Comparative evaluation of Ni-based bimetallic catalysts for dry reforming of methane at low temperature: The effect of alloy itself on performance

Dry reforming of methane assisted by 5 wt% Ni-X alloy catalysts (X: Co, Cu, Pd, and Rh) anchored on γ-alumina is evaluated for comparing the synergetic effect of alloys at once as catalysts for dry reforming of methane at low temperatures of 400°C-600°C. Characterization of catalysts confirms alloy formation, structural properties, and adsorption properties that affect the performance of each bimetallic catalyst. Catalytic performance is evaluated from the perspective of initial activity, syngas production and selectivity, long-term stability, as well as energy efficiency at powder level not previously addressed, followed by post-analysis for carbon formation. The results show that Ni-Rh/Al₂O₃ and Ni-Co/Al₂O₃ are highly active and stable during the reaction. Ni-Rh/Al₂O₃ shows higher CH₄ and CO₂ conversions at 550°C as 32.71% and 84.69% of those at equilibrium, respectively. Similarly, CH₄ and CO₂ conversions of Ni-Co/Al₂O₃ at 550°C are 26.17% and 71.76% of those at equilibrium. They exhibit better long-term stability than a Ni monometallic catalyst, decreasing the degradation rate by 60% for Ni-Rh/Al₂O₃ and 40% for Ni-Co/Al₂O₃. Such improvement is even more pronounced when the temperature decreases from 500°C to 400°C, implying their potential as catalysts for dry reforming of methane at low temperatures. However, for every performance indicator, Ni-Pd/Al₂O₃ and Ni-Cu/Al₂O₃ exhibit low performance. These tendencies are mainly attributed to the synergetic effect of alloy and apparent activation energies for reactions. Based on such experimental results, it is discussed that Ni-Rh/Al₂O₃ and Ni-Co/Al₂O₃ are feasible and promising catalysts for dry reforming of methane even at low temperatures.