CO2-assisted pyrolysis of Mn-loaded biomass for syngas generation and periodate-activating biochar production.

Mn-biochar composite, which incorporates redox-active Mn sites into a carbon scaffold, is an active catalyst for periodate (PI) activation. Nevertheless, its scalable production remains challenging because conventional pyrolysis offers limited energy recovery. Here, Mn-impregnated switchgrass (SG) was pyrolyzed under CO2-assisted conditions to redirect biomass carbon conversion from condensable oxygenates to syngas. The temporal evolution of gaseous products indicated that Mn impregnation into SG promoted syngas generation during CO2-assisted pyrolysis. Correspondingly, analysis of biocrude composition indicated that Mn and CO2 facilitated the secondary conversion of condensable oxygenates. Mn-biochar composite produced under CO2-assisted pyrolysis (MnSGB (CO2)) displayed pronounced redox features, indicating the presence of active Mn species. MnSGB (CO2) showed lower charge-transfer resistance than Mn-free biochars. Consequently, MnSGB (CO2) exhibited superior catalytic performance for PI activation, achieving >99% bisphenol A removal. Mechanistic investigations also suggested that enhanced catalytic activity was driven by Mn-mediated interfacial electron transfer and the resulting 1O2 generation.