A study of cellulose pyrolysis chemistry and global kinetics at high heating rates

Abstract

Cellulose pyrolysis has been studied in a laminar entrained flow reactor (LEFR). As described in the previous companion paper, the reactor is capable of high heating rates (104 K/s) and has been characterized in detail to ensure that pyrolysis of lignocellulosic materials occurs under kinetic control at the conditions of the reactor. The extent of cellulose pyrolysis in the LEFR was monitored by sampling the gas phase products with a molecular beam mass spectrometer system, and independently by sampling and weighing residues on a filter paper. Varying the reactor furnace temperature controls the pyrolysis severity. Quantitative cellulose pyrolysis data have been compared to several published reaction rates. Published models that involve low activation energy rates from other high temperature experiments described in the literature best approximate the results obtained in this study. Factor analysis of the mass spectral data requires two principal components to interpret the gas phase product composition. This suggests that the primary cellulose pyrolysis products were involved in subsequent secondary reactions that directly compete with the primary release of products at the conditions in this reactor. A rate is presented that describes the observed thermal destruction of primary pyrolysis products.