Evaluation of synergy during co-pyrolysis of torrefied sawdust, coal and paraffin. A kinetic and thermodynamic study

The pyrolysis of coal (C), torrefied sawdust (SPT), paraffin (P), and their blends was evaluated. Iso-conversional methods (i.e. Friedman, Flynn-Wall-Ozawa, and Kissinger-Akahira-Sunose) were used to determine the activation energy (Ea); the Kissinger method allowed the frequency factor (A) calculation and Criado and CoatsRedfern were used to elucidate the reaction mechanism. Thermodynamic parameters of the transition state (?H?, ?G? and ?S?) were calculated by Eyring equations. Paraffin decomposition was influenced by the initial mass. The SPT/P blend (1:1) showed significant synergy during the pyrolysis process which decreased the char yield, changed the reaction mechanism (from Contracting Sphere to Avrami-Erofeev), and shifted the paraffin decomposition peak to higher temperatures. As a result, the Ea of the blend was higher than calculated. The use of paraffin allowed a reduction in the Ea of SPT and C thermal decomposition. However, the C/SPT blend presented an average Ea similar to that of the coal.

Automated summary

The pyrolysis of coal, torrefied sawdust, paraffin, and their blends was evaluated using various methods to determine activation energy, reaction mechanism, and thermodynamic parameters. The SPT/P blend showed significant synergy, changing the reaction mechanism and increasing the activation energy.