Catalyst used for ethylene polymerization or copolymerization, its preparation method and application

Abstract

A catalyst for the polymerizing or copolymerizing of ethene with wide distribution of molecular weights in dual reactors is composed of a solid carrier containining Mg / Ti, at least one Ti compound, at least one proper donor and at least one hydrogenating performance improver. Its advantages are very good hydrogenating sensitivity, high catalyst activity, and good granular form. Its preparing process is also disclosed.

Description

technical field [0001] The present invention relates to a catalyst component for ethylene polymerization or copolymerization, its preparation method and its application in ethylene polymerization. Background technique [0002] The polymerization of olefins, especially in the polymerization of ethylene or the copolymerization of ethylene and α-olefin, mostly uses magnesium, titanium, halogen and electron donor as the basic components of the catalyst. When this type of catalyst is used in a gas-phase fluidized bed polymerization process, in order to ensure that the shape and particle size distribution of the catalyst particles are more suitable for the operation in a fluidized state, the above-mentioned catalyst components are usually supported on a carrier such as silica gel. For example: the catalysts disclosed in US4,302,565, US4,379,759 and CN 1064870A for gas-phase fluidized bed reactions are impregnated with matrix components prepared from titanium compounds, magnesium c...

AI Technical Summary

Problems solved by technology

[0003] In the above-mentioned published patents, in order to make the catalyst applicable to the gas-phase fluidized bed polymerization process, there are relatively strict requirements on the average particle size, surface area, and pore size of the carrier-silicon dioxide used, and the price of this carrier material More expensive; and the active components of the catalyst are loaded on the carrier by impregnation and other methods, and the catalyst efficiency is not satisfactory due to the limitation of the amount of titanium loaded

In addition, the amount of fine powder in the polyethylene powder produced by using this catalyst is relatively large, usually the particles below 150 microns account for about 15wt% of the whole powder, which is very undesirable in industrial production

At the same time, when the catalyst is applied to the ethylene gas-phase fluidized bed polymerization industrial device, the catalyst is mostly fed in the form of solid, and the feeding method is poor in stability, and prone to pipe plugging and bridging.

[0004] In the Chinese patent CN85100997, a catalyst for olefin polymerization is disclosed, which is formed by dissolving magnesium halide in organic epoxy compounds and organic phosphorus compounds to form a uniform solution, and then giving it with at least one precipitation aid and a polycarboxylic acid ester. It is prepared by the action of electron bodies and transition metal titanium halides and their derivatives. When the catalyst is used for propylene polymerization, it shows high polymerization activity and good stereospecificity, but when it is used for ethylene polymerization, the activity is low. , and the particle size distribution of the polymer is relatively wide, and the hydrogen tuning sensitivity of the catalyst is not ideal

However, the hydrogen adjustment sensitivity of the catalyst is not ideal, which will not be conducive to the production of polymers with a wide molecular weight distribution with one catalyst