Abstract: Three kinds of feedstock, including Arabian light VGO,Arabian heavy VGO and VGO blending with deasphalted oil (DAO), were respectively hydrotreated to obtain hydrotreated gas oil with different hydrogen content, and the deep catalytic cracking(DCC) experiments were carried out to study the effects of different properties of hydrotreated gas oil on the yield of propylene. The results of DCC tests with different hydrogen content of the hydrotreated gas oil obtained from the Arabian heavy VGO deep-drawn gas oils showed that the hydrogen content and the aromatic carbon ratio were the key factor on the propylene yield of catalytic cracking. The results of DCC tests with three kinds of hydrotreated gas oils showed that the yield of propylene was the highest when the mixture of gas oil with DAO was hydrotreated, the second was HVGO, the lowest was LVGO. The proportion of high carbon number hydrocarbons in the hydrotreated gas oil of the VGO blending DAO was significantly higher than that of the other two materials, indicating that the carbon number of the hydrotreated gas oil was one of the key factors affecting the yield of propylene in DCC process. Compared with the combined process of solvent deasphalting + VGO hydrotreating and residue oil fixed bed hydrotreating process, the former had lower investment, longer operation period and better product properties, it was more suitable to be used as feedstock of catalytic cracking unit, but its energy consumption was higher than the latter.

Key words: gas oil hydrotreating, solvent deasphalting, deep catalytic cracking, carbon number, propylene yield