Ti-salalen mediated asymmetric epoxidation of olefins with H2O2: Effect of ligand on the catalytic performance, and insight into the oxidation mechanism

2016 ◽  
Vol 421 ◽  
pp. 131-137 ◽  
Author(s):  
Evgenii P. Talsi ◽  
Tatyana V. Rybalova ◽  
Konstantin P. Bryliakov
Keyword(s):  
Oxidation Mechanism ◽  
Catalytic Performance ◽  
Asymmetric Epoxidation ◽  
Epoxidation Of Olefins ◽  
Insight Into

scholarly journals Insight into Active Centers and Anti-Coke Behavior of Niobium-Containing SBA-15 for Glycerol Dehydration

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 488
Author(s):  
Katarzyna Stawicka ◽  
Maciej Trejda ◽  
Maria Ziolek
Keyword(s):  
Coke Formation ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Silica Matrix ◽  
High Concentration ◽  
Active Centers ◽  
Acidic Sites ◽  
Glycerol Dehydration ◽  
Adsorption Desorption ◽  
Insight Into

Niobium containing SBA-15 was prepared by two methods: impregnation with different amounts of ammonium niobate(V) oxalate (Nb-15/SBA-15 and Nb-25/SBA-15 containing 15 wt.% and 25 wt.% of Nb, respectively) and mixing of mesoporous silica with Nb2O5 followed by heating at 500 °C (Nb2O5/SBA-15). The use of these two procedures allowed obtaining materials with different textural/surface properties determined by N2 adsorption/desorption isotherms, XRD, UV-Vis, pyridine, and NO adsorption combined with FTIR spectroscopy. Nb2O5/SBA-15 contained exclusively crystalline Nb2O5 on the SBA-15 surface, whereas the materials prepared by impregnation had both metal oxide and niobium incorporated into the silica matrix. The niobium species localized in silica framework generated Brønsted (BAS) and Lewis (LAS) acid sites. The inclusion of niobium into SBA-15 skeleton was crucial for the achievement of high catalytic performance. The strongest BAS were on Nb-25/SBA-15, whereas the highest concentration of BAS and LAS was on Nb-15/SBA-15 surface. Nb2O5/SBA-15 material possessed only weak LAS and BAS. The presence of the strongest BAS (Nb-25/SBA-15) resulted in the highest dehydration activity, whereas a high concentration of BAS was unfavorable. Silylation of niobium catalysts prepared by impregnation reduced the number of acidic sites and significantly increased acrolein yield and selectivity (from ca. 43% selectivity for Nb-25/SBA-15 to ca. 61% for silylated sample). This was accompanied by a considerable decrease in coke formation (from 47% selectivity for Nb-25/SBA-15 to 27% for silylated material).

1,3-Butadiene production from aqueous ethanol over ZnO/MgO-SiO2 catalysts: Insight into H2O effect on catalytic performance

2021 ◽  
Vol 616 ◽  
pp. 118081
Author(s):  
Pavlo I. Kyriienko ◽  
Olga V. Larina ◽  
Dmytro Yu. Balakin ◽  
Anatolii O. Stetsuk ◽  
Yurii M. Nychiporuk ◽  
...  
Keyword(s):  
Aqueous Ethanol ◽  
Catalytic Performance ◽  
Insight Into

Synthesis of salen Mn(III) immobilized onto the ZnPS-PVPA modified by 1,2,3-triazole and their application for asymmetric epoxidation of olefins

Tetrahedron ◽  
2013 ◽  
Vol 69 (26) ◽  
pp. 5460-5467 ◽  
Author(s):  
Jing Huang ◽  
Jiali Cai ◽  
Hao Feng ◽  
Zhiguo Liu ◽  
Xiangkai Fu ◽  
...  
Keyword(s):  
Asymmetric Epoxidation ◽  
Epoxidation Of Olefins

Theoretical insight into adsorption and dissociation of water on NiCr binary alloy surfaces: Early-stage oxidation mechanism

2021 ◽  
Vol 130 (11) ◽  
pp. 115303
Author(s):  
Ya-Ru Yin ◽  
Cui-Lan Ren ◽  
Zhao-Feng Liang ◽  
Jian-Xing Dai ◽  
He-Fei Huang ◽  
...  
Keyword(s):  
Binary Alloy ◽  
Early Stage ◽  
Oxidation Mechanism ◽  
Adsorption And Dissociation ◽  
Theoretical Insight ◽  
Insight Into

The strain induced type-II band re-alignment of blue phosphorus-GeX (X = C/H/Se) heterostructures

2020 ◽  
Vol 89 (1) ◽  
pp. 10103
Author(s):  
Honglin Li ◽  
Yuting Cui ◽  
Haijun Luo ◽  
Wanjun Li
Keyword(s):  
High Performance ◽  
Strain Range ◽  
Interlayer Coupling ◽  
Photovoltaic Cell ◽  
Catalytic Performance ◽  
Band Alignment ◽  
First Principles Calculation ◽  
Type Ii ◽  
2D Structure ◽  
Insight Into

Efforts to efficiently use of the next generation 2-dimension (2D) structured monolayers is getting a lot of attention for their excellent properties recently. In this work, we composite the blue phosphorus (BP) and monolayer GeX (X = C/H/Se) via van der Waals force (vdW) interaction to obtain well defined type-II band alignment heterostructures. A systematic theoretic study is conducted to explore the interlayer coupling effects and the bands re-alignment of BP-GeX (X = C/H/Se) heterostructure after the strain imposed. To devise usable and efficient materials to degrade pollutant or used as a potential photovoltaic cell material, previous researches have proved that using 2D materials as components is a feasible way to obtain high performance. Here, we prudently present a comprehensive investigation on the BP and GeX (X = C/H/Se) with different twisted angles via first-principles calculation to lay a theoretical framework on the band alignment and carriers' separation. It reveals that the intrinsic electronic properties of BP and GeX are roughly preserved in the corresponding heterostructures. Upon strain applied, band alignment can be flexibly manipulated by varying external imposed strain. The heterostructures can maintain type-II character within a certain strain range, and thus the carriers are spatially separated to different portions. This work not only provides a deep insight into the construction of the heterostructure, but presents a new possibility to search for a flexible and feasible approach to promote its catalytic performance. The corresponding results would provide meaningful guidelines for designing 2D structure based novel materials.

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