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he effect was studied of using in-situ catalyst based on a HZSM-5 zeolite in flash ( ) pyrolysis with an inert gas N of sawdust of pinus insignis in a conical spouted-bed 2 reactor in the 400 ᎐ 500ЊC range and for a gas residence time of 50 ms. The use of the catalyst increases the yield of gases and decreases the yields of liquid and char. Like-( wise, the yield of CO decreases, whereas the yield of C hydrocarbons increases 15.9 2 4y) wt. % at 450ЊC . The catalyst is efficient for partial deoxygenation of the liquid product.

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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).

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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 °C. Both catalysts significantly affect the yields and composition obtained in thermal pyrolysis for the fractions corresponding to C1−C4 gases, nonaromatic C5−C10, aromatic C10−, and tar. The shape selectivity characteristic of each zeolite has a considerable influence on catalyst performance. The HZSM-5 zeolite catalyst produces an 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 an 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 on 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 10.87 g of tire treated/g of catalyst), product yields remain almost constant, which is evidence that the catalyst does not undergo deactivation.

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