A Comprehensive Mechanistic Study for Dry Reforming of Methane over CeO2-Supported TM4 clusters (TM = Ru, Pt, Co, Ni)

In this work, the mechanism of dry reforming of methane (DRM) over a series of CeO2 (111)-supported transition metal (TM) clusters, TM4/CeO2(111) (TM = Ru, Pt, Co, Ni), was investigated by using density functional theory (DFT) and microkinetic modeling. According to the results of DFT calculations, Ru4/CeO2(111) and Co4/CeO2(111) exhibit strong oxygen adsorption capabilities due to the oxophilic properties of Ru and Co metals, which facilitate CO2 activation more effectively than other metals. Ru4/CeO2(111) demonstrates the highest efficiency for both CH4 and CO2 activation. Pt4/CeO2(111) has great anticoking ability because the C* coupling has a higher energy barrier. Microkinetic simulations indicate that the turnover frequency (TOF) rate follows the trend: Ru4/CeO2(111) > Pt4/ CeO2(111) > Co4/CeO2 (111) > Ni4/ CeO2(111). Ru/CeO2 exhibits the highest activity and selectivity. Pt/CeO2 has the best ability for anticoking due to the high energy barrier of C* coupling. Co/CeO2 is prone to deactivation from oxygen poisoning, attributed to its strong oxophilic properties and weak CH4 activation ability, Ni/CeO2 shows the poorest activity and stability, as it is easily deactivated by coke formation and has the lowest selectivity. The analysis of key steps indicates that there are different rate-controlled steps for various metals due to inherent differences in their properties. We anticipate that our results will offer a strategy for designing DRM catalysts by selecting the appropriate metal catalysts.