Catalytic cracking of heavy fractions from the pyrolysis of waste HDPE and PP

• Published in: Fuel (Guildford) 2017-09, Vol.203, p.244-252
• Main Authors: Lovás, Peter, Hudec, Pavol, Jambor, Boris, Hájeková, Elena, Horňáček, Michal
• Format: Article
• Language: English
• Subjects: Alkanes; Aromatic compounds; Automotive fuels; Catalytic cracking; Dilution; Distillation; FCC; Fluid catalytic cracking; Gas oil; Gases; Gasoline; HDPE; High density polyethylenes; Liquefied petroleum gas; Natural gas; Oil; Polyethylene; Polymers; Polypropylene; Propylene; Pyrolysis; Raw materials; Vacuum; Viscosity; Waxes
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2017.04.128

•Pyrolysis of automotive waste HDPE and PP plastics.•Preparation of distillation ends from HDPE and PP pyro-oils.•Catalytic cracking of HDPE-wax and PP-wax in MAT.•Comparison of cracking products of linear and branched polymer-waxes.•HDPE-wax increases gas-yield while PP-wax increases gasoline-yield. In the present paper, automotive waste plastics were considered as a potential source of fuels and chemicals. The feedstock in the experimental tests was represented by the heaviest fractions from the distillation of pyro-oil from the pyrolysis of high-density polyethylene (HDPE-wax) and polypropylene (PP-wax). Due to their very high viscosity both polymer-waxes were, prior to processing, diluted in atmospheric gas oil (GO). Mixtures with hydrotreated vacuum gas oil (HVGO) were also prepared and processed under simulated fluid catalytic cracking conditions via a MAT-test. The product distribution was similar to the one shown by the commercial FCC process: light gases (C1, C2), LPG, gasoline fraction, light and heavy cycle oil. To maintain optimal performance a commercial FCC equilibrium catalyst (FCC-ECAT) was used. When processing HDPE and PP waxes, high yields of profiling products – propylene and gasoline were obtained. In the case of the PP-wax feed without HVGO, the yield of gasoline was even higher than in case of pure HVGO. When cracking HDPE-wax feed mixtures the product distribution was oriented more towards the production of propylene. The composition of liquid products considering all types of feedstock consisted mainly of iso-alkanes and aromatics. The calculated values of microactivity for the HDPE-wax and PP-wax feedstock, with or without HVGO, were significantly higher than in the case of pure HVGO.