(181n) Conversion of CO2 and CH4 to CO over Bifunctional Catalysts Synthesized By Combustion Technique

Increasing levels of greenhouse gases, particularly carbon dioxide and methane, in the atmosphere is considered the primary factor leading to global warming, triggering interest in capture and utilization carbon dioxide. While CO₂ is generally regarded as an inert molecule, several processes can be employed to activate it and turn it into useful compounds and fuels. Among the most promising methods for utilizing CO₂ is the methane dry reforming (MDR) reaction, which occurs when CO₂ and CH₄ combine to form CO and H₂ as syngas, which can be fed into another unit like the Fischer-Tropsch process to produce fuels and other value-added chemicals. This way, two of the greenhouse gases can be reacted to produce platform molecules leading to many possibilities in terms of fuel and chemical production. Although MDR is thermodynamically favorable at high temperatures, coking becomes a major challenge leading to catalysts deactivation. Operating the reaction at lower temperature saves energy and reduces coke formation, nonetheless requires suitable catalysts to have a meaningful conversion and appropriate selectivity for syngas production. It has been proved that transition metal catalysts, particularly nickel and nickel composites, are effective catalysts for DRM. The present study investigates the role of reducible ceria, lanthanum oxide supports with Ni active metals prepared via the solution combustion synthesis method (SCS) for MDR. Additionally, perovskites containing nickel, lanthanum are also tested for MDR reaction. The results showed that increasing the temperature improved CO₂ and CH₄ conversion in all cases, with a high selectivity for hydrogen at elevated temperatures. The syngas quality, H2/CO ratio is also improved with an increase in temperature. The perfect synergistic interaction among the active nickel species with support oxygen vacancy may be the cause of the high catalytic activity. The catalysts were evaluated for stability test at 650 -700°C temperature for 24 – 40h TOS runs, and relatively low carbon depositions were observed for all the samples. For both fresh and used catalysts, several studies including XRD, TEM, SEM-EDX, and TPR were carried out in order to understand the morphological characteristics of the catalysts as well as the impact of the reaction on the surfaces of the catalysts. The findings may open up new possibilities for the support role of reducible oxides in RWGS and other hydrogenation processes.