Complementary use of generalized logistic mixture model and distributed activation energy model in exploring kinetic mechanisms of wheat straw and torrefied rice husk pyrolysis

Abstract

Lignocellulosic biomass pyrolysis is a multi-step overlapping process, which leads to some difficulties in exploring biomass pyrolysis mechanisms. A kinetic approach combining the generalized logistic mixture model (GLMM) and the distributed activation energy model (DAEM) was proposed to explore the kinetic mechanisms of lignocellulosic biomass pyrolysis. The pyrolysis process of wheat straw could be effectively deconvoluted into three sub-processes by the GLMM, which corresponded to the thermal decomposition of pseudo-hemicellulose, pseudo-cellulose, and pseudo-lignin, respectively. These sub-processes could be adequately represented by the DAEMs and their activation energy distributions peaked at 164.2 kJ mol−1 (with a standard deviation of 2.6 kJ mol−1), 173.4 kJ mol−1 (with a standard deviation of 1.0 kJ mol−1) and 185.1 kJ mol−1 (with a standard deviation of 27.4 kJ mol−1). However, the pyrolysis process of torrefied rice husk was described by two sub-processes corresponding to the thermal decomposition of pseudo-cellulose and pseudo-lignin, with their activation energies peaked at 173.5 kJ mol−1 (with a standard deviation of 2.8 kJ mol−1) and 164.0 kJ mol−1 (with a standard deviation of 12.9 kJ mol−1). The combination of the GLMM and DAEM could provide a methodological guideline to obtain the detailed reactivity distributions involved in biomass pyrolysis, facilitating the optimization of biomass pyrolysis processes and subsequently extending the efficient and clean use of biomass for biofuel production.