Synergy of macro-meso bimodal pore and Ni-Co alloy for enhanced stability in dry reforming of methane

Abstract

Dry reforming of methane (DRM) is an ideal reaction to chemically utilize two important greenhouse gases, methane and carbon dioxide, but the serious carbon deposition often makes the catalysts deactivated, which limits its industrialized application of DRM. To improve the catalytic performance and stability of the catalyst, a bimodal pore structure Ni-Co catalyst was prepared and applied for DRM in this work. The fresh and spent samples were characterized by SEM, TEM, XRD, XPS, TPR, TPH, Raman spectra and N2 adsorption–desorption. The results indicated that Ni-Co alloy phases and bimodal meso-macroporous structure were formed in catalysts. The effect of Co/Ni and bimodal structure on catalytic activity and carbon deposition resistance were investigated at 700 °C, W/F = 1 g·h/mol. Results show that the catalyst with bimodal pore structure of cobalt and nickel ratio of 0.5 (NC0.5-M100-MA) exhibited the best catalytic performance after 100 h reaction, the conversion of CH4 and CO2 are 73.1% and 81.6%, respectively, 4.5% and 4.7% higher than that of the Ni-M100-MA, respectively. The amount of carbon deposits has a small increased compared to that of Ni-M100-MA, but it’s stable in whole reaction since most of the carbon deposits are amorphous carbon, which is easy to eliminate. The stability is mainly contributed to the synergy effect of Ni-Co alloy and macro-meso bimodal pore structure, which helps suppress the conversion of amorphous carbon into coke.