Catalytic coprocessing of low-density polyethylene with VGO using metal supported on activated carbon

The main objective of this study was to explore nonacidic catalysts for recycling of low-density polyethylene (LDPE) by coprocessing with vacuum gas oil (VGO). The focus of this study is to investigate processability of coprocessing LDPE with VGO, and to obtain environmentally friendly liquid fuels from such coprocessing. LDPE and VGO were cracked over activated carbon-supported metal catalysts (M - Ac) and acidic catalysts (HZSM-5, DHC-8) using a batch autoclave at 425, 435, and 450 °C under hydrogen atmosphere. In hydrocracking of LDPE in VGO, the most suitable temperature was found to be 435 °C. The amount of sulfur in liquid products obtained from hydrocracking over activated carbon-supported metal catalysts was lower than that over HZSM-5. Activated carbon-supported metal catalysts acted as an absorbent for sulfur compounds and H₂S and also facilitated hydrodesulfurization (HDS). The hydrocarbon types in liquids were determined by nuclear magnetic resonance (NMR) analysis. In the cases of activated carbon-supported metal catalysts, aromatic species were found between 4% and 8.9%, whereas the liquid product obtained over HZSM-5 has 28% aromatic species. In the presence of activated carbon-supported metal catalysts, the isoparaffin index was found to be between 0.32 and 0.66. However, the isoparaffin index was 0.01 in the liquid obtained over HZSM-5. The presence of lower aromatics and higher isoparaffin index in liquid products obtained over the activated carbon-supported metal catalysts suggest an improved hydrocarbon fuel from an environmental viewpoint.