Study on the effect of Kankara zeolite-Y-based catalyst on the chemical properties of liquid fuel from mixed waste plastics (MWPs) pyrolysis

We report in this study the effect of Kankara zeolite-Y-based catalyst on the chemical properties of liquid fuel from mixed waste plastics pyrolysis using a batch reactor. Fourteen set of 200 g of waste plastics comprising 27 wt%HDPE, 33 wt%LDPE, 13 wt%PP, 18 wt%PS, 9 wt%PET were de-polymerized with catalyst and a set without catalyst. The catalyst used comprises of a mixture of zeolite-Y, metakaolin, aluminum hydroxide and sodium silicate all synthesized from Kankara kaolin from Kankara in Katsina state, Nigeria. Fourteen different catalyst combinations derived from design of experiment using Design expert 11.0 were used to produce fourteen different liquid fuel samples, and the liquid sample with the highest yield was determined. Fourier transform infrared spectroscopy was used to detect various characteristic functional groups present in the samples. Furthermore, the various compounds in the uncatalyzed (thermal pyrolysis) and catalyzed samples with highest yield were determined using GC/MS. The results show that the highest yield of liquid fuel from the fourteen catalyst combination was 46.7 wt% while the thermal pyrolysis gave a yield of 66.9 wt%. The GC/MS result shows carbon in the range of C₆–C₁₃ and absence of long straight chain paraffins in the catalyzed fuel samples while the uncatalyzed sample has carbon in the range of C₇–C₂₀. Consequently, the thermal pyrolysis sample consists of 59%, 36% and 5% of gasoline, diesel and fuel oil, respectively, while the catalyzed sample consists of 93% gasoline and 7% diesel fraction.