Uncontrolled emissions of greenhouse gases cause global warming and subsequent climate change. Dry Reforming of Methane (DRM) is a promising catalytic process as it converts two major greenhouse gases (CH4 and CO2) into synthesis gas (CO+H2), providing an efficient way to directly use biogas and recycle CO2 emissions [1]. Syngas is a key feedstock for the petrochemical industry for producing liquid fuels, blue hydrogen, and high-value chemicals. The biggest challenges of the DRM process in practical applications are catalyst deactivation due to thermal sintering and carbon deposition [1]. In this study, the effect of support on the DRM performance (activity and selectivity) of Ir nanoparticles, carbon deposition phenomena, and their stability under reaction (at 500-750oC) and/or after oxidative thermal aging conditions is investigated. Supports studied include γ-Al2O3, Alumina-Ceria-Zirconia (ACZ), and Ceria-Zirconia (CZ). Their textural, structural and physicochemical properties, as well as those of the corresponding supported Ir catalysts, were determined using various techniques, such as BET, XRD, HRTEM, H2-TPR, H2-chemisorption, ICP-OES, and TPO. All catalysts studied were found to be highly stable under DRM conditions, while the carbon deposition rate was particularly low for all, although there seemed to be a clear decreasing trend in carbon deposition: Ir/γ-Al2O3 > Ir/ACZ > Ir/CZ. It was also found that Ir/CZ and Ir/ACZ catalysts, due to their high population of oxygen defects (oxygen vacancies), favor the conversion of CO2, thereby producing syngas enriched in CO. They also promote carbon removal through a bifunctional reaction mechanism. It was also demonstrated that supports with sufficient mobile lattice oxygen enhance the resistance to agglomeration of sensitive Ir crystallites, even under intense (~750°C) oxidative thermal aging conditions. In summary, Ir nanoparticles dispersed on CZ-based supports appear to be highly promising catalysts for the DRM reaction at low temperatures.
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