CO2 gasification of biomass wastes enhanced by Ni/Al2O3 catalyst in molten eutectic carbonate salt

Abstract

Catalytic enhancement of syngas production rate and yield by combined ternary eutectic carbonate salt–Ni/Al2O3 (MS-Ni) medium was investigated by CO2 gasification of cellulose, biomass wastes (chopstick, newspaper, sawdust), and sawdust char in a lab-scale reactor. Compared to the case of only molten salt (MS), MS-Ni medium could increase syngas production yields of the above-listed 5 feedstock by 28, 23, 18, 17, and 12%, respectively, at 1173 K. In fact, H2 production yield increased by up to 300% while the CO production yield slightly increased by 10–15% with the temperature at peak rate shifted lower by approximately 100 K. Arrhenius rate expressions for char gasification were derived to give activation energies of 125 and 105 kJ mol−1 for the MS and MS-Ni mediums, respectively. The Ni/Al2O3 catalyst in MS-Ni medium was not only active for H2 production but also could enhance CO production. The reaction mechanism of CO2 gasification of cellulose in MS-Ni medium was schematically proposed.