Enhancement of syngas for H2 production via catalytic pyrolysis of orange peel using CO2 and bauxite residue

This study investigated co-pyrolysis of orange peel and bauxite residue, focusing on enhancing syngas generation through CO2-cofeeding. The results revealed that adopting CO2 as a reactive gas medium led to an increase of CO generation through the gas phase reactions of CO2 and pyrolysates. Such phenomena were further enhanced by the presence of bauxite residue, yielding 75% enhancement of CO generation, which is likely due to the catalytic role of metallic components in the bauxite residue. These observations offered useful implications in H2 production. First, CO generated from the process could be converted into H2 by adopting an additional chemical unit operation (i.e., water-gas-shift reaction). Second, considering that the final products of the water-gas-shift reaction are H2 and CO2, the CO2 from water-gas-shift reaction could be reutilized by looping CO2 into the pyrolysis process to further expedite H2 production. Apart from H2 production perspective, the more carbon conversion into CO is practically beneficial for reducing coke formation. Hence, the overall results of this study suggest that careful selection of biomass wastes and proper utilization of industrial waste materials could provide a viable platform for developing more efficient energy-harvesting process in thermolysis technology.