CO2 reforming of CH4 on Ni-Al-Ox catalyst using pure and coal gas feeds: Synergetic effect of CoO and MgO in mitigating carbon deposition

Highlights: • Catalysts effectively converted major greenhouse gases to useful product. • Less carbon deposition was observed in catalyst for coal gas compared to pure gas. • Mixed oxide of Ni-Co and MgO-solid phase were observed in catalysts when Mg/Al >1. • When Mg/Al>1, Co stabilized Ni active sites and prevent catalyst deactivation. • Relationship among structure, metal reduction and performance were observed. Mg-Al-Ox supported monometallic (Ni) and bimetallic (Ni-Co) catalysts with different compositions of Mg and Al were investigated for CO₂ reforming of CH₄, using both coal and pure gas feeds, to limit the emission of these environmental pollutant gases into the atmosphere. Results showed that all the catalysts were active for dry reforming reaction using both feeds. Reactants conversion, stoichiometric product selectivity, and resistance to carbon deposition of catalysts remarkably improved when the Mg/Al ratio was greater than 1. Characterization results revealed changes in the bulk structure, textural and surface properties as the Mg/Al ratio and composition of catalysts changed. Improved active metal reduction, metal-support and metal-metal interaction (in the bimetallic) were also noted in the catalysts with Mg/Al ratio greater than 1. With respect to feed composition, less carbon deposition was recorded in the corresponding catalysts using coal gas compared to the pure gas. Ni-Co interaction and their interaction with MgO facilitated better basicity, increased metal dispersion and smaller particle size in Ni-Co-Mg_1.7-Al₁-Ox, which showed best catalytic performance with no carbon deposition in both feeds. These interactions and properties stabilized the Ni site, which made the Ni-Co-Mg_1.7-Al₁-Ox, catalyst resistant to sintering and carbon deposition.