Pyrolysis Kinetics of Herbaceous Biomass Feedstocks Using Isoconversion Methods

Pyrolysis is a major thermochemical conversion technology utilized in converting biomass to liquid fuel and bioproducts. A major process in this technology is the thermal decomposition of biomass which determines the pyrolysis products distribution. In order to optimize the distribution of these pyrolysis products, it is imperative to understand the thermal decomposition behaviors of the biomass feedstocks. The objective of this study was to investigate the thermal decomposition behaviors of Public Miscanthus and Kanlow Switchgrass using isoconversional methods. Thermogravimetric analysis was carried out by heating the biomass samples from room temperature to 700 ⁰C in an inert condition at heating rates of 5, 15, and 25 ºC/min. Three isoconversional methods (Friedman, Ozawa-Flynn-Wall, and Kissinger-Akhira-Sunrose) were used in estimating the kinetic parameters. The thermal decomposition process for the biomass samples was divided into three broad stages based on the temperature range, namely, moisture & light volatile release (< 200 ℃), devolatilization & biochar formation (200 – 400 ℃), and poly-condensation & biochar aromatization (> 400 ℃). The estimated activation energy values were influenced by the fractional conversion. There was a variation in the activation energy values estimated by the isoconversional methods, which is due to the difference in their estimation approach.