Molecular-level understanding of reaction path optimization as a function of shape concerning the metal–support interaction effect of Co/CeO2 on water-gas shift catalysis

2019 ◽  
Vol 9 (18) ◽  
pp. 4928-4937 ◽  
Author(s):  
Yingying Zhan ◽  
Yi Liu ◽  
Xuanbei Peng ◽  
Weitao Zhao ◽  
Yongfan Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Molecular Level ◽  
Reaction Path ◽  
Hydrogen Reduction ◽  
Water Gas Shift ◽  
Wgs Reaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Water Gas

In this work, the active sites generated in hydrogen reduction and the reaction pathways for the water gas shift (WGS) reaction over Co/CeO2 catalysts were studied by in situ XAS and XPS coupled with DFT+U calculations.

scholarly journals Identification of intrinsic active sites in ternary CuZnTi catalysts toward low-temperature water gas shift reaction

2021 ◽  
Author(s):  
Jian Zhang ◽  
Pan Yin ◽  
Ming Xu ◽  
Guoqing Cui ◽  
Jun Yu ◽  
...  
Keyword(s):  
Low Temperature ◽  
Active Sites ◽  
Interfacial Structure ◽  
Water Gas Shift ◽  
High Catalytic Activity ◽  
Water Gas Shift Reaction ◽  
Metal Support ◽  
Shift Reaction ◽  
Water Gas

Abstract In the heterogeneous field, modulation over strong metal-support interactions (SMSI) plays a crucial role in boosting catalytic performance toward interface-sensitive reactions (e.g., water gas shift reaction, WGSR). Herein, a CuZnTi ternary catalyst was prepared via in situ structural topological transformation from CuZnTi-layered double hydroxides precursor (CuZnTi-LDHs). The resulting catalyst Cu/ZnTi-MMO(H350) exhibits an extraordinarily high catalytic activity toward low temperature-WGSR with a reaction rate of 19.7 μmolCO gcat-1 s-1 at 250 °C, among the highest level in Cu-based catalysts. Advanced electron microscope and in situ spectroscopy characterizations verify that Cu nanoparticles (particle size: 7~10 nm) are modified by ZnTi-mixed metal oxides with abundant Cuδ+−Ov−Ti3+ (0<δ<1) interfacial sites. Incorporation of Ti element facilitates the reduction of ZnO to stabilize Cuδ+ species at the interface, which enhances the chemisorption of CO molecule. Simultaneously, neighboring Ov−Ti3+ species significantly promotes the dissociation of H2O molecule. The structure-activity correlation studies based on quasi-in situ XPS, in situ DRIFTS, in situ and operando EXAFS reveal that the interfacial sites (Cuδ+−Ov−Ti3+) serve as the intrinsic active sites of WGS reaction. A combination of in situ characterization techniques and DFT calculations further substantiate that associative mechanism is the predominant reactive path below 200 °C whilst redox mechanism is overwhelming above 250 °C in the presence of Cu/ZnTi-MMO catalyst. This work demonstrates a facile modulation on metal-support interfacial structure via LDHs approach, which paves a way for rational design and preparation of heterogeneous catalysts.

scholarly journals Dynamic structure of active sites in ceria-supported Pt catalysts for the water gas shift reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuanyuan Li ◽  
Matthew Kottwitz ◽  
Joshua L. Vincent ◽  
Michael J. Enright ◽  
Zongyuan Liu ◽  
...  
Keyword(s):  
Active Sites ◽  
Synergistic Effects ◽  
Dynamic Structure ◽  
Water Gas Shift ◽  
Considerable Uncertainty ◽  
Active Structure ◽  
Noble Metal Catalysts ◽  
Wgs Reaction ◽  
Metal Support ◽  
Water Gas

AbstractOxide-supported noble metal catalysts have been extensively studied for decades for the water gas shift (WGS) reaction, a catalytic transformation central to a host of large volume processes that variously utilize or produce hydrogen. There remains considerable uncertainty as to how the specific features of the active metal-support interfacial bonding—perhaps most importantly the temporal dynamic changes occurring therein—serve to enable high activity and selectivity. Here we report the dynamic characteristics of a Pt/CeO2 system at the atomic level for the WGS reaction and specifically reveal the synergistic effects of metal-support bonding at the perimeter region. We find that the perimeter Pt0 − O vacancy−Ce3+ sites are formed in the active structure, transformed at working temperatures and their appearance regulates the adsorbate behaviors. We find that the dynamic nature of this site is a key mechanistic step for the WGS reaction.

scholarly journals Visualizing H2O molecules reacting at TiO2 active sites with transmission electron microscopy

Science ◽  
2020 ◽  
Vol 367 (6476) ◽  
pp. 428-430 ◽  
Author(s):  
Wentao Yuan ◽  
Beien Zhu ◽  
Xiao-Yan Li ◽  
Thomas W. Hansen ◽  
Yang Ou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Active Sites ◽  
Molecular Level ◽  
Adsorbed Water ◽  
Transmission Electron ◽  
Shift Reaction ◽  
Water Gas ◽  
Catalytic Reaction Mechanism

Imaging a reaction taking place at the molecular level could provide direct information for understanding the catalytic reaction mechanism. We used in situ environmental transmission electron microscopy and a nanocrystalline anatase titanium dioxide (001) surface with (1 × 4) reconstruction as a catalyst, which provided highly ordered four-coordinated titanium “active rows” to realize real-time monitoring of water molecules dissociating and reacting on the catalyst surface. The twin-protrusion configuration of adsorbed water was observed. During the water–gas shift reaction, dynamic changes in these structures were visualized on these active rows at the molecular level.

scholarly journals Cu supported on mesoporous ceria: water gas shift activity at low Cu loadings through metal–support interactions

2017 ◽  
Vol 19 (27) ◽  
pp. 17708-17717 ◽  
Author(s):  
Dimitriy Vovchok ◽  
Curtis J. Guild ◽  
Jordi Llorca ◽  
Wenqian Xu ◽  
Tahereh Jafari ◽  
...  
Keyword(s):  
Water Gas Shift ◽  
Wgs Reaction ◽  
Metal Support ◽  
Metal Support Interactions ◽  
Water Gas

We synthesized, characterized and tested Cu supported mesoporous CeO2 catalyst for the water-gas shift (WGS) reaction.

scholarly journals The role of metal–support interaction for CO-free hydrogen from low temperature ethanol steam reforming on Rh–Fe catalysts

2017 ◽  
Vol 19 (6) ◽  
pp. 4199-4207 ◽  
Author(s):  
Catherine K. S. Choong ◽  
Luwei Chen ◽  
Yonghua Du ◽  
Martin Schreyer ◽  
S. W. Daniel Ong ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Active Sites ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Free Hydrogen ◽  
Metal Support ◽  
Fe Catalysts ◽  
Ethanol Steam

Effect of metal–support interaction on the generation of Rh–FexOy active sites is investigated via various in situ techniques.

scholarly journals The active sites of Cu–ZnO catalysts for water gas shift and CO hydrogenation reactions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhenhua Zhang ◽  
Xuanye Chen ◽  
Jincan Kang ◽  
Zongyou Yu ◽  
Jie Tian ◽  
...  
Keyword(s):  
Active Sites ◽  
Co Hydrogenation ◽  
Water Gas Shift ◽  
Reaction Conditions ◽  
Hydrogenation Reactions ◽  
Cu Catalysts ◽  
Water Gas ◽  
Zn Alloy ◽  
Methanol Reactions

AbstractCu–ZnO–Al2O3 catalysts are used as the industrial catalysts for water gas shift (WGS) and CO hydrogenation to methanol reactions. Herein, via a comprehensive experimental and theoretical calculation study of a series of ZnO/Cu nanocrystals inverse catalysts with well-defined Cu structures, we report that the ZnO–Cu catalysts undergo Cu structure-dependent and reaction-sensitive in situ restructuring during WGS and CO hydrogenation reactions under typical reaction conditions, forming the active sites of CuCu(100)-hydroxylated ZnO ensemble and CuCu(611)Zn alloy, respectively. These results provide insights into the active sites of Cu–ZnO catalysts for the WGS and CO hydrogenation reactions and reveal the Cu structural effects, and offer the feasible guideline for optimizing the structures of Cu–ZnO–Al2O3 catalysts.

Sign in / Sign up

Export Citation Format

Share Document