The removal of tar and the production of methane-rich gas from biomass hydrogen pyrolysis by using biochar-based catalysts

The metal-doped pine wood activated char (PWA) was used in the catalytic reforming of the pyrolysis vapor of pine sawdust in the H2 atmosphere, to promote the removal of tar and methane-rich gas production. Ni-Co/PWA showed the best catalytic performance compared with Ni/PWA, Co/PWA, Fe/PWA, and Ni-Fe/PWA. The acquired tar yield was as low as 1.2 wt%, and the carbon yield of methane was 56.0 %. The characterization data of catalysts revealed that the NiCo active species in the catalyst was better dispersed and had a smaller particle size of 11.8 nm. Density functional theory (DFT) calculations showed that the introduction of Co reduced the adsorption energy of naphthalene on Ni/PWA catalysts. In addition, a synergistic effect of the H2 atmosphere and the metal-doped PWA catalyst was observed by comparing the reaction products under H2 and N2 atmospheres. According to DFT calculations, center dot H radical combines with naphthalene to release 104 kJ/mol of energy, promoting the decomposition of naphthalene. As a result, a high efficiency of Ni-Co/PWA in tar removal and methane generation was obtained. This study provides references for the efficient utilization of biomass energy.