- Hydrogenation of lactic acid to propylene glycol over a carbon-supported ruthenium catalyst
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Catalytic hydrogenation of lactic acid to propylene glycol is performed in a high-pressure batch reactor over ruthenium on various carbon supports (i.e., VulcanXC-72, ketjen black, CNTs, CNFs, and graphite) prepared using the incipient wetness impregnation method. The crystallinity of the synthesized catalyst is investigated via X-ray diffraction, and the particle sizes are determined using transmission electron microscopy. The surface areas of the synthesized catalysts are analyzed using the BET method; the catalytic activity correlates remarkably with the BET surface area. The yield of propylene glycol increases with pressure, and the highest yield is achieved at 130 C. The catalytic activity is strongly dependent on the type of support. Among the catalysts tested, Ru on ketjen black shows the highest yield of propylene glycol.
- Jang, Hyuk,Kim, Sung-Hwan,Lee, Duwon,Shim, Sang Eun,Baeck, Sung-Hyeon,Kim, Beom Sik,Chang, Tae Sun
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- Effect of nickel on catalytic behaviour of bimetallic Cu-Ni catalyst supported on mesoporous alumina for the hydrogenolysis of glycerol to 1,2-propanediol
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The catalytic conversion of glycerol to 1,2-propanediol by hydrogenolysis has potential use in the commercial biomass industry. However, the high hydrogen pressure required for the reaction is a major drawback. To overcome this limitation, in this study, we added nickel metal to a copper-based catalyst for both supplying hydrogen via aqueous-phase reforming (APR) of glycerol and improving selectivity for 1,2-propanediol in hydrogenolysis. The bimetallic Cu-Ni catalyst supported on mesoporous alumina (MA) was prepared by a sol-gel method. The prepared Cu-Ni catalyst contains ordered mesopores with high surface area and well-dispersed active sites, as confirmed by BET, TEM, XRD, and TPR. The 9Cu-1Ni/MA (molar ratio of copper to nickel: 9:1) catalyst showed the highest catalytic performance among the various xCu-yNi/MA catalysts in a low pressure of H2. The XPS results showed that the surface ratio of Ni to (Cu + Ni) and Cu0/(Cu0 + Cu2+) is closely related to catalytic performance, selectivity and yield. The effect of nickel on the hydrogen production was experimentally proven by the time-on-stream tests over monometallic (Cu) and bimetallic (Cu-Ni) catalysts in the absence of hydrogen. The optimum value of the ratio of Ni to Cu is varied with the conditions in the presence of H2. The reaction mechanism was proposed for the Cu-Ni bimetallic catalysts for hydrogenolysis with APR of glycerol. the Partner Organisations 2014.
- Yun, Yang Sik,Park, Dae Sung,Yi, Jongheop
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- A significant enhancement of catalytic activities in oxidation with H 2O2 over the TS-1 zeolite by adjusting the catalyst wettability
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Hydrophilic TS-1 (H-TS-1) with rich hydroxyl groups, which were confirmed by 29Si and 1H NMR techniques, exhibits much higher activities in the oxidation than conventional TS-1. This phenomenon is strongly related to the unique features of high enrichment of H2O2 on H-TS-1.
- Wang, Liang,Sun, Jing,Meng, Xiangju,Zhang, Weiping,Zhang, Jian,Pan, Shuxiang,Shen, Zhe,Xiao, Feng-Shou
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- Hydrogenolysis of Glucose into Propylene Glycol over Pt/SiO2@Mg(OH)2 Catalyst
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One-pot selective conversion of glucose is a green approach compared with petroleum-based processes to produce 1,2-propylene glycol (1,2-PG), but its realization is hindered by various side reactions. Here we demonstrate a feasible strategy of Pt/SiO2@Mg(OH)2 core-shell catalyst to achieve the 1,2-PG yield of 53.8 % by a three-pronged promotion, including enhancement of the glucose-fructose isomerization and retro-aldol condensation (RAC), as well as re-conversion of by-product hexitol into 1,2-PG. We realized the in situ synthesis of the core-shell structure using a self-existent Mg(OH)2 base instead of an extraneous base in the hydrothermal process and it achieved a stable performance during reuse by protecting Pt from leaching.
- Gu, Minyan,Shen, Zheng,Zhang, Wei,Xia, Meng,Jiang, Jikang,Dong, Wenjie,Zhou, Xuefei,Zhang, Yalei
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- Robust Iridium Coordination Polymers: Highly Selective, Efficient, and Recyclable Catalysts for Oxidative Conversion of Glycerol to Potassium Lactate with Dihydrogen Liberation
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Along with the rapid expansion of the biodiesel industry to deal with the world energy crisis, inexpensive glycerol is also produced in large scale as the main byproduct in biodiesel production via transesterification. Much attention has been paid to the development of environmentally benign technologies for the transformation of glycerol to valuable DL-lactic acid and its derivatives. Herein, a series of NHC-Ir coordination polymers were readily synthesized via reaction of some structurally rigid bis-benzimidazolium salts with iridium precursors under alkaline conditions and were successfully applied as robust self-supported catalysts in the oxidative dehydrogenation of glycerol to potassium lactate with dihydrogen liberation. Extremely high activity and selectivity were attained in open air under the mild reaction conditions even with ppm-level loadings of the catalysts, which were readily recovered after reaction by simple filtration and reused for up to 31 runs without obvious loss of activity or selectivity. Probably owing to the effective suppression of inactive binuclear iridium species in a homogeneously catalyzed reaction, the catalysts assembled via self-supported strategy exhibited high selectivity and productivity for potassium lactate, with up to 1.24 × 105 turnover numbers (TON) being attained even in large-scale reactions of neat glycerol at an elevated temperature. The high catalytic activity, recyclability, and scalability of the robust self-supported catalysts highlight their potential toward the development of practical technologies for transformation of glycerol to value-added chemicals.
- Sun, Zheming,Liu, Yaoqi,Chen, Jiangbo,Huang, Changyu,Tu, Tao
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- Kinetics and mechanism of the catalytic hydration of propylene oxide
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The kinetics of propylene oxide hydration in the presence of bis(ethane-1,2-diol)molybdate is reported. A mathematical description of PO disappearance and propylene glycol formation is suggested. The most probable scheme for the process is presented. The basic kinetic constants are calculated.
- Shaikhutdinov,Petukhov,Sapunov,Kharlampidi,Petukhov
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- Determination of intramolecular δ13C from incomplete pyrolysis fragments. Evaluation of pyrolysis-induced isotopic fractionation in fragments from the lactic acid analogue propylene glycol
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Intramolecular carbon isotope ratios reflect the source of a compound and the reaction conditions prevailing during synthesis and degradation. We report here a method for determination of relative (Δδ13C) and absolute (δ13C) intramolecular isotope ratios using the volatile lactic acid analogue propylene glycol as a model compound, measured by on-line gas chromatography-pyrolysis coupled to GC-combustion-isotope ratio mass spectrometry. Pyrolytic fragmentation of about one-third of the analyte mass produces optimal fragments for isotopic analysis, from which relative isotope ratios (Δδ13C) are calculated according to guidelines presented previously. Calibration to obtain absolute isotope ratios is achieved by quantifying isotope fractionation during pyrolysis with an average fractionation factor, α, and evaluated by considering extremes in isotopic fractionation behavior. The method is demonstrated by calculating ranges of absolute intramolecular isotope ratios in four samples of propylene glycol. Relative and absolute isotope ratios were calculated with average precisions of SD(Δδ13C) 13C) 13C range of 2‰ for each position in each sample. Relative isotope ratios revealed all four samples originated from unique sources, with samples A, B, and D only distinguishable at the position-specific level. Regardless of pyrolysis fractionation distribution, absolute isotope ratios showed a consistent pattern for all samples, with δ 13C(3) > δ13C(2) > δ13C(1). The validity of the method was determined by examining the difference in relative isotope ratios calculated through two independent methods: Δδ13C calculated directly using previous methods and Δδ13C extracted from absolute isotope ratios. Deviation between the two Δδ13C values for all positions averaged 0.1-0.2‰, with the smallest deviation obtained assuming equal fractionation across all fragment positions. This approach applies generally to all compounds analyzed by pyrolytic PSIA.
- Wolyniak, Christopher J.,Sacks, Gavin L.,Metzger, Sara K.,Brenna, J. Thomas
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- Stability and regeneration of Cu-ZrO2 catalysts used in glycerol hydrogenolysis to 1,2-propanediol
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A series of Cu-ZrO2 catalysts with different copper contents have been prepared by the coprecipitation method. Their catalytic behavior was studied for glycerol hydrogenolysis reaction to obtain 1,2-propanediol (1,2-PDO) joint to deactivation mechanism and regeneration protocols. A number of physical chemical techniques as X-ray diffraction (XRD), evolved gas analysis by mass spectrometry (EGA-MS), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and chemical analysis have been used to characterize the precursors, activated and spent catalysts. Cu-ZrO2 catalysts with higher atomic ratio Cu/Zr showed higher selectivity while glycerol conversion values were not significantly changed. In terms of stability a decreasing of yield to 1,2-PDO due to a decrease of its selectivity was observed with the number of cycles. The main cause of deactivation was associated to the progressive formation of organic deposits on the surface of catalyst. A regeneration process highly efficient, where almost complete recovery of yield to 1,2-PDO shown by the fresh catalyst was reached, has been identified.
- Durán-Martín,Ojeda,Granados, M. López,Fierro,Mariscal
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- Selective hydrogenolysis of glycerol to propanediols on supported Cu-containing bimetallic catalysts
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Supported Cu-containing bimetallic catalysts were prepared and used to convert glycerol to propanediols. The effects of supports, metals, metal loadings, and impregnation sequences were examined. A synergistic effect was observed between Cu and Ag when they were impregnated on γ-Al 2O3. Characterizations revealed that the addition of Ag not only resulted in an in situ reduction of CuO, but also improved the dispersion of the Cu species on the support. A CuAg/Al2O3 catalyst with optimal amounts of Cu and Ag (Cu/Ag molar ratio 7:3, 2.7 mmol Cu+Ag per gram of γ-Al2O3) showed a near 100% selectivity to propanediols with a glycerol conversion of about 27% under mild reaction conditions (200 °C, 1.5 MPa initial H2 pressure, 10 h, (Cu+Ag)/glycerol molar ratio of 3/100). Compared with a commercial copper chromite catalyst commonly used for this reaction, the CuAg/Al2O 3 catalyst had much higher activity and did not need a reduction pretreatment.
- Zhou, Jinxia,Guo, Liyuan,Guo, Xinwen,Mao, Jingbo,Zhang, Shuguang
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- Shape effect of ZnO crystals as cocatalyst in combined reforming- hydrogenolysis of glycerol
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Disk- and rod-shaped hexagonal ZnO crystals with various length-to-diameter aspect ratios were controllably synthesized via a facile solution route by adjusting the precursor concentration. The shape and the dimension of the synthesized ZnO crystals were observed by scanning electron microscopy (SEM). The wurtzite structure and the growth habit were determined by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) coupled with selected-area electron diffraction (SAED). It is found that with the lowering of the precursor concentrations, the ZnO crystals were elongated along the c-axis, and the diameter of the {001} planes was reduced, leading to shape evolution from hexagonal disk to prismatic rod. As a result, the ZnO crystals were different from each other in the proportion of the {100} nonpolar planes and the {001} polar planes. The well-defined ZnO crystals were used as the cocatalyst with skeletal Ni40Mo10 in the combined reforming-hydrogenolysis (CRH) of glycerol in the absence of adventitious H 2. A remarkable shape-dependent effect on the selectivity to the C3 hydrogenolysis products and the production rate of 1,2-propandiol (1,2-PDO) was identified. ZnO with a larger proportion of the nonpolar planes was more effective in the CRH of glycerol to the C3 products. An excellent linear relationship between the surface area of the {100} nonpolar planes and the production rate of 1,2-PDO was identified. This is attributed to the in situ enhancement of the Lewis acidity of the nonpolar planes of ZnO by chemisorbed CO2 from the reforming of glycerol, which greatly accelerates the dehydration of glycerol to acetol, the intermediate to 1,2-PDO.
- Hu, Jiye,Fan, Yiqiu,Pei, Yan,Qiao, Minghua,Fan, Kangnian,Zhang, Xiaoxin,Zong, Baoning
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- Catalytic coproduction of methanol and glycol in one pot from epoxide, CO2, and H2
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An atom (100%) and energy-efficient approach to coproduce two commodity chemicals, methanol and glycol, has been demonstrated for the first time using H2, CO2, and epoxide as feeds. A basic medium used for CO2 capture, polyethyleneimine (PEI600), is shown to facilitate the formation of a key reaction intermediate, cyclic carbonates. Upon hydrogenation of cyclic carbonates in the presence of a homogenous Ru-PNP catalyst, a 1 : 1 mixture of methanol and glycol is produced. This approach has been demonstrated in one pot by adding all the required reactants directly or stepwise. The stepwise addition of reactants resulted in good yields (>95% for PG and 84% for methanol) and selectivity of products. This journal is
- Heldebrant, David J.,Kothandaraman, Jotheeswari
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- Selectively Chemocatalytic Conversion of Fructose to 1,2-Propylene Glycol over Ru-WOx/Hydroxyapatite Catalyst?
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The conversion of fructose to 1,2-propylene glycol (PG) is an important process from cellulosic biomass to high-value added chemicals. Herein, Ru-WOx/hydroxyapatite (HAP) catalyst was employed for this reaction and reached up to 91.3% yield of PG at 180 °C, 1 MPa initial hydrogen for 8 h in water. On this catalyst, Ru and WOx were highly dispersed on HAP support and they interacted with each other to form a special catalytic center. The lack of isolated Ru or RuW alloy site led to a moderate activity for hydrogenolysis and hindered the further conversion of PG to propanol. The weak basic HAP support efficiently prevented the humin formation. This precisely controlled catalyst has potential in green PG production.
- Fu, Yao,Li, Chuang,Xu, Guangyue,Zhang, Xiang
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- Template-induced: In situ dispersion of enhanced basic-sites on sponge-like mesoporous silica and its improved catalytic property
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Catalytic performance of heterogeneous catalysis is strongly dependent on the dispersity of catalytic active sites, and especially a high exposure of the unit active phase is promising for the overall catalytic process. In this study, a novel strategy was developed to fabricate an unprecedented CaO-based mesoporous solid strong base catalyst. Relying on the physicochemical assembly of Ca2+ in the interface between a micelle and siliceous wall, thin-layer-like calcium oxide species were formed in situ and dispersed in the mesochannels of silica. Wherein, the gradual coverage of CaO on the mesoporous wall was controlled by adjusting the amounts of Ca2+ on alkylamine micelles. Interestingly, a novel sponge-like microscale structure of silica was discovered in the CaO-based mesoporous-composites for the first time, which completely differs from the reported mesoporous silica. More importantly, the introducing of a CaO solid base on the pore wall is nearly non-destructive for the textural properties of the mesoporous matrix. The direct template-induced mesoporous solid strong base not only received extremely dispersed and unexpected enhanced strong basic sites (CO2-desorption temperature ≥718 °C), but also avoided repeated thermal processes for the degradation of the basic resource, and saved energy and time. This heterogeneous alkaline catalyst shows excellent catalytic activity for the synthesis of dimethyl carbonate under a milder reaction condition (30 °C, 25 min) and holds stability and reusability beyond comparison with the conventional catalysts. The dispersed and enhanced strong basic sites, combined with excellent mesoporous properties, are demonstrated to be responsible for such a high catalytic performance.
- Yang, Fu,Wang, Bangbang,Zhou, Shijian,Yang, Xiaoning,Kong, Yan
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- Promoter effect of Pd in CuCr2O4 catalysts on the hydrogenolysis of glycerol to 1,2-propanediol
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CuCr2O4 catalysts containing various amounts of Pd (Pd-CuCr) were prepared by a co-precipitation method and examined for use in the conversion of glycerol to 1,2-propanediol (1,2-PDO). Pd was observed to be highly dispersed in a CuCr2O4 spinel structure and conferred unique reduction characteristics of a CuCr2O4 catalyst. After reduction, the amounts of surface exposed Cu0 species and occluded hydrogen species were much larger in the case of added Pd, the Pd-CuCr catalyst, compared to a pure copper chromite catalyst. The Pd-CuCr catalyst utilized hydrogen very efficiently, resulting in an enhancement in the catalytic activity for the conversion of glycerol to 1,2-PDO, even at a relatively low hydrogen pressure. The Pd0.5-CuCr catalyst (containing 0.5 wt% of Pd) showed a total yield of 93.9%, with a selectivity approaching 100% for 1,2-PDO at a hydrogen pressure of 4 MPa. In a kinetic study, the effects of H2 pressure and the concentration of glycerol on the initial rate were examined. Based on the results, the palladium promoter (Pd-CuCr) enhanced the rate constant by about 1.7 times compared with copper chromite. The results provide a basis for the production of 1,2-PDO from glycerol using a process which is both environmentally benign and has improved economics.
- Kim, Nam Dong,Park, Jae Ryul,Park, Dae Sung,Kwak, Byoung Kyu,Yi, Jongheop
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- Ruthenium Nanoparticles Supported on Carbon: An Active Catalyst for the Hydrogenation of Lactic Acid to 1,2-Propanediol
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The hydrogenation of lactic acid to form 1,2-propanediol has been investigated using Ru nanoparticles supported on carbon as a catalyst. Two series of catalysts which were prepared by wet impregnation and sol-immobilization were investigated. Their activity was contrasted with that of a standard commercial Ru/C catalyst (all catalysts comprise 5 wt % Ru). The catalyst prepared using sol-immobilization was found to be more active than the wet impregnation materials. In addition, the catalyst made by sol-immobilization was initially more active than the standard commercial catalyst. However, when reacted for an extended time or with successive reuse cycles, the sol-immobilized catalyst became less active, whereas the standard commercial catalyst became steadily more active. Furthermore, both catalysts exhibited an induction period during the first 1000 s of reaction. Detailed scanning transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray absorption fine structure analysis data, when correlated with the catalytic performance results, showed that the high activity can be ascribed to highly dispersed Ru nanoparticles. Although the sol-immobilization method achieved these optimal discrete Ru nanoparticles immediately, as can be expected from this preparation methodology, the materials were unstable upon reuse. In addition, surface lactide species were detected on these particles using X-ray photoelectron spectroscopy, which could contribute to their deactivation. The commercial Ru/C catalysts, on the other hand, required treatment under reaction conditions to change from raft-like morphologies to the desired small nanoparticle morphology, during which time the catalytic performance progressively improved.
- Iqbal, Sarwat,Kondrat, Simon A.,Jones, Daniel R.,Schoenmakers, Dani?l C.,Edwards, Jennifer K.,Lu, Li,Yeo, Benjamin R.,Wells, Peter P.,Gibson, Emma K.,Morgan, David J.,Kiely, Christopher J.,Hutchings, Graham J.
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- Transesterification of propylene carbonate by methanol using KF/Al 2O3 as an efficient base catalyst
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Dimethyl carbonate was synthesized via transesterification of propylene carbonate by methanol using KF/Al2O3 as base catalyst. The catalyst was characterized using FT-IR, XRD, surface area measurement, alkalinity measurement and SEM analysis. The effect of KF loading on Al 2O3, reaction parameters such as reaction temperature, reactant ratio and amount of catalyst on the product yield were investigated. It was found that the catalyst with 20 wt% KF loading on neutral alumina showed 70.9% propylene carbonate conversion with >98% DMC selectivity. Springer Science+Business Media, LLC 2010.
- Murugan,Bajaj,Jasra
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- Bio-propylene glycol by liquid phase hydrogenolysis of glycerol with Ni/SiO2-C catalysts
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The development of catalytic materials, hydrothermally stable and selective to the desired products, is still a challenge. The aim of the present work is to prepare a nickel catalyst with a metal loading of 5 wt% Ni supported on a SiO2-C composite, to be used in the liquid-phase glycerol hydrogenolysis reaction. The most active and selective catalyst to 1,2-propylene glycol (1,2-PG) was Ni/SC-095, which presented surface acidity fundamentally represented by the presence of carboxylic groups which promoted the C[sbnd]O cleavage reactions of the glycerol primary carbon to produce acetol, and subsequently by hydrogenation to produce 1,2-PG. Concerning the selection of operating conditions, the influence of the most relevant variables of the process were analyzed, i.e., temperature (220–260 °C), glycerol concentration (30–65%), and hydrogen partial pressure (0–4 MPa). The best result was obtained at 260 °C with 30 wt% glycerol, 6 h on reaction and a hydrogen partial pressure of 2 MPa. Under these conditions, selectivities of 77% towards 1,2-PG and 3% to acetol were obtained, with 56% of conversion. It was demonstrated that there are no important structural changes through the characterization of the used samples. Both the SC-095 support and the Ni/SC-095 catalyst maintained their BET surface area. By XRD and TEM, there could be a slight increase in particle size, which would indicate good resistance to sintering against the severe hydrothermal conditions of this reaction.
- Gatti, Martín N.,Pompeo, Francisco,Santori, Gerardo F.,Nichio, Nora N.
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- A thermally stable and easily recycled core-shell Fe2O 3@CuMgAl catalyst for hydrogenolysis of glycerol
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Core-shell structured magnetic Fe2O3@CuMgAl layered double hydroxide (LDH) catalysts were synthesized in a facile route and used in selective hydrogenolysis of glycerol. Characterization disclosed that the thermal stability of the LDH framework, the dispersion of Cu and its activity were enhanced simultaneously in the presence of Fe2O3. This journal is the Partner Organisations 2014.
- Xia, Shuixin,Du, Weichen,Zheng, Liping,Chen, Ping,Hou, Zhaoyin
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- One-pot synthesis of propylene glycol and dipropylene glycol over strong basic catalyst
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The synthesis of propylene glycol (PG) and dipropylene glycol (DPG) was carried out by the hydrolysis of propylene oxide over solid base catalysts. Among them, sol-gel derived Na2O-ZrO2 showed the excellent performance. It was found that Na2O-ZrO2 had a mesoporous framework in which Na2O nanoparticles were homogeneously dispersed. Such a structure led to the strong basicity and then the excellent performance in the hydrolysis of propylene oxide. As a result, one-pot synthesis of propylene glycol (PG) and dipropylene glycol (DPG) could take place at a low H2O/PO ratio of 3 without any condensation reactions. Crown Copyright
- Liu, Zhuo,Zhao, Wenbo,Xiao, Fukui,Wei, Wei,Sun, Yuhan
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- Electrocatalytic hydrogenation of oxygenates using earth-abundant transition-metal nanoparticles under mild conditions
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Electrocatalytic hydrogenation (ECH) is a sustainable pathway for the synthesis of value-added organic compounds, provided affordable catalysts with high activity, selectivity and durability are developed. Here, we synthesize Cu/C, Ni/C, and CuNi/C nanoparticles and compare their performance to Pt/C, Ru/C, PtRu/C for the ECH of hydroxyacetone, a bio-derived feedstock surrogate containing a carbonyl and a hydroxyl functional group. The non-precious metal electrocatalysts show promising conversion-time behavior, product selectivities, and Faradaic efficiencies. Ni/C forms propylene glycol with a selectivity of 89 % (at 80 % conversion), while Cu/C catalyzes ECH (52 % selectivity) and hydrodeoxygenation (HDO, 48 % selectivity, accounting for evaporation). CuNi/C shows increased turnover frequencies but reduced ECH selectivity (80 % at 80% conversion) as compared to the Ni/C catalyst. Importantly, stability studies show that the non-precious metal catalysts do not leach at operating conditions.
- Carroll, Kyler J.,Burger, Thomas,Langenegger, Lukas,Chavez, Steven,Hunt, Sean T.,Román-Leshkov, Yuriy,Brushett, Fikile R.
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- Hydrogenation of Lactic Acid to 1,2-Propanediol over Ru-Based Catalysts
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The catalytic hydrogenation of lactic acid to 1,2-propanediol with supported Ru catalysts in water was investigated. The influence of catalyst support (activated carbon, γ-Al2O3, SiO2, TiO2, and CeO2) and promoters (Pd, Au, Mo, Re, Sn) on the catalytic performance was evaluated. Catalytic tests revealed that TiO2 yields the best Ru catalysts. With a monometallic Ru/TiO2 catalyst, a 1,2-propanediol yield of 70 % at 79 % lactic acid conversion was achieved at 130 °C after 20 h reaction. Minor byproducts of the hydrogenation reaction were propionic acid, ethanol, 1-propanol, and 2-propanol. For the bimetallic catalysts, the addition of Pd and Au slightly enhanced the performance of Ru/TiO2, whereas the addition of common hydrogenation promoters such as Re, Mo, and Sn impaired the activity.
- Liu, Kaituo,Huang, Xiaoming,Pidko, Evgeny A.,Hensen, Emiel J. M.
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- Enhancement of Catalytic Activity in Epoxide Hydration by Increasing the Concentration of Cobalt(III)/Salen in Porous Polymer Catalysts
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The rational design of catalytic materials from the reaction characteristics is expected to be a useful strategy to create highly efficient catalysts. Herein, according to a well-established reaction pathway of epoxide hydration catalyzed a dual-molecular system of Co3+/salen in which a high concentration of active sites is favorable to enhance the activity, we provide an alternative way to prepare a highly efficient heterogeneous catalyst with a high concentration of Co3+/salen from the polymerization of vinyl-functionalized salen monomers followed by the loading of Co3+ species (Co3+/POL-salen). Co3+/POL-salen has a hierarchical porosity and an extraordinary hydrothermal stability. Importantly, catalytic tests in epoxide hydration demonstrate that Co3+/POL-salen affords excellent high activities, which are even better than those of the homogeneous version. This phenomenon is related to the very high concentration of Co3+/salen in the catalyst. In addition, this catalyst can be recycled readily because of its excellent hydrothermal stability.
- Dai, Zhifeng,Sun, Qi,Chen, Fang,Pan, Shuxiang,Wang, Liang,Meng, Xiangju,Li, Jixue,Xiao, Feng-Shou
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- Enhanced activity of Ru/TiO2 catalyst using bisupport, bentonite-TiO2 for hydrogenolysis of glycerol in aqueous media
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A combination of bentonite-TiO2 was used as support to enhance the activity of Ru/TiO2 catalyst in hydrogenolysis of aqueous glycerol to 1,2-propanediol. A series of bentonite, TiO2, SiO 2 and Al2O3 supported Ru catalyst were fabricated and characterized by XRD, XPS, BET, FESEM-EDX and TEM to establish some physicochemical properties of the catalysts. The activity of the catalysts was tested in glycerol hydrogenolysis reaction and were found to be in the following increasing order: Ru/SiO2 2 ≈ Ru/Al2O3 2 with a reaction duration of 7 h. The Ru/TiO2 catalyst exhibited the highest selectivity (83.7%) for hydrogenolysis of glycerol to 1,2-propanediol and with 38.8% conversion only. The activity of Ru/TiO2 catalyst was enhanced by adding bentonite to the titania support at 1:2 ratio resulting in an 80% increasing the activity from 38.8% to 69.8% under the same optimum condition for Ru/TiO2 while maintaining an 80% selectivity to 1,2-propanediol. TPD-NH3 analysis found that mixed support could increase catalyst acidity. CO pulse chemisorption analysis revealed that Ru particles was well dispersed with the smallest average size particles (1.5 nm) which could contribute to high activity of Ru/TiO2 catalyst for hydrogenolysis of glycerol.
- Hamzah, Noraini,Nordin, Norasikin Mohamad,Nadzri, Ainol Hayah Ahmad,Nik, Yah Awg,Kassim, Mohamad B.,Yarmo, Mohd Ambar
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- Hydrogenation of lactic acid on reduced copper-containing catalysts
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The copper-containing catalysts were prepared by reduction of various oxide precursor compounds. Their catalytic properties were studied in the hydrogenation of lactic acid to propylene glycol under atmospheric pressure. An efficient catalyst, whose precursor compound is copper hydroxosilicate with the structure close to the natural mineral chrysocolla, was developed. The optimum conditions for the synthesis of propylene glycol were established that make it possible to achieve a conversion of lactic acid of 97% at atmospheric hydrogen pressure and 473 K. ; 2009 Springer Science+Business Media, Inc.
- Simonov,Simakova,Minyukova,Khassin
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- Superbasic sodium stannate as catalyst for dehydrogenation, Michael addition and transesterification reactions
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It has been shown that sodium stannate with superbasic sites generated on its surface can be obtained through simple thermal treatment of sodium stannate hydrate in pure N2. In this study, we analyzed the as-prepared materials using powder X-ray diffraction, X-ray photoelectron spectroscopy, and N2 physisorption methods. The superbasic sites were characterized by techniques of Hammett indicators and temperature-programmed desorption using CO2 as adsorbate. It was shown that after undergoing calcination at 623 K, there are ample superbasic sites on sodium stannate: up to 0.254 mmol/g. The superbasicity of the materials was further confirmed by employing the 1-hexene as well as cyclohexa-1,4-diene double bond isomerization reactions. The superbasicity is attributed to the higher electron-donating ability of surface O2-. The sodium stannate samples showed excellent catalytic efficiency towards selected reactions, namely the dehydrogenation of propa-2-nol, Michael addition of electron-deficient olefins, and transesterification of cyclic carbonate with methanol. It was observed that with rise of heat-treatment temperature from 573 to 623 K, both superbasicity and catalytic activity increased, reaching a maximum at 623 K, and then declined. It is deduced that catalytic efficiency is closely related to superbasicity of the sodium stannate catalysts.
- Zhang, Shu-Guo,Wei, Yu-Dan,Yin, Shuang-Feng,Luo, Sheng-Lian,Au, Chak-Tong
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- A low-cost method for obtaining high-value bio-based propylene glycol from sugar beet pulp
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A new low-cost pathway for the production of high-value propylene glycol (PG) is proposed. This route of waste biomass utilization employs catalytic reduction of lactic acid obtained from fermented enzymatic digests of sugar beet pulp. This journal is
- Berlowska,Binczarski,Dudkiewicz,Kalinowska,Witonska,Stanishevsky
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- Covalent triazine frameworks as heterogeneous catalysts for the synthesis of cyclic and linear carbonates from carbon dioxide and epoxides
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The base catalytic properties of a series of triazine-based covalent organic frameworks were evaluated for the conversion of CO2 to organic carbonates. The high number of basic nitrogen sites of the as-synthesized frameworks efficiently catalyzed the formation of cyclic carbonates via the cycloaddition of CO2 to different starting epoxides. The structural and chemical tunability of the covalent triazine frameworks allowed the fine evaluation of key parameters influencing the observed catalytic activities. An increased surface area and presence of additional mesopores dramatically enhance the activity of the investigated catalytic materials. The chemical composition was also found to influence the reaction, as evidenced by an increased activity at lower reaction temperatures, when a more basic, pyridine-based, framework was used as catalyst. Finally, the activity in the two-step cycloaddition/transesterification catalysis of dimethyl carbonate was evaluated in a one-batch process. Copyright
- Roeser, Jerome,Kailasam, Kamalakannan,Thomas, Arne
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- Effects of the precipitation agents and rare earth additives on the structure and catalytic performance in glycerol hydrogenolysis of Cu/SiO 2 catalysts prepared by precipitation-gel method
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The effects of the precipitation agents (NaOH, Na2CO 3, NH4OH and NH4HCO3) and rare earth additives (La, Ce, Y, Pr and Sm) were studied on the structure and catalytic performance in glycerol hydrogenolysis of the Cu/SiO2 catalysts prepared by precipitation-gel method. The physical-chemical properties of the catalysts were characterized by means of FTIR, H2-TPR, N2O chemisorption, XRD, XPS, BET and TEM. The results showed that precipitation agents had obvious effects on the phase structure, reduction property and catalytic performances (activity, selectivity and stability) of the catalysts. The Cu/SiO2 catalyst precipitated with NaOH presented the highest activity and stability than those with other precipitants, most likely due to its more even dispersion of Cu particles, higher resistant to sintering during glycerol reaction. The incorporation of rare earth additives to Cu/SiO 2 catalyst could promote the structural stability and inhibit the sintering and leaching of the catalysts, especially noticeable for Y and La, and thus contribute to the long-term stability of the catalysts. Clearly, this study provides directions for the design of more efficient and stable Cu catalysts toward the industrial application of glycerol hydrogenolysis.
- Huang, Zhiwei,Liu, Hailong,Cui, Fang,Zuo, Jianliang,Chen, Jing,Xia, Chungu
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- Epoxides hydration on CoIII(salen)-OTs encapsulated in silica nanocages modified with prehydrolyzed TMOS
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The silylation for reducing the pore entrance size is crucial for the success encapsulation of molecular catalysts. Herein, we reported the preparation of an efficient solid catalyst for epoxide hydration via encapsulation of CoIII(salen)-OTs in the nanocages of FDU-12 using prehydrolyzed tetramethylorthosilicate (TMOS) as silylation reagent under mild condition. CoIII(salen)-OTs in nanocages could afford TOF of 2760 h-1 in the hydration of propylene epoxide (PO), which is the highest ever reported at low PO/H2O molar ratio. Comparison of the activity of CoIII(salen)-OTs accommodated in nanocages with different microenvironments suggests that CoIII(salen)-OTs in hydrophilic microenvironment was more active than that in hydrophobic microenvironment in the hydration of propylene epoxide. Moreover, studies show that the deactivation rate of CoIII(salen)-OAc is lower than that of CoIII(salen)-OTs in nanocages due to the confinement effect of the nanoreactor.
- Zhong, Mingmei,Zhao, Yaopeng,Yang, Qihua,Li, Can
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- Hydrogenolysis of glycerol over a highly active CuO/ZnO catalyst prepared by an oxalate gel method: Influence of solvent and reaction temperature on catalyst deactivation
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The hydrogenolysis of glycerol was performed in an autoclave at temperatures between 190 and 225 °C and at a H2 pressure of 5 MPa over a CuO/ZnO catalyst prepared by an oxalate gel (OG) method. Compared to a CuO/ZnO catalyst prepared by coprecipitation, much higher conversions of glycerol and space-time yields up to 9.8 gpropylene glycol g Cu-1 h-1 are achieved with CuO/ZnO-OG, whereas both catalysts produced propylene glycol with selectivities of about 90%. Additionally, the influence of the temperature and the solvent was examined. Compared to a conversion of glycerol of only 5% in an aqueous glycerol solution, the use of 1,2-butanediol as a solvent leads to a high conversion of 55%. Moreover, experiments were carried out in pure glycerol and from transmission electron microscopy images of fresh and spent catalysts, it was obvious that the morphology of the catalyst changed during the reaction. By X-ray diffraction and N2O chemisorption, it was proved that a tremendous loss of copper surface area occurred during the hydrogenolysis of glycerol. Taking together the influence of the solvent on the conversion of glycerol and the results of the catalyst characterization, it can be concluded that water, as an unavoidable by-product of the reaction, is responsible for a strong deactivation of the catalyst.
- Bienholz, Arne,Schwab, Frederick,Claus, Peter
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- Efficient and selective conversion of glycidol to 1,2-propanediol over Pd/C catalyst
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The present work deals with the catalytic hydrogenolysis of glycidol to 1,2-propanediol. Reactions were carried out in a closed steel reactor using noble metal based heterogeneous catalysts (Pd, Rh, Pt) under hydrogen pressure (1-8 bars) in the temperature range of 25-140°C. Pd/C shows the highest glycidol conversion (96%) under solvent free conditions after 24 h with high selectivity to 1,2-propanediol (93%). The effect of the solvent was also investigated and it was demonstrated that ethanol reduces drastically oligomer production enhancing selectivity up to 99% with a significant reaction time reduction (6 h). The Pd/C catalyst shows high recyclability and could be reused several times (9 cycles) without losses in activity and selectivity.
- Cucciniello, Raffaele,Pironti, Concetta,Capacchione, Carmine,Proto, Antonio,Di Serio, Martino
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- Hydrogenolysis of glycerol on bimetallic Pd-Cu/solid-base catalysts prepared via layered double hydroxides precursors
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A series of bimetallic Pd-Cu/solid-base catalysts were prepared via thermal decomposition of PdxCu0.4Mg5.6-xAl 2(OH)16CO3 layered double hydroxides precursors and used in hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2O oxidation and followed H2 titration characterizations confirmed that well structured layered double hydroxides PdxCu0.4Mg 5.6-xAl2(OH)16CO3 crystals could be prepared when the amount of added Pd was less than x xCu0.4/Mg 5.6-xAl2O8.6-x and Pd improved the reduction of Cu. Hydrogenolysis of glycerol proceeded easily on bimetallic Pd-Cu/solid-base catalysts than separated Pd and Cu. On Pd0.04Cu0.4/Mg 5.56Al2O8.56, the conversion of glycerol and selectivity of 1,2-PDO reached 88.0 and 99.6%, respectively, at 2.0 MPa H 2, 180 °C, 10 h in ethanol solution. And this catalyst is stable in five recycles. It was concluded that H2-spillover from Pd to Cu increased the activity of PdxCu0.4/Mg 5.6-xAl2O8.6-x in hydrogenolysis of glycerol.
- Xia, Shuixin,Yuan, Zhenle,Wang, Lina,Chen, Ping,Hou, Zhaoyin
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- Synthesis of dimethyl carbonate over waste eggshell catalyst
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Dimethyl carbonate is an important methylating and carbonylating agent. Eggshell catalysts, prepared from eggshell waste, were tested in the synthesis of dimethyl carbonate from propylene carbonate and methanol. The eggshell-derived catalyst was characterized by using techniques of nitrogen physisorption, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and energy dispersive X-ray spectroscopy (EDS). The effects of calcination temperature on structure and activity of eggshell catalysts were investigated. The reusability of eggshell catalysts was also examined. It was found that highly active, reusable solid catalyst was obtained by just calcining eggshell. Dimethyl carbonate yield of 75% can be achieved at 25 °C and 1 atm pressure. Utilization of eggshell as a catalyst for dimethyl carbonate production not only provides a cost-effective and environmental friendly way of recycling this solid eggshell waste, but also makes the process of dimethyl carbonate production economic and fully ecologically friendly.
- Gao, Yuan,Xu, Chunli
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- Cu/SiO2 catalysts prepared by hom- and heterogeneous deposition-precipitation methods: Texture, structure, and catalytic performance in the hydrogenolysis of glycerol to 1,2-propanediol
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Cu/SiO2 catalysts prepared by homogeneous deposition- precipitation (Hom-DP) and heterogeneous deposition-precipitation (Het-DP) methods have been systematically characterized focusing on the effect of precipitation manner during catalyst preparation. It is found that the texture, structure and composition of the dried, calcined and reduced catalysts were largely affected by the precipitation manner. Based on characterizations and previous findings, the copper species on the dried, calcined, and reduced catalysts as well as on the catalysts after work were assigned. Due to a homogeneous precipitation manner, the catalyst prepared by Hom-DP method presented a much higher dispersion, a smaller copper particle size and thus a larger copper surface area than those of its counterpart prepared by Het-DP method. Unexpectedly, catalytic activity tests in the hydrogenolysis of glycerol showed that the catalyst prepared by Het-DP method inversely surpassed the former catalyst, mainly due to a larger number of copper species in the Het-DP catalyst was prereduced to active Cu0 sites, which also presented remarkably higher stability during aqueous phase glycerol reaction as compared to those in the former catalyst. In addition, the selectivity to 1,2-propanediol product is found to be affected by both the precipitation agent applied and the structure of the catalysts.
- Huang, Zhiwei,Cui, Fang,Xue, Jingjing,Zuo, Jianliang,Chen, Jing,Xia, Chungu
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- Selective hydrogenolysis of glycerol to 1,2-propanediol over bimetallic Cu-Ni catalysts supported on γ-Al2O3
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A series of Cu or Ni monometallic and Cu-Ni bimetallic catalysts supported on γ-Al2O3 were synthesized by incipient wetness impregnation method. X-ray diffraction results exhibited the formation of bimetallic Cu-Ni phase in the reduced Cu-Ni(1:1)/γ-Al2O3 catalyst. Among the catalyst examined for hydrogenolysis of glycerol, bimetallic catalysts exhibited higher catalytic activity than monometallic catalysts due to synergetic effect of Cu-Ni bimetal. Cu-Ni(1:1)/γ-Al2O3 catalyst displayed a maximum glycerol conversion of 71.6percent with 92.8percent selectivity to 1,2-propanediol at 210 °C and 4.5 MPa hydrogen pressure. The superior performance of Cu-Ni(1:1)/γ-Al2O3 catalyst was attributed to the formation of bimetallic Cu-Ni phase, high active metal surface area, small Cu-Ni particle size, and high acidic strength of the catalyst. Stability and reusability of Cu.Ni(1:1)/γ-Al2O3 catalyst was performed and detailed characterization results of fresh and used catalysts suggested that bimetallic Cu-Ni phase remained stable after reuses.
- Pudi, Satyanarayana M.,Biswas, Prakash,Kumar, Shashi,Sarkar, Biswajit
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- Catalytic conversion of lactic acid into propylene glycol over various metals supported on silica
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Catalytic hydrogenation of lactic acid to propylene glycol was performed over various metals (Ag, Co, Cu, Ni, Pt, and Ru) supported on silica prepared by an incipient wetness impregnation method. The loading amount of each metal was 5 wt%. Crystallinity of the synthesized catalysts was investigated by X-ray diffraction (XRD), and the BET method was utilized to examine the surface area. Pore volume and pore size of catalysts were determined using BJH analysis of the N2 adsorption isotherm. Particle sizes of various metals were determined from transmission electron microscopy (TEM) images. The catalytic activity was found to be strongly dependent on the supported metal. Among catalysts tested, Ru/SiO2 showed the highest propylene glycol yield. The yield of propylene glycol increased with pressure, and the highest yield was achieved at 130 °C.
- Jang, Tae Young,Chung, Ku Bong,Eom, Hye Ri,Noh, Dong Kyun,Song, In Kyu,Yi, Jongheop,Baeck, Sung-Hyeon
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- Mg(OH)2-Facilitated Liquid-Phase Conversion of Lactic Acid into 1,2-Propanediol over Cu: An Experimental and Theoretical Study
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Mg(OH)2 is found to exhibit superior performance in the liquid-phase conversion of lactic acid (LA) into 1,2-propanediol over Cu. A conversion of 90 % with a selectivity of 98 % is achieved at 513 K and 5 MPa H2. Mg(LA)2 could be identified as a crucial intermediate in this reaction, as it undergoes faster conversion than the combination of LA and Mg(OH2) and regeneration of Mg(OH)2 through the conversion of Mg(LA)2 as a substrate. DFT calculations reveal that the energetic span of the reaction decreases from 46.6 kcal mol?1 catalyzed with no cation to 43.6 kcal mol?1 with [Mg(OH)]+, confirming the facilitating effect of Mg(OH)2.
- Wang, Xinde,Beine, Anna Katharina,Hausoul, Peter J. C.,Palkovits, Regina
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- A Nuclear Magnetic Resonance Kinetic and Product Study of the Ring Opening of Propylene Oxide. Nucleophilic and General Catalysis by Phosphate
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Systematic kinetic and product studies have been performed in an examination of the ring opening of propylene oxide over the entire pH region.The NMR kinetic method, which involves the integration of reactant and product resonances as a function of time, provided the rate data.The plots of log (areat - areainfinite) vs. time were linear to better than three half-life times of reactiom.Reproducibility error for rate measurements run under identical conditions wes less than 5percent.Products were identified by 1H and 13C NMR spectroscopy and with gated decoupler techniques.The latter was used to quantitatively determine the product composition.The validity of this method of product analysis was carefully established with a series of control experiments.The error in these determinations was shown to be less than 4percent.Emphasis was placed on the search for general and nucleophilic mechanisms of catalysis.Kinetic and product analyses were performed on reaction solutions in both aqueous formate and aqueous phosphate buffers.The glycol monoformate esters proved to be labile under kinetic conditions.By contrast the glycol monophosphate esters permitted a complete dissection of the buffer catalytic components into nucleophilic and general modes.Thus careful analysis of the reaction species present in the buffer matrix shows that glycol monophosphate esters are always produced in amounts less than the buffer contribution to the overall rate and furthermore arise almost exclusively from HPO42- attack upon neutral epoxide.This nucleophilic catalysis accounts for 80 +/- 6percent of kHPO42- and leads to almost equal amounts of 1,2-propanediol-1-phosphate and 1,2-propanediol-2-phosphate.The remaining 20 +/- 6percent of kHPO42- and the total kH2PO4- represent general catalysis.These contributions arise mechanistically though hydrogen bonding which operates to increase the nucleophilic capacity of rear side water molecules or to enhance the electrophilic character of the epoxide ring, respectively.
- Pocker, Y.,Ronald, B. P.,Ferrin, L.
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- Enzyme-based nanoscale composites for use as active decontamination surfaces
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Perhydrolase S54V (AcT) effectively catalyzes the perhydrolysis of propylene glycol diacetate (PCD) to generate peracetic acid (PAA). PAA is a potent oxidant used for sanitization and disinfection, with broad effectiveness against bacteria, yeasts, fungi, and spores. In this study, active and stable composites are developed by incorporating AcT-carbon nanotube conjugates into polymer and latex-based paint At a conjugate loading of 0.16% (w/v), the composite generated 11mM PAA in 20 min, capable of killing more than 99% spores initially charged at 106 colony-forming units per milliliter.
- Dinu, Cerasela Zoica,Zhu, Guangyu,Bale, Shyam Sundhar,Anand, Gaurav,Reeder, Philippa J.,Sanford, Karl,Whited, Gregg,Kane, Ravi S.,Dordick, Jonathan S.
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- One-pot Fixation of CO2 into Glycerol Carbonate using Ion-Exchanged Amberlite Resin Beads as Efficient Metal-free Heterogeneous Catalysts
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The one-pot synthesis of glycerol carbonate from carbon dioxide and glycerol was achieved using ion-exchanged Amberlite resin beads as metal-free heterogeneous catalysts. Two commercially available Amberlite resin beads consisting of polystyrene cross-linked with divinylbenzene and functionalized with either trimethyl ammonium chloride (IRA-900) or dimethyl ethanol ammonium chloride (IRA-910) groups were used as starting materials to prepare the catalysts. These polymeric beads were transformed into their iodide (Amb-900-I, Amb-OH-910-I) or hydroxide (Amb-900-OH and Amb-OH-910-OH) counterparts through straightforward ion-exchange reactions. First, the two resin bead catalysts in hydroxide form were tested in the base-catalyzed transcarbonation reaction of glycerol with propylene carbonate. Both resin bead catalysts were more active compared to benchmark basic catalysts as hydrotalcites and attained 80 % yield of glycerol carbonate over Amb-OH-910-OH after 2 h at 115 °C, employing a 4 : 1 ratio between propylene carbonate and glycerol. Then, the one-pot reaction of CO2, glycerol and propylene oxide to produce propylene carbonate, glycerol carbonate and propylene glycol was investigated as the main target of this study. The reaction involves two steps: the reaction of propylene oxide with CO2 yielding propylene carbonate, and the transcarbonation of the formed cyclic carbonate with glycerol. Amb-900-I, Amb-OH-910-I, Amb-OH-910-OH and combinations of the latter two were employed as catalysts. Although Amb-OH-910-I alone is poorly active in the transcarbonation reaction, it showed the highest catalytic activity in the one-pot cascade reaction, surprisingly surpassing the performance of the Amb-OH-910-I/Amb-OH-910-OH mixtures and reaching high yields of glycerol carbonate (81 %, 115 °C, 4 h). These findings led to proposing a mechanism for the one-pot reaction using the Amb-OH-910-I catalyst. The bead format led to easy recovery of the catalyst, which displayed good reusability in consecutive runs.
- Alassmy, Yasser A.,Paalman, Patrick J.,Pescarmona, Paolo P.
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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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- 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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p. 2992 - 3000
(2021/05/07)
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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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- Highly efficient catalytic transfer hydrogenation of furfural over defect-rich amphoteric ZrO2with abundant surface acid-base sites
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Currently, the catalytic transformation and utilization of biomass-derived compounds are of great importance to the alleviation of environmental problems and sustainable development. Among them, furfural alcohol derived from biomass resources has been found to be one of the most prospective biomass platforms for high-value chemicals and biofuels. Herein, high-surface-area ZrO2 with abundant oxygen defects and surface acid-base sites was synthesized and used as a heterogeneous catalyst for the catalytic transfer hydrogenation of furfural into furfural alcohol using alcohol as a hydrogen donor. The as-synthesized ZrO2 exhibited excellent catalytic performance with 98.2% FA conversion and 97.1% FOL selectivity, even comparable with that of a homogeneous Lewis acid catalyst. A series of characterization studies and experimental results revealed that acid sites on the surface of ZrO2 could adsorb and activate the CO bond in furfural and base sites could facilitate the formation of alkoxide species. The synergistic effect of surface acid-base sites affords a harmonious environment for the reaction, which is crucial for catalytic transfer hydrogenation of furfural with high efficiency. Furthermore, the as-prepared ZrO2 catalyst also exhibited a potential application for the efficient catalytic transfer hydrogenation of a series of biomass-derived carbonyl compounds. This journal is
- Zhu, Zekun,Yang, Lingling,Ke, Changxuan,Fan, Guoli,Yang, Lan,Li, Feng
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p. 2616 - 2626
(2021/03/03)
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- MOF-derived hcp-Co nanoparticles encapsulated in ultrathin graphene for carboxylic acids hydrogenation to alcohols
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Highly efficient conversion of carboxylic acids to valuable alcohols is a great challenge for easily corroded non-noble metal catalysts. Here, a series of few-layer graphene encapsulated metastable hexagonal closed-packed (hcp) Co nanoparticles were fabricated by reductive pyrolysis of metal-organic framework precursor. The sample pyrolyzed at 400 °C (hcp-Co@G400) presented outstanding performance and stability for converting a variety of functional carboxylic acids and its turnover frequency was one magnitude higher than that of conventional facc-centered cubic (fcc) Co catalysts. In situ DRIFTS spectroscopy of model reaction acetic acid hydrogenation and DFT calculation results confirm that carboxylic acid initially undergoes dehydroxylation to RCH2CO* followed by consecutive hydrogenation to RCH2CH2OH through RCH2COH*. Acetic acid prefers to vertically adsorb at hcp-Co (0 0 2) facet with a much lower adsorption energy than parallel adsorption at fcc-Co (1 1 1) surface, which plays a key role in decreasing the activation barrier of the rate-determining step of acetic acid dehydroxylation.
- Dong, Mei,Fan, Weibin,Gao, Xiaoqing,Zhu, Shanhui
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p. 201 - 211
(2021/06/03)
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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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- 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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- Hydrogenolysis of glycerol to 1,3-propanediol over H-ZSM-5-supported iridium and rhenium oxide catalysts
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The hydrogenolysis of glycerol to 1,3-propanediol (1,3-PrD) over Ir-ReOx catalysts supported on H-ZSM-5 (denoted as Ir-ReOx/H-ZSM-5) was investigated. The glycerol conversion and 1,3-PrD yield strongly depended on the catalyst composition (Re/Ir) and the amount of metal loading. The analyses of the catalysts using X-ray powder diffraction and transmission electron microscopy revealed that a higher metal dispersion of Ir and a smaller Ir particle were encouraged by the addition of Re to the catalyst. Furthermore, a strong electronic interaction between Ir and Re in the Ir-ReOx/H-ZSM-5 catalyst was observed from X-ray photoelectron spectroscopy measurements. In the study on the effects of operating conditions, increasing the temperature and reaction time resulted in a higher glycerol conversion at the expense of 1,3-PrD selectivity due to over-hydrogenolysis, whereas increasing the pressure had a positive effect on 1,3-PrD selectivity. The highest 1,3-PrD yield observed was achieved at 2.8% with 14.9% glycerol conversion and 19.0% 1,3-PrD selectivity.
- Chanklang, Sarun,Chareonpanich, Metta,Faungnawakij, Kajornsak,Mondach, Wongsaphat,Seubsai, Anusorn,Somchuea, Pooripong,Witoon, Thongthai
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- Hydrogenolysis of glycerol in an aqueous medium over Pt/WO3/zirconium phosphate catalysts studied by1H NMR spectroscopy
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Bifunctional Pt/WO3/zirconium phosphate catalyzes the liquid-phase hydrogenolysis of glycerol in an aqueous medium.1H NMR spectroscopy (solvent suppression pulse program) is employed to monitor this reaction. Propanediols (1,3 + 1,2-PDO) formed as the major product along with propanols (1- and 2-POs) as the minor product. A synergistic enhancement in glycerol conversion and selectivity to 1,3-PDO was observed when both Pt and WO3were present in the catalyst. Avolcano-shapevariation of catalytic activity with W content was observed. A catalyst with 8 wt% W and 1 wt% Pt exhibited the highest selective hydrogenolysis performance (glycerol conversion = 92.3% and total PDOs selectivity = 45.9% and 1,3-PDO selectivity = 20.8% at 200 °C). Dispersed Pt in contact with polytungstate-type WO3species was found to be the active catalytic site.1H NMR spectroscopy is demonstrated as an attractive technique toquantifythe products of a glycerol hydrogenolysis reaction.
- Bhowmik, Susmita,Enjamuri, Nagasuresh,Darbha, Srinivas
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p. 5013 - 5022
(2021/03/26)
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- Facilitating Pt?WOx Species Interaction for Efficient Glycerol Hydrogenolysis to 1,3-Propanediol
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Designing efficient catalysts for glycerol hydrogenolysis to 1,3-propanediol (1,3-PDO), which involves the selective cleavage of the secondary C?O bond, is a challenging task. Current Pt?WOx-based catalysts often provide low atom efficiency of W and Pt toward 1,3-PDO production due to undesired catalyst structures. Herein, we fabricate the highly-dispersed substantially uniform WOx species on inert α-Al2O3 support by simple high-temperature heat-treatment, and the amount of Pt?WOx interface active sites could be adjusted by Pt loading, showing an excellent catalytic performance in glycerol hydrogenolysis at high concentration of glycerol, especially the unprecedented W efficiency (76 g1,3-PDOgW?1 h?1) toward 1,3-PDO. The high catalytic efficiency is attributed to the strong interaction between the isolated WO4 species and platinum, which could in-situ generate the Br?nsted acid sites during the reaction as evidenced by IR analysis with NH3 adsorption.
- Zhao, Binbin,Liang, Yu,Liu, Lei,He, Qian,Dong, Jin-Xiang
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p. 3695 - 3705
(2021/07/02)
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- GNCC AND/OR PCC AS A CATALYTIC CARRIER FOR METAL SPECIES
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The present invention refers to a catalytic system comprising a transition metal compound on a solid carrier, wherein the content of the transition metal compound on the surface of the solid carrier is from 0.1 to 30 wt.-%, based on the dry weight of the solid carrier. Furthermore, the present invention refers to a method for manufacturing the catalytic system, the use of the inventive catalytic system in a chemical reaction, the use of a solid carrier loaded with a transition metal compound as a catalyst and to granules mouldings or extrudates comprising the catalytic system.
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Page/Page column 31-32
(2021/04/02)
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- Integrated capture and conversion of CO2 to methanol or methanol and glycol
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A process for producing methanol includes combining a hydrogenation catalyst, hydrogen, and CO2 with a condensed phase solution comprising an amine under conditions effective to form methanol and water. A process for coproduction of methanol and a glycol includes combining an epoxide, a hydrogenation catalyst, hydrogen, and CO2 with a condensed phase solution comprising an amine under conditions effective to form methanol and a glycol.
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Page/Page column 37-38
(2021/03/31)
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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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- 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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- 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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- Cu boosting the collaborative effect of Ni and H+in alloyed NiCu/saponite catalysts for hydrogenolysis of glycidol
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The effect of copper on various acid saponite supported Ni-Cu bimetallic catalysts, prepared with different Ni?:?Cu ratios, was studied for the liquid phase hydrogenolysis of glycidol on a batch reactor at 393 and 453 K. Characterization of the catalysts showed that Ni and Cu are in close contact as the XRD measurements evidenced the formation of an alloy. H2chemisorption results revealed that the measured metallic area progressively decreased with an increase in the wt% of copper. In the presence of high metal activity (higher Ni wt%), the formation of 1,2-propanediol (1,2-PD) outweighed, while acid activity led to the formation of dimerization and oligomerization products. The addition of Cu and the increase of the reaction temperature decreased the diol formation but boosted the 1,3-PD/1,2-PD ratio. This could be explained by an improvement of the collaborative effect between the metal Ni and the H+of the saponite. Therefore, the presence of an appropriate amount of Cu allowed the control of the hydrogenation capacity of Ni and enhanced the collaborative effect of Ni and H+favouring the formation of 1,3-propanediol with respect to 1,2-propanediol.
- Cesteros, Yolanda,Gebretsadik, Fiseha Bogale,González, María Dolores,Ruiz-Martinez, Javier,Salagre, Pilar
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p. 9198 - 9207
(2021/07/12)
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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.
- -
-
Page/Page column 7-9
(2021/08/27)
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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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- 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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- The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Br?nsted acid catalysts
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The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Br?nsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled.
- Belokon, Yuri N.,Dmitrienko, Artem O.,Gak, Alexander S.,Gerasimov, Igor S.,Kuznetsova, Svetlana A.,Larionov, Vladimir A.,Li, Han,Medvedev, Michael G.,Nelyubina, Yulia V.,North, Michael,Saghyan, Ashot S.,Smol'yakov, Alexander F.,Zhereb, Vladimir P.
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supporting information
p. 1124 - 1134
(2020/07/10)
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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.
- -
-
Paragraph 0032-0034; 0043-0045
(2020/11/25)
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- Selective hydrogenolysis of biomass-derived sorbitol to propylene glycol and ethylene glycol on in-situ formed PdZn alloy catalysts
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Sorbitol hydrogenolysis to industrially important propylene glycol and ethylene glycol receives increasing attention, recently. Here, we developed an efficient and stable PdZn alloy catalyst, in-situ formed from a physical mixture of Pd/ZrO2 and ZnO, for the sorbitol hydrogenolysis with Mg3AlOx as a solid base, and obtained a 54.6% yield of the two target glycols (493 K and 5.0 MPa H2). The amounts of ZnO and Mg3AlOx strongly influenced the activity and selectivity, due to their effects on the formation of the PdZn alloys and the competitive metal-catalyzed dehydrogenation/hydrogenation and base-catalyzed retro-aldol condensation steps. The kinetic isotope effects, combined with the inhibiting effects of H2 pressure on the activity in a broad range (3.0–8.0 MPa), confirm that the sorbitol dehydrogenation to hexose intermediates is the kinetically-relevant step in the sorbitol hydrogenolysis. This study provides insights into the catalytic functions and reaction parameters for the hydrogenolysis of polyols to the target glycols.
- Jia, Yuqing,Liu, Haichao,Sun, Qianhui
-
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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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- 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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- Studies on continuous selective hydrogenolysis of glycerol over supported Cu-Co bimetallic catalysts
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Alumina supported copper-cobalt catalysts were made and screened for continuous hydrogenolysis of glycerol to 1,2-propanediol at atmospheric pressure. BET surface area, temperature-programmed reduction, X-ray diffraction, pulse N2O chemisorption, transmission electron microscopy and X-ray photoelectron spectroscopy techniques were used to derive the characteristics of the catalysts. The presence of Co in Cu/alumina significantly increased the reducibility of CuO species and also the metallic Cu surface area. The catalyst with 10%Cu-7%Co on Al2O3 afforded complete glycerol conversion with 77% selectivity to 1,2-propanediol. The catalysts activity was found to be mainly due to the existence of Cu in a highly dispersed state with a high metal surface area and synergistic interactions between the Cu-Co moieties. The influence of the reaction parameters was investigated and the best possible parameters were determined. The most active catalyst showed high stability during the time on stream analysis.
- Raju, Narsinga,Rekha, Voggu,Abhishek, Burri,Kumar, Peddagolla Mahesh,Sumana, Chenna,Lingaiah, Nakka
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supporting information
p. 3122 - 3128
(2020/03/03)
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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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- Multiporous Carbon Encapsulated Ni Nanoparticles Promoting Glycerol Valorisation towards Hydrogenation against Rearrangement?
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A dual-templating method was used to synthesize a series of hierarchical carbon supports containing different proportions of spherical macropores (ca. 200 nm in diameter) and mesoporous channels (ca. 4 nm in diameter). These and some other conventional carbon materials were subsequently impregnated with Ni and tested for the conversion of glycerol. The hierarchical catalysts exhibited a significantly higher conversion (96%) and selectivity (77%) to 1,2-propanediol, and the specificity selectivity coefficient (6.1) towards 1,2-propanediol against lactic acid was three times higher than that observed over a conventional Ni/Cmicro catalyst (2.1). The enhanced performance of these materials, compared with the Ni nanoparticles supported on conventional carbon supports, was attributed to their high surface areas (> 1110 m2?g?1) and large pore volumes (ca. 0.4 cm3?g?1) permitting greater accessibility of substrate and/or intermediates to Ni active sites. Given that the concentration of accessible Ni sites in these materials is higher, a competitive benzilic-acid-rearrangement reaction to produce lactic acid was suppressed, leading to an enhanced hydrogenation selectivity to 1,2-propanediol. This study evidences the potential benefits, which can be established from utilizing hierarchical support materials in the valorization of biomass.
- Chen, Bin,Douthwaite, Mark,Ma, Ding,Tang, Lipeng,Wang, Meng,Zhang, Bin,Zhang, Yibo
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p. 439 - 444
(2020/04/20)
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- Cu catalysts supported on CaO/MgO for glycerol conversion to lactic acid in alkaline medium employing a continuous flow reaction system
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The production of lactic acid (LA) from glycerol in alkaline medium was investigated using Cu catalysts supported on CaO, MgO and xCaO/MgO (x = 5, 10, 15 wt%), employing a continuous flow reaction system over a period of 30 h. In addition to assessing the effect of the composition of the catalytic support, the influence of the temperature (200-260 °C), NaOH/glycerol molar ratio (0.5-1.5), hydroxide type (NaOH and KOH), as well as the influence of concentration (10 and 20 vol%) and purity of glycerol was investigated. The catalysts were prepared by a wet impregnation method and characterized by XRF, XRD, N2 adsorption-desorption, H2-TPR and CO2-TPD. The catalytic tests showed that the use of NaOH results in higher yields to LA. Cu catalysts supported on xCaO/MgO exhibited better catalytic performance than the CuCa and CuMg catalysts. The LA yield increases with the increase of the reaction temperature from 200 to 240 °C, and then decreases with a subsequent increase to 260 °C. NaOH/glycerol molar ratios greater than 1.25 are not necessary, since high yield to LA (96.9%) was obtained in the catalytic test performed using a molar ratio of 1.25. The catalysts showed excellent stability without evidence of deactivation over the evaluated period. This journal is
- Bruno, Arthur M.,Manfro, Robinson L.,Sim?es, Thiago D. R.,Souza, Mariana M. V. M.
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p. 31123 - 31138
(2020/11/17)
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- PNN tridentate ligand, ruthenium complex, and preparation method and application of ruthenium complex
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The invention discloses a PNN tridentate ligand, a ruthenium complex, and a preparation method and an application of the ruthenium complex. The structure of the ruthenium complex is represented by formula I, and the ruthenium complex has good catalytic activity in a reaction of converting cyclic carbonate into methanol and a reaction of hydrogenating and degrading polyester and polycarbonate. In addition, the PNN tridentate ligand and the ruthenium complex of the PNN tridentate ligand are good in stability, and the synthesis process is simple.
- -
-
Paragraph 0159-0191
(2020/06/04)
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- Understanding the deactivation behavior of Pt/WO3/Al2O3 catalyst in the glycerol hydrogenolysis reaction
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The selective hydrogenolysis of glycerol to 1,3-propanediol is a highly important reaction for both improving the profitability of biodiesel and valorization of biomass. While intensive research efforts have been devoted to enhancing the catalytic activity and selectivity, little is focused on the stability although the latter is of paramount importance to practical applications. In this work, we investigated the stability of Pt/WO3/Al2O3 and observed a continuous deactivation trend during a 700 h time-on-stream run. Neither the leaching of active W nor the coking was responsible for the deactivation. Instead, XRD, HAADF-STEM and CO chemisorption results clearly showed the occurrence of significant aggregation of Pt particles, which caused a remarkable decrease of Pt-WOx interfacial sites. As a consequence, strong Br?nsted acid sites which were in situ formed by H2 dissociation at the Pt-WOx interfacial sites were reduced, leading to the deactivation of the catalyst.
- Lei, Nian,Liu, Fei,Miao, Zhili,Pan, Xiaoli,Wang, Aiqin,Wang, Hua,Zhang, Tao
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p. 1261 - 1267
(2020/03/13)
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- One-pot synthesis of 1,3-butanediol by 1,4-anhydroerythritol hydrogenolysis over a tungsten-modified platinum on silica catalyst
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Chemical production of 1,3-butanediol from biomass-derived compounds was first reported by 1,4-anhydroerythritol hydrogenolysis over a Pt-WOx/SiO2 catalyst. The reaction proceeded by ring opening hydrogenolysis of 1,4-anhydroerythritol followed by selective removal of secondary OH groups in 1,2,3-butanetriol, and an overall 1,3-butanediol yield up to 54% was then obtained. The performance of the Pt-WOx/SiO2 catalyst for 1,4-anhydroerythritol hydrogenolysis was closely correlated with that for glycerol hydrogenolysis to 1,3-propanediol. The optimized Pt-WOx/SiO2 (Pt: 4 wt% and W: 0.94 wt%) catalyst showed 57% yield of 1,3-propanediol.
- Asano, Takehiro,Liu, Lujie,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
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supporting information
p. 2375 - 2380
(2020/05/14)
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- Discovering positively charged Pt for enhanced hydrogenolysis of glycerol to 1,3-propanediol
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Atomically-dispersed Pt supported on WOx-modified tantalum oxide was developed as a highly active catalyst for selective hydrogenolysis of glycerol, with the productivity of 30.80 g gPt-1 h-1 toward 1,3-propanediol. The WOx species pre-deposited on T-Ta2O5 were found to assist the atomic dispersion of platinum. The WOx-stabilized Ptδ+ species adsorb hydrogen easily and facilitate the hydrogen heterolytic dissociation, which significantly enhances the capability of in situ generated Br?nsted acid sites and the hydrogenation activity. This provides a new strategy for developing bi-functional catalysts for a broad range of hydrogen and acid-involved reaction.
- Zhao, Binbin,Liang, Yu,Liu, Lei,He, Qian,Dong, Jinxiang
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supporting information
p. 8254 - 8259
(2020/12/31)
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- Engineering Catalysts for Selective Ester Hydrogenation
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The development of efficient catalysts and processes for synthesizing functionalized (olefinic and/or chiral) primary alcohols and fluoral hemiacetals is currently needed. These are valuable building blocks for pharmaceuticals, agrochemicals, perfumes, and so forth. From an economic standpoint, bench-stable Takasago Int. Corp.'s Ru-PNP, more commonly known as Ru-MACHO, and Gusev's Ru-SNS complexes are arguably the most appealing molecular catalysts to access primary alcohols from esters and H2 (Waser, M. et al. Org. Proc. Res. Dev. 2018, 22, 862). This work introduces economically competitive Ru-SNP(O)z complexes (z = 0, 1), which combine key structural elements of both of these catalysts. In particular, the incorporation of SNP heteroatoms into the ligand skeleton was found to be crucial for the design of a more product-selective catalyst in the synthesis of fluoral hemiacetals under kinetically controlled conditions. Based on experimental observations and computational analysis, this paper further extends the current state-of-the-art understanding of the accelerative role of KO-t-C4H9 in ester hydrogenation. It attempts to explain why a maximum turnover is seen to occur starting at 25 mol % base, in contrast to only 10 mol % with ketones as substrates.
- Dub, Pavel A.,Batrice, Rami J.,Gordon, John C.,Scott, Brian L.,Minko, Yury,Schmidt, Jurgen G.,Williams, Robert F.
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supporting information
p. 415 - 442
(2020/03/04)
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- PtRu/Zn3Ce1Oxcatalysts with Lewis acid-base pairs show synergistic performances for the conversion of glycerol in the absence of externally added H2
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Previous studies revealed that tandem dehydration, dehydrogenation and hydrogenation, promoted by metal-support interfacial catalysis, play a critical role in determining the intrinsic kinetics of transfer hydrogenolysis of bio-oxygenates. However, the synergism of metal and acid-base pairs for tunable C-H, O-H and C-O cleavage and metal-H strength is under debate in this area. Herein, we present a series of bimetallic PtRu/Zn3Ce1-LDO catalysts, with abundant Lewis acid-base pairs and heterojunction structures at the metal-support interface, exhibiting enhanced performances of transfer hydrogenolysis of glycerol. The key finding is that the incorporation of ZnO unexpectedly induced the formation of large amounts of oxygen vacant sites and surface hydroxyl sites on the CeOx support, leading to abundant Lewis acid-base pairs. The strong electron coupling effect of PtRu and Lewis acid-base pairs results in weakened PtRu-H bonding, facilitating a hydrogen transfer reaction. Synergism between enhanced Lewis acid-base pairs and weaker PtRu-H hydride bonding is critical for remarkable catalytic activity (TOF: 526 h-1) and selectivity towards glycols (70.8percent), and results in one of the best performances in the current literature. Moreover, the influence of hydrogen donors, reaction temperature and time on conversion and product distribution was further investigated in detail. An alternative reaction pathway for the transfer hydrogenolysis of glycerol over the proposed acid-base pair catalysts was proposed and validated with experimental data. The outcome of this work will provide new insights into the rational design of efficient catalytic materials for energy and environmental applications.
- Chen, Xiaobo,Cheng, Yinlei,Feng, Xiang,Jin, Xin,Liu, Yibin,Yang, Chaohe,Zhang, Guangyu,Zhang, Quanxing
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p. 4386 - 4395
(2020/07/30)
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- A mechanism study on the efficient conversion of cellulose to acetol over Sn-Co catalysts with low Sn content
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Efficient conversion of renewable cellulose to high value-added C3 chemicals is a great challenge in the field of biomass valorization. In this work, we found that the combination of Co and Sn could significantly improve the efficiency of cellulose conversion to acetol. 54.4% yield of acetol and 66.6% total yield of C3 products were obtained when using 2%Sn-10%Co/SiO2 (2 wt% Sn content) as a catalyst. However, using the same Sn content of 2%Sn-10%Ni/SiO2, no acetol and only 7.1% yield of C3 products were produced. By studying the effects of different Sn and Co concentrations on cellulose conversion, it was found that the Sn species play an important role in catalyzing glucose conversion to C3 intermediates, while Co mainly played a role in hydrogenation, the same as Ni. The study demonstrated that Sn-Co/SiO2 with low Sn content can convert glucose to C3 intermediates more efficiently than the Sn-Ni/SiO2 catalyst. Moreover, Sn-Co/SiO2 could effectively convert C3 intermediates to acetol at a high temperature which is essential for acetol production from cellulose; but under the same conditions, the Sn-Ni/SiO2 catalyst tended to catalyze the polymerization of C3 intermediates. A series of characterization methods including AAS, TEM, HRTEM, EDS, XRD, ex situ XPS, in situ XPS, and CO2-TPD found that the combination of Sn and Co could significantly increase the noninteger valent SnOx species in the catalyst. These species increased the basicity of the catalyst and were beneficial in catalyzing the isomerization of glucose and the retro-aldol condensation of fructose. This journal is
- Liu, Xiaodong,Liu, Xiaohao,Ma, Longlong,Wang, Haiyong,Xiao, Tianci,Zhang, Ying
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p. 6579 - 6587
(2020/11/16)
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- Hydrogenolysis of biomass-derived sorbitol over la-promoted ni/zro2 catalysts
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Ni/La2O3/ZrO2 catalysts were prepared by a step-by-step impregnation method through regulation of the contents of the active component and alkali. The introduction of an alkaline promoter not only enhanced the alkalinity of the catalyst but also improved the dispersion of Ni on the catalyst owing to the strong interaction between Ni2+ and alkali promoter. The synergistic effect between Ni and La2O3 was beneficial to selective hydrogenolysis of sorbitol. Under the optimal reaction conditions, sorbitol conversion reached nearly 100% and target products (ethylene glycol, 1,2-propanediol, and glycerol) selectivity reached 74.8%. Metal-alkali coordination mechanism and possible pathways for target products formation were proposed.
- Cai, Chiliu,Wang, Haiyong,Xin, Haosheng,Zhu, Changhui,Zhang, Qi,Zhang, Xinghua,Wang, Chenguang,Liu, Qiying,Ma, Longlong
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p. 3993 - 4001
(2020/02/04)
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- Boron oxide modified bifunctional Cu/Al2O3 catalysts for the selective hydrogenolysis of glucose to 1,2-propanediol
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A series of B2O3 modified Cu/Al2O3 catalysts were prepared for the hydrogenolysis of glucose. The catalysts were fully characterized by BET, ICP, N2O adsorptive decomposition, XRD, SEM, TG, H2-TPR, CO-FTIR, XPS, and NH3-TPD. The strong interaction between B2O3 and CuO could promote the dispersion of copper and inhibit the reduction of CuO, creating a proper mol ratio of Cuδ+/Cu0 for the hydrogenolysis of glucose to oxygen-containing chemicals. Furthermore, the doping of B2O3 also introduced more acid sites onto the CuB/Al2O3 catalysts, which is favorable for the cleavage of hydroxyl through dehydration. Therefore, the selective hydrogenolysis of glucose to 1,2-propanediol was dependent on the contribution of Cuδ+, Cu0, and acid sites. The catalytic activity and 1,2-propanediol selectivity were improved significantly by doping B2O3 into Cu/Al2O3. Among the catalysts, 1CuB/Al2O3 showed the highest selectivity for 1,2-propanediol, with the value of 49.5% at 96.6% conversion of glucose.
- Liu, Chengwei,Shang, Yaning,Wang, Shen,Liu, Xin,Wang, Xianzhou,Gui, Jianzhou,Zhang, Chenghua,Zhu, Yulei,Li, Yongwang
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- Recycling of CO2 by Hydrogenation of Carbonate Derivatives to Methanol: Tuning Copper–Oxide Promotion Effects in Supported Catalysts
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The selective hydrogenation of organic carbonates to methanol is a relevant transformation to realize flexible processes for the recycling of waste CO2 with renewable H2 mediated by condensed carbon dioxide surrogates. Oxide-supported copper nanoparticles are promising solid catalysts for this selective hydrogenation. However, essential for their optimization is to rationalize the prominent impact of the oxide support on performance. Herein, the role of Lewis acid centers, exposed on the oxide support at the periphery of the Cu nanoparticles, was systematically assessed. For the hydrogenation of propylene carbonate, as a model cyclic carbonate, the conversion rate, the apparent activation energy, and the selectivity to methanol correlate with the Lewis acidity of the coordinatively unsaturated cationic sites exposed on the oxide support. Lewis sites of markedly low and high electron-withdrawing character promote unselective decarbonylation and decarboxylation reaction pathways, respectively. Supports exposing Lewis sites of intermediate acidity maximize the selectivity to methanol while inhibiting acid-catalyzed secondary reactions of the propanediol product, and thus enable its recovery in cyclic processes of CO2 hydrogenation mediated by condensed carbonate derivatives. These findings help rationalize metal–support promotion effects that determine the performance of supported metal nanoparticles in this and other selective hydrogenation reactions of significance in the context of sustainable chemistry.
- Kim, Jonglack,Pf?nder, Norbert,Prieto, Gonzalo
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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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- Insight into the nature of Br?nsted acidity of Pt-(WOx)n-H model catalysts in glycerol hydrogenolysis
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In glycerol hydrogenolysis, the conventional preparation methods for Pt-WOx catalysts on active supports usually result in the coexistence of various active sites, causing complex reaction network and declining the atom efficiency of W toward 1
- Huang, Shouying,Li, Wei,Li, Ying,Ma, Xinbin,Wang, Shengping,Wang, Xiaofei,Wang, Yue,Yao, Dawei,Zhao, Yujun,Zhou, Wei
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p. 154 - 163
(2020/06/01)
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- Olefin reaction in the catalyst and the olefin production
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PROBLEM TO BE SOLVED: To provide a catalyst for obtaining an olefin in high selectivity with a vicinal diol as a raw material.SOLUTION: A catalyst for olefination reaction for use in a reaction to produce an olefin by a reaction of a polyol, having two adjacent carbon atoms each having a hydroxy group, with hydrogen comprises: a carrier; at least one oxide selected from the group consisting of oxides of the group 6 elements and oxides of the group 7 elements supported on the carrier; and at least one metal selected from the group consisting of silver, iridium, and gold supported on the carrier.SELECTED DRAWING: None
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Paragraph 0141-0143; 0145; 0149-0150
(2020/10/31)
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- Efficient transfer hydrogenation of carbonate salts from glycerol using water-soluble iridium N-heterocyclic carbene catalysts
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The transfer hydrogenation of CO2and carbonates from biomass-derived alcohols, such as glycerol, to afford formic and lactic acid is a highly attractive path to valorizing two waste streams, and is significantly more thermodynamically favorable than direct carbonate hydrogenation. Expanding on our seminal report of the first homogeneous catalyst for this process, here we show that thermally-robust and water-soluble Ir(i) and Ir(iii) N-heterocyclic carbene (NHC) complexes with sulfonate-functionalized wingtips are highly prolific and robust catalysts for carbonate transfer hydrogenation from glycerol, requiring no additives in aqueous media. The most prolific catalyst of the nine examined, [Ir(NHC-Ph-SO3?)2CO2]Na (cat7), effectively facilitates the reaction at low catalyst loading (10 ppm) at 150 °C using microwave or conventional heating. The cation of the carbonate salt significantly impacts catalytic activity, with highest activity observed with Cs2CO3(27?850 and 13?350 TONs for lactate and formate respectively in 6 hours, compared to 15?400 and 8120 with K2CO3). Catalytic amounts of Cs+were found to significantly enhance activity with K2CO3. Catalyst7is even more prolific with conventional heating under a positive N2pressure, reaching TOFs of >3000 h?1and >2100 h?1respectively for lactate and formate with K2CO3. The high activity of this catalyst compared to non-sulfonated and cyclooctadiene analogs is attributed to a combination of catalyst solubility in aqueous media and presence of π-acceptor carbonyl ligands. A catalytic mechanism is proposed for7involving O-H oxidative addition of glycerol, β-hydride elimination, bicarbonate dehydroxylation, insertion and reductive elimination.
- Ainembabazi, Diana,Finn, Matthew,Ridenour, James,Voutchkova-Kostal, Adelina,Wang, Kai
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supporting information
p. 6093 - 6104
(2020/10/18)
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- Synthesis of CNTs@POP-Salen Core-Shell Nanostructures for Catalytic Epoxides Hydration
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Microporous polymers have been considered as promising heterogeneous catalysts for versatile chemical transformations. However, the mass diffusion barriers through the microporous network still remains a big hindrance. Herein, an efficient and versatile strategy for shortening the mass diffusion pathway through microporous polymer was reported by constructing a CNTs@POP-salen core-shell nanostructure. CNTs@POP-Co(salen) could efficiently catalyze the epoxide hydration reaction at H2O/epoxides ratio as low as 2, demonstrating the efficient cooperation of Co(salen) integrated in the polymer network. CNTs@POP-Co(salen) showed much higher activity than bulk polymer in propylene oxide (PO) hydration reaction (TOF: 3150 versus 1470 h?1) due to the shortened diffusion pathway, which was further confirmed by adsorption experiment using phenol as probe molecule. Our primary results demonstrated the advantages of core-shell nanostructures to improve the catalytic activity of microporous polymers by enhancing the mass diffusion during the catalytic process.
- Li, He,Zhong, Mingmei,Li, Chunzhi,Ren, Yiqi,Chen, Jian,Yang, Qihua
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p. 3952 - 3958
(2019/04/30)
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- Carboxylate ionic liquid as well as preparation method and application thereof
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The invention provides carboxylate ionic liquid as well as a preparation method and application thereof. According to the carboxylate ionic liquid provided by the invention, an imidazole group or a pyridine group is introduced into the cationic part of the carboxylate ionic liquid and a carboxylic acid group is introduced into the anionic part of the carboxylate ionic liquid; and the ionic liquidcatalyst provided by the invention is simple and convenient in synthesis route, high in yield and easy to recover. Anion carboxylate radical in the carboxylate ionic liquid provided by the invention serves as an active site, so that synthesis of diol can be realized through high-efficiency and high-selectivity catalysis of hydration reaction of epoxy compounds under the condition of not adding other catalysts.
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Paragraph 0161-0165
(2019/10/23)
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- Topotactic Conversion of Alkali-Treated Intergrown Germanosilicate CIT-13 into Single-Crystalline ECNU-21 Zeolite as Shape-Selective Catalyst for Ethylene Oxide Hydration
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The conversion of the alkali-treated intergrowth germanosilicate CIT-13 into the single-crystalline high-silica ECNU-21 (named after East China Normal University) zeolite, with a novel topology and a highly crystalline zeolite framework, has been realized through a creative top-down strategy involving a mild alkaline-induced multistep process consisting of structural degradation and reconstruction. Instead of acid treatment, hydrolysis in aqueous ammonia solution not only readily cleaved the chemically weak Ge(Si)?O?Ge bonds located within the interlayer double four ring (D4R) units of CIT-13, but also cleaved the metastable Si?O?Si bonds therein. This led to extensive removal of the D4R units, and also generated silanol groups on adjacent silica-rich layers, which then condensed to form a novel daughter structure upon calcination. Individual oxygen bridges in the reassembled ECNU-21 replaced the germanium-rich D4R units in CIT-13, thereby eliminating the original intergrowth phenomenon along the b axis. With an ordered crystalline structure of 10-ring (R) channels as well as suitable germanium-related Lewis acid sites, ECNU-21 serves as a stable solid Lewis acid catalyst for the shape-selective hydration of ethylene oxide (EO) to ethylene glycol (EG) at greatly reduced H2O/EO ratios and reaction temperature in comparison with the noncatalytic industrial process.
- Liu, Xue,Mao, Wenting,Jiang, Jingang,Lu, Xinqing,Peng, Mingming,Xu, Hao,Han, Lu,Che, Shun-ai,Wu, Peng
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p. 4520 - 4529
(2019/03/07)
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