Catalyzed pyrolysis of scrap tires rubber

Abstract

Every day, a huge volume of scrap tires are produced worldwide, and landfill is an ineffective method of disposing of such hazardous waste. Pyrolysis can be used to convert tire rubber into energy, allowing for the management of such waste in the context of a circular economy. The composition and pyrolysis kinetics of granulated (0.6–0.8 mm) scrap tire rubber (TR) were assessed using thermogravimetry (TG). Data on rubber composition revealed that TG is a quick and accurate technique for determining TR composition. The TG tests with catalysts revealed that using alkali (K, Ca, and Mg) carbonates as catalysts improved the thermal degradation rate. The MgCO3 was able to duplicate the rate of TR thermal degradation. Data from a fixed bed pyrolysis reactor revealed oil yields of around 50% in the 673–773 K temperature range. The effect of alkali carbonate catalysts inferred from TG tests was confirmed by catalyzed pyrolysis tests. The calcium and magnesium carbonate catalysts significantly increased the gas product yield, with the CaCO3 catalyst having the greatest drop in oil yield due to likely secondary pyrolysis processes. Because of the low pyrolysis temperature, the acidic catalysts (SiO2, TiO2, Al2O3, and montmorillonite) had almost no effect on the pyrolysis product distribution. For all of the catalysts used, the ATR-FTIR spectra of the produced oils exhibited characteristics similar to those of diesel fuel. Data showed that alkali carbonate catalysts (mainly Mg and Ca), cheap and environmentally benign materials, can be used to tailor the TR pyrolysis products distribution allowing a more profitable process.