TiO2–x-Modified Ni Nanocatalyst with Tunable Metal–Support Interaction for Water–Gas Shift Reaction

ACS Catalysis ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 7600-7609 ◽  
Author(s):  
Ming Xu ◽  
Shan He ◽  
Hao Chen ◽  
Guoqing Cui ◽  
Lirong Zheng ◽  
...  
Keyword(s):  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Support Interaction ◽  
Metal Support Interaction ◽  
Metal Support ◽  
Shift Reaction ◽  
Water Gas

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 Combined DFT and Operando Spectroscopic Study of the Water-Gas Shift Reaction over Ceria-Based Catalysts: The Role of the Noble Metal and Ceria Faceting

2020 ◽  
Vol 2 (1) ◽  
pp. 23
Author(s):  
Marc Ziemba ◽  
Danny Stark ◽  
Christian Hess
Keyword(s):  
Density Functional ◽  
Noble Metals ◽  
Active Material ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Metal Support Interaction ◽  
Vis Spectroscopy ◽  
Shift Reaction ◽  
Water Gas

Ceria loaded with noble metals (Cu, Au) is a highly active material for the low-temperature water-gas shift reaction (LT-WGSR), but nevertheless details of the metal support interaction as well as the role of the ceria surface termination and the metal loading are still unclear. Using operando Raman and UV/Vis spectroscopy combined with theoretical density functional theory (DFT) calculations, we aim at a molecular-level understanding of LT-WGSR catalysts. In particular, by using this combined approach, we are able to draw conclusions about the reducibility state of the ceria support during reaction conditions. Our results show that the defect formation energy of the support does not play a major role for the WGSR, but rather other reaction steps such as the dissociation of water or the desorption of CO2.

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