Preparation Of Novel ?-diimine Nickel Catalyst And Metallocene Catalyst

The development of the polyolefin industry symbolizes the development of a country's petrochemical industry,in which polyethylene is the most widely used variety of polymer materials.The key to the development of polyethylene is the catalyst,and the improvement of the performance of polyethylene is closely related to the development of polyethylene catalyst.The late transition metal ?-diimine catalyst,the limited geometry metallocene catalyst,and the supported catalyst are all hot fields in the research of polyethylene catalysts.The ?-diimine catalyst has the advantages of a single active center,high activity,and good stability,but the problem of poor thermal stability has hindered its industrial development.In this paper,two novel ?-diimine ligand was synthesized with acenaphthenequinone and introducing a large steric hindrance group,then characterized by a series of means.With diethylaluminium chloride to polymerize ethylene,by changing the polymerization conditions,the effects of polymerization temperature?steric hindrance on the thermal stability were investigated.The experiments show that the two catalysts exhibit high catalytic activity at 50 ?,and the highest activity is similar.At 70 ? and 80 ?,although the catalytic activities of the two catalysts are reduced,they still have high utilization value.At the same time,Catalyst Cat1 exhibited higher thermal stability due to its higher steric hindrance than Catalyst Cat2.It is proved that the larger the steric hindrance of the substituent on the imine,the better the heat resistance of the catalyst,which indicates the direction for preparing the heat-resistant polyethylene catalyst in the future.The limited geometry metallocene catalyst is characterized by a relatively narrow molecular weight distribution,low density,good copolymerization performance,high comonomer insertion ability in ethylene copolymerization,but low yield and harsh synthesis conditions and other issues also limit its development.In this paper,a new synthetic route was designed by preferentially synthesize t-BuNHSi(Me)2Cl to improve the yield.The correctness of the product and the feasibility of the synthetic route were proved by NMR analysis.Due to the lack of experimental conditions,it is difficult to completely isolate the air,resulting in impure product,which has not been applied to ethylene polymerization,but provides a new idea for the synthesis of metallocene catalysts in the future.Homogeneous catalysts have many problems in industrial applications,such as:easy to stick in the polymerization process,difficult to withdraw reaction heat,difficult to control polymer form,but these problems can be well solved by catalyst loading.A novel ?-diimine nickel catalyst based on butanedione was designed and synthesized,and supported on 955#silica support treated with AlMe3 to prepare a supported catalyst.The correctness of the structure was confirmed by various means,and the polymerization of ethylene showed that the homogeneous catalyst activity was higher under the polymerization conditions,but the catalyst loading effectively solved the problem of the sticking in the polymerization process.