Investigation of hot char catalytic role in the pyrolysis of waste tires in a two-step process

This study pursues the valorization of waste tires by pyrolysis using a different approach for tire parts, specifically, the tire tread rubber and side wall rubber. Tire tread rubber was used to produce hot char with the purpose of using it as cracking catalyst. Side wall rubber was valorized by pyrolysis and online catalytic pyrolysis over tire tread rubber derived hot char in two fixed bed reactor. This work aims to improve the quality of pyrolysis products using tire tread rubber derived hot char as catalyst. The thermal decomposition behavior and products characteristics were tested by means of TG-FTIR, GC, GC-MS, nitrogen adsorption and SEM. Under catalytic pyrolysis temperature of 500−550 °C, a high yield of valuable single ring aromatics (concentration in the oil of 50 %) was obtained. The yield of gas can reach 10.5 wt.% after catalytic pyrolysis, which only 3.0 wt.% without catalytic pyrolysis. The yield of undesirable byproducts as PAHs and carbon deposits was also limited. This strategy represents a novel and feasible alternative to traditional waste tire catalytic pyrolysis processes using expensive catalysts as zeolite.