A preparation method of a composite support for a propylene high temperature polymerization catalyst, a component of the propylene high temperature polymerization catalyst and the propylene high temperature polymerization catalyst

Abstract

The invention relates to a preparation method of a composite support for a propylene high temperature polymerization catalyst, a component of the propylene high temperature polymerization catalyst andthe propylene high temperature polymerization catalyst. The composite support is prepared by a chemical reaction of a molten magnesium chloride alcohol adduct and a silica gel support treated by Lewis base. The composite support with good spherical shape and uniform particle distribution can be obtained by compounding a molten magnesium halide alcohol adduct with treated SiO2 through mechanical stirring. A titanium-containing catalyst and a cocatalyst prepared by the composite support exhibits excellent performance when used in olefin polymerization, especially in propylene polymerization athigh temperature (>=93 DEG C). The catalyst has high polymerization activity. An obtained high temperature polymer is good in particle form. Products have high bulk density and good stereoregularity.

Description

technical field [0001] The present invention relates to a magnesium chloride composite carrier and a propylene polymerization catalyst prepared therefrom. Specifically, magnesium chloride is compounded with silicon dioxide treated with a Lewis base to form a carrier and a catalyst solid component prepared from the carrier. The component When used in olefin polymerization, especially propylene high-temperature (≥93°C) polymerization, it shows excellent performance. The catalyst has high catalytic activity. The obtained high-temperature polymer particles have good shape, high bulk density and good stereoregularity. Background technique [0002] At present, the high-efficiency carrier-type Ziegler-Natta (Z-N) catalyst commonly used in olefin polymerization is to highly disperse the active components (such as Ti compounds) on the surface of the carrier, greatly increasing the specific surface area of ​​the catalyst, and significantly improving the catalytic efficiency of the cata...

AI Technical Summary

Problems solved by technology

[0005] Chinese patent CN 1524886A utilizes spray method to prepare MgCl 2 -SiO 2 Composite carrier, the composite carrier is made by contacting magnesium halide such as magnesium chloride with one or more electron donor compounds such as fatty alcohol, tetrahydrofuran, etc. to form a solution, which is mixed with silica gel with an average particle size of less than 30 μm, and spray-dried to obtain Spherical particles, the catalyst component and the cocatalyst component are used together for olefin polymerization, especially for propylene polymerization, showing high polymerization activity and stereospecificity, but the preparation of the carrier by spraying method needs to evaporate a large amount of Solvent, high energy and material consumption and the alcohol content of the obtained carrier is not easy to control

[0008] When the traditional Z-N catalyst is used for propylene polymerization, the polymerization temperature is generally below 80°C. When the polymerization temperature is higher than 80°C, the polymerization activity and the isotacticity and molecular weight of the prepared polymer will be greatly affected. The reason is that as the polymerization temperature increases, the deactivation of the active center of the catalyst is accelerated, resulting in a decrease in the polymerization activity of the system, an increase in the number of oligomers generated, and a low isotacticity of the final polymer.

[0009] For example, U.S. Patent No. 5,385,993 discloses a catalyst that can carry out propylene polymerization at a polymerization temperature of 150 to 300°C to obtain polypropylene with relatively high isotacticity. The propylene polymerization reaction has a wider molecular weight distribution, but at such a high polymerization temperature, the obtained polymer is no longer granular, and there will be problems such as difficult transportation in actual production. At the same time, the preparation process of the catalyst is relatively complicated , the activity of the catalyst is not satisfactory

Chinese patent CN1421468A discloses a method for polymerizing or copolymerizing propylene at high temperature and a catalyst prepolymer suitable for the method. In this polymerization method, the process conditions and the prepolymerization ratio during the prepolymerization process are controlled to finally make the traditional The Z-N catalyst is suitable for the polymerization of propylene at a higher temperature (>85°C), but the process conditions used in this method and the means of controlling the prepolymerization ratio are relatively complicated, and the isotacticity of the obtained polymer is the same as that prepared at 70°C. Still low compared to polymer

Chinese patent CN1621421A also discloses a method for preparing a catalyst. The catalyst realizes the high-temperature polymerization of propylene by introducing a mixture of aluminoxane and alkylaluminum as a cocatalyst during the polymerization process. There is also the problem that the process is complicated and new components need to be introduced. , and high temperature polymerization activity and polymer isotacticity need to be further improved

[0010] Aiming at the problems that the active center of the catalyst is easily deactivated and the isotacticity of the prepared polymer is relatively low when the existing traditional Z-N catalyst is used for high-temperature (≥93°C) polymerization of propylene, the present invention provides a composite carrier with a simple preparation method and Its catalyst, the composite carrier catalyst, has high catalytic activity when used for high-temperature polymerization of propylene, the particle shape of the obtained polymer is good, the bulk density is high, and the problem of low isotacticity of the prepared high-temperature polymer is solved