Model free kinetic analysis of biomass/sorbent blends for gasification purposes

Biomass is one of the main renewable energy sources. Lignocellulose biomass materials can be converted to useful energy through the gasification process. The use of carbon dioxide adsorbent material such as calcium oxide (CaO) and or magnesium oxide (MgO) sorbent enhances the biomass conversion efficiency during gasification. Kinetic study of materials is vital to the assessment of parameters including the feasibility, design, and scaling of industrial biomass conversion applications. This study aims to investigate the thermal degradation behavior and the kinetic parameters of biomass/sorbent blends in order to establish the mixing ratio that results in higher conversion efficiency during gasification. Thermal stability is the ability of the material to resist change in physical shape as its temperature change. Thermogravimetric analysis (TGA) was employed to determine the thermal stability as well as the kinetics of biomass and sorbent mixtures of pine-wood, CaO and MgO, which will ultimately determine the gasification characteristics of the blends. The kinetic parameters were obtained through Kissinger and Flynn-Wall-Ozawa (FWO) model-free methods. A mixture of 809 pine-wood and 12.5% CaO and 12.5% MgO to make 25% CaO. MgO resulted in the highest thermal stability compared to others with the activation energy of 139.63 kJ/mol obtained from the Kissinger method and the average value of 143.74 kJ/mol from a FWO method. For this reason this mixture was found to be the one suitable for gasification. The thermal analyses obtained from biomass and other blends are presented and discussed in detail in this paper. (C) 2015 Elsevier Ltd. All rights reserved.