of the Mg-doped CuFeO2 powder is remarkably better than that of the CuFeO2 powder, which can be attributed to its higher carrier concentration. Furthermore, at an external bias of ?1.2 V, these delafossite catalysts are able to convert CO2 to ethylene glycol through an electrocatalytic reaction.
- Bai, Shi-Yun,Chang, Yu-Hsu,Chiu, Te-Wei,Kuo, Chun-Hong,Lee, Yuan-Han,Liao, Ching-Wen,Siao, Ting-Fong,Wang, Haicheng,Zhuang, Jie-Kai
-
-
- H2-Free Selective Dehydroxymethylation of Primary Alcohols over Palladium Nanoparticle Catalysts
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The dehydroxymethylation of primary alcohols is a promising strategy to transform biomass-derived oxygenates into hydrocarbon fuels. In this study, a novel, highly efficient, and reusable heterogeneous catalyst system was established for the H2-free dehydroxymethylation of primary alcohol using cerium oxide-supported palladium nanoparticles (Pd/CeO2). A wide range of aliphatic and aromatic alcohols including biomass-derived alcohols were converted into the corresponding one-carbon shorter hydrocarbons in high yields in the absence of any additives, accompanied by the production of H2 and CO. Pd/CeO2 was easily recovered from the reaction mixture and reused, retaining its high activity, thus, providing a simple and sustainable methodology to produce hydrocarbon fuels from biomass-derived oxygenates.
- Yamaguchi, Sho,Kondo, Hiroki,Uesugi, Kohei,Sakoda, Katsumasa,Jitsukawa, Koichiro,Mitsudome, Takato,Mizugaki, Tomoo
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p. 1135 - 1139
(2020/12/29)
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- C-H activations of methanol and ethanol and C-C couplings into diols by zinc-indium-sulfide under visible light
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Herein, an environmentally friendly CoP/Zn2In2S5 catalyst is reported as a visible-light photocatalyst for the selective activation of the α-C-H bond of methanol to generate ethylene glycol with a selectivity of as high as 90%. The catalytic system also illustrates the first example of visible-light-driven dehydrogenative coupling of ethanol to 2,3-butanediol.
- Zhang, Haikun,Xie, Shunji,Hu, Jinyuan,Wu, Xuejiao,Zhang, Qinghong,Cheng, Jun,Wang, Ye
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p. 1776 - 1779
(2020/02/20)
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- Method for preparing dihydric alcohol through catalysis of ionic liquid porous composite material
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The invention belongs to the technical field of green catalysis, and relates to a method for preparing dihydric alcohol through catalysis of an ionic liquid porous composite material. The method comprises the following steps: doping green and high-activity carboxyl anion-containing ionic liquid into a porous material space skeleton structure to form a composite hybrid material, and maintaining theintrinsic high activity of the ionic liquid through physical hybridization, wherein the space skeleton of the material can provide support for stable existence of the ionic liquid, and generation ofmacromolecular by-products is limited through the pore channel size. According to the invention, by combining the advantages of high activity of the ionic liquid and the space structure of the material, the purpose of improving the epoxide conversion rate and the dihydric alcohol selectivity is achieved; the reaction is completed by taking epoxide and water as raw materials through one-step reaction, wherein the reaction temperature is 323.15-423.15 K, the reaction pressure is 0-3.0 MPa, and the water ratio (H2O/epoxide) is (1-15):1; an ionic liquid porous hybrid material is added as a catalyst, and reacting is performed for 0.2-4.0 hours to obtain the dihydric alcohol product; and the synthesis method has the advantages of low raw material-water ratio, high reaction selectivity, mild reaction conditions and recyclable catalyst, effectively reduces the catalyst cost, and simplifies the reaction route.
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Paragraph 0032-0034; 0035-0036; 0037-0038; 0039-0042
(2020/11/25)
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- Universal strategy of 3D and 2D hybrid perovskites single crystal growth via in situ solvent conversion
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A novel strategy of hybrid halide perovskite single crystal growth based on a new type of “fugitive” solvent system is proposed. To demonstrate the universality of the developed approach, we have grown a set of high-quality single crystals of 3D hybrid perovskites APbX3 (A = MA+, FA+; X = Br?, I?) with pure and mixed compositions, layered 2D perovskites (BA)2(A)n ? 1PbnI3n + 1 (n = 1?4), and iodobismuthates A3Bi2I9. The crystallization was governed by gradual chemical conversion of the initial mixed solvent to a nonsolvent and thus gave yields up to 90%. The growth proceeded within a few hours at moderate temperatures and required no heating/cooling or low-pressure evaporation steps, antisolvents, or any toxic solvents, which makes the whole process uniquely facile and eco-friendly. The high quality of the grown single crystals was confirmed by absorption and photoluminescence spectroscopy, revealing unexpectedly high charge carrier lifetime for 2D perovskites.
- Fateev, Sergey A.,Petrov, Andrey A.,Ordinartsev, Artem A.,Grishko, Alexey Y.,Goodilin, Eugene A.,Tarasov, Alexey B.
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p. 9805 - 9812
(2020/12/01)
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- Method for Catalytically Hydrogenating Oxalates
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The invention discloses a method for catalytically hydrogenating oxalates. In the method, an oxalate and hydrogen gas are contacted with a nanotube assembled hollow sphere catalyst, to produce a product comprising glycolate or glycol. The predominant chemical components of the catalyst include copper and silica, in which the copper is in an amount of 5 to 60% by weight of the catalyst, and the silica is in an amount of 40-95% by weight of the catalyst. The catalyst has a specific surface area of 450-500 m2/g, an average pore volume of 0.5-1 cm3/g, and an average pore diameter of 5-6 nm. The catalyst is in a structure of assembling nanotubes on hollow spheres, wherein the hollow spheres have a diameter of 50-450 nm, and a wall thickness of 10-20 nm, and the nanotubes, vertically arranged on the surfaces of the hollow spheres, have a diameter of 3-5 nm, and a length of 40-300 nm. Even in the case of a low H2/DMO feeding ratio, the method of the invention still can exhibit an excellent activity of hydrogenating oxalates and an excellent selectivity to ethylene glycol, and reduce circulation quantity of hydrogen gas, thereby to save power costs and apparatus costs, and it can flexibility adjust the selectivity of ethylene glycol and glycolate. Thus, the method has high industry prospects and application values.
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Paragraph 0041; 0057
(2020/05/29)
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- Synthesis of nitrogen-containing ordered mesoporous carbon materials with tunable nitrogen distributions and their application for metal-free catalytic synthesis of dimethyl carbonates
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Dicyandiamide (DCDA) was utilized as a facile nitrogen source for the fabrication of nitrogen-containing ordered mesoporous carbon (NOMC) samples via a one-pot soft-templating approach under aqueous phase. X-ray diffraction, N2 adsorption–desorption, Transmission electron microscopy, Scanning electron microscopy, Raman and X-ray photoelectron spectroscopy have been applied to analyze the physicochemical properties of the synthesized NOMC materials. The characterization results showed that the textural parameters (545–589 m2 g?1), graphitic crystallinity and distribution of various nitrogen species of the synthesized NOMC materials were largely dependent on the adding mass of DCDA. Besides DCDA, NOMC materials have been also successfully fabricated by employing urea and melamine as nitrogen sources. As metal-free heterogeneous catalysts, the NOMC materials showed good catalytic activity and selectivity in the transesterification of ethylene carbonate to dimethyl carbonate, affording a maximum yield of dimethyl carbonate up to 76 % at 3 h under 120 °C.
- Gan, Yu-Lin,Wen, Lin-Zhi,Xu, Jie,Xue, Bing
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- START-UP PROCESS FOR THE PRODUCTION OF GLYCOLS
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The invention provides a start-up method for a process for the preparation of glycols from a starting material comprising one or more saccharides in the presence of hydrogen and a catalyst system comprising one or more retro-aldol catalysts comprising tungsten and one or more catalytic species suitable for hydrogenation in a reactor, said method comprising introducing the one or more retro-aldol catalysts to the reactor whilst also in the presence of one or more agents suitable to suppress tungsten precipitation.
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Paragraph 0056-0057
(2020/05/07)
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- Partial hydrogenation of dimethyl oxalate on Cu/SiO2 catalyst modified by sodium silicate
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Cu/SiO2 catalyst modified with Na2SiO3 was prepared by the ammonia evaporation impregnation method and applied in the partial hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG). The addition of Na2SiO3 led to a serious shrinkage of those accumulation pores in the catalyst, but hardly affect the structure of the mesopores bellow 8 nm. Moreover, the trace amount of Na2SiO3 enhanced the formation of copper phyllosilicate, which resulted in a minor increment in Cu+ species as well as a decrease of Cu0 species. An unexpected high MG yield of about 83% and MG selectivity of 99.8% was achieved over the Cu/SiO2 catalyst modified with 0.5% Na2SiO3 in the partial hydrogenation of DMO. The loss of some smaller accumulation pores due to the presence of Na2SiO3 dopant could be key reason for the higher selectivity, because the larger pores can ensure the fast transfer of MG to the external surface. Thus, the further hydrogenation of MG can be prevented. Moreover, the decrement of Cu0 species induced by doping of Na2SiO3 could be another reason for the higher selectivity to MG, since insufficient activated H2 could be provided for the further hydrogenation of MG.
- Huang, Huijiang,Wang, Bo,Wang, Yue,Zhao, Yujun,Wang, Shengping,Ma, Xinbin
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- Effect of Cu loading on the structural evolution and catalytic activity of Cu-Mg/ZnO catalysts for dimethyl oxalate hydrogenation
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The influence of Cu loading on the structural evolution and catalytic behavior in selective hydrogenation of dimethyl oxalate (DMO) by Mg2+ doped nanoscaled Cu-Mg/ZnO catalysts has been investigated. It is found that the accessible Cu0 surface area and ZnO dispersion increased gradually with the Cu loading increasing from 10.0 wt% to 40.0 wt%, and that the Cu and ZnO NP size distribution has a great effect on the chemical interaction between the Cu and ZnO phase, further determining the surface chemical properties of the catalysts. On the other hand, the catalytic behavior of the Cu-Mg/ZnO catalyst in DMO hydrogenation is closely related to the Cu loading introduced into the system. Most of all, the 30Cu-Mg/ZnO catalyst with 30 wt% Cu loading exhibits 100.0% DMO conversion and 98.0% ethylene glycol (EG) yield even under LHSV = 3.5 h-1, superior to those of the other catalysts. This excellent catalytic behavior should be attributed to the strengthened Cu-Zn synergistic effect and suppressed strong surface basic sites, originating from the enhanced Cu-ZnO interface area. Additionally, the correlation between catalytic activity and Cu species distribution suggests that the DMO dissociation on the Cu+ sites generated on the Cu-ZnO interface is the rate-determining step in the presence of enough exposed Cu0 sites over the Cu-Mg/ZnO catalysts.
- Kong, Xiangpeng,Wu, Yuehuan,Ding, Lifeng,Wang, Ruihong,Chen, Jiangang
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p. 4486 - 4493
(2020/04/03)
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- HYDROGENATION CATALYST AND PREPARATION AND USES THEREOF
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A hydrogenation catalyst is disclosed. The catalyst comprises an active component in the form of nanoparticles comprising copper or a cooper oxide; an auxiliary agent in the form of nanoparticles comprising an element selected from the group consisting of nickel, cobalt, manganese, zinc, aluminum, zirconium, cerium, lanthanum, molybdenum, barium, vanadium, titanium, iron, yttrium, niobium, tungsten, tin, bismuth, strontium, boron and phosphorus; and a carrier in the form of hollow silica microspheres having microsphere surfaces, wherein the nanoparticles of the active component and the nanoparticles of the auxiliary dispersed on the microsphere surfaces. The hydrogenation catalyst is useful for hydrogenating an oxalate to ethylene glycol, providing a high oxalate conversion rate, a high selectivity for ethylene glycol, strong stability and high yield. Preparation and uses of the catalyst are also disclosed.
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Page/Page column 9-16
(2020/06/10)
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- Magnesium hydroxide-supported ruthenium as an efficient and stable catalyst for glycerol-selective hydrogenolysis without addition of base and acid additives
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In this work, Ru-based catalysts with the synthesized and commercial Mg(OH)2and MgO as supports such as Ru/Mg(OH)2(S) (or Ru/Mg(OH)2(B), Ru/MgO(S), and Ru/MgO(B)), S and B representing “synthesized” and “commercial”, respectively, were prepared at room temperature by a simple chemical reduction approach. The Ru/Mg(OH)2(S) catalyst exhibited the best catalytic activity (TOF = 134 h?1) and the highest selectivity to 1,2-propanediol (65%) for glycerol hydrogenolysis. Moreover, this reaction was performed over the as-prepared catalysts without adding any liquid acid (e.g., HCl) or base (e.g., NaOH). Selectivity of 1,2-propanediol increased with an increase in the reaction temperature or time, but that towards ethylene glycol did not show any obvious change. Characterization techniques such as XRD, SEM, XPS, TG, TEM, HRTEM, STEM, STEM-EDX elemental analysis (mapping and line-scanning), and CO2-TPD were used to explore related properties of the as-synthesized catalysts to explain the difference in their catalytic activity and selectivity. The reasons for Ru/Mg(OH)2(S) to exhibit high catalytic activity are as follows: Ru with high dispersion on the support, Mg(OH)2with a cotton-like morphology, numerous defect sites and strong basic active sites.
- Liu, Jun,Ruan, Luna,Liao, Jianhua,Pei, An,Yang, Kai,Zhu, Lihua,Chen, Bing Hui
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p. 16054 - 16061
(2020/10/08)
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