Properties, kinetics and pyrolysis products distribution of oxidative torrefied camellia shell in different oxygen concentration

Abstract

Bio-energy would become an important energy supply in the future, but the inherent defects of biomass limit its energy utilization. Torrefaction could improve the energy performance for biomass, and oxidative torrefaction is more practical to reduce the energy consumption and improve the efficiency. In present work, the properties, kinetics and pyrolytic products distribution of oxidative torrefied camellia shell (CS) have been investigated with the oxygen concentration of 0–8% in torrefaction atmosphere. The results show that oxidative torrefaction would alter the cellulose crystals from Iα to Iβ of CS and improve their hydrophobicity, and their surface functional groups have also undergone major changes. Based on the Flynn-Wall-Ozawa method and Distributed Activation Energy Model, torrefaction causes the pyrolysis activation energy to increase first and then decrease. According to the evaluated by Criado method, order of reaction and random nucleation have been identified as the most likely mechanism for thermal degradation of torrefied CS. In addition, Oxidative torrefaction would improve the phenols compounds in pyrolytic products. The present work may provide a reference for the energy utilization of CS.