Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2000-04-05
2001-05-22
Bell, Marc L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S224000, C502S229000, C502S326000, C502S327000, C502S328000, C502S330000
Reexamination Certificate
active
06235673
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a solid phase catalyst that is useful for the carbonylation of alkyl alcohols, ethers and ester-alcohol mixtures to produce esters and carboxylic acids. More particularly, the present invention relates to a supported catalyst which includes a catalytically effective amount of an active metal selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, and Sn in which the active metal is supported on a carbonized polysulfonated divinylbenzene-styrene copolymer resin. The catalyst is particularly useful for the carbonylation of methanol and its derivatives to produce acetic acid and acetates in a vapor-phase carbonylation process.
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.
Currently, the best industrial practices for the carbonylation of methanol to acetic acid uses homogeneous catalysts consisting of either a mixture of rhodium and lithium, as exemplified in U.S. Pat. No. 5,510,524, or a mixture of iridium and ruthenium, as exemplified in European Patent Application EP 0 752 406 A1.
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.
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.
European Patent Application EP 0 752 406 A1 teaches that ruthenium, osmium, rhenium, zinc, cadmium, mercury, gallium, indium, or tungsten improve the rate and stability of the liquid phase Ir-I catalyst system. Generally, the homogeneous carbonylation processes presently being used to prepare acetic acid provide relatively high production rates and selectivity. However, heterogeneous catalysts offer the potential advantages of easier product separation, lower cost materials of construction, facile recycle, and even higher rates.
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 similar 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. Pimblett, in U.S. Pat. No. 5,258,549, teaches that the combination of rhodium and nickel on a carbon support is more active than either metal by itself.
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 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).
Evans et al., in U.S. Pat. No. 5,185,462, describe heterogeneous catalysts for halide-promoted vapor phase methanol carbonylation based on noble metals attached to nitrogen or phosphorus ligands attached to an oxide support.
Panster et al., in U.S. Pat. No. 4,845,163, describe the use of rhodium-containing organopolysiloxane-ammonium compounds as heterogeneous catalysts for the halide-promoted liquid phase carbonylation of alcohols.
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. Although supported ligands and anion exchange resins may be of some use for immobilizing metals in liquid phase carbonylation reactions, in general, the use of supported ligands and anion exchange resins offer no advantage in the vapor phase carbonylation of alcohols compared to the use of the carbon as a support for the active metal component.
Nickel on activated carbon has been studied as a heterogeneous catalyst for the halide-promoted vapor phase carbonylation of methanol, and increased rates are observed when hydrogen is added to the feed mixture. Relevant references to the nickel-on-carbon catalyst systems are provided by Fujimoto et al. In
Chemistry Letters
(1987) 895-898 and in
Journal of Catalysis,
133 (1992) 370-382 and in the references contained therein. Liu et al., in
Ind. Eng. Chem. Res.,
33 (1994) 488-492, report that tin enhances the activity of the nickel-on-carbon catalyst. Mueller et al., in U.S. Pat. No. 4,918,218, disclose the addition of palladium and optionally copper to supported nickel catalysts for the halide-promoted carbonylation of methanol. In general, the rates of reaction provided by nickel-based catalysts are lower than those provided by the analogous rhodium-based catalysts when operated under similar conditions.
A number of solid materials have been reported to catalyze the carbonylation of methanol without the addition of the halide promoter. Gates et al., in
Journal of Molecular Catalysis,
3 (1977/78) 1-9, describe a catalyst containing rhodium attached to polymer bound polychlorinate
Carver Donald Lee
Singleton Andy Hugh
Tustin Gerald Charles
Zoeller Joseph Robert
Bell Marc L.
Eastman Chemical Company
Gwinnell Harry
Hailey Patricia L.
Smith Mathew
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