Pyrolysis kinetics and product distribution of alpha-cellulose: Effect of potassium and calcium impregnation

Abstract

Cellulose accounts for the largest proportion of lignocellulosic biomass. Herein, experimental and simulation studies are used to deeply understand the kinetic characteristics of the thermal decompo-sition of alpha-cellulose. The simulated data is in good agreement with the experimental data in the aspects of the conversion and the conversion rate versus temperature. The decomposition of alpha-cellulose, mainly occurring at 270-420 degrees C, induced an apparent activation energy ranging from 175.42 kJ/mol to 197.73 kJ/ mol at a conversion of 10-90%. With 0.1-0.2 wt% K or Ca impregnation into the alpha-cellulose, the mean activation energy for pyrolysis was lowered (from 181.47 kJ/mol (for alpha-cellulose) to 141.11 kJ/mol (for 0.2 wt% K/alpha-cellulose) and 159.46 kJ/mol (for 0.1 wt% Ca/alpha-cellulose)) and higher amounts of liquid and gas products were produced. Furthermore, the addition of potassium and calcium increased the pro-duction of lower molecular weight components, such as furfural and its derivatives. The kinetic pa-rameters of the alpha-cellulose pyrolysis were determined based on a nonlinear least-squares regression of the experimental data assuming first-order kinetics and correlated with the simulated result. The kinetic rate constants indicate that the predominant reaction pathway is from alpha-cellulose into a liquid product, rather than from alpha-cellulose into a gas product. (C) 2021 Elsevier Ltd. All rights reserved.