Microwave-assisted catalytic pyrolysis of paraffin wax

Abstract

It is a great challenge to find an efficient process for upgrading or recycling waste hydrocarbons, such as heavy oil, waxes, and plastics. The microwave-assisted pyrolysis process has drawn considerable attention as a new method because of its volumetric and selective heating. In this study, we designed a unique catalyst, SiC foam @HZSM-5, in which the SiC core was microwave absorbent and the HZSM-5 shell coated over the core provided active acid sites for the cracking reaction. By implementing the SiC in the foam shape, the heat and mass transfer was enhanced during the pyrolysis process. Solid paraffin wax (PW) was chosen as the main feedstock to investigate the designed process performances for the catalytic pyrolysis of high-density hydrocarbons under microwave irradiation. We mainly investigated the effect of MW absorbent, catalyst, and temperature at the same time. Results showed that the number of SiC@HZSM-5 foams determined the process temperature and affected the quality and yield of the products. In this regard, the highest yield of the collected liquid oil was 80 wt%, which contained more than 77% gasoline (C6-C10) fractions, comprising 57% BTX of the collected liquid yield, achieved by employing three coated SiC foams and a recorded temperature of 530 °C. In addition, a considerable volume of olefins (C2-C5), as high as 49%, was detected in the collected gases, while the portion of residue solid after the process was less than 2 wt%.