Investigations of the structure and thermal kinetic analysis of sugarcane bagasse char during non-isothermal CO2 gasification

Abstract

The CO2 gasification reactivity, thermal behaviour and activation energies of sugar cane bagasse (SCB) chars prepared at 500, 800 and 900°C were investigated by using thermogravimetric analysis (TGA) under non isothermal conditions at different heating rates of 20, 30 and 40°Cmin−1. The characteristics (physical and chemical structures) of the sugar cane chars as a function of pyrolysis temperature have been studied by applying Brunauer–Emmett–Teller (BET) surface area and Fourier transform infrared spectroscopy (FTIR) techniques. The results have demonstrated that the gasification of SCB chars took place almost completely in one-stage process as it has been shown by the presence of only one peak in DTG curve. The char reactivity is an inversely proportional to the pyrolysis temperature and directly to a gasification heating rate. As pyrolysis temperature increases, the char physical structures (BET surface area, pores characteristics) are directly proportional to the pyrolysis temperature. The hydroxyl, aliphatic C–H, carbonyl and olefinic C=C groups were lost at high pyrolysis temperatures (800 and 900°C). The activation energies were estimated by using Vyazovkin and Ozawa–Flynn–Wall methods, which have resulted in the mean of activation energy values of 70.44–88.37, 89.16–101.55 and 107.20–115.29kJmol−1, respectively for char prepared at 500, 800 and 900°C. Finally, Vyazovkin and Ozawa–Flynn–Wall methods were effectively applied to predict the reaction mechanism of thermal gasification.