Tar microwave reforming over different biochar-based Ni catalysts by experiments and DFT

In order to remove tars generated during biomass pyrolysis. In this study, tar steam reforming was investigated using toluene as a tar model compound and a biochar-based nickel catalyst under microwave conditions. Based on the catalyst characterization results, density functional theory (DFT) calculations were performed to investigate the effect of different forms of nickel presence in the catalyst on toluene cracking. The experimental and simulation results indicate that the formation of Ni3S2 negatively affects the cracking of toluene. The catalyst prepared by Ni(NO3)2 impregnation demonstrated relatively good catalytic activity and stability, with 81.6 % conversion even after 190 min of pyrolysis. The ratio of water to carbon (S/C) has a significant impact on the steam reforming of toluene. A high S/C can lead to the destruction of the catalyst carbon matrix, resulting in catalyst deactivation. Conversely, a low S/C can cause a slow increase in the catalytic effect of the catalyst. The catalytic effect of the Ni(NO3)2 catalytic remains good even without the addition of water, with 78.6 % hydrogen conversion remaining at the end of 190 min pyrolysis. The addition of water molecules will inhibit the production of CH4.