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Encapsulated oxo-bridged organometallic cluster catalyst and a process for the preparation thereof

a cluster catalyst and oxo-bridge technology, applied in the field of encapsulation of oxo-bridged organometallic cluster complex catalysts, can solve the problems of reducing the reusability of catalysts, reducing the oxidation efficiency of catalysts, etc., to achieve simple filtration process, enhance the effect of oxidation activity of alkyl aromatic compounds to aromatic carboxylic acids, and easy separation from reaction products

Inactive Publication Date: 2003-01-09
COUNCIL OF SCI & IND RES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015] It is a further object of the invention to provide a novel encapsulated oxo-bridged organometallic cluster complex catalyst useful for the manufacture of aromatic carboxylic acids that provides high yield in use while being easily separable from the product stream.
[0016] It is yet another object of the invention to provide a novel encapsulated oxo-bridged organometallic cluster complex catalyst useful for the manufacture of aromatic carboxylic acids that renders the process of preparation of the aromatic carboxylic acids more economical and environmentally safe.
[0017] The present invention relates to the preparation of solid catalysts wherein the oxo-bridged organometallic cluster complex of at least one atom of cobalt and manganese is encapsulated in micro and mesoporous porous solids like aluminosilicate zeolites, aluminophosphates, carbon molecular sieves, silica. The solid oxidation catalysts have been found to be particularly effective for oxidation of aromatic alkyl groups to the carboxyl groups in high yields.
[0032] It is an unique feature of the present invention that when the solid catalyst contains certain organometallic, cluster complexes of cobalt and manganese wherein each molecule of the cluster complex contains both cobalt and manganese, then their activity in the oxidation of alkyl aromatic compounds to aromatic carboxylic acids is enhanced significantly. The novel solid catalysts of the invention retain all the advantages of the homogeneous catalysts, such as high yields of the desired aromatic carboxylic acids (in the range of 96 to 98% weight) and are at the same time easily separated from the reaction products by simple filtration processes. This avoids the tedious process of catalyst recovery characteristic of prior art processes, and also eliminates the presence of toxic elements such as cobalt, manganese and nickel in the waste effluent from the process. Processes utilizing these novel solid catalysts are, hence, environmentally more beneficial.

Problems solved by technology

The homogeneous catalyst used is not easily separable from the products thereby limiting the reusability of the catalysts.
Prior art methods also use corrosive bromide promoters requiring the use of expensive titanium steel thereby rendering the process itself more expensive.
Another disadvantage of prior art methods is that acetic acid is oxidised to CO and carbon dioxide.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example-2

[0039] This example illustrates the preparation of zeolite-Y-encapsulated Co.sub.3O)(CH.sub.3COO).sub.6(pyridine).sub.3 complex designated as catalyst system (2). Co(II) exchanged zeolite-HY was prepared by the ion-exchange method, in which zeolite HY(7 g) was interacted with 4.3 g of Co(CH.sub.3COO).sub.2.4H.sub.2O dissolved in 100 ml distilled water at 60.degree. C. with constant stirring. The solid product was then washed thoroughly with water (500 ml) and dried at 100.degree. C. CoY, thus obtained, was used in the preparation of catalyst system 2. In a typical preparation of catalyst system (2), CoY(1.5 g) was taken in 15 ml glacial acetic acid and to it was added pyridine (3 ml), NaBr (0.5 g), aq. H.sub.2O.sub.2 (50%, 10 ml) and distilled water (5 ml). The reaction mixture was stirred while passing air, for 2 h, at 25.degree. C. The brown solid zeolite (Co.sub.3 cluster encapsulated in zeolite-Y; catalyst system 2) was then filtered and dried at 25.degree. C. under vacuum.

example-3

[0040] This example illustrates the preparation of zeolite-Y-encapsulated Mn.sub.3(O)(CH.sub.3COO).sub.6(pyridine).sub.3 complex designated as catalyst system (3). Mn(II) exchanged zeolite-HY was prepared by ion-exchange method, in which zeolite HY (7 g) was interacted with 4.3 g of Mn(CH.sub.3COO).sub.2.4H.sub.2O dissolved in 100 ml distilled water at 60.degree. C. with constant stirring. The solid product was then washed thoroughly with water (500 ml) and dried at 100.degree. C. MnY, thus obtained, was used in the preparation of catalyst system 3. In a typical preparation of catalyst system (3), MnY(1.5 g) was taken in glacial acetic acid (15 ml) and to it was added pyridine (3 ml), NaBr (0.5 g) and aq. H.sub.2O.sub.2 (50%, 10 ml) and distilled water (5 ml). The reaction mixture was stirred while passing air, for 2 h, at 25.degree. C. The brown solid zeolite (Mn.sub.3 cluster encapsulated in zeolite-Y; catalyst system 3) was then filtered and dried at 25.degree. C. under vacuum.

example 4

[0041] This example illustrates the preparation of zeolite-Y-encapsulated CoMn.sub.2(O)(CH.sub.3COO).sub.6 complex designated as catalyst system 4. Mixed metal Co--Mn(II) exchanged zeolite HY (CoMnY) was prepared by ion exchange method as described in Example 1. CoMnY (1.5 g) was taken in 15 ml glacial acetic acid and to this NaBr (0.5 g) and aq. H.sub.2O.sub.2 (50%, 10 ml) and distilled water (5 ml) was added. The reaction mixture was stirred while passing air, for 2 hours at 25.degree. C. The brown solid zeolite (CoMn) cluster complex encapsulated in zeolite-Y was then filtered and dried at 90.degree. C.

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Abstract

The present invention relates to a novel encapsulated organometallic cluster complex catalyst and to a process for the preparation thereof. The oxo-bridged organometallic cluster complex of the invention has at least one atom of cobalt and manganese encapsulated in micro and mesoporous porous solids like aluminosilicate zeolites, aluminophosphates, carbon molecular sieves, silica and is particularly effective for oxidation of aromatic alkyl groups to the carboxyl groups in high yields.

Description

[0001] The present invention relates to an encapsulated oxo-bridged organometallic cluster catalyst and a process for the preparation thereof. More particularly the present invention relates to a solid catalyst containing an organometallic cluster complex having the general formula[M.sub.xM'.sub.x'(O)(RCOO).sub.nL.sub.n']Y.sub.n"[0002] wherein M and M' are transition metal ions, x and x' are in the range of 0 to 3 with the proviso that only one of x and x' may be 0, R is selected from the group consisting of an alkyl group containing 1 to 5 carbon atoms, an aryl group with 1 to 3 benzene rings, substituted alkyl and substituted aryl group, n is in the range of 3 to 6, L is selected from the group consisting of RCOO, pyridine, nitrogen containing organic bases, H.sub.2O, organic solvent or any like ligand, Y comprises a halide ion selected from the group consisting of ClO.sub.4.sup.-, BF.sub.4.sup.-, PF.sub.6.sup.-, and BrO.sub.3.sup.- and other like ions, n' and n" are each in the r...

Claims

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Application Information

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IPC IPC(8): B01J29/14B01J31/22C07C51/265
CPCB01J29/146B01J31/04B01J31/1616B01J31/1805B01J31/181B01J31/2208B01J31/2226B01J31/28B01J31/32B01J2229/186B01J2229/34B01J2231/70B01J2531/0222B01J2531/72B01J2531/845C07C51/265C07C63/00
Inventor SRINIVAS, DARBHACHAVAN, SUHAS ARUNKUMARRATNASAMY, PAUL
Owner COUNCIL OF SCI & IND RES
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