Catalytic hydrocracking of petroleum-derived asphaltenes by transition metal-loaded zeolite catalysts

In this study, correlation between structural parameters and reactivity for hydrocracking of asphaltene samples was investigated. Two different crude oils- (Arabian light/medium mixture and Brazilian Marlim) and Indonesian natural asphalt-derived asphaltenes were employed as samples. These asphaltene samples were submitted to elemental and spectroscopic analyses to obtain structural information such as H/C atomic ratio, heteroatom contents, carbon aromaticity, average size of aromatic clusters, and number-average molecular weight. These asphaltenes were also submitted to hydrocracking reaction at 400–450 °C for 3 h under H2 pressure in the presence of palladium and nickel co-loaded Y-type zeolite catalyst. Reactivities of these samples were different to each other depending on their properties, the order of the reactivity obeying the following sequence: Indonesian natural asphalt-derived one>Arabian mixture-derived one>Brazilian Marlim-derived one. By increasing reaction temperature for hydrocracking or a pre-treatment with tetralin or with H2-catalyst prior to hydrocracking, more than 60% of asphaltene feeds could be converted to C1–C4 hydrocarbon gases, H2S, naphtha, and gas oil. Based on these experimental results, the correlation between structural features and reactivity of the samples was discussed. Among the parameters examined, both average molecular weight and nitrogen contents of the samples were found to be correlated with the reactivity.