Carbonylation of lower alkyl alcohols and their derivatives...

Details Carbonylation of lower alkyl alcohols and their derivatives... Carbonylation of lower alkyl alcohols and their derivatives...

2000-04-05

2002-09-17

Geist, Gary (Department: 1623)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acid esters

C560S175000, C560S206000, C560S207000, C560S233000, C562S517000, C562S518000, C562S519000, C562S521000, C562S522000

Reexamination Certificate

active

06452043

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method for the carbonylation of alkyl alcohols, ethers and ester-alcohol mixtures to produce their corresponding esters and carboxylic acids. More specifically, the present invention relates to a method for producing acetic acid, methyl acetate and mixtures thereof by the carbonylation of methanol or a methanol source using a catalyst having an active metal specie selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, and Sn in which the active metal species is supported on a carbonized polysulfonated divinylbenzene-styrenic copolymer resin. A particularly preferred embodiment of the present invention is the aforementioned catalyst used in a vapor-phase carbonylation process for the production of acetic acid, methyl acetate and mixtures thereof.
BACKGROUND OF THE INVENTION
Lower carboxylic acids and esters such as acetic acid and methyl acetate have been known as industrial chemicals for many years. Acetic acid is used in the manufacture of a variety of intermediary and end-products. For example, an important derivative is vinyl acetate which can be used as monomer or co-monomer for a variety of polymers. Acetic acid itself is used as a solvent in the production of terephthalic acid, which is widely used in the container industry, and particularly in the formation of PET beverage containers. There has been considerable research activity in the use of metal catalysts for the carbonylation of lower alkyl alcohols, such as methanol, and ethers to their corresponding carboxylic acids and esters.
Carbonylation of methanol is a well known process for the preparation of carboxylic acids and particularly for producing acetic acid. Such processes are typically carried out in the liquid phase with a catalyst. The prior art teaches the use of a number of catalysts for the synthesis of carboxylic acids by reaction of alcohols with carbon monoxide at elevated temperatures and pressures using a fixed bed reactor in both gas and liquid phase reactions. Generally, the liquid phase carbonylation reaction for the preparation of acetic acid using methanol is performed using homogeneous catalyst systems comprising a Group VIII metal and iodine or an iodine-containing compound such as hydrogen iodide and/or methyl iodide. Rhodium is the most common Group VIII metal catalyst and methyl iodide is the most common promoter. These reactions are conducted in the presence of water to prevent precipitation of the catalyst.
U.S. Pat. No. 5,144,068 describes the inclusion of lithium in the catalyst system which allows the use of less water in the Rh-I homogeneous process. Iridium also is an active catalyst for methanol carbonylation reactions but normally provides reaction rates lower than those offered by rhodium catalysts when used under otherwise similar conditions.
U.S. Pat. No. 5,510,524 teaches that the addition of rhenium improves the rate and stability of both the Ir-I and Rh-I homogeneous catalyst systems.
Schultz, in U.S. Pat. No. 3,689,533, discloses using a supported rhodium heterogeneous catalyst for the carbonylation of alcohols to form carboxylic acids in a vapor phase reaction. Schultz further discloses the presence of a halide promoter.
Schultz in U.S. Pat. No. 3,717,670 describes a supported rhodium catalyst in combination with promoters selected from Groups IB, IIIB, IVB, VB, VIB, VIII, lanthanide and actinide elements of the Periodic Table.
Uhm, in U.S. Pat. No. 5,488,143, describes the use of alkali, alkaline earth or transition metals as promoters for supported rhodium for the halide-promoted, vapor phase methanol carbonylation reaction.
European Patent Applications EP 0 120 631 A1 and EP 0 461 802 A2 describe the use of special carbons as supports for single transition metal component carbonylation catalysts.
The literature contains several reports of the use of rhodium-containing zeolites as vapor phase alcohol carbonylation catalysts at one bar pressure in the presence of halide promoters. The lead references on this type of catalyst are presented by Maneck et al. in
Catalysis Today
, 3 (1988), 421-429. Gelin et al., in
Pure & Appl. Chem
., Vol 60, No. 8, (1988) 1315-1320, provide examples of the use of rhodium or iridium contained in zeolite as catalysts for the vapor phase carbonylation of methanol in the presence of halide promoter. Krzywicki et al., in
Journal of Molecular Catalysis
, 6 (1979) 431-440, describe the use of silica, alumina, silica-alumina and titanium dioxide as supports for rhodium in the halide-promoted vapor phase carbonylation of methanol, but these supports are generally not as efficient as carbon. Luft et al., in U.S. Pat. No. 4,776,987 and in related disclosures, describe the use of chelating ligands chemically attached to various supports as a means to attach Group VIII metals to a heterogeneous catalyst for the halide-promoted vapor phase carbonylation of ethers or esters to carboxylic anhydrides.
Drago et al., in U.S. Pat. No. 4,417,077, describe the use of anion exchange resins bonded to anionic forms of a single transition metal as catalysts for a number of carbonylation reactions including the halide-promoted carbonylation of methanol.
Unfortunately, these catalysts suffer from the typical difficulties associated with the use of homogeneous catalysis. In particular, upon separation of the catalyst and liquid components, catalyst precipitation and volatilization can occur, particularly if one tries to remove most of the liquid component. Further, mass transfer limitations, which are inherent in the transfer of gaseous carbon monoxide into a liquid reaction medium, limit the ultimate achievable rates in these homogeneously catalyzed processes.
To overcome the problems associated with separation, a number of investigators have attempted to develop heterogeneous processes. U.S. Pat. No. 5,900,505 issued to Tustin, et. al., discloses the carbonylation of methanol to acetic acid using iridium and a second metal as the active components on a support such as activated carbon and inorganic oxides, including silica, alumina, titania, and several zeolites.
Of these active carbonylation catalysts, carbon based supports are generally substantially better from a rate perspective, with Ni, Sn, and Pb displaying negligible activity on inorganic oxides. The normally large difference in rates upon changing from and activated carbon to an inorganic support has been exemplified in M. J. Howard, et. al.,
Catalysis Today
, 18, 325 (1993), where, on p. 343, a mixed Rh-Ni catalyst on activated carbon support can be compared to a rhodium on inorganic oxides. With the Rh-Ni on activated carbon, the rate is reported as being ca. 5 mol of acetyl/g of Rh/h at 188° C., 9 bar of 1:2 CO:H
2
, whereas the range for inorganic oxides is only 0.1 to 0.5 mol of acetyl/g of Rh/h despite being operated at substantially higher temperature (220° C.) and substantially higher CO pressures (40 bar CO pressure).
Although many of the earlier catalysts have been demonstrated to be operable in the liquid phase, the active metal is generally rapidly removed from the support by dissolution in the harsh environments associated with carbonylation of methanol and it derivatives. Attempts to overcome the leaching problem include binding the rhodium to the catalyst using ligands that were chemically bound to a polymer or oxide. For example, U.S. Pat. Nos. 5,155,261; 4,328,125; 5,364,963; and 5,360,929 disclose using tertiary phosphines or other functional groups to retain the rhodium catalyst component on a solid support. Although earlier investigators sought to anchor the rhodium component via ligation, it is now understood that these functional groups are quaternized in the process, forming phosphonium and ammonium salts, and the rhodium, which is present as Rh(CO)
2
I
2
−
, is bound by electrostatic attraction.
Unfortunately, although the catalysts containing functional groups have been successful in retarding the leaching of the Rh catalyst into the liquid phase, they still do not overcome the problems associated with diffusion. Further,

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