Kinetic and thermodynamic evaluation of almond shells pyrolytic behavior using Coats–Redfern and pyrolysis product distribution model

Abstract

ABSTRACT Rigid environmental regulations and the energy crisis are pursuing researchers to investigate eco-friendly and more energy-generating alternatives to conventional resources. Biomass has the required potential and is drawing keen attention, especially in the field of energy. This work includes the thermal decomposition of almond shells under pyrolysis (N2) conditions in a thermogravimetric analyzer (TGA) and estimated pyrolysis product gas composition and thermo-kinetic parameters. Pyrolysis experiments were conducted at heating rates of 10°C/min, 20°C/min, and 30°C/min. Using 11 reaction models, the Coats–Redfern method was applied to determine kinetic and thermodynamic parameters. The pyrolysis product gas composition was estimated using correlations based on elemental composition and pyrolysis temperature. Thermal decomposition mainly occurred in the temperature range 150–550°C with a peak temperature of 292°C, 310°C, and 321°C for the three heating rates, i.e. 10°C/min, 20°C/min, and 30°C/min, respectively, and 99.40% total weight loss. High regression coefficients (R2) in the range of 0.90–0.99 were obtained for the Coats–Redfern models. High mean relative reactivity (0.04%min−1°C−1) and low activation energies showed a high tendency to degrade thermally. The overall activation energy Eα range for almond shell was 2–84 kJ/mol at all heating rates. The pyrolysis gas composition showed good agreement with the experimental results of similar biomass.