Study On Catalytic Cracking Performance Of Hydrotreated Heavy Cycle Oil

In order to improve the conversion,the conventional catalytic cracking process often recycle heavy cycle oil in the device.However,heavy cycle oil riched in polycyclic aromatics can result in low gasoline yield coupled with high coke yield and the increase load in the regenerator.This work aims at figuring out the catalytic cracking performance of hydrotreated heavy cycle oil and using tetralin,decalin as model compounds to further clarify the specific conversion in the catalytic cracking process of the naphthenic ring structure.Firstly,Hydro-HCO and HCO were used as the fluid catalytic cracking feed and the results showed that,compared with HCO,the conversion of the Hydro-HCO catalytic cracking increased by 12.35 wt.% and the gasoline yield increased by 16.83 wt.%.Meanwhile,the yield of dry gas,diesel and coke reduced.With the increase of hydrogenation depth,the yield of light aromatics(C6-C8)increased firstly and then decreased.The yield of chain hydrocarbons and naphthenes of deep hydrogenation feedstock catalytic cracking was relatively high,and there were less monocyclic aromatics,which indicated that moderate hydrogenation depth of heavy cycle oil was beneficial to produce more light aromatics.Secondly,the catalytic cracking performance of tetralin was investigated from different reaction temperature,catalyst-to-oil ratio and zeolites.The results showed that the range of 500 °C to 520 °C was beneficial to the conversion of tetralin and more light aromatics were produced.When catalyst-to-oil ratio was 8,catalytic cracking performance of tetralin was better,which promoted the ring opening reaction.The excessive catalyst-to-oil ratio had little effect on the increase of high value products.The results of Y zeolite showed better conversion and higher yield of light aromatics.But ZSM-5 zeolite exhibited a better naphthenic ring-opening selectivity than Y zeolite.Finally,the effects of different reaction conditions(temperature,catalyst-to-oil ratio)on the FCC product distribution of Hydro-HCO were investigated.The results showed that,as the reaction temperature increased,the conversion of Hydro-HCO increased and the yield of LPG and gasoline also increased,coupled with increase of dry gas yield.When the reaction temperature was 520 °C,the gasoline yield reached the highest.The yield of gasoline and the conversion increased with the catalyst-to-oil ratio increasing.However,the excessive catalyst-to-oil ratio had little effect on the yield of light oil and the yield of coke would be too high.