Polypropylene catalyst spherical carrier and solid catalyst and preparation method thereof

Abstract

The invention discloses a polypropylene catalyst spherical carrier and a solid catalyst and a preparation method thereof. The preparation method comprises the following steps: carrying out a heating reaction between a magnesium chloride alcohol compound formed by complexing magnesium chloride and alcohol and fumed silica in a dispersing medium, and forming uniform slurry containing the magnesium chloride alcohol compound; dispersing the slurry in an inert dispersing medium under the high shearing action, introducing the slurry into a low-temperature inert dispersing medium, and carrying out freeze curing to form the spherical particle carrier containing the magnesium chloride alcohol compound. A solid catalyst prepared by adopting the carrier is used for olefin polymerization, namely propylene polymerization, and has relatively high polymerization activity, relatively low fine powder content and good polymer particle form.

Description

technical field [0001] The invention relates to a spherical carrier and a solid polypropylene catalyst prepared therefrom, in particular to a spherical carrier composed of magnesium chloride, alcohol and smoky silica gel and a solid polypropylene catalyst prepared therefrom. Background technique [0002] There are many methods for preparing the spherical magnesium chloride carrier disclosed in the prior art, such as high-speed stirring method, narrow tube extrusion method, supergravity method, spray cooling method and spray drying method, etc., the catalyst prepared by these methods is used for olefin During polymerization, it is easy to break and cause too much polymer fine powder. There may be many reasons: one is that the mechanical strength of the carrier / catalyst is low, and the other is that the active center of the catalyst is not evenly distributed. The severe unevenness of the polymerization reaction rate leads to uneven internal stress of the polymer particles. ...

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Problems solved by technology

[0002] There are many methods for preparing the spherical magnesium chloride carrier disclosed in the prior art, such as high-speed stirring method, narrow tube extrusion method, supergravity method, spray cooling method and spray drying method, etc., the catalyst prepared by these methods is used for olefin During polymerization, it is easy to break and cause too much polymer fine powder. There may be many reasons: one is that the mechanical strength of the carrier / catalyst is low, and the other is that the active center of the catalyst is not evenly distributed. Severely variable polymerization reaction rate leads to non-uniform internal stress of polymer particles

[0003] In the prior art, the magnesium chloride carrier prepared by the spray drying method, due to the rapid gasification of the organic solvent (such as alcohol) in the drying process, the primary particles in the particle are not tightly combined, the mechanical strength of the carrier is low, the average pore size is large, and the porosity is high. High, and easy to form more hollow particles, the catalyst prepared by it replicates such a particle structure, so the polymer particle fine powder content obtained by polymerization of this type of catalyst is relatively high, and the bulk density is low, generally less than 0.40g / cm 3

When the catalyst prepared by using the existing spherical magnesium chloride carrier is used for olefin polymerization, it will seriously affect the polymerization activity and stereoregularity, and directly affect the quality of the obtained polymer

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