Impacts of nickel supported on different zeolites on waste tire-derived oil and formation of some petrochemicals

Abstract

Waste tire-derived oils commonly contain the considerable valuable aromatics such as benzene, toluene, ethylbenzene, toluene, xylenes and etc., but they also contain a significantly-high amount of sulfur compounds, which cause a low quality of pyrolytic oil. Ni is a cheap metal, which exhibits hydrogenation/dehydrogenation and ring-opening like a noble metal, and widely used as promoter in desulfurization of fuels. In this work, Ni was expected to be a catalyst promoter of zeolites for reduction of sulfur content in oil and enhancement of petrochemical formation in oil. Therefore, the effect of 5wt.% nickel loading on different four type zeolites (HZSM-5, HMOR, HY, HBETA) on the sulfur removal and quality of waste-tire derived oil was studied. The results show that the incorporations of nickel on all zeolites significantly reduced sulfur contents in oil. However, the quality of waste tire-derived oil did not only depend on the nickel promoter, but also strongly depended on zeolite supports. The introduction of nickel on HZSM-5 zeolite, which possesses a smaller pore size than HBETA zeolites, provided a lighter oil with higher proportion of gasoline and kerosene than Ni/HBETA catalyst, and produced a higher amounts of valuable aromatic such as ethylbenzene, toluene, cumene, and mixed-xylenes than Ni/HBETA catalyst. Moreover, the addition of nickel on HMOR zeolite, which possesses a 1D zeolite channel structure, also provided a lighter oil with a high proportion of gasoline and kerosene than the Ni-loaded on HBETA (3D zeolite channel structure), and exhibited a better petrochemical production with a higher concentrations of ethylbenzene, toluene, cumene and styrene in maltene. On the other hand, Ni/HBETA provided the lower sulfur content in oil than Ni/HMOR catalyst, but the sulfur removal ability by nickel species on HMOR was higher than nickel species on HBETA zeolite. Furthermore, the introduction of nickel on HY zeolite provided the heavier oil with higher proportion of gas oil, LVGO and HVGO and lower proportion of petrochemical than Ni/HBETA zeolite whereas the sulfur removal of nickel species on the HBETA support with higher acid strength was better than on the HY support.