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 gamma-alumina is evaluated for comparing the synergetic effect of alloys at once as catalysts for dry reforming of methane at low temperatures of 400 degrees C-600 degrees 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 degrees C as 32.71% and 84.69% of those at equilibrium, respectively. Similarly, CH4 and CO2 conversions of Ni-Co/Al2O3 at 550 degrees 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 degrees C to 400 degrees 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.