Process for the preparation of a support for catalysts, catalyst

Details Process for the preparation of a support for catalysts, catalyst Process for the preparation of a support for catalysts, catalyst

1996-02-02

1998-11-10

Wu, David W.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

526352, 526135, 502 9, 502117, 502120, 502121, 502125, 502256, 502319, C08F 422

Patent

active

058345728

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a process for the manufacture of a support for catalysts, containing silica and at least one constituent chosen from alumina and aluminium phosphate. Additionally, it relates to catalysts for the polymerization of olefins containing chromium on such a support, as well as to the use of these catalysts in the polymerization of olefins.


TECHNOLOGY REVIEW

Supports consisting of mixtures of oxides suited for the conversion of hydrocarbons are known. For instance, the patent application FR-A-231 59 97 describes a process for the preparation of supports containing alumina and aluminium phosphate according to which an aluminium alkoxide is reacted with an aqueous solution of phosphate ions, the support is collected and calcined.
The patent application EP-A-283 815 describes a process for the preparation of a composition containing alumina as the preponderant constituent, and silica, the process comprising the following steps: with a first quantity of an aqueous solution (II) of an alkaline metal aluminate to obtain a hydrogel suspension of alumina precipitated at a pH of from 8 to 10, to 4, to 10, alumina-silica hydrogel suspension, of a solution containing a phosphorous compound followed by heating steps.
A description is given, in Example IA of Patent Application GB-A-2,090,158, of a process for the preparation of a support for catalysts composed of silica and aluminium phosphate, according to which a solution containing isopropanol, water, phosphoric acid, silicon ethoxide and sulphuric acid is prepared, aluminium nitrate, aminodihydroxyphosphine and chromium nitrate are added thereto and ammonium hydroxide is introduced therein to produce cogelling.
This known support shows a high degree of heterogeneity and consequently crystallizes very quickly when it is calcined at temperatures greater than 700.degree. C. Moreover, this support does not simultaneously combine a high specific surface with a high pore volume. The result thereof is that this known support does not make it possible to manufacture chromium-based catalysts for the polymerization of olefins which show, at the same time, a high catalytic activity, a low induction period for the polymerization and a good response to hydrogen. Moreover, it does not make it possible to obtain polyolefins having a molecular mass distribution which can be adjusted between a moderately broad distribution and a very broad distribution for a given melt index and it generally gives rise to a significant formation of oligomers.


SUMMARY OF THE INVENTION

The invention overcomes these disadvantages by providing a new process, which makes it possible to obtain a support of homogeneous and amorphous structure, which is resistant to crystallization, which simultaneously possesses a high pore volume and a high specific surface, and which, when it is used as a support for a chromium-based catalyst in the polymerization of olefins, confers the following combined advantages on this catalyst: broad distribution and a very broad distribution for a given melt index, and


BRIEF DESCRIPTION OF THE DRAWING

The FIGURE represents a ternary phase diagram of catalyst compositions of silica, alumina, and aluminum phosphate.


DETAILED DESCRIPTION OF THE INVENTION

Consequently, the invention relates to a process for the preparation of a support for catalysts containing silica and at least one constituent chosen from alumina and aluminium phosphate, according to which, in a first stage, an alcohol, water, a silicon alkoxide and an acid are mixed in amounts such that the water/silicon molar ratio is from 2 to 50, the first stage being carried out at acid pH and comprising, on the one hand, the addition of water, acid, silicon alkoxide and alcohol, the temperature, during the addition, being less than or equal to 30.degree. C. and, on the other hand, a maturing of the hydrolysis medium thus obtained at a temperature at least equal to 20.degree. C. and lower than the boiling temperature of the medium, so as to substitute at least part

REFERENCES:
patent: 4225464 (1980-09-01), Scholten
patent: 4228260 (1980-10-01), Scholten
patent: 4444963 (1984-04-01), McDaniel et al.

Affiliated with

Also associated with

Rating

Process for the preparation of a support for catalysts, catalyst does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the preparation of a support for catalysts, catalyst, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of a support for catalysts, catalyst will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1517644