Study Of Hydrocracked Residue Recycling On Slurry-Bed Hydrocracking Of Venezuela Residue

Slurry-bed hydrocracking technology has obvious advantages in aspects of product quality and high yield of light fuel oil produced with a portion of hydrocracked residues,a high yield of hydrocracked residue restricts the economical efficiency.Hydrocracked residue recycling was processed under moderate conditions,decreases the yield of hydrocracked residue while controlling the formation of coke.However,the current research of hydrocracked residue recycling on slurry-bed hydrocracking is not sufficient and systematic to provide guidance and theoretical support for the promotion of this technology.To study the effects of reaction parameters on slurry-bed hydrocracking of heavy oil,the reactions of slurry-bed hydrocracking of Venezuela atmospheric residue were processed in autoclave in this thesis.The practicability of recycling hydrocracked residues of different distillation range and the effects of operation conditions on reactions were investigated under moderate condition.And then the microstructure of coke and structural parameters of asphaltene during recycling reactions were characterized by ~1H-NMR,FT-IR,XRD,etc.The results showed that the appropriate operation conditions for slurry-bed hydrocracking of Venezuela atmospheric residue were: concentration of catalyst was 150?g·g-1,ratio of Mo to Ni was 3:2,concentration of sulfur power was 300?g·g-1,concentration of additive was 200?g·g-1,temperature of reaction at 435?,pressure of reaction at 12 MPa.When selected fractions(>500?)as recycling residues,the coke yield always increased as the times of recycling reactions increased,but when selected fractions(>400?or >350?)as recycling bottom oil,after four times of recycling reactions,the yield of coke and the content of asphaltene were changeless basically.In addition,recycling residues of appropriate distillation range under moderate conditions,decreasing the ratio of swing hydrocracked residues to fresh oil could increase the yield of light oil.Research on the constitution and structure of coke and asphaltene in recycling reactions showed that when recycling for certain times,the yield and microstructure of coke was changeless basically,after the cracking of rings and long alkyl side chains outside the aromatic sheets,asphaltene kept the structural form of associating aromatic rings with short side chains and did not condense with each other,it helped controlling the formation of coke in recycling reactions.