Heating strategies for the system of PP and Spherical Activated Carbon during microwave cracking for obtaining value-added products

Abstract

Microwave catalytic cracking of waste plastics is a promising technology. However, how to mix effectively microwave absorber, catalyst and feedstock, and reuse microwave absorbers and catalysts is obviously a challenge. This study has focused on the heat transfer performance and reuse of microwave absorber and the influence of heating strategies on cracked products. Commercial Spherical Activated Carbon (SAC), containing some catalysts, has been used for microwave cracking of polypropylene. The effect of heating strategies on product distribution has been studied. Meanwhile, SAC has been reused many times to test the possibility of industrialization of the system. The results show that the heating strategies such as reducing the input power, choosing appropriate intermittent heating time and co-cracking of PP-Wax are beneficial to the formation of light oil. Compared with the first use, the subsequent heating rate of SAC will decrease, but the average heating rate shows a certain stability in the subsequent multiple use (the change range <1 °C/min at 32% input power). From the point of view of heat transfer and reuse, SAC has obvious advantages as microwave absorber. However, the catalytic performance is not significant and needs to be improved in the next study.