An experimental study of CO2 gasification kinetics during activation of a spent tyre pyrolysis char

•CO2 gasification kinetics during spent tyre pyrolysis char activation was studied.•Higher temperature, time and CO2 concentration led to greater carbon conversion.•The CO2 gasification reaction was kinetically controlled under present conditions.•Volumetric model was found to best describe gasification rate behavior.•The kinetic parameters are n 0.7, E 112kJmol−1 and A 6.24×10−4s−1. The reaction kinetics of CO2 gasification during the activation of a spent tyre pyrolysis char was investigated. Activation experiments were conducted under atmospheric pressure to examine the effect of CO2 concentration (33.3% to 66.7vol.% CO2 in CO2/N2 mixture), temperature (750 to 1050°C) and reaction time (1 to 6h) on the fixed carbon conversion. The BET surface area of the activated chars as a function of carbon conversion were also determined. It was confirmed that the CO2 gasification reaction was indeed under kinetic control. Four gasification kinetic models, namely volumetric model, shrinking core model, random pore model, and Dutta model were applied to describe the rate behaviour of the char during activation with CO2. The kinetic parameters (reaction order, activation energy and pre-exponential factor) of each model were determined using the non-linear least-squares method by fitting the experimental data with the models and minimising the sum of square of the error between the experimental data and the predicted results. The volumetric model was found to best describe the experimental data under all conditions. The reaction order, activation energy and pre-exponential factor were found to be 0.7, 112kJmol−1 and 6.24×10−4s−1, respectively.