Catalyst effect on the composition of tire pyrolysis products

The use of HY and HZSM-5 zeolite catalysts in situ in the pyrolysis of used tires in a conical spouted bed reactor significantly modifies the yields and composition of product fractions, which augurs well for valorizing these fractions. The importance of the different shape selectivity of HY and HZSM-5 zeolites is evident in the transformation reactions of thermal pyrolysis primary products. The capacity of the HZSM-5 zeolite catalyst is significant for obtaining high yields of olefins (particularly ethene and propene), for decreasing the molecular weight of the liquid fraction, and for decreasing the yield of tar compared to thermal pyrolysis. Both catalysts increase the yield of the aromatic fraction (with a high concentration of xylenes) compared to thermal pyrolysis, but the HZSM-5 zeolite catalyst has a low capacity for PAH generation due to its shape selectivity. The catalysts main influence on the carbon black (almost no adulteration with spouted bed reactor technology) is lower S content (amorphous form).