Ceria-based model catalysts: fundamental studies on the importance of the metal–ceria interface in CO oxidation, the water–gas shift, CO2 hydrogenation, and methane and alcohol reforming

Model metal/ceria and ceria/metal catalysts have shown to be excellent systems for studying fundamental phenomena linked to the operation of technical catalysts.

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The behavior of inverse oxide/metal catalysts: CO oxidation and water-gas shift reactions over ZnO/Cu(111) surfaces

Surface Science ◽

10.1016/j.susc.2018.09.008 ◽

2019 ◽

Vol 681 ◽

pp. 116-121 ◽

Cited By ~ 12

Author(s):

Mausumi Mahapatra ◽

Ramón A. Gutiérrez ◽

Jindong Kang ◽

Ning Rui ◽

Rebecca Hamlyn ◽

...

Keyword(s):

Co Oxidation ◽

Metal Catalysts ◽

Water Gas Shift ◽

Water Gas

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The Study of Reverse Water Gas Shift Reaction Activity over Different Interfaces: The Design of Cu-Plate ZnO Model Catalysts

Catalysts ◽

10.3390/catal10050533 ◽

2020 ◽

Vol 10 (5) ◽

pp. 533

Author(s):

Jinjun Wen ◽

Chunlei Huang ◽

Yuhai Sun ◽

Long Liang ◽

Yudong Zhang ◽

...

Keyword(s):

Reaction Temperature ◽

Direct Contact ◽

Co2 Hydrogenation ◽

Model Catalysts ◽

Water Gas Shift ◽

Clear Understanding ◽

Reverse Water Gas Shift ◽

Rwgs Reaction ◽

Temperature Programmed ◽

Water Gas

CO2 hydrogenation to methanol is one of the main and valuable catalytic reactions applied on Cu/ZnO-based catalysts; the interface formed through Zn migration from ZnO support to the surface of Cu nanoparticle (ZnOx-Cu NP-ZnO) has been reported to account for methanol synthesis from CO2 hydrogenation. However, the accompanied reverse water gas shift (RWGS) reaction significantly decreases methanol selectivity and deactivates catalysts soon. Inhibition of RWGS is thus of great importance to afford high yield of methanol. The clear understanding of the reactivity of RWGS reaction on both the direct contact Cu-ZnO interface and ZnOx-Cu NP-ZnO interface is essential to reveal the low methanol selectivity in CO2 hydrogenation to methanol and look for efficient catalysts for RWGS reaction. Cu doped plate ZnO (ZnO:XCu) model catalysts were prepared through a hydrothermal method to simulate direct contact Cu-ZnO interface and plate ZnO supported 1 wt % Cu (1Cu/ZnO) catalyst was prepared by wet impregnation for comparison in RWGS reaction. Electron paramagnetic resonance (EPR), XRD, SEM, Raman, hydrogen temperature-programmed reduction (H2-TPR) and CO2 temperature-programmed desorption (CO2-TPD) were employed to characterize these catalysts. The characterization results confirmed that Cu incorporated into ZnO lattice and finally formed direct contact Cu-ZnO interface after H2 reduction. The catalytic performance revealed that direct contact Cu-ZnO interface displays inferior RWGS reaction reactivity at reaction temperature lower than 500 °C, compared with the ZnOx-Cu NP-ZnO interface; however, it is more stable at reaction temperature higher than 500 °C, enables ZnO:XCu model catalysts superior catalytic activity to that of 1Cu/ZnO. This finding will facilitate the designing of robust and efficient catalysts for both CO2 hydrogenation to methanol and RWGS reactions.

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Production of Fuels and Chemicals from a CO2/H2 Mixture

Reactions ◽

10.3390/reactions1020011 ◽

2020 ◽

Vol 1 (2) ◽

pp. 130-146

Author(s):

Yali Yao ◽

Baraka Celestin Sempuga ◽

Xinying Liu ◽

Diane Hildebrandt

Keyword(s):

Co2 Hydrogenation ◽

Water Gas Shift ◽

Liquid Fuels ◽

Saturated Hydrocarbons ◽

Reverse Water Gas Shift ◽

Cu Catalyst ◽

In Series ◽

Fuels And Chemicals ◽

Water Gas ◽

Aspen Simulation

In order to explore co-production alternatives, a once-through process for CO2 hydrogenation to chemicals and liquid fuels was investigated experimentally. In this approach, two different catalysts were considered; the first was a Cu-based catalyst that hydrogenates CO2 to methanol and CO and the second a Fisher–Tropsch (FT) Co-based catalyst. The two catalysts were loaded into different reactors and were initially operated separately. The experimental results show that: (1) the Cu catalyst was very active in both the methanol synthesis and reverse-water gas shift (R-WGS) reactions and these two reactions were restricted by thermodynamic equilibrium; this was also supported by an Aspen plus simulation of an (equilibrium) Gibbs reactor. The Aspen simulation results also indicated that the reactor can be operated adiabatically under certain conditions, given that the methanol reaction is exothermic and R-WGS is endothermic. (2) the FT catalyst produced mainly CH4 and short chain saturated hydrocarbons when the feed was CO2/H2. When the two reactors were coupled in series and the presence of CO in the tail gas from the first reactor (loaded with Cu catalyst) significantly improves the FT product selectivity toward higher carbon hydrocarbons in the second reactor compared to the standalone FT reactor with only CO2/H2 in the feed.

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Facet-Dependent Reactivity of Ceria Nanoparticles Exemplified by CeO2-Based Transition Metal Catalysts: A Critical Review

Catalysts ◽

10.3390/catal11040452 ◽

2021 ◽

Vol 11 (4) ◽

pp. 452

Author(s):

Michalis Konsolakis ◽

Maria Lykaki

Keyword(s):

Transition Metal ◽

Co Oxidation ◽

Critical Review ◽

Rational Design ◽

Metal Catalysts ◽

Co2 Hydrogenation ◽

Transition Metal Catalysts ◽

Fine Tuning ◽

Ceria Nanoparticles ◽

Highly Active

The rational design and fabrication of highly-active and cost-efficient catalytic materials constitutes the main research pillar in catalysis field. In this context, the fine-tuning of size and shape at the nanometer scale can exert an intense impact not only on the inherent reactivity of catalyst’s counterparts but also on their interfacial interactions; it can also opening up new horizons for the development of highly active and robust materials. The present critical review, focusing mainly on our recent advances on the topic, aims to highlight the pivotal role of shape engineering in catalysis, exemplified by noble metal-free, CeO2-based transition metal catalysts (TMs/CeO2). The underlying mechanism of facet-dependent reactivity is initially discussed. The main implications of ceria nanoparticles’ shape engineering (rods, cubes, and polyhedra) in catalysis are next discussed, on the ground of some of the most pertinent heterogeneous reactions, such as CO2 hydrogenation, CO oxidation, and N2O decomposition. It is clearly revealed that shape functionalization can remarkably affect the intrinsic features and in turn the reactivity of ceria nanoparticles. More importantly, by combining ceria nanoparticles (CeO2 NPs) of specific architecture with various transition metals (e.g., Cu, Fe, Co, and Ni) remarkably active multifunctional composites can be obtained due mainly to the synergistic metalceria interactions. From the practical point of view, novel catalyst formulations with similar or even superior reactivity to that of noble metals can be obtained by co-adjusting the shape and composition of mixed oxides, such as Cu/ceria nanorods for CO oxidation and Ni/ceria nanorods for CO2 hydrogenation. The conclusions derived could provide the design principles of earth-abundant metal oxide catalysts for various real-life environmental and energy applications.

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