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 (H2 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 N2, 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 °C) and catalyst loadings (0.2, 0.5, and 1 g), and the GPRs were independent with H2 formation. All experimental findings indicated that CO2-assisted catalytic pyrolysis significantly improved H2 and CO formations from a cellulosic biomass waste material, controlling the CO concentration with an introduction of CO2.