The Study On Reaction Behavior Of Coal Tar Vacuum Residue Slurry-Bed Hydrocracking

With coal tar vacuum residue(CTVR)as material,reaction behavior of CTVR slurry-bed hydrocracking was investigated in the autoclave under the different reaction temperature,time,initial hydrogen pressure,catalyst concentration.The properties and chemical composition of the vacuum residue was also inspected under the different hydrogenation conditions.At the same time,the composition and structure of asphaltenes in CTVR and after hydrocracking were analyzed by modified B-L methods.The toluene insolubles before and after hydrocracking were analyzed by means of SEM and FT-IR.Furthermore,the altered states of toluene insolubles in the system were associated with the changes of asphaltenes.The experiments result showed that,the conversion of CTVR increased as the reaction temperature increased,while when the reaction temperature was higher than 360?,the conversion of CTVR would tend to be stable.Interestingly the content of total toluene insoluble reduced firstly and then increased as the reaction temperature increased,and the minimum value of the toluene insoluble was 8.95%,the liquid toluene insoluble was more,while the wall toluene insoluble was less relatively.And compared with the raw material,the basic properties of the vacuum residue tail oil after hydrocracking would become worse.Asphaltene units in CTVR were mainly composed of polycyclic aromatics linked with naphthene rings,the diameter of the unit was big,the layer structure was obvious,it was easy to condense to generate coke.The asphaltene had a stable structure,as a result it didn't react when the reaction temperature was low.Nonetheless the content of asphaltenes raised slowly as the reaction temperature increased,but the asphaltenes gradually converted into toluene insoluble when the temperature was about 360?,as a result the content of asphaltenes sharply decreased and the content of toluene insoluble rapidly increased in slurry-bed hydrocracking.The toluene insoluble of CTVR consists of inorganic minerals and organic compounds.The inorganic minerals are mainly composed of inorganic mineral salts of metal elements,and polycyclic aromatics are important parts of the organic compounds.The organic compounds in toluene insoluble could convert into the vacuum gas oil and vacuum residue under the lower reaction temperature,this is the main reason why the content of total coke in the system promptly reduced when the reaction temperature was lower than 360?.