Microwave pyrolysis of tire powders: Evolution of yields and composition of products

•The dynamic evolution of yields and composition of products were obtained.•More limonene was generated at microwave pyrolysis than conventional heating.•The pyrolysis gases contained large proportion of H2 and CH4.•Most sulfur in the raw material was maintained in the solid products.

The evolution of products of tire powders, with special attention to the yields and composition over time under microwave pyrolysis, was studied. The solid, liquid, and gaseous products generated were all collected separately during the pyrolysis process and characterized. In addition, temperature was measured using a thin thermocouple intermittently. The sample temperature first rose, then fell, and finally stabilized at approximately 500 °C. The major components of the pyrolysis gases were H2, CH4, and C2H4. The liquid products were complex mixtures of organic compounds with large proportions of aromatics and limonene. The solid residues, with high contents of carbon black and S, pyrolyzed almost completely at 20 min, and the samples in the center of the reactor were pyrolyzed earlier than those in the surrounding areas were. At the end of the pyrolysis, 43% of the solid residues, 45% of the oils, and 12% of the pyrolysis gases were obtained.