Study On Hydrotreating Process For Producing High Viscosity Index Lubricating Base Oil

In order to increase the output of API II+/III lubricant base oil,it is necessary to vigorously develop the lubricant hydrogenation process.The hydrogenation process route is:hydrogenation pretreatment-hydroisomerization-supplementary refining.Hydrotreating pretreatment is the first step in the hydrogenation process route,and it is also a crucial part in determining the properties of lubricating oil products.In this topic,three kinds of feedstock oils with different bases were used to carry out hydrogenation pretreatment research,to explore the influence of different reaction conditions on the properties of tail oil,and to analyze the composition of raw materials and different tail oils,and finally get the law of the change of tail oil properties.Determine the appropriate reaction conditions for the hydropretreatment reaction.For the intermediate or naphthenic raw materials that are difficult to process,it is necessary to optimize the hydropretreatment scheme and increase the hydrocracking reaction.Finally,the tail oil that meets the requirements will be evaluated for hydroisomerization.The following conclusions are drawn from the above research:The variation law of tail oil properties under different reaction conditions was investigated.Increasing the temperature or reducing the space velocity can reduce the sulfur and nitrogen content of the tail oil,the high viscosity refers to the increase of components,the viscosity index increases,but the viscosity decreases.The properties of the tail oil obtained from the hydropretreatment of different feedstocks are different.The paraffin content of the minus four-line paraffin-based raw material is 31.3%,and the viscosity index is 132.Under the conditions of reaction temperature of 375℃and space velocity of 1.0 h^-1,the viscosity index increased to 145 after hydrotreatment.The reduced four-line intermediate base raw material and the reduced three-line cycloalkyl raw material have high aromatic hydrocarbon content and a viscosity index of about 85.Even under the reaction conditions of high temperature and low space velocity,the viscosity index after hydroprocessing alone does not meet the requirements of hydroisomerization.Research on the combined process of hydrogenation pretreatment-hydrogenation viscosity improvement for intermediate and cycloalkyl raw materials.The viscosity index of the minus four-line intermediate base material and the minus three-line cycloalkyl material after hydrogenation pretreatment does not meet the requirements of hydroisomerization.Prepare two viscosity-enhancing catalysts with different cracking activities increases the hydrocracking reaction and improves the viscosity index of the tail oil.The low-activity viscosity-improving catalyst was used for the minus four-line intermediate base material,and the tail oil viscosity index was 132 and the viscosity was7.49 mm²/s with a conversion rate of 26.8%.The reduced three-line naphthenic raw material uses a viscosity-increasing catalyst with high cracking activity.When the conversion rate of tail oil reaches about 43.0%,the viscosity index is above 130.The hydroisomerization evaluation was carried out by using the generated oil accumulated over a long period of three raw materials as the feed of the hydroisomerization section.Minus four-line paraffin-based raw materials,minus four-line intermediate base materials and minus three-line naphthenic base materials can cut out API II+/III class lubricating base oils,with viscosities ranging from 9.78,7.77 to5.65 mm²/s.By changing the cutting plan,the reduced three-line naphthenic raw material can also cut API III base oil with a viscosity of 7.54 mm²/s,the yield is24.44%.