Catalytic Reactivity Assessment of AgM and CuM (M = Cr, Fe) Catalysts for Dry Reforming of Methane Process with CO₂

CuM and AgM (M = Cr, Fe) catalysts were synthesized, characterized, and evaluated in methane reforming with CO₂ with and without pretreatment under a H₂ atmosphere. Their textural and structural characteristics were evaluated using various physicochemical methods, including XRD, B.E.T., SEM-EDS, XPS, and H₂-TPR. It was shown that the nature of the species has a significant effect on these structural, textural, and reactivity properties. AgCr catalysts, presenting several oxidation states (Ag⁰, Ag⁺¹, Cr³⁺, and Cr⁶⁺ in Ag, AgCrO₂, and AgCr₂O₄), showed the most interesting catalytic performance in their composition. The intermediate Cr₂O₃ phase, formed during the catalytic reaction, played an important role as a catalytic precursor in the in situ production of highly dispersed nanoparticles, being less prone to coke formation in spite of the severe reaction conditions. In contrast, the AgFe catalyst showed low activity and a low selectivity for DRM in the explored temperature range, due to a significant contribution of the reverse water–gas shift reaction, which accounted for the low H₂/CO ratios.