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

Abstract

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.