Owing to the increasing emissions of carbon dioxide (CO2), human life and the ecological environment have been affected by global warming and climate changes. To mitigate the concentration of CO2 in the atmosphere various strategies have been implemented such as separation, storage, and utilization of CO2. Although it has been explored for many years, hydrogenation reaction, an important representative among chemical conversions of CO2, offers challenging opportunities for sustainable development in energy and the environment. Indeed, the hydrogenation of CO2 not only reduces the increasing CO2 buildup but also produces fuels and chemicals. In this critical review we discuss recent developments in this area, with emphases on catalytic reactivity, reactor innovation, and reaction mechanism. We also provide an overview regarding the challenges and opportunities for future research in the field (319 references).

Recent advances in catalytic hydrogenation of carbon dioxide

Unlike homogeneous catalysts, heterogeneous catalysts that have been optimized through decades are typically so complex and hard to characterize that the nature of the catalytically active site is not known. This is one of the main stumbling blocks in developing rational catalyst design strategies in heterogeneous catalysis. We show here how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. Using a combination of experimental evidence from bulk-, surface-sensitive and imaging methods collected on real high-performance catalytic systems in combination with DFT calculations. We show that the active site consists of Cu steps peppered with Zn atoms, all stabilized by a series of well defined bulk defects and surface species that need jointly to be present for the system to work.

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The Active Site of Methanol Synthesis over Cu/ZnO/Al2O3 Industrial Catalysts

Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Oxidation into CO2 is a major solution to CO abatement in air depollution treatments. The development of catalytic converters led to an extraordinary high number of publications on metal catalysts during the last fifty years. Due to the increasing price of noble metals and to remarkable progresses in oxide syntheses, catalytic oxidation of carbon monoxide over oxide catalysts has recently gained in interest, even if some oxides are known to present remarkable activity since the beginning of the 20th century. In this Review, the kinetics and mechanism of CO oxidation on single and mixed oxides are examined, alongside the catalyst structures

Catalytic Oxidation of Carbon Monoxide over Transition Metal Oxides

Fossil fuel depletion, global warming, climate change, and steep hikes in the price of fuels are driving scientists to investigate on commercial and environmentally friendly fuels. The process of CO2 conversion to value-added products has been considered as a possible remedy to fulfill the requirements. The present review paper comprehensively discusses two different processes, namely hydrocarbon and methanol synthesis which are extensively used to convert CO2 to value-added products. Reaction mechanisms as well as the effects of catalyst, reactor type and operating conditions on product efficiency enhancement of each process are reviewed. Furthermore a brief overview on the reactor types as the most effective component of the theoretical and experimental reported results on the process improvement is given. All the information is tabulated in order to make the gathered information easily conclusive. Finally, by taking the available information into account the best reactor configuration which is adjustable to reaction mechanism is proposed.

Hydrogenation of CO2 to value-added products—A review and potential future developments

Perovskite type oxides may potentially replace noble metal catalysts as full oxidation catalysts of hydrocarbons, as present in combustion exhaust streams, due to their high activity and fair hydrothermal stability. Presently we have investigated the catalytic activities of a series of Ce substituted La–Mn perovskites, prepared by coprecipitation, in the oxidation of carbon monoxide. The composition, bulk structure and the surface properties were established using elemental analysis, XRD and XPS. The properties tested include the reducibility and reoxidation behavior, the thermal stability of these perovskites and the oxidation activity. It was observed that Ce is not totally incorporated in the perovskite lattice. For a high degree of substitution, an excess Ce forms a separate CeO 2 phase. Simultaneously, an increase in the atomic Mn 4+ /Mn 3+ ratio and a decreasing surface oxygen concentration are observed. This suggests that cation vacancies are created at A (La) sites, resulting in the formation of unsaturated Mn (B) site ions on the surface. The catalytic activity of the La–Mn perovskites systematically changes as a function of the degree of Ce substitution. A plausible explanation for this behavior is the nonstoichiometry induced by Ce substitution, which results in the formation of cation/anion vacancies near the surface. The specific surface area and the atomic surface composition play a less pronounced role in the catalytic activity.

Surface properties and catalytic performance in CO oxidation of cerium substituted lanthanum–manganese oxides

Dynamic behavior of the surface structure of Cu/ZnO/SiO2 catalysts

https://pure.uva.nl/ws/files/4088557/46316_batyrev_jcat_05_postprint.pdf

The effect of the reduction temperature on the structure of Cu/ZnO/SiO2 catalysts for methanol synthesis

https://pure.uva.nl/ws/files/3671997/36967_zhang_jcat_04_postprint.pdf

J. Beckers

Papers

Surface properties and catalytic performance in CO oxidation of cerium substituted lanthanum–manganese oxides

Dynamic behavior of the surface structure of Cu/ZnO/SiO2 catalysts

The effect of the reduction temperature on the structure of Cu/ZnO/SiO2 catalysts for methanol synthesis

Dielectric heating effects on the activity and SO2 resistance of La0.8Ce0.2MnO3 perovskite for methane oxidation