Upgrading petroleum residue by two-stage hydrocracking

Two-stage hydrocracking of petroleum residue consisting of hydrogenation (at low temperature) and thermocracking (at high temperature) has been investigated. Compared with one-stage reaction, two-stage reaction seems to have the following advantages: lower coke formation, higher cracking and higher removal of heteroatoms. Anthracene had been regarded as the model compound of coke precursor. After two-stage hydrocracking, about 51% of anthracene was hydrogenated at a low temperature (416 °C), and about 10% of the hydrogenated compound (9,10-dihydroanthracene) released the activated hydrogen which could prevent the residue from coke formation and removed the heteroatoms (i.e. sulfur and nitrogen) at a high temperature (436 °C). Comparison of two kinds of reactions showed that the two-stage reaction was superior to the one-stage reaction.