Synergistic benefits for hydrogen production through CO2-cofeeding catalytic pyrolysis of cellulosic biomass waste

Abstract

Direct valorization of cellulosic biomass waste into energy is beneficial based on the concept of waste-to-energy. Pyrolysis of the biomass waste opens a chance to upgrade the valueless waste into value-added platform chemicals such as syngas (H-2 and CO). This study focused on valorization of sesame seed waste (SSW), a biomass waste material collected after sesame oil extraction, into syngas. To enhance syngas production and make this process more environmentally benign, CO2 was added as co-reactant during SSW pyrolysis. In the presence of CO2, pyrolysis of SSW showed enhanced CO formation (670 %), comparing with pyrolysis under N-2, due to the gas phase reactions (GPRs) between CO2 and volatile hydrocarbons resulted from pyrolysis of SSW. To enhance syngas production from SSW pyrolysis, mesoporous nickel-based catalyst was used for catalytic pyrolysis due to its known catalytic capability for chemical bond scissions of hydrocarbons and biomass-derived oxygenates. The enhanced production of syngas was proportionate to catalytic bed temperature (500, 600, and 700 degrees C) and catalyst loadings (0.2, 0.5, and 1 g), and the GPRs were independent with H-2 formation. All experimental findings indicated that CO2-assisted catalytic pyrolysis significantly improved H-2 and CO formations from a cellulosic biomass waste material, controlling the CO concentration with an introduction of CO2.