The catalytic gasification of biochar by CeO2 nano-catalytic systems with different morphologies

This paper investigates the potential of the rare earth catalyst CeO2 to catalyse the CO2 gasification of biomass-derived char. The hydrothermal process conditions were optimised to prepare CeO2 catalysts with varying morphologies and oxygen vacancy abundancies. The catalytic performance of CeO2 was examined in a laboratory-scale fixed-bed reactor during char gasification under CO2 atmosphere. The experimental results demonstrate that the increasing temperature and catalyst dispersion significantly enhance the gasification efficiency in CeO2-catalysed processes. The gasification performance of CeO2 nanocatalysts with varying morphologies (rod, cube, polygon) was assessed under identical experimental conditions. The morphology of the catalyst is indirectly related to its catalytic performance and catalytic structure, and the rod-shaped catalysts exhibit more oxygen vacancies. The CeO2-R(N) catalyst, which exhibited the highest oxygen vacancy content, gave the best catalytic performance. It is believed that these oxygen vacancies serve as active sites that enhance CO2 adsorption and activation, facilitating the Boudouard reaction and improving gasification efficiency. This morphology-driven variation in vacancy formation directly impacts the catalytic properties of CeO2, accelerating reaction kinetics and increasing syngas yield.