Kinetics of the low-temperature pyrolysis of walnut shell

Abstract

The walnut shell with particle size less than 0.154 mm pyrolysis mass loss behaviour was studied at different heating rates (5, 10, 20, 30, 40?C/min) using pyris1 thermogravimetric analysis (TGA) instrument. Results showed that the activation energies of walnut shell pyrolysis under the different fractions decomposed were centred on 134?172 kJ/mol by Ozawa method and Kissinger?Akahira?Sunose method and centred on 109?120 kJ/mol by Coats?Redfern method and Achar method. In the process of deducing walnut shell pyrolysis mechanism function, first, possible mechanism functions of walnut shell pyrolysis were preliminary judged according to the TG/DTG curves shape using the Dollimore method. Then, the possible expressions of reaction mechanism function of walnut shell pyrolysis were deduced through Coats?Redfern method, Achar method, and thermal analysis kinetic triplet comparative method. It was found that the experimental data were ideally described by the equation of Zhuralev?Lesokin?Tempelman. The mechanism was the three-way transport diffusion. The research has provided a beneficial reference for the technological parameters optimisation of biomass pyrolysis.