Preparation method for self-forming vinyl polymerization catalyst granules

Abstract

The invention relates to a preparation method for self-forming vinyl polymerization catalyst granules. The preparation method comprises the following steps: 1, the preparation of dry powder in a slurry catalyst through the technology of gas-phase polyethylene fluidized bed; and 2, secondary spraying formation: adding recycled catalyst fine powder and organic solvent into an agitated vessel, increasing the temperature to 40 to 120 DEG C, then adding magnesium halide, titanium halide, alkyl aluminium and the like and agitating for 1 to 6 hours, then adding a thickening agent and agitating for 3 to 6 hours, adding slurry dry powder collected in a cloth bag filter into the agitated vessel and agitating for 3 to 6 hours at a low speed to prepare secondary spraying slurry, atomizing the secondary spraying slurry in an atomizer, drying the secondary spraying slurry in a drying tower, and then carrying out separation in a cyclone separator to obtain secondary spraying formed slurry catalyst dry powder. Compared with the prior art, the preparation method has the advantages that catalyst dry powder with smaller granules, low degree of fragmentation and poor strength, which is collected in the cloth bag filter, is subject to a secondary formation to be changed into that with larger particle diameters and good particle morphology, so as to meet product requirements, reduce waste and improve product yield.

Description

technical field [0001] The invention relates to the field of catalyst synthesis, in particular to a method for preparing self-formed ethylene polymerization catalyst particles. Background technique [0002] The U.S. Patent US6590046 disclosed by South Korea’s Samsung Chemical Company in 2003 uses a titanium chelate as the catalyst body, MgCl 2 As an activator, the prepared high-efficiency catalyst can obtain a polymer product with a narrow molecular weight distribution; the catalyst reported in the patent US6051525 published by Mobil in 2000 is obtained by reacting silicon dioxide, dibutylmagnesium, butanol and titanium tetrachloride ; The patent US4894424 disclosed by British BP Company, the catalyst is prepared by reacting magnesium powder in alkanes with halogens under a nitrogen atmosphere, and then adding titanium tetrachloride, propyl titanate and halogenated butane. The patent CN1788024A published by United Carbonation Chemical and Plastic Technology Company of the U...

AI Technical Summary

Problems solved by technology

[0006] 1. Too much polyethylene fine powder in the gas-phase fluidized bed will lead to serious stratification of the fluidized bed in the reactor and deterioration of the fluidized state. In severe cases, the bed will be emptied or even the reactor will be shut down;

[0007] 2. Excessive polymer fine powder will easily lead to static fluctuations in the reactor; thus causing flakes on the reactor wall, and in severe cases, the reactor will be shut down;

[0008] 3. The fine polymer powder will enter the circulating gas system, causing blockage of the heat exchanger and compressor system, blockage of the distribution plate of the reactor, and shutdown of the reactor;

[0010] It has been reported that polymer fines can be removed from the reactor by using a cyclone on the recycle line, but this reduces productivity and increases operating costs

If the small particle dry powder is directly removed from the catalyst dry powder, since the catalyst dry powder is produced by the spray drying process, the small particle size in the bag filter accounts for about 5% of the total catalyst dry powder, which increases the production cost and causes huge product waste. put enormous pressure on the environment

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