Kinetic and thermodynamic analysis of biomass catalytic pyrolysis with nascent biochar in a two-stage reactor

Abstract

The interaction between nascent biochar and volatiles is critical and complex during the biomass thermochemical conversion processes. Despite various experiments showing a link between pyrolysis products and biochar catalysts, it is difficult to interpret the detailed mechanistic for the interplay between kinetic and thermal effects. To improve the understanding of the effect of nascent biochar catalyst on the pyrolysis of biomass, both kinetic and thermodynamic analysis was carried out in this work. Several catalytic processes were designed to analyze the catalytic reactivity combined with the online characterization of TG-MS and TG-FTIR. The catalytic pyrolysis kinetics analysis revealed that the particle size exhibited limited influence on the pyrolysis activation energy and product evolution. However, the nascent biochar could effectively decrease the pyrolytic activated energy of corn cob and facilitate the decomposition of lignin. Furthermore, the biochar promoted the conversion from CO2 to CO and the production of H2. In addition, the nascent biochar effectively improved the purity of the pyrolysis product and reduced the selectivity of acid, alcohol and ester. In-situ and ex-situ catalysis achieved high selectivity of phenolic products, whose selectivity reached 46.71% and 55.96%, respectively. Hybrid feeding catalysis attained significant productions of ethers, achieving the selectivity of 48.88%.