Synergistic intensification of membrane reactor with biochar catalyst for efficient production of clean syngas from biomass gasification

Clean syngas can be used in fuel cells and for the production of high-value fuels and chemicals, however, tar and particulate matter (PM) in syngas are major challenges in its utilization. Herein, we report an advanced and integrated reactor employing silicon carbide (SiC) membrane and biochar-based catalysts for the concurrent and efficient in-situ removal of tar and PM from syngas produced by biomass gasification at 800 °C. The integrated reactor showed superior synergies between the SiC membrane and activated biochar (A-biochar) catalyst, achieving the removal of 96.4 % tar and 95.9 % PM that are superior over the cases with either a single membrane reactor or the A-biochar catalyst alone. Tar and PM yields were reduced to 3.6 g/m³ and 0.03 g/m³ of syngas, respectively, meeting the technical specifications for syngas used in solid oxide fuel cells. More specifically, the membrane with a thickness of 2.6 μm effectively captured PM with an aerodynamic size larger than 0.24–0.28 μm; the porous carbon matrix in A-biochar catalyst had a strong cracking effect on heavy volatiles (e.g., fluorene and anthracene); and the inherent Ca and Al-bearing species in A-biochar catalyst were the main active sites for the cracking and reforming of relatively lighter tar fragments (e.g., naphthalene and phenol). Cyclic tests confirmed a relatively stable performance of the integrated reactor coupled with A-biochar catalyst, maintaining a high PM removal efficiency at 95–98 % over nine cycles, whereas the tar conversion declined from 95–97 % to 84 % after seven cycles, likely due to carbon depletion in the catalyst.