Comprehensive kinetic study of Imperata Cylindrica pyrolysis via Asym2sig deconvolution and combined kinetics

摘要

This study examined the non-isothermal kinetics of the slow pyrolysis of Imperata Cylindrica (IC). Pyrolysis conditions were developed under the pure N-2 flow and non-isothermal conditions at the heating rates of 2.5, 5, 10, and 17.5 K/min and over the temperature range of 303-1173 K. The IC pyrolysis profiles could be identified into three parallel reactions, each of which corresponded to pseudo-hemicelluloses (P-Hem), pseudo-cellulose (P-Cell), and pseudo-lignin (P-Lig) decomposition. A systematic kinetic study of the pyrolysis of IC via thermogravimetric analysis (TGA) deconvolution using Asymmetric Double Sigmoidal (Asym2sig), Friedman differential iso-conversional and combined kinetics of biomass pseudo-components was carried out. The kinetics parameters of pseudo components fitted well with the pyrolysis experimental data for all the heating rates. Differential master-plots showed that the reaction mechanisms for pseudo hemicellulose (P-Hem) and pseudo cellulose (P-Cell) were diffusional and order based, and high order based (3rd order) for the pseudo lignin (P-Lig). Mechanism of P-Hem, P-Cell and P-Lig could be further reconstructed to Sestak and Berggren model of f(alpha) = alpha(-0.9875)(1 - alpha)(1.325) [-ln(sic)(1 - alpha)](0.0209), f(alpha) = alpha(0.3313)(1 - alpha)(1.4731) [-ln(sic)(1 - alpha)](0.0215) and f(alpha) = alpha(-2.9551)(1 - alpha)(2.7642) [-ln(sic)(1 - alpha)](0.0074), respectively. The combined kinetic reported the activation energies of pseudo-components were as 194.709 kJ/mol, 179.968 kJ/mol and 219.226 kJ/mol for P-Hem, P-Cell and P-Lig, respectively.