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1. Characterization of deactivated and regenerated zeolite ZSM-5-based catalyst extrudates used in catalytic pyrolysis of biomass

Author:
Heracleous, E.; Pachatouridou, E.; Hernández-Giménez, A.M.; Hernando, H.; Fakin, T.; Paioni, A.L.; Baldus, M.; Serrano, D.P.; Bruijnincx, P.C.A.; Weckhuysen, B.M.; Lappas, A.A.
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
Bronsted acids; air; biomass; catalysts; catalytic activity; catalytic cracking; egg shell; fluorescence microscopy; oxidation; pyrolysis; temperature; zeolites; zirconium oxide
Abstract:
... A major issue in the catalytic fast pyrolysis (CFP) of biomass is the rapid deactivation of the typically employed zeolite-based catalysts. Detailed understanding of the deactivation pathways and the type and location of coke deposits are essential for the further development of improved or new catalyst materials, including appropriate regeneration protocols. Such deactivation and regeneration stu ...
DOI:
10.1016/j.jcat.2019.10.019

2. Clay nanotubes catalyzed solvent-free synthesis of octahydro-2H-chromenols with pharmaceutical potential from (-)-isopulegol and ketones

Author:
Sidorenko, A.Yu.; Kravtsova, A.V.; Il'ina, I.V.; Wärnå, J.; Korchagina, D.V.; Gatilov, Yu.V.; Volcho, K.P.; Salakhutdinov, N.F.; Murzin, D.Yu.; Agabekov, V.E.
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
acetone; acidity; alcohols; aldehydes; antiviral properties; byproducts; carbonyl compounds; catalysts; catalytic activity; halloysite; heterocyclic compounds; hydrochloric acid; hydrolysis; models; nanotubes; stereoselectivity; temperature; terpenoids
Abstract:
... Natural halloysite nanotubes (HNT) pretreated with hydrochloric acid were applied for the first time for selective synthesis of octahydro-2H-chromenols (as 4R- and 4S-diastereomers) using terpenoid (-)-isopulegol and ketones as reactants. The main attention was paid to the reaction with acetone, because the resulting 4R-isomer displays antiviral activity. While the drawback of the isopulegol Prins ...
DOI:
10.1016/j.jcat.2019.10.015

3. CoxFe1-xAl2O4+δ composite oxides supported Pt nanoparticles as efficient and recyclable catalysts for the liquid-phase selective hydrogenation of cinnamaldehyde

Author:
Xin, Huiyue; Xue, Yujie; Zhang, Wenbo; Wu, Peng; Li, Xiaohong
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
X-ray photoelectron spectroscopy; active sites; alcohols; catalysts; catalytic activity; glucose; hydrogenation; kinetics; models; moieties; nanoparticles; oxides; platinum; sol-gel processing; temperature
Abstract:
... CoxFe1-xAl2O4+δ composite oxides were prepared using a sol-gel method with glucose as hard template. Pt nanoparticles supported on CoxFe1-xAl2O4+δ were employed for the liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to yield the desired cinnamyl alcohol (COL). The activity increased with the x value; while the selectivity to COL almost kept above 90% despite of different x values. Up ...
DOI:
10.1016/j.jcat.2019.09.042

4. Evolution of steady-state material properties during catalysis: Oxidative coupling of methanol over nanoporous Ag0.03Au0.97

Author:
Zugic, Branko; van Spronsen, Matthijs A.; Heine, Christian; Montemore, Matthew M.; Li, Yuanyuan; Zakharov, Dmitri N.; Karakalos, Stavros; Lechner, Barbara A.J.; Crumlin, Ethan; Biener, Monika M.; Frenkel, Anatoly I.; Biener, Juergen; Stach, Eric A.; Salmeron, Miquel B.; Kaxiras, Efthimios; Madix, Robert J.; Friend, Cynthia M.
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
alloys; carbon dioxide; catalysts; catalytic activity; formates; gold; methanol; nanogold; nanopores; nanosilver; oxidation; oxygen; ozone; silver; temperature
Abstract:
... Activating pretreatments are used to tune surface composition and structure of bimetallic-alloy catalysts. Herein, the activation-induced changes in material properties of a nanoporous Ag0.03Au0.97 alloy and their subsequent evolution under steady-state CH3OH oxidation conditions are investigated. Activation using O3 results in AgO and Au2O3, strongly enriching the near-surface region in Ag. These ...
DOI:
10.1016/j.jcat.2019.08.041

5. Insights into the key to utilization efficiency of hydrogen peroxide over titanosilicates/H2O2 system

Author:
Yu, Yunkai; Tang, Zhimou; Wang, Jia; Wang, Rui; Chen, Zhen; Liu, Haoxin; Shen, Kaixu; Huang, Xin; Liu, Yueming; He, Mingyuan
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
Lewis acids; Lewis bases; catalytic activity; epoxidation reactions; hydrogen bonding; hydrogen peroxide; hydrophobicity; solvents; synergism; temperature; zeolites
Abstract:
... The key to high utilization efficiency of hydrogen peroxide (H2O2) over titanosilicates/H2O2 system was discovered thanks to a comprehensively catalytic investigation. The H2O2 utilization efficiency depended chiefly on the competition between epoxidation and decomposition pathways of H2O2 reaction. In terms of epoxidation pathway, the formation of Ti-OOH species could be promoted by enhancing the ...
DOI:
10.1016/j.jcat.2019.09.045

6. Lewis acidic supports promote the selective hydrogenation of carbon dioxide to methyl formate in the presence of methanol over Ag catalysts

Author:
Corral-Pérez, Juan José; Copéret, Christophe; Urakawa, Atsushi
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
acidity; aluminum oxide; carbon dioxide; catalysts; catalytic activity; formates; hydrogenation; methanol; nanosilver; silica; silver; temperature; zirconium oxide
Abstract:
... Silica-supported silver nanoparticles exhibit outstanding efficiency in the CO2 hydrogenation to methyl formate in the presence of methanol under high pressure. Here, we show that ZrO2 and Al2O3 supports significantly increase the catalyst activity, in line with their higher Lewis acidity. The weight time yield of methyl formate over Ag/ZrO2 is up to 16.2 gMF gAg h−1 without detectable side-produc ...
DOI:
10.1016/j.jcat.2019.10.013

7. Mechanistic origins of the high-pressure inhibition of methanol dehydration rates in small-pore acidic zeolites

Author:
Di Iorio, John R.; Hoffman, Alexander J.; Nimlos, Claire T.; Nystrom, Steven; Hibbitts, David; Gounder, Rajamani
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
Bronsted acids; aluminum; catalytic activity; kinetics; methanol; physical phases; protons; temperature; zeolites
Abstract:
... Turnover rates of Brønsted acid-catalyzed methanol dehydration to dimethyl ether become inhibited at high methanol pressures (>10 kPa, 415 K) on small-pore zeolites (CHA, AEI, LTA, LEV), irrespective of the distribution of framework Al and their attendant H+ sites, but not on medium-pore or large-pore zeolites. High-pressure kinetic inhibition occurs concomitantly with the stabilization of higher- ...
DOI:
10.1016/j.jcat.2019.10.012

8. Origin of weak Lewis acids on silanol nests in dealuminated zeolite Beta

Author:
Yi, Fengjiao; Chen, Yunlei; Tao, Zhichao; Hu, Caixia; Yi, Xianfeng; Zheng, Anmin; Wen, Xiaodong; Yun, Yifeng; Yang, Yong; Li, Yongwang
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
Bronsted acids; Lewis acids; catalytic activity; hydrogen bonding; isomerization; nuclear magnetic resonance spectroscopy; temperature; zeolites
Abstract:
... We report the structure of weak Lewis acid sites from silanol nests in high-silica zeolite Beta obtained by dealumination. Hydrogen bond interactions in silanol nests resulted in more electropositive hydrogens as Lewis acid sites compared with isolated silanols. The structure of the Lewis acid sites was confirmed using various characterization methods, such as NMR and IR, and DFT calculations. The ...
DOI:
10.1016/j.jcat.2019.10.008

9. Silicon nitride as a new support for copper catalyst to produce acrolein via selective oxidation of propene with very low CO2 release

Author:
Guo, Ling-Ling; Yu, Jing; Shu, Miao; Shen, Lu; Si, Rui
Source:
Journal of catalysis 2019
ISSN:
0021-9517
Subject:
X-ray absorption spectroscopy; X-ray diffraction; acrolein; air; carbon dioxide; carbon monoxide; catalysts; catalytic activity; copper; cuprous oxide; heat treatment; oxidation; propylene; silicon nitride; temperature; thermal stability; transmission electron microscopy
Abstract:
... To obtain thermally stable copper-based catalysts with excellent catalytic performance in the selective propene (C3H6) oxidation reaction, amorphous silicon nitride (Si3N4) was selected to anchor active copper species using a deposition–precipitation approach followed by air calcination at different temperatures. We found that the thermal treatment temperature remarkably modified the reactivity of ...
DOI:
10.1016/j.jcat.2019.09.019