Fuel gas production from microwave-induced biomass pyrolysis using char-supported metal composites as both catalysts and microwave absorbers

Abstract

In this study, char-supported metal composites (0.2Ni-RHC, 0.2Fe-RHC and 0.2Co-RHC) were prepared via impregnation and subsequent microwave heating method, which were used as both microwave absorbers and catalysts for in-situ microwave-induced pyrolysis of pine sawdust, aiming to obtain high-quality fuel gas based on the interaction of microwave radiation and metal active sites in catalysts. The results showed that well-dispersed nanoparticles were generated in the three catalysts, which were firmly anchored on the matrix of the char support by several layers of graphitic carbon. The catalysts exhibited excellent microwave absorbing properties, a rapid heating rate was achieved which realized the temperature rise from room temperature to 800 °C within 110 s 0.2Fe-RHC exhibited the best catalytic performance among these three catalysts, with a high gas yield of 73.4% and low solid and bio-oil yield of only 4.1% and 13.6%, respectively. The yield of H2 and CO increased from 137.7 to 190.6 mL/g and from 241.2 mL/g to 393.9 mL/g compared with that of pure RHC. The microwave heating behavior and the catalytic activity of char-supported Fe catalyst were also influenced by the loading amount of Fe.