Vacuum Pyrolysis of Waste Tires by Continuously Feeding into a Conical Spouted Bed Reactor

The continuous pyrolysis of waste tires under vacuum conditions (25 and 50 kPa) has been studied in a pilot plant equipped with a conical spouted bed reactor and operating with continuous feed at 425 and 500 degrees C. The effects of vacuum on product distribution and properties have been studied. The main effect of vacuum is an increase in the diesel fraction yield of the liquid product. A remarkable yield of isoprene has been obtained operating under vacuum, reaching yields of higher than 7 wt % Moreover, a positive effect on the quality of the residual carbon black has been observed, given that a decrease in pore blockage gives way to higher surface areas of the carbon blacks obtained. The results show that vacuum operation does not limit the good perspectives for waste tire valorization by pyrolysis in a conical spouted bed, and energy requirements for heating the inert gas and the condensation section are significantly reduced.