Catalytic steam reforming of waste tire pyrolysis volatiles using a tire char catalyst for high yield hydrogen-rich syngas

Abstract

The production of hydrogen and syngas (H₂/CO) from waste tires by pyrolysis catalytic steam reforming was investigated in a two-stage fixed bed reactor. In this study, tire char served as a sacrificial catalyst, facilitating the combination of catalytic steam reforming and char steam gasification reactions. The tire char acted as both a catalyst and a gasification reactant, enhancing the gas product yield. The process parameters investigated were, a reforming temperature range of 700–1000 °C, steam space velocity between 2 and 12 g h⁻¹ g⁻¹_char and reaction times of 0.5–2 h. The influence of the parameters on the yield and composition of the product gases and the characteristics of the used catalyst were analyzed in detail. The results indicated that higher temperature and steam space velocity increased H₂ and CO yields in the presence of a tire char catalyst. Elemental analysis of the used tire char, surface morphology and pore structure provided insights into the extent of tire char consumption in the reaction. Prolonged reaction time allowed for more thorough reactions between the pyrolysis volatiles and tire char, promoting the production of H₂. At a reaction time of 2 h, the H₂ yield reached 223 mmol g⁻¹, representing 74 wt% of the maximum hydrogen yield.