Research On Hydrogenation Catalysts For Vacuum Cut4 Distillate Oil Of Karamay Refinery

Rubber oil is one of the three major raw materials in rubber industry.In our country,traditional aromatic hydrocarbon oils which contain a lot of carcinogenic polycyclic aromatic hydrocarbons?PCA?has a wide range of application.As an increasing need for protecting the environment and the strict restrictions around the world,especially in the developed countries,its market is becoming smaller and smaller.As a great deal of rubber product are exported to the developed countries every year from China,the development and application of environment-friendly rubber oils is necessary.The raw material is Karamay refinery vacuum cut4 distillate oil,with a PCA mass content of 5.5%,aromatic carbon mass content of 13.0%,and naphthenic carbon mass content of 36%.The target is to lower the PCA of the raw material below 3%and maintain the aromatic carbon mass content to about 10%by catalytic hydrogenation.This kind of hydrogenated oil is the ideal material to produce naphthenic environment-friendly rubber oil.This thesis is to study the catalyst containing transition metals and phosphate that can fulfill the above target.The catalysts were synthensized by co-impregnation.N₂ adsorption-desorption analysis results showed that the specific surface areas of all catalysts are high than 180 m²·g^-1 and the average pore sizes are around 8.0nm.Hydrothermal treatment is beneficial to enlarging the catalyst pore size at the condition of 140?for 4 hours and the average pore size is 9.3nm.Py-IR analysis showed that the prepared carriers and catalysts is full of Lewis acid,almost no Br?nsed acid.NH₃-TPD analysis results showed that the carriers'acid sites are composed of strong acid sites and weak acid sites.The amount of strong acid sites and weak acid sites can be increased at the same time when the citric acid solution is used as the carrier binder,but hydrothermal treatment can decrease the amount of strong acid sites obviously.The prepared catalysts acid sites are mainly composed of weak acid sites,only the catalyst with phosphorus content of 2.5%has a small amount of strong acid sites.XRD analysis results showed that active metal component of the prepared catalysts is evenly distributed on the carriers.The catalysts hydrogenation evaluation results showed that the Ni-Mo-W type hydrotreating catalysts have a better performance than Ni-W type hydrotreating catalysts.Adding suitable phosphorous on catalysts is beneficial to polycyclic aromatic hydrocarbons selective hydrogenation.The PCA content of hydrogenated oils can be decreased to 2.95%and the aromatic carbon rate can be maintained at 10.1%by using the prepared catalyst?NiO6%,MoO₃7%,WO₃17%?with phosphorus content of 1.5%at the conditions of 275?,pressure 7MPa,hydrogen to oil ratio 800:1.The hydrothermal treated catalyst?NiO 6%,MoO₃7%,WO₃17%?has the same activity with the catalyst with phosphorus content of 1.5%at the same conditions,and the PCA content of hydrogenated oils can be decreased to 2.90%and aromatic carbon rate can be maintained at 9.9%.The two catalysts have preferable hydrogenation activity than industrial catalyst.The study on the influence of process conditions showed that the conditions of 275?-290?,pressure 7 MPa-8MPa,LHSV 0.8h^-1-0.9h^-1 and hydrogen to oil ratio 800:1-1000:1are most appropriate in consideration of lowering the oil PCA content and maintaining the aromatic carbon rate.