Recovery of enhanced gasoline-range fuel from catalytic pyrolysis of waste polypropylene: Effect of heating rate, temperature, and catalyst on reaction kinetics, products yield, and compositions

Abstract

The present study focuses on the recovery of superior-quality pyrolytic oil (PO) from the pyrolysis of waste polypropylene (WPP). The optimum heating rate, temperature and catalyst dosing were identified from experimental pyrolysis runs in a batch pyrolyzer. The thermal pyrolysis at 550 0C at 20 0C/min produced 83.5% PO, the maximum yield. The activated zeolite and kaolin catalyst prepared from the low-cost natural zeolite and kaolin clay were used for catalytic pyrolysis. The specific surface areas were determined to be 16.45 and 13.62 m2/g, with pore sizes 18.5 and 20.6 nm for zeolite and kaolin, respectively. The catalytic dosing of 12% zeolite and 10% kaolin was found to be the most optimum towards maximum PO yield. The FTIR and GC-MS analysis provided the qualitative and quantitative identification of various hydrocarbons (HCs) in PO. The HCs were classified as diesel-range (DHC) and gasoline-range (GHC) based on the carbon numbers. The catalyst zeolite and kaolin enhanced the yield of GHC components in PO by 6.45 and 7.7%, respectively. The catalyst considerably reduced the density, viscosity and improved the flash and pour points of PO. Finally, the reaction mechanism and reaction kinetics of pyrolysis reaction were determined from thermogravimetric data obtained under identical reaction conditions as in batch pyrolyzer. A shift of the reaction mechanism with lower activation energy was identified in the presence of a catalyst. The detailed characterization of gaseous products and solid residues were also performed.