Effects of Al2O3-based catalysts on bio-oil composition during biomass pyrolysis

•Investigated Al2O3-based supported catalysts' effect on bio-oil in biomass pyrolysis.•Explored Ce, fe and mo as loaded metals and discussed the reaction mechanism.•Al2O3-based supported catalysts reduced phenols and increase aldehydes in bio-oil.•Phenols were reduced by 8.63 %, while aldehydes increased by 11.06 %.•Provide guidance for the high-value utilization of bio-oil in biomass pyrolysis. Biomass catalytic pyrolysis is one of the effective methods for biomass utilization. Understanding the compound composition changes in bio-oil from biomass pyrolysis with catalysts is crucial for efficient biomass utilization. This study investigated the use of Al2O3-based catalysts with Ce, Fe and Mo as loaded metals for biomass pyrolysis. Detailed analysis was conducted on the influence of Al2O3-based catalysts on bio-oil compound composition during biomass pyrolysis. Furthermore, the reaction mechanism was explored and discussed. The research found that the introduction of Al2O3-based catalysts increased the residual mass during biomass pyrolysis. And addition of loaded metals promoted oxidation–reduction of surface deposits on the catalyst, decreasing residual mass. Through pyrolysis-gas chromatography/mass spectrometry testing, the introduction of Al2O3-based catalysts reduced phenols, ketones, alcohols and other bio-oil compounds. Phenols showed the highest decrease, with a maximum reduction of 8.63 %. Aldehydes, acids and hydrocarbons showed an increasing trend, with aldehydes exhibiting the highest increase of 11.06 %. Furans and esters remained relatively unchanged. This study will provide guidance for the changes in bio-oil compound composition during biomass pyrolysis and the high-value utilization of bio-oil. [Display omitted]