Abstract:
The study of catalyst type and dispersion on pyrolysis of high density polyethylene (HDPE) was investigated in batch and semi-batch reactor system. The separation system in semi-batch was rapidly separated between oil and gas products while in batch system was separated after cooling down process. The obtained oil products in semi-batch system had higher in short-chain hydrocarbon. Because the increased pressure and the high severity in batch system led to occur side reactions. Two types of catalyst were studied, Cat A was acid catalyst with 200 m2/g surface area and 20 A average pore diameter and HZSM-5 zeolite was stronger acid catalyst with 550 m2/g surface area and 7 A average pore diameter. The catalytic pyrolysis of HZSM-5 zeolite had lower reaction temperature around 400 °C and produced higher gas yield. These lower temperatures come from high consumed heat for cracking HDPE to gas products. Cat A catalyst was obtained naphtha as main product. The thermal pyrolysis of HDPE was obtained higher in heavy hydrocarbon products such as wax and diesel from lower rate of cracking reaction. The thermal pyrolysis and catalytic pyrolysis of Cat A had the reaction temperature around 430 °C because lower rate of cracking reaction. The higher acidity of HZSM-5 led to higher rate of cracking reaction and produce higher gas yield products than Cat A. For dispersion of catalyst in HDPE, the extruded plastic with catalyst shows the highest activity of catalyst than mixing with impeller because waxy state before oil formation in pyrolysis of HDPE was difficult to make the dispersion. The increased dispersion of catalyst was higher rate of cracking reaction. This result was obtained in both Cat A and HZSM-5 zeolite.
