Effect of power level on the microwave pyrolysis of tire powder

The pyrolytic performance of tire powder treated under different specific microwave powers (SMP), powers per 1 g sample, (9, 15, and 24 W/g) was investigated. The experimental results show that the pyrolysis level of tire powder was enhanced with increasing SMP. The maximum yields of liquid product (45%) and gas product (18.5%) were obtained at 15 and 24 W/g, respectively. In addition, the conversion rates of main organic elements transferred to three-phase products were calculated. All of the evolved gases were collected in successive gasbags, and 80% of the volumes were low-molecular-weight gases like H2, CH4 and C2H4; the fraction of gases generated increased with increasing SMP. The liquid products contained a large amount of aromatic hydrocarbons, and more limonene (nearly 10%) was produced in microwave pyrolysis than in conventional pyrolysis of tires. The proximate and ultimate analyses of the solid product showed a slight difference in composition as a function of SMP. Furthermore, there may be a competitive reaction between the sulfur release to the volatiles and sulfur fixation, forming ZnS; the amount of ZnS varied with SMP. The energy recovery was examined, which provides a useful measure of the energy efficiency of microwave pyrolysis process.