Investigation of synergism and kinetic analysis during CO2 co-gasification of scrap tire char and agro-wastes

Abstract

Tire char (TC), the by-product of waste tire pyrolysis, suffers from low reactivity in CO2 gasification reaction due to high content of acid oxides in its ash and its graphitic structure, with low degree of structural conformations. To address this limitation, TC was co-gasified with several biomass residues including cattle manure (CM), palm empty fruit bunch (EFB), almond shell (AS) and rubber seed shell (RSS). The CO2 gasification reactivity of the TC/biomass blends was investigated at different heating rates by non-isothermal thermogravimetric method. Results signified the incidence of synergy during CO2 gasification of TC/biomass blends where the reactivities of blends were superior to that of individual TC. This was attributed to the inherent alkali and/or alkaline earth metals of biomass fuels acting as natural catalysts to enhance the gasification rate of TC. Several isoconversional kinetic methods also confirmed the occurrence of synergism in blends where the activation energy of all blends in CO2 gasification reaction was lower than sole TC (238 kJ/mol), with TC/CM blend (172 kJ/mol) leading other combinations. Thermodynamic studies also revealed that blending of TC with biomass was effective to improve the reaction rate of TC with CO2 and favorability of the reaction.