Study of Cu–Ni–Ca Composite Catalysts in Catalytic Hydrogasification of Char

Abstract

The catalytic hydrogasification of char to synthetic natural gas was carried out in a pressurized fixed-bed reactor over Cu–Ni–Ca composite catalysts. The effect of the Cu–Ni ratio, Cu–Ni loading, reaction temperature on methane yield, and the methane formation rate was investigated. The characterization of these catalysts by X-ray diffraction showed that the Cu–Ni alloy was formed with a suitable Cu–Ni ratio during hydrogasification. Experiment results indicated that a suitable Cu–Ni ratio of 1:1 was favored for the formation of Cu–Ni alloy, which presented the highest catalytic activity. Methane yield and methane formation rate for 2.5%Cu–2.5%Ni–1.0%Ca reached 88.3% and 11.56 mL/(min·g char) at 800 °C and 2 MPa H2 pressure in 450 min, respectively. The high catalytic performance of the Cu–Ni alloy was due to the isolation of Cu and Ni atoms from their adjacent atoms, resulting in more adsorption and dissociation of hydrogen molecules as well as the interaction between metal atoms and carbon. Moreover, a possible reaction mechanism for coal/char catalytic hydrogasification over Cu–Ni–Ca composite catalysts was proposed.