ZA200604363B - Layered support material for catalysts - Google Patents

Description

Layered Support Material for Catalysts

Claim of Priority

[0001] This application claims the benefit of U.S. Provisional Application No. 60/530,936, filed December 19, 2003, which is hereby incorporated by reference.

Field of the Invention

[0002] The present invention relates to catalysts, methods of making the catalysts, and methods of making alkenyl alkanoates. More particularly, the invention relates to methods of making vinyl acetate.

Background of the Invention

[0003] Certain alkenyl alkanoates, such as vinyl acetate (VA), are commodity chemicals in high demand in their monomer form. For example, VA is used to make polyvinyl acetate (PVAc), which is used commonly for adhesives, and accounts for a large portion of VA use.

Other uses for VA included polyvinyl alcohol (PVOH), ethylene vinyl acetate (EVA), vinyl acetate ethylene (VAE), polyvinyl butyral (PVB), ethylene vinyl alcohol (EVOH), polyvinyl formal (PVF), and vinyl chloride-vinyl acetate copolymer. PVOH is typically used for textiles, films, adhesives, and photosensitive coatings. Films and wire and cable insulation often employ

EVA in some proportion. Major applications for vinyl chloride-vinyl acetate copolymer include coatings, paints, and adhesives often employ VAE having VA in some proportion. VAE, which contains more than 50 percent VA, is primarily used as cement additives, paints, and adhesives.

PVB is mainly used for under layer in laminated screens, coatings, and inks. EVOH is used for barrier £lms and engineering polymers. PVF is used for wire enamel and magnetic tape.

[0004] Because VA is the basis for so many commercially significant materials and products, the demand for VA is large, and VA production is frequently done on a relatively large scale, e.g. 50,000 metric tons or more per year. This large scale production means that significant economies of scale are possible and relatively subtle changes in the process, process conditions or catalyst characteristics can have a significant economic impact on the cost of the production of

VA.

[0005] Many techniques have been reported for the production of alkenyl alkanoates. For example, in making VA, a widely used technique includes a catalyzed gas phase reaction of ethylene with acetic acid and oxygen, as seen in the following reaction: cH, + CH,COOH + 050, —» CH,COOCH=CH, + H,0 Several side reactions may take place, including, such as, the formation of CO. The results of this reaction are discussed in terms of the space-time yield (STY) of the reaction system, where the

STY is the grams of VA produced per liter of catalyst per hour of reaction time (g/1*h).

[0006] The composition of the starting material feed can be varied within wide limits.

Typically, the starting material feed includes 30-70% ethylene, 10-30% acetic acid and 4-16% oxygen. The feed may also include inert materials such as CO», nitrogen, methane, ethane, propane, argon and/or helium. The primary restriction on feed composition is the oxygen level in the effluent stream exiting the reactor must be sufficiently low such that the stream is outside the flammability zone. The oxygen level in the effluent is affected by the oxygen level in the starting material stream, O, conversion rate of the reaction and the amount of any inert material in the effluent.

[0007] The gas phase reaction has been carried out where a feed of the starting materials is passed over or through fixed bed reactors. Successful results have been obtained through the use of reaction temperatures in the range of - 125°C to 200°C, while reaction pressures of 1-15 atmospheres are typical.

[0008] While these systems have provided adequate yields, there continues to be a need for reduced production of by-products, higher rates of VA output, and lower energy use:during production. One approach is to improve catalyst characteristics, particularly as to CO; selectivity and/or activity of the catalyst. Another approach is to modify reaction conditions, such as the ratio of starting materials to each other, the O, conversion of the reaction, the space velocity (SV) of the starting material feed, and operating temperatures and pressures.

[00095] The formation of CO: is one aspect which may be reduced through the use of improved catalysts. The CO2 selectivity is the percentage of the ethylene converted that goes to

CO,. Decreasing the CO; selectivity permits a larger amount of VA per unit volume and unit time in existing plants, even retaining all other reaction conditions.

[0010] VAoutputofa particular reaction system is affected by several other factors including the activity of the catalyst, the ratio of starting materials to each other, the Oz conversion of the reaction, the space velocity (SV) of the starting material feed, and operating temperatures and pressures. All these factors cooperate to determine the space-time yield (STY) of the reaction system, where the STY is discussed in terms of grams of VA produced per liter of catalyst per hour of reaction time or g/I*h.

[0011] Generally, activity is a significant factor in determining the STY, but other factors may still have a significant impact on the STY. Typically, the higher the activity of a catalyst, the higher the STY the catalyst is able to produce.

[0012] The O2 conversion is a measure of how much oxygen reacts in the presence of the catalyst. The O; conversion rate is temperature dependent such that the conversion rate generally climbs with the reaction temperature. However, the amount of CO, produced also increases along with the O, conversion. Thus, the O, conversion rate is selected to give the desired VA output balanced against the amount of CO; produced. A catalyst with a higher activity means that the overall reaction temperature can be lowered while maintaining the same 02 conversion.

Alternatively, a catalyst with a higher activity will give a higher O; conversion rate at a given temperature and space velocity.

[0013] It is common that catalysts employ one or more catalytic components carried on a relatively inert support material. In the case of VA catalysts, the catalytic components are typically a mixture of metals that may be distributed uniformly throughout the support matenal (““all through-out catalysts”), just on the surface of the support material (“shell catalysts”), just below a shell of support material (“egg white catalysts”) or in the core of the support material (“egg yolk catalysts”).

[0014] Numerous different types of support materials have been suggested for use in VA catalyst including silica, cerium doped silica, alumina, titania, zirconia and oxide mixtures. But very little investigation of the differences between the support materials has been done. For the most part, only silica and alumina have actually been commercialized as support materials.

[0015] One useful combination of metals for VA catalysis is palladium and gold. Pd/Au catalysts provide adequate COz selectivity and activity, but there continues to be a need for improved catalysts given the economies of scale that are possible in the production of VA. {0016} One process for making Pd/Au catalysts typically includes the steps of impregnating the support with aqueous solutions of water-soluble salts of palladium and gold; reacting the impregnated water-soluble salts with an appropriate alkaline compound e.g., sodium hydroxide, to precipitate (often called fixing) the metallic elements as water-insoluble compounds, e.g. the hydroxides; washing the fixed support material to remove un-fixed compounds and to otherwise cleanse the catalyst of any potential poisons, €.g. chloride; reducing the water insoluble compounds with a typical reductant such as hydrogen, ethylene or hydrazine, and adding an alkali metal compound such as potassium or sodium acetate.

[0017] Various modifications to this basic process have been suggested. For example, in :

U.S. Patent No. 5,990,344, it is suggested that sintering of the palladium be undertaken after the reduction to its free metal form. In U.S. Patent No. 6,022,823, it suggested that calcining the support in a non-reducing atmosphere after impregnation with both palladium and gold salts might be advantageous. In WO094/21374, it is suggested that after reduction and activation, but before its first use, the catalyst may be pretreated by successive heating in oxidizing, inert, and reducing atmospheres.

[0018] In U.S. Patent No. 5,466,652, it is suggested that salts of palladium and gold that are hydroxyl-, halide- and barium-free and soluble in acetic acid may be useful to impregnate the support material. A similar suggestion is made in U.S. Patent No. 4,902,823, i.e. use of halide- and sulfur-free salts and complexes of palladium soluble in unsubstituted carboxylic acids having two to ten carbons.

[0019] In U.S. Patent No. 6,486,370, it suggested that a layered catalyst may be used in a dehydrogenation process where the inner layer support material differs from the outer layer support material. Similarly, U.S. Patent No. 5,935,889 suggests that a layered catalyst may useful as acid catalysts. But neither suggests the use of layered catalysts in the production of alkenyl alkanoates. 10020) Taken together, the inventors have recognized and addressed the need for continued improvements in the field of VA catalysts to provide improved VA production at lower costs.

Summary of the Invention (6021) The present invention addresses at least four different aspects relating to catalyst structure, methods of making those catalysts and methods of using those catalysts for making alkenyl alkanoates. Separately or together in combination, the various aspects of the invention are directed at improving the production of alkenyl alkanoates and VA in particular, including reduction of by-products and improved production efficiency. A first aspect of the present invention pertains to a unique palladium/gold catalyst or pre-catalyst (optionally calcined) that includes rhodium or another metal. A second aspect pertains to a palladium/gold catalyst or pre- catalyst that is based on a layered support material where one layer of the support material is substantially free of catalytic components. A third aspect pertains to a palladium/gold catalyst or pre-catalyst on a zirconia containing support material. A fourth aspect pertains to a palladium/gold catalyst or pre-catalyst that is produced from substantially chloride free catalytic components.

Detailed Description

[0022] Catalysts (0023) For present purposes, a catalyst is any support material that contains at least one catalytic component and that is capable of catalyzing a reaction, whereas a pre-catalyst is any material that results from any of the catalyst preparation steps discussed herein.

[0024] Catalysts and pre-catalysts of the present invention may include those having at least one of the following attributes: 1) the catalyst will be a palladium and gold containing catalyst that includes at least another catalytic component, €.8. rhodium where the one or more of the catalytic components have been calcined; 2) the catalyst will be carried on a layered support, 3) the catalyst will be carried on a Zirconia containing support material; 4) the catalyst will be produced with chloride free precursors or any combination of the foregoing. Effective use of the catalyst accordingly should help improve CO; selectivity, activity or both, particularly as pertaining to VA production.

[0025] It should be appreciated that the present invention is described in the context of certain illustrative embodiments, but may be varied in any of a number of aspects depending on the needs of a particular application. By way of example, without limitation, the catalysts may have the catalytic components uniformly distributed throughout the support material or they may be shell catalysts where the catalytic components are found in a relatively thin shell around a support material core. Egg white catalysts may also be suitable, where the catalytic components ceside substantially away from the center of support material. Egg yolk catalysts may also be suitable.

[0026] Catalytic Components

[0027] In general, the catalysts and pre-catalysts of the present invention include metals and particularly include a combination of at least two metals. In particular, the combination of metals includes at least one from Group VIIIB and at least one from Group IB. It will be appreciated that “catalytic component” is used to signify the metal that ultimately provides catalytic functionally to the catalyst, but also includes the metal in a variety of states, such as salt, solution, sol-gel, suspensions, colloidal suspensions, free metal, alloy, or combinations thereof.

Preferred catalysts include palladium and gold as the catalytic components.

[0028] One embodiment of the catalyst includes a combination of catalytic components having palladium and gold combined with a third catalytic component. The third catalytic component is preferably selected from Group VIB, with Rh being the most preferred. Other preferred catalysts include those where the third catalytic component is selected from W, Ni, Nb,

Ta, Ti, Zr, Y, Re, Os, Fe, Cu, Co, Zn, In, Sn, Ce, Ge, Ga and combinations thereof.

[0029] Another embodiment of the catalyst includes a combination of catalytic components including proportions of palladium, gold, and rhodium. Optionally a third catalytic component (as listed above) may also be included in this embodiment in place of Rh. In another embodiment, two or more catalytic components from the above list may be employed.

[0030] In one example, palladium and gold may be combined with Rh to form a catalyst that shows improved CO; selectively (i.e. decreased formation of CO;) compared to Pd/Au catalysts that lack Rh. Also, the addition of Rh does not appear to adversely affect the activity of the catalyst. The CO; selectivity of the palladium, gold, rhodium catalyst may also be improved through calcining during the catalyst preparation and/or through the use of water-soluble halide free precursors (both discussed below), although these are not necessary to observe the Rh effect.

[0031] The atomic ratio of the third catalytic component to palladium may be in the range of about 0.005 to about 1.0, more preferably about 0.01 to about 1.0. In one embodiment, the catalyst contains between about 0.01 and about 5.0 g of the third catalytic component per liter of catalyst.

[0032] Another preferred embodiment of the catalyst includes between about 1 to about 10 grams of palladium, and about 0.5 to about 10 grams of gold per liter of catalyst. The amount of gold is preferably from about 10 to about 125 wt % based on the weight of palladium.

[0033] In one embodiment for ground catalysts, Au to Pd atomic ratios between about 0.5 and about 1.00 may be preferred for ground catalysts. The atomic ratio can be adjusted to balance the activity and CO, selectivity. Employment of higher Aw/Pd weight or atomic ratios tends to favor more active, more selective catalysts. Stated alternatively, a catalyst with an atomic ratio of about 0.6 is less selective for COs, but also has less activity than a catalyst with a ratio of about 0.8. The effect of the high Au/Pd atomic ratio on ground support material may also be enhanced through the use of relatively high excess of hydroxide ion, as discussed below with respect to the fixing step. A ground catalyst may be one where the catalytic components are contacted to the support material followed by a reduction in the particle size (e.g. by grinding or ball milling) or one where the catalytic components are contacted to the support material after the support material has been reduced in size.

[0034] For shell catalysts, the thickness of the shell of catalytic components on the support materia! ranges from about 5 pm to about 500 pm. More preferred ranges include from about 5 pm to about 300 pm.

[0035] Support Materials

[0036] As indicated, in one aspect of the invention, the catalytic components of the present invention generally will be carried by a support material. Suitable support materials typically include materials that are substantially uniform in identity or a mixture of materials. Overall, the support materials are typically inert in the reaction being performed. Support materials may be composed of any suitable substance preferably selected so that the support materials have a relatively high surface area per unit mass or volume, such as a porous structure, a molecular sieve structure, a honeycomb structure, or other suitable structure. For example, the support material may contain silica, alumina, silica-alumina, titania, zirconia, niobia, silicates, aluminosilicates, titanates, spinel, silicon carbide, silicon nitride, carbon, cordierite, steatite, bentonite, clays, metals, glasses, quartz, pumice, zeolites, non-zeolitic molecular sieves combinations thereof and the like. Any of the different crystalline form of the materials may also be suitable, e.g. alpha or gamma alumina. Silica and zirconia containing support materials are the most preferred. In addition, multilayer support materials are also suitable for use in the present invention.

[0037] The support material in the catalyst of this invention may be composed of particles having any of various regular or irregular shapes, such as spheres, tablets, cylinders, discs, rings, stars, or other shapes. The support material may have dimensions such as diameter, length or width of about 1 to about 10 mm, preferably about 3 to about 9 mm. In particular having a regular shape (e.g. spherical) will have as its preferred largest dimension of about 4 mm to about 8 mm. In addition, a ground or powder support material may be suitable such that the support material has a regular or irregular shape with a diameter of between about 10 microns and about 1000 micron, with preferred sizes being between about 10 and about 700 microns, with most preferred sizes being between about 180 microns and about 450 microns. Larger or smaller sizes may be employed, as well as polydisperse collections of particles sizes. For example, for a fluid bed catalyst a preferred size range would include 10 to 150 microns. For precursors used in layered catalysts, a size range of 10 to 250 microns is preferred.

[0038] Surface areas available for supporting catalytic components, as measured by the BET (Brunauer, Emmett, and Teller) method, may generally be between about 1 m%/g and about 500 m?*/g, preferably about 100 m?/g to about 200 m?/g. For example, for a porous support, the pore volume of the support material may generally be about 0.1 to about 2 ml/g, and preferably about 0.4 to about 1.2 ml/g. An average pore size in the range, for example, of about 50 to about 2000 angstroms is desirable, but not required. : 10039] Examples of suitable silica containing support materials include KA160 from Sud

Chemie, Aerolyst350 from Degussa and other pyrogenic or microporous-free silicas with a particle size of about 1 mm to about 10 mm.

[0040] Examples of suitable zirconia containing support materials include those from

NorPro, Zirconia Sales (America), Inc., Daichi Kigenso Kagaku Kogyo, and Magnesium

Elektron Inc (MEI). Suitable zirconia support materials have a wide range of surface areas from less than about 5 m?/g to more than 300 m/g. Preferred zirconia support materials have surface areas from about 10 m¥/g to about 135 m’/g. Support materials may have their surfaces treated through a calcining step in which the virgin support material is heated. The heating reduces the surface area of the support material (e.g. calcining). This provides a method of creating support materials with specific surface areas that may not otherwise be readily available from suppliers. 0041] In another embodiment, it is contemplated to employ at least a plural combination of support materials, each with a different characteristic. For example, at least two support materials (e.g. zirconia) with different characteristics may exhibit different activities and CO» selectivities, thus permitting preparation of catalysts with a desired set of characteristics, i.e. activity of a catalyst may be balanced against the CO; selectivity of the catalyst.

[0042] In one embodiment, plural different supports are employed in a layered configuration.

Layering may be achieved in any of a number of different approaches, such as a plurality of lamella that are generally flat, undulated or a combination thereof. One particular approach is to utilize successively enveloping layers relative to an initial core layer. In general, herein, layered support materials typically include at least an inner layer and an outer layer at least partially surrounding the inner layer. The outer layer preferably contains substantially more of catalytic components than the inner layer. In one embodiment, the inner and outer layers are made of different materials; but the materials may be the same. While the inner layer may be non-porous, other embodiments include an inner layer that is porous. 10043] The layered support material preferably results in a form of a shell catalyst. But the layered support material offers a well defined boundary between the areas of the support material that have catalytic components and the areas that do not. Also, the outer layer can be constructed consistently with a desired thickness. Together the boundary and the uniform thickness of the outer layer result in a shell catalyst that is a shell of catalytic components that is of a uniform and known thickness.

[0044] Several techniques are known for creating layered support materials includes those described in U.S. Patent Nos. 6,486,370; 5,935,889; and 5,200,382, each of which is incorporated by reference. In one embodiment, the materials of the inner layer are also not substantially penetrated by liquids, e.g., metals including but not limited to aluminum, titanium and zirconium. Examples of other materials for the inner layer include, but are not limited to, alumina, silica, silica-alumina, titania, zirconia, niobia, silicates, aluminosilicates, titanates, spinel, silicon carbide, silicon nitride, carbon, cordierite, steatite, bentonite, clays, metals, glasses, quartz, pumice, zeolites, non-zeolitic molecular sieves and combinations thereof. A preferred inner layer is silica and KA160, in particular.

[0045] These materials which make up the inner layer may be in a variety of forms such as regularly shaped particulates, irregularly shaped particulates, pellets, discs, rings, stars, wagon wheels, honeycombs or other shaped bodies. A spherical particulate inner layer is preferred. The inner layer, whether spherical or not, has an effective diameter of about 0.02 mm to about 10.0 mm and preferably from about 0.04 mm to about 8.0 mm.

[0046] The outermost layer of any multilayer structure is one which is porous, has a surface area in the range of about 5 m’/g to about 300 m¥g. The material of the outer layer is a meta,

Claims (1)

1. We Claim:

   1. A method of producing a catalyst or pre-catalyst suitable for assisting in the production of alkenyl alkanoates, comprising: layering a first support material on to a second support material to produce a layered support material, wherein catalytic components of palladium, gold or combinations thereof are contained in the first support material of the layered support material.

   2. The method of claim 1, further comprising contacting the catalytic components to the first support material before the layering step.

   3. The method of either claims 1 or 2; further comprising contacting the catalytic components to the first support material after the layering step.

   4. The method of any of claims 1-3, wherein the catalytic components comprise palladium, gold, or combinations thereof.

   5. The method of any of claims 1-4, further comprising contacting palladium to the first support material before the layering step and contacting gold to the first support material after the layering step.

   6. The method of any of claims 1-5, further comprising contacting gold to the first support material before the layering step and contacting palladium to the first support material after the layering step.

   7. The method of any of claims 1-6, wherein the second support material is an inner layer and is substantially free of catalytic components.

   8. The method of any of claims 1-7, further comprising contacting at least a third component to the first support material selected from W, Ni, Nb, Ta, Ti, Zr, Y, Re, Os, Fe, Cu, Co, Zn, In, Sn, Ce. Ge, Rh, Ga and combinations thereof.

   9. The method of any of claims 1-8, further comprising contacting the third component to the first support material after the layering step.

   10. The method of any of claims 1-9, further comprising contacting the third component to the first support material before the layering step.

   11. The method of any of claims 1-10, wherein the third component is 2 third catalytic component.

   12. The method of any of claims 1-11, further comprising a calcining step before the layering step.

   13. The method of any of claims 1-12, further comprising a calcining step after the layering step.

   14. The method of any of claims 1-13, further comprising a reducing step before the layering step.

   15. The method of any of claims 1-14, further comprising a reducing step after the layering step.

   16. The method of any of claims 1-15, further comprising a reducing step following a calcining step.

   17. The method of any of claims 1-16, further comprising contacting an alkali metal acetate to the support material before the layering step.

   18. The method of any of claims 1-17, further comprising contacting an alkali metal acetate to the support material after the layering step. 19, The method of any of claims 1-18, further comprising impregnating the first support material with palladium, calcining the first support material, impregnating the first support material with gold. )

   20. The method of any of claims 1-19, further comprising impregnating the first support material with palladium, layering the first support material on to the second support material, calcining the layered support material, and impregnating the first support material with gold.

   21. The method of any of claims 1-20, further comprising calcining the layered support material before contacting the catalytic components to the layered support material.

   22. The method of any of claims 1-21, further comprising contacting an alkali metal acetate to the layered support material before contacting the catalytic components to the layered support material.

   23. The method of any of claims 1-22, wherein the first and second support materials are porous.

   24. The method of any of claims 1-23, wherein the second support material is non-porous. The method of any of claims 1-24, wherein the first and second support materials comprise the same material.

   26. The method of any of claims 1-25, wherein the first and second support materials comprise different materials.

   97. The method of any of claims 1-26, wherein the first support material is selected from the group consisting of alumina, silica/alumina, zeolites, non-zeolitic molecular sieves, titania, zirconia, niobia, silica, bentonite, clays, and combinations thereof.

   28. The method of any of claims 1-27, wherein the first support material comprises zirconia, silica, alumina or combinations thereof.

   29. The methed of any of claims 1-28, wherein the second support material is selected from the group consisting of alumina, silicon carbide, zirconia, titania, steatite, niobia, silica, bentonite, clays, metals, glasses, quartz, silicon nitride, alumina-silica, pumice, non-zeolitic molecular sieves and combinations thereof.

   36. The method of any of claims 1-29, wherein the second support material comprises zirconia, silica or alumina.

   31. The method of any of claims 1-36, wherein the second support material comprises a spherical bead of about 1 to about 10 mm in diameter.

   32. The method of any of claims 1-31, wherein the first support material has a BET surface area of between about 5 and about 300 m%/g.

   33. The method of any of claims 1-32, wherein the first support material has a BET surface area of between about 5 and about 150 m?/g.

   34. The method of any of claims 1-33, further comprising contacting an alkali metal acetate {o the support material.

   35. The method of any of claims 1-34, further comprising a fixing step utilizing a fixing agent.

   36. The method of any of claims 1-35, wherein the first support material has a thickness of between about 5 and about 500 microns.

   37. The method of any of claims 1-36, wherein the layering step comprises layering the second support material on to the first support material.

   38. The method of any of claims of 1-37, wherein the contacting step comprises contacting the catalytic components to the first support material in the form of substantially chloride free precursor solutions.

   39. The method of any of claims 1-38, wherein the layering step comprises contacting a bonding agent to the first or second support material to promote adhesion between the materials.

   40. The method of any of claims 1-39, wherein the bonding agent is selected from organic and inorganic bonding agents.

   41. The method of any of claims 1-40, wherein the bonding agent is a zirconia bonding agent.

   42. A composition for catalyzing the production of an alkenyl alkanoates, comprising: a layered support material comprising an inner layer and an outer layer with at least palladium in combination with gold contacted thereon to form a catalyst or pre-catalyst, wherein the inner layer is substantially free of palladium and gold.

   43. The composition of claim 42, wherein the outer layer comprises material selected from the group consisting of alumina, silica/alumina, zeolites, non-zeolitic molecular sieves, titania, zirconia, niobia, silica, bentonite, clays, and combinations thereof.

   44. The composition of either claims 42 or 43, wherein the outer layer comprises zirconia, silica , alumina or combinations thereof.

   45. The composition of any of claims 42-44, wherein the inner layer comprises material selected from the group consisting of alumina, silicon carbide, zirconia, titania, steatite, niobia, silica, bentonite, clays, metals, glasses, quartz, silicon nitride, alumina-silica, pumice, non- zeolitic molecular sieves and combinations thereof.

   46. The composition of any of claims 42-45, wherein the inner layer comprises zirconia, silica and alumina.

   47. The composition of any of claims 42-46, wherein the palladium and gold have been calcined.

   48. The composition of any of claims 42-47, wherein the palladium and gold have been reduced.

   49. The composition of any of claims 42-48, wherein the catalyst or pre-catalyst comprises between about 1 to about 10 grams of palladium, and about 0.5 to about 10 grams of gold per liter of catalyst, with the amount of gold being from about 10 to about 125 wt % based on the weight of palladium.

   50. The composition of any of claims 42-49, wherein the atomic ratio of gold to palladium is between about 0.50 and about 1.00.

   51. The composition of any of claims 42-50, wherein palladium, gold and a third component are contacted on the outer layer and wherein the third metal is selected from W, Ni, Nb, Ta, Ti, Zr, Y, Re, Os, Fe, Cu, Co, Zn, In, Sn, Ce, Ge, Rh, Ga and combinations thereof.

   52. The composition of any of claims 42-51, wherein the catalyst or pre-catalyst comprises rhodium and palladium in a rhodium to palladium atomic ratio of between about 0.01 and about

   0.5.

   53. The composition of any of claims 42-52, wherein the layered support material comprises particle support material or a ground support material.

   54. A method of producing alkenyl alkanoates, comprising: contacting a feed comprising an alkene, an alkanoic acid and an oxidizer to a catalyst or pre-catalyst comprising palladium in combination with gold or rhodium on a layered support material.

   55. The method of claim 54, wherein the alkene is ethylene, the alkanoic acid is acetic acid and the oxidizer is an oxygen containing gas.

   56. The method of either claims 54 or 55, wherein the atomic ratio of gold to palladium is between about 0.50 and about 1.00

   57. The method of any of claims 54-56, wherein the catalyst or pre-catalyst comprises between about 1 to about 10 grams of palladium, and about 0.5 to about 10 grams of gold per liter of catalyst, with the amount of gold being from about 10 to about 125 wt % based on the weight of palladium.

   58. The method of any of claims 54-56, wherein the inner layer comprises silica.

   59. The method of any of claims 54-57, wherein the outer layer comprises zirconia.

   60. The method of any of claims 54-59, wherein the catalyst or pre-catalyst is a shell catalyst or pre-catalyst, an egg yolk catalyst or pre-catalyst, egg white catalyst or pre-catalyst, or an all throughout catalyst or pre-catalyst. i