HZSM-5 and HY Zeolite Catalyst Performance in the Pyrolysis of Tires in a Conical Spouted Bed Reactor

A study has been carried Out on the in situ use of two catalysts (prepared based on HZSM-5 and HY zeolites) in the pyrolysis of tires in a conical Spouted bed reactor at 425 and 500 degrees C. Both catalysts significantly affect the yields and composition obtained in thermal pyrolysis for the fractions corresponding to C-1-C-4 gases, nonaromatic C-5-C-10, aromatic C-10-, and tar. The shape selectivity characteristic of each zeolite has a considerable influence oil catalyst performance. The HZSM-5 zeolite catalyst produces all increase in the yield of gases, with an increase in the yield of propene and the same yield of butadiene as in thermal pyrolysis, in which it is already high. Concerning the liquid fraction, the catalysts give way to a decrease in the yield of d-limonene (the conical spouted bed reactor performs very well in thermal pyrolysis for this purpose), whereas the yield of BTX aromatics increases. with all increase in the yield of xylenes. A positive fact to be noted is the decrease in the formation of tar (C10+) compared to thermal pyrolysis. As the reaction occurs, a carbonaceous material is deposited oil the catalyst, in which the following are identified: (i) carbon black externally coating the particles and deposited on the catalyst macropores and mesopores and (ii) coke deposited on zeolite micropores. due to hydrocarbon condensation activated by catalyst active sites. This condensation preferably takes place in the HY zeolite due to both the larger size of intersections between micropore channels and to greater hydrogen-transfer capacity. Nevertheless. under the reaction conditions tested (up to 10.97 of tire treated/g, of catalyst). product yields remain almost constant, which is evidence that the catalyst does not undergo deactivation.