Investigation of the relationship between functional groups evolution and combustion kinetics of microcrystalline cellulose using in situ DRIFTS

Abstract

Functional groups evolution characteristics of biomass during the combustion process have a significant influence on the combustion mechanism because they directly affect the diffusion of oxygen to the surface of biomass. In this paper, microcrystalline cellulose was chosen as the feedstock. The functional groups evolution characteristics were studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermogravimetric (TG) analysis was also conducted to be compared. In situ DRIFTS and TG of cellulose were performed from 20 °C to 500 °C at different heating rates in different atmospheres. The results of in situ DRIFTS showed that oxygen-containing functional groups firstly increased and then decreased with increasing temperature, while hydrogen-bonded functional groups showed the opposite characteristics. Compared with TG experiments, it can be obtained that the O–H bonds maintained the crystal structure of cellulose at low temperature, and promoted further reactions at high temperature. The production of C=O functional groups prevented further decomposition of cellulose. The relationship of combustion kinetics during the initial stage of combustion and in situ functional groups evolution characteristics were obtained. This study demonstrated that the combustion kinetics can be predicted by the surface functional groups evolution of biomass, which provides a potential way for studying biomass combustion.