Abstract
Catalytic conversion of rubber wastes to produce an alternative fuel resource is a promising approach to dispose of solid wastes and address environmental issues. In this study, catalytic fast pyrolysis (CFP) of rubber wastes over acidic zeolites was conducted, and the effect of SiO2/Al2O3 mole ratio of USY zeolites on the formation of aromatic hydrocarbons was explored. Experimental results indicated that alkenes and aromatic hydrocarbons were the main pyrolytic products obtained from fast pyrolysis of rubber wastes, and the pyrolysis temperature played a vital role in the formation of aromatics with the highest concentration achieved at 750 °C. Moreover, catalyst types also affected the catalytic degradation of rubber wastes since limonene was completely decomposed in the presence of zeolites. Compared to SAPO-34, zeolites with higher external surface area, stronger Brønsted acid sites, and larger pore size, including USY, HY, and Hβ, were more effective in the production of aromatic hydrocarbons with the highest content obtained from USY catalyzed run. Given the observed effect of SiO2/Al2O3 mole ratio of USY zeolites on the formation of aromatic hydrocarbons during the CFP of rubber wastes, USY with low SiO2/Al2O3 ratio of 5.3 was more beneficial to the generation of aromatic hydrocarbons, while that with higher SiO2/Al2O3 mole ratio (11.5) facilitated the formation of alkenes. Simultaneously, the product distribution of aromatic hydrocarbons obtained from CFP of rubber wastes over USY zeolites was dominated by xylenes, alkylbenzenes, and toluene, and USY with SiO2/Al2O3 mole ratio of 5.3 was more active in the production of toluene and xylenes.
