Process for preparing a catalyst for producing methacrylic acid

Details Process for preparing a catalyst for producing methacrylic acid Process for preparing a catalyst for producing methacrylic acid

1993-02-08

1995-06-06

Pal, Asok

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Organic compound containing

502200, 502205, 502206, 502209, B01J 3100

Patent

active

054223261

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a process for preparing a catalyst used for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein.


BACKGROUND ART

There have been made a large number of proposals on processes and catalysts for producing methacrylic acid by vapor phase catalytic oxidation of methacrolein. In one of these proposals, there has been disclosed a process using an organic substance such as a cellulose, a polyvinyl alcohol or the like in preparation of a catalyst, for the purpose of controlling pores (the specification of British Patent Laid-Open Application No. 2037604). As an invention for controlling pores, there is the invention disclosed in Japanese Patent Unexamined Publication No. 60-239439. These catalysts, however, have defects such as unsatisfactory reaction results, a large decrease of catalytic activity with the lapse of time, and a troublesome after-treatment, and there is a desire to seek further improvement in them for their employment as industrial catalysts.


DISCLOSURE OF THE INVENTION

The present invention is intended to provide a novel process for preparing a catalyst for advantageous production of methacrylic acid from methacrolein.
The present inventors earnestly investigated in order to improve conventional catalyst preparation processes, and consequently found a novel process for preparing a catalyst which gives mothacrylic acid in a higher yield than does that prepared by a conventional process. The present invention is a process for preparing a catalyst for producing methacrylic acid by vapor phase catalytic oxidation of methacroiein with molecular oxygen which catalyst is obtained by adding an organic high-molecular weight compound with an average particle size of 0.01 .mu.m to 10 .mu.m to a catalyst component having a composition represented by the conoral formula: respectively; X denotes at least one element selected from the group consisting of arsenic, antimony, bismuth, germanium, zirconium, tellurium, silver and boron; Y denotes at least one element selected from the group consisting of iron, copper, zinc, chromium, magnesium, tantalum, manganese, barium, gallium, cerium and lanthanum; Z denotes at least one element selected from the group consisting of potassium, rubidium, cesium and thallium; a, b, c, d, e and f denotes atomic ratio values for the individual elements: in the case of b being 12, a=0.5 to 3, c=0.01 to 3, d=0 to 3, e=0 to 3, f=0.01 to 3; and g is a number of oxygen atoms which is necessary for giving the above valences of the individual constituents) to obtain a mixture, and molding the resulting mixture, followed by heat treatment.


BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, it is important that at the time of the molding of the catalyst, the organic high-molecular weight compound with an average particle size in a specified range of 0.01 .mu.m to 10 .mu.m has been previously added to the catalyst components. When the average particle size of the organic high-molecular weight compound is less than 0.01 .mu.m, there are caused problems in handling, for example, secondary aggregation of particles of the organic high-molecular weight compound used occurs, and dust tends to be raised during handling of the organic high-molecular weight compound. When the average particle size is more than 10 .mu.m, the proportion of pores preferable for the reaction in the catalyst obtained by the heat treatment after the molding is decreased, so that the catalytic capability is deteriorated.
Although the effect of the addition of the organic high-molecular weight compound with the above specified average particle size on the improvement of the catalytic capability is not exactly clear, it can be speculated from the increase of pores with a diameter of approximately 100-10,000 .ANG. in the catalyst by the heat treatment (200.degree.-500.degree. C.) carried out after the molding into the catalyst that a pore structure ideal for the oxidation reaction for production of methacrylic acid from methacrol

REFERENCES:
patent: 4092269 (1978-05-01), Mount et al.
patent: 4966877 (1990-10-01), Langerbeins et al.
patent: 5250485 (1993-10-01), Kuroda et al.
European Search Report dated Aug. 20, 1993.

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