JOURNAL OF CATALYSIS
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2016
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IF 7.354
Junjie Su,Zhengpai Zhang,Donglong Fu,Da Liu,Xin-Chao Xu,Bianfang Shi,Xu Wang,Rui Si,Zheng Jiang,Jing Xu,Yi-Fan Han
A comparative study of higher alcohols synthesis directly from syngas has been performed over monometallic Co and bimetallic CoCu/SiO 2 catalysts. Particularly, the role of Cu on the origin of active sites and reaction mechanism were investigated thoroughly using multiple techniques such as ex situ X-rays diffraction (XRD), X-ray absorption spectroscopy (XAS) and Raman spectroscopy. Reduction process of CoCu/SiO 2 catalysts was also determined using in situ XRD and in situ Raman spectroscopy while the surface structure of reduced catalysts was detected by CO-DRIFTS. CoCu bimetallic particles covered by Cu atoms are responsible for alcohols synthesis. The intrinsic kinetics was performed over both catalysts under realistic reaction conditions. By comparing the kinetic parameters, including apparent activation energies and reaction orders, the promotional effects of Cu have been identified as: (1) weakening the CO/HCO dissociation and reducing the formation of CH x species; (2) controlling surface Co ensemble size and inhibiting CH x insertion.
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
BIOCHEMICAL ENGINEERING JOURNAL
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2017
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IF 2.892
Ya-Jun Wang,Xiao-Peng Chen,Wei Shen,Zhi-Qiang Liu,Yu-Guo Zheng
In our previous work, we constructed a carbonyl reductase (CR) and glucose dehydrogenase (GDH) co-expression strain E. coli BL21(DE3)/pCDFDuet- gdh - cr , and a biocatalytic process of chiral diol t -butyl 6-cyano-(3 R ,5 R )-dihydroxyhexanoate ((3 R ,5 R )- 2 ) was established by using its free cells. Herein, a (3 R ,5 R )- 2 process with celite-polyethyleneimine (PEI)-glutaraldehyde (GA) immobilized E. coli BL21(DE3)/pCDFDuet- gdh - cr whole cells was developed for the first time. It was demonstrated that immobilization via cross-linking was preferred, and the optimized immobilization conditions were as follows: 0.6% (w/v) celite, 4% (w/v) PEI and 1% (w/v) GA, pH7. The immobilizate can be used at pH 7.0, 30 °C for intermittent 7 batch, yielding a total of 17.5 g (3 R ,5 R )- 2 per gram of celite-PEI-GAimmobilizates in de p (diastereomeric excess) >99.5%. Compared with the free cells, there was a dramatic improvement in celite- PEI-GA immobilizate stability and recyclability. In this way, a promising platform technology based on a combination of cells immobilization and multiple enzymes co-expression is constructed, enabling efficiently converting inexpensive prochiral ketones to high-valued chiral alcohols.
研究领域:
生物化学
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酶工程
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合成生物学
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产品关联
DOI
高影响因子
Journal of the American Chemical Society
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2013
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IF 10.677
Yehong Wang,Feng Wang,Qi Song,Qin Xin,Shutao Xu,Jie Xu
The use of a heterogeneous Lewis acid catalyst, which is insoluble and easily separable during the reaction, is a promising option for hydrolysis reactions from both environmental and practical viewpoints. In this study, ceria showed excellent catalytic activity in the hydrolysis of 4-methyl-1,3-dioxane to 1,3-butanediol in 95% yield and in the one-pot synthesis of 1,3-butanediol from propylene and formaldehyde via Prins condensation and hydrolysis reactions in an overall yield of 60%. In-depth investigations revealed that ceria is a water-tolerant Lewis acid catalyst, which has seldom been reported previously. The ceria catalysts showed rather unusual high activity in hydrolysis, with a turnover number (TON) of 260, which is rather high for bulk oxide catalysts, whose TONs are usually less than 100. Our conclusion that ceria functions as a Lewis acid catalyst in hydrolysis reactions is firmly supported by thorough characterizations with IR and Raman spectroscopy, acidity measurements with IR and 31P magic-angle-spinning NMR spectroscopy, Na+/H+ exchange tests, analyses using the in situ active-site capping method, and isotope-labeling studies. A relationship between surface vacancy sites and catalytic activity has been established. CeO2(111) has been confirmed to be the catalytically active crystalline facet for hydrolysis. Water has been found to be associatively adsorbed on oxygen vacancy sites with medium strength, which does not lead to water dissociation to form stable hydroxides. This explains why the ceria catalyst is water-tolerant.
研究领域:
催化化学
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材料科学
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环境化学
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DOI
PubMed
高影响因子
ChemCatChem
·
2022
·Vol. 14
·期 14
·e202200341
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IF 5.497
Junxiu Zhao,Bo Hou,Heqin Guo,Litao Jia,Pengyu Niu,Congbiao Chen,Hongjuan Xi,Debao Li,Jianli Zhang
Graphical Surface hydroxyl groups of the support play a crucial role for WO x -support interaction. A strong interaction between WO x species and support can improve the dispersion of WO x species and generate more WO x -support interface Brønsted acid sites, which are beneficial for 1,3-propanediol synthesis in glycerol hydrogenolysis. For Pt-WO x -based catalysts, researchers pay much attention to study the influence of Pt-WO x interaction on glycerol hydrogenolysis, ignoring the interaction between WO x and support. Herein, four Pt/W/SiZr-T catalysts with different surface hydroxyl groups on support are prepared and characterized. The results show that bibridged (OH II ) and tribridged hydroxyl groups (OH III ) on SiZr-T supports could react with WO x species through forming Zr−O−W bands and retard the agglomeration of WO x species. The highly dispersed WO x species and Zr−O−W bands are the origination of inherent and in-situ generated Brønsted acid, which are beneficial for 1,3-propanediol synthesis. As a result, Pt/W/SiZr-70 exhibits outstanding performance due to abundant OH II and OH III on SiZr-70. The initial space time yield of 1,3-propanediol on Pt/W/SiZr-70 reaches 2.280 g 1,3-PDO ⋅ g cat −1 ⋅ h −1 , the highest among reported results. This r esearch reveals the role of WO x -support interaction on glycerol hydrogenolysis and provides a new direction to design Pt-WO x -based catalysts for selective hydrogenation reactions.
研究领域:
催化
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化学工程
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材料科学
✓ 已验证
DOI
高影响因子
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