Advancements in Methane Dry Reforming: Investigating Nickel-Zeolite Catalysts Enhanced by Promoter Integration

A promising method for converting greenhouse gases such as CO2 and CH4 into useful syngas is the dry reformation of methane (DRM). 5Ni-ZSM-5 and 2 wt.% Ce, Cs, Sr, Fe, and Cu-promoted 5Ni-ZSM-5 catalysts are investigated for the DRM at 700 degrees C under atmospheric pressure. The characterization, including XRD, TPR, TPD, TPO, N2 adsorption-desorption, TGA, TEM, and Raman spectroscopy, revealed that the catalyst's active sites are distributed throughout the pore channels and on the surface, contributing to the stability of the catalyst. Specifically, the CO2-TPO followed by the O2-TPO experiment using spent catalysts confirmed the oxidizing capacity of CO2 during the DRM reaction. The Ce-promoted catalyst showed the greatest increase in catalytic activity among other catalysts. The 5Ni+2Ce-ZSM-5 catalyst exhibited twice the concentration of acid sites compared to the Cs-promoted counterpart, even though both catalysts achieved similar quantities of active and basic sites. Without compromising H2 and CO selectivity, this finding underscores the crucial role of acid sites in enhancing CH4 and CO2 conversion. With a GHSV of 42,000 mL/(h.gcat), the 5Ni+2Ce-ZSM-5 catalyst demonstrated impressive CH4 conversion rates of 42% at 700 degrees C and 70% at 800 degrees C. The reactants spend more time over catalysts during the subsequent reduction of GHSV to 21,000 mL/(h.gcat), resulting in the best catalytic performance with 80% CH4 and 83% CO2 conversions.