107-21-1

Efficient conversion of microcrystalline cellulose to 1,2-alkanediols over supported Ni catalysts

Wang, Xicheng,Meng, Lingqian,Wu, Feng,Jiang, Yijun,Wang, Lei,Mu, Xindong

, p. 758 - 765 (2012)

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.

Hydrogenation of dimethyl oxalate to ethylene glycol over Cu/KIT-6 catalysts

Yu, Xinbin,Burkholder, Michael,Karakalos, Stavros G.,Tate, Gregory L.,Monnier, John R.,Gupton, B. Frank,Williams, Christopher T.

, p. 2403 - 2413 (2021)

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.

One-pot synthesized core/shell structured zeolite@copper catalysts for selective hydrogenation of ethylene carbonate to methanol and ethylene glycol

Ding, Yu,Tian, Jingxia,Chen, Wei,Guan, Yejun,Xu, Hao,Li, Xiaohong,Wu, Haihong,Wu, Peng

, p. 5414 - 5426 (2019)

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%.

Adams,Baxendale

, p. 4215 (1958)

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

Hutson, Alan C.,Lin, Minren,Basickes, Naomi,Sen, Ayusman

, p. 69 - 74 (1995)

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

Hydrogenolysis of glycerol over supported bimetallic Ni/Cu catalysts with and without external hydrogen addition in a fixed-bed flow reactor

Cai, Fufeng,Pan, Donghui,Ibrahim, Jessica Juweriah,Zhang, Jun,Xiao, Guomin

, p. 172 - 182 (2018)

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.

Glycerol hydrogenolysis promoted by supported palladium catalysts

Musolino, Maria Grazia,Scarpino, Luciano Antonio,Mauriello, Francesco,Pietropaolo, Rosario

, p. 1143 - 1150 (2011)

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.

Effect of Calcination Temperature on the Textural Properties and Catalytic Behavior of the Al2O3 Doped Mesoporous Monometallic Cu Catalysts in Dimethyl Oxalate Hydrogenation

Kong, Xiangpeng,Wu, Yuehuan,Yuan, Peihong,Wang, Man,Wu, Peng,Ding, Lifeng,Wang, Ruihong,Chen, Jiangang

, p. 2107 - 2115 (2021)

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.]

Design and preparation of hydrated MgAl supported Cu catalysts with high alkalinity by MOCVD for the hydrogenolysis of cellulose

Xiao, Zihui

, p. 343 - 349 (2017)

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.

1,3-Dimethylimidazolium-2-carboxylate: A zwitterionic salt for the efficient synthesis of vicinal diols from cyclic carbonates

Sun, Jian,Yao, Xiaoqian,Cheng, Weiguo,Zhang, Suojiang

, p. 3297 - 3304 (2014)

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.

Studies on mechanism for homogeneous catalytic hydration of ethylene oxide: Effects of pH window and esterification

Yang, Zhi-Jian,Ren, Nan,Zhang, Ya-Hong,Tang, Yi

, p. 447 - 450 (2010)

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

Efficient Photoelectrochemical Conversion of Methane into Ethylene Glycol by WO3 Nanobar Arrays

Ma, Jun,Mao, Keke,Low, Jingxiang,Wang, Zihao,Xi, Dawei,Zhang, Wenqing,Ju, Huanxin,Qi, Zeming,Long, Ran,Wu, Xiaojun,Song, Li,Xiong, Yujie

, p. 9357 - 9361 (2021)

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.

Physical and chemical studies of tungsten carbide catalysts: Effects of Ni promotion and sulphonated carbon

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

, p. 23874 - 23885 (2015)

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.

Enhanced catalytic performance for SiO2-TiO2 binary oxide supported Cu-based catalyst in the hydrogenation of dimethyloxalate

Wen, Chao,Yin, Anyuan,Cui, Yuanyuan,Yang, Xinli,Dai, Wei-Lin,Fan, Kangnian

, p. 82 - 89 (2013)

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.

A New Aspect of the Pressure Effect in Syngas Conversion to Ethylene Glycol

Masuda, Takashi,Murata, Kazuhisa,Matsuda, Akio

, p. 1287 - 1289 (1986)

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.

Chiral Polyol Synthesis Catalyzed by a Thermostable Transketolase Immobilized on Layered Double Hydroxides in Ionic liquids

Ali, Ghina,Moreau, Thomas,Forano, Claude,Mousty, Christine,Prevot, Vanessa,Charmantray, Franck,Hecquet, Laurence

, p. 3163 - 3170 (2015)

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.

Selective Hydrogenolysis of Glycerol to Propylene Glycol on Supported Pd Catalysts: Promoting Effects of ZnO and Mechanistic Assessment of Active PdZn Alloy Surfaces

Sun, Qianhui,Wang, Shuai,Liu, Haichao

, p. 4265 - 4275 (2017)

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).

Vapour phase hydrogenolysis of glycerol over nano Ru/SBA-15 catalysts on the effect of preparatory routes and metal precursors

Pavankumar, Vanama,Srikanth, Chakravartula S.,Rao, Anipindi Nageswara,Chary, Komandur V. R.

, p. 3137 - 3146 (2014)

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

-

Ciamician,Silber

, (1911)

-

Platinum on carbonaceous supports for glycerol hydrogenolysis: Support effect

Oberhauser, Werner,Evangelisti, Claudio,Jumde, Ravindra P.,Psaro, Rinaldo,Vizza, Francesco,Bevilacqua, Manuela,Filippi, Jonathan,Machado, Bruno F.,Serp, Philippe

, p. 111 - 117 (2015)

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.

-

Carnahan et al.

, p. 3766 (1955)

-

Effect of surface hydroxyl group of ultra-small silica on the chemical states of copper catalyst for dimethyl oxalate hydrogenation

Wang, Yue,Yang, Wenlong,Yao, Dawei,Wang, Shengping,Xu, Yan,Zhao, Yujun,Ma, Xinbin

, p. 127 - 135 (2020)

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.

-

Milas,Sussman

, (1937)

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Efficient hydrogenation of dimethyl oxalate to ethylene glycol: Via nickel stabilized copper catalysts

Zhu, Junhua,Ye, Yingchun,Tang, Yi,Chen, Liangfeng,Tang, Kangjian

, p. 111415 - 111420 (2016)

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.

Influence of Ni species on the structural evolution of Cu/SiO2 catalyst for the chemoselective hydrogenation of dimethyl oxalate

Yin, Anyuan,Wen, Chao,Guo, Xiaoyang,Dai, Wei-Lin,Fan, Kangnian

, p. 77 - 88 (2011)

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.

Utilizing in situ spectroscopic tools to monitor ketal deprotection processes

Ralbovsky, Nicole M.,Lomont, Justin P.,Ruccolo, Serge,Konietzko, Janelle,McHugh, Patrick M.,Wang, Sheng-Ching,Mangion, Ian,Smith, Joseph P.

, (2021/12/08)

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.

Selectively chemo-catalytic hydrogenolysis of cellulose to EG and EtOH over porous SiO2 supported tungsten catalysts

Fan, Maohong,Mu, Shifang,Sun, Qi,Wang, Haiyong,Wang, Xiaolong,Wang, Yan,Weng, Yujing,Zhang, Mingwei,Zhang, Yulong

, (2022/03/15)

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.

CO2atmosphere enables efficient catalytic hydration of ethylene oxide by ionic liquids/organic bases at low water/epoxide ratios

Ding, Tong,Gao, Guohua,Xia, Fei,Yuan, Huixia,Zha, Jinyin,Zhang, Dawei,Zhang, Jingshun

supporting information, p. 3386 - 3391 (2021/05/25)

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.