Process modelling of waste tyre pyrolysis for gas production using response surface methodology

The search for cleaner and renewable energy sources coupled with the need for environmental protection has necessitated the conversion of municipal solid wastes to energy sources. In this study, the pyrolysis of waste tyres in a fixed-bed reactor was carried out in a bid to generate non-condensable gases. The influence of process variables such as sample weight, reaction temperature, and reaction time were modelled and optimized using the central composite design of the response surface methodology. Based on the central composite design of the response surface methodology, the R², adjusted R² and predicted R² values of 0.968, 0.941 and 0.750 respectively, indicated that the model properly fitted the experimental data. This implied the accuracy of the model prediction. The maximum predicted gas yield of 10.212 wt% was estimated under optimal conditions with desirability of 0.697, a dimensionless value indicating the closeness of the combination of input variables to the desired values for the response variables. The gases obtained upon pyrolysis of waste tyres can serve as a source of hydrocarbon gases in the petroleum and petrochemical industry.