Decomposition and coupling of methane over Pd–Au/Al2O3 catalysts to form COx-free hydrogen and C2 hydrocarbons

Abstract

Catalytic decomposition of methane (CDM; CH4 → C + 2H2) is expected to be used for clean hydrogen production because CDM does not emit carbon dioxide. Recently, it was reported that Pd–based catalysts promotes CDM, simultaneously facilitating coupling of CH4 to form C2 hydrocarbons. In this study, varieties of supported Pd–M alloy catalysts (M = Fe, Co, Ni, Cu, Zn, Ga, In, Sn, Au, Pb, and Bi) were synthesized and their activities for the CDM and CH4 coupling were examined. The catalytic activity for CH4 strongly depended on the types of Pd–M. Pd–M/Al2O3 (M = Ni, Fe, Co, Au) showed high activity for CDM. In addition to the production of hydrogen by the CDM, Pd–Au/Al2O3 formed C2 hydrocarbons such as ethane and ethylene via the coupling of CH4. Effects of Pd/Au ratio and reaction temperatures were examined and the role of Au for the CH4 conversion reaction was discussed.