CO2 GASIFICATION OF BIOCHARS PREPARED FROM AGROINDUSTRIAL WASTE: A KINETIC STUDY

The objective of this study was to evaluate the kinetic parameters of a gasification process, under CO2 atmosphere, of biochars produced from the agroindustrial wastes: castor bean presscake (CBP) and mesquite pod bagasse (MPB). The biochars were produced by pyrolysis under atmospheric pressure with N-2 gas flow of 400 mL min(-1) at two conditions, the first at 700 degrees C (heating rate of 160 degrees C min(-1)) and the second at 900 degrees C (heating rate of 224 degrees C min(-1)), both with a 5 min residence time at the final temperature. The biochars showed a potential to be used in energy production systems due to their HHV compared with some fossil fuels. The isothermal gasification of the biochar runs were performed in a thermogravimetric analyzer at atmospheric pressure. The theoretical kinetic models used to adjust the experimental data were volumetric model (VM), shrinking model (SCM) and random pore model (RPM). In terms of CO2 reactivity, the biochars from MPB were more reactive than biochars from the CBP, in the temperature range of 760-920 degrees C. The E-A values related to the biochars gasification were around 187-238 kJ mol(-1), and the theoretical kinetic model of RPM proved more appropriate for representing the experimental data.