Study On Preparation Of High Viscosity PAO Synthesized By Mixed ?-Olefin

Poly-?-olefin?PAO?synthetic lubricating base oils are Group IV base oils.Compared with mineral oils and other synthetic base oils,PAO has a regular and uniform comb-like molecular chain structure,and its special molecular chain structure makes it have excellent viscosity-temperature properties,low-temperature flow properties and thermal oxidation stability properties.To meet the increasingly stringent performance requirements of lubricants,it is an ideal lubricant base oil with good development and research prospects.Viscosity-temperature performance is an important indicator of lubricating base oil,and polymerization temperature is the main factor affecting the viscosity and temperature performance of PAO.A large number of literatures show that low temperature is conducive to the formation of high polymer,but the polymerization rate is low,the product yield is low;as the polymerization temperature increases,the polymerization degree of the polymer decreases,the viscosity-tem-perature performance deteriorates,and the product yield is better high.In order to be able to synthesize high yield and high viscosity PAO,this paper uses two polymerization temperature combined polymerization mode to synthesize PAO:firstly at low temperature?low temperature reaction?;then increase polymerization temperature to continue polymerization?high temperature reaction?.Firstly,the effect of species of?-olefin on the performance and yield of synthetic PAO was investigated with Lewis acid cationic catalyst.The experimental results show that the species of?-olefin mainly affects the viscosity-temperature performance and low-temperature performance of PAO,and has little effect on the yield.As the carbon number of raw material olefin increases,the viscosity-temperature performance of PAO products gradually increase,and the low temperature performance gradually decreases.The viscosity-temperature performance and low temperature performance of PAO prepared by using mixed olefins as raw materials between PAOs of single olefins.According to the production requirements,different production raw materials can be selected.The mixed olefin(V_1-octene:V_1-decene=1)was used as raw material.The effects of polymerization temperature and time of two-stage polymerization and the amount of catalyst on the performance and yield of the polymerization product were investigated.Optimized process conditions:catalyst dosage is 3%?accounting for the mass fraction of raw materials?,reacting for 10h in 10?in low temperature section,reacting for 2h in 80?in high temperature section.Under this condition,the kinematic viscosity of PAO at 40°C was 402.23 mm²/s,and the kinematic viscosity at100°C was 42.63 mm²/s,and the viscosity index was 160,and the freezing point was-45°C,and the yield of synthetic PAO was 95.53%.Its main properties are close to the physical properties of PAO-40.In this thesis,the PAO40 experimentally synthesized has been hydrotreated under the conditions of a reaction temperature of 230°C,a reaction pressure of 4.0 MPa,a volume space velocity of 0.2 h^-1 and a hydrogen oil volume ratio of 300:1.Pd-supported catalyst was used to hydrotreat the PAO40 experimentally synthesized.Under this condition,hydrogenated PAO40 has a kinematic viscosity of 41.1mm ²/s at 100°C,a viscosity index of 156,a flash point of 280°C,a Poset color of 30,and a bromine number of less than 0.1 gBr/100g.The degree of hydrogenation saturation and performance can reach the level of similar foreign products.Then using Ziegler-Natta catalyst,mixed olefin(V_1-decene:V_1-octene=1)as raw material,and the effects of process conditions such as polymerization temperature and time,catalyst dosage and aluminum-titanium molar ratio on the properties and yield of the polymerized product were investigated.The experimental results show that optimize process conditions:the catalyst dosage 4%,the aluminum-titanium molar ratio 3.5,reacting for 8h in 20?in low temperature section,reacting for 2h in 80?in high temperature section.Under this condition,the kinematic viscosity of PAO at 40°C was 306.03 mm²/s,and the kinematic viscosity at 100°C was 35.93mm²/s,and the viscosity index was 165,and the freezing point was-43°C,and the yield of synthetic PAO was 94.01%.