Carbon Dioxide Gasification of Biochar: A Sustainable Way of Utilizing Captured CO2 to Mitigate Greenhouse Gas Emission

Abstract

This study proposes CO2 gasification of biochar as a potential carbon utilization pathway for greenhouse gas emission reduction. It aims to evaluate the effects of CO2 concentration on carbon and CO2 conversion and output CO yield. It also performs kinetic analysis, using the volume reaction model, to determine the activation energy and pre-exponential factor. The operating conditions utilized include gasification temperatures of 700, 800, and 900 °C; inlet CO2 concentrations of 15%, 30%, 45%, and 60% by volume (N2 balance); and a CO2 flow rate of 5 L/min. Carbon dioxide gasification of biochar was performed in a fixed bed batch reactor, and the composition of the output gases was analyzed. Increases in the temperature and inlet CO2 concentration both resulted in an increase in carbon conversion, with the maximum carbon conversion of 57.1% occurring at 900 °C and a 60% inlet CO2 concentration. The results also showed that CO2 conversion increased against temperature but decreased with an increasing inlet CO2 concentration. The maximum CO2 conversion of 76% was observed at 900 °C and a 15% inlet CO2 concentration. An activation energy in the range of 109 to 117 kJ/mol and a pre-exponential factor in the range of 63 to 253 s−1 were determined in this study.