Determination of Composition of Cellulose and Lignin Mixtures Using Thermogravimetric Analysis

The proportional composition of cellulose, hemicellulose, lignin, and minerals in a biomass plays a significant role in the proportion of pyrolysis products (bio-oil, char, and gases). Traditionally, the composition of biomass is chemically determined, which is a time consuming process. This paper presents the results of a preliminary investigation of a method using thermogravimetric analysis for predicting the fraction of cellulose and lignin in lignin-cellulose mixtures. The concept is based on a newly developed theory of pyrolytic unit thermographs (PUTs). The PUT is a thermograph showing rate of change in biomass weight with respect to temperature for a unit weight loss. These PUTs were used as input for two predictive mathematical procedures that minimize noise to predict the fractional composition in unknown lignin-cellulose mixtures. The first model used linear correlations between cellulose/lignin content and peak decomposition rate while the second method used a system of linear equations. Results showed that both models predicted the composition of lignin-cellulose mixture within 7–18% of measured value. The promising results of this preliminary study will certainly motivate further refinement of this method through advanced research.