Role of porous structure and active O-containing groups of activated biochar catalyst during biomass catalytic pyrolysis

Activated biochar contains developed porosity and is rich in O-containing groups, both of which can allow the biochar to act as a catalyst in biomass catalytic pyrolysis and produce valuable chemicals. In this study, the role of porous structure and active O-containing groups of activated biochar catalyst during biomass pyrolysis at 600 °C was investigated in a fixed-bed reaction system. Activated biochar catalysts, obtained from bamboo-derived biochar activation at 800 °C with KOH, K2CO3, KHCO3, or CH3COOK, exhibited large surface area (SBET) and lots of O-containing groups. With the introduction of the activated biochar catalyst, the bio-oil yield reduced and the gaseous product yield increased, especially for CO, CO2, and CH4. The content of phenols (reaching 67%) and aromatics increased greatly, while content of O-containing compounds and acetic acid significantly reduced. Phenols content exhibited a positive linear correlation with the SBET of the catalyst, while aromatics content showed a negative linear correlation with the SBET. The SBET and active O-containing groups were both reduced after catalytic pyrolysis, especially in the –OH, O–CO, and C–O groups, which showed higher catalytic activity for biomass pyrolysis. Activated biochar catalyst acted both as a catalyst and reactant during catalytic pyrolysis process.