Conversion of polypropylene (PP) plastic waste to liquid oil through catalytic pyrolysis using Philippine natural zeolite

Abstract The accumulation of plastic waste compelled the need to develop energy recovery methods, such as pyrolysis, which could convert plastics into valuable energy sources. Pyrolysis requires high operating temperatures; thus, a catalyst is often utilized to speed up the process. In this study, the viability of Philippine Natural Zeolite (PNZ) as a catalyst was investigated through the conversion of polypropylene (PP) waste into liquid oil using catalytic pyrolysis. The PP waste feedstocks were pre-mixed with the PNZ in a 1:10 ratio. Pyrolysis was carried out in a heating mantle for three trials of non-catalytic and catalytic pyrolysis. SEM and XRD were conducted to characterize the PNZ, while FTIR was carried out for the pyrolysis oil. SEM analysis showed the voids formed from the pores of the catalyst that influenced the pyrolysis reaction. Results from the XRD pattern also revealed clinoptilolite, mordenite, and heulandite as the main minerals found in the PNZ. Non-catalytic pyrolysis of PP yielded an average of 75.03% liquid oil, 13.66% residue, and 11.31% uncondensed gas. Meanwhile, catalytic pyrolysis produced higher yields with 86.39% liquid oil, 12.49% residue, and 1.12% uncondensed gas. FTIR results exhibited clear peaks for both processes, with similar components but different intensities.