The method of producing vinyl acetate using a catalyst comprising palladium, gold and any of certain third metal

 

This invention relates to new and improved catalysts for production of vinyl acetate by reaction of ethylene, oxygen and acetic acid. A catalyst comprising a porous carrier, on the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, and a third metal selected from the group consisting of magnesium, calcium, barium, zirconium and cerium, in the form of its oxide or mixture of oxide and metal, get in any way, including the impregnation of the porous carrier with an aqueous solution of water-soluble salts of palladium and specified third metal binding specified palladium and the third metal in the form of water-insoluble compounds by reaction with an appropriate alkaline compound, the subsequent impregnation of the catalyst with a solution of water-soluble gold salts, binding of gold in solution, used for the last impregnation, in the form of water-insoluble compounds by reaction with an appropriate alkaline compound, and recovering the related palladium and gold to their metallic state, and the associated third metal to its oxide or mixture of oxide and metal, in any way, including the stage of impregnation of the carrier with a solution of the metal in the final solution in the form of water-insoluble compounds by the way, including phase rotation and/or rotation in the drum impregnated carrier at the time of his immersion in the solution of the corresponding alkali compounds, and recovery associated palladium and gold to their metallic state, and the third metal to its oxide or mixture of oxide and metal. Effect: the use of the catalyst causes a reaction with relatively high activity and/or low selectivity towards heavy fractions. 2 C. and 8 C.p. f-crystals, 2 tab.

The present invention relates to a method for producing vinyl acetate by reaction of ethylene, oxygen and acetic acid.

Prerequisites FOR the CREATION of the INVENTION description of the prior art Known to produce vinyl acetate by reaction of ethylene, oxygen and acetic acid using a catalyst consisting of palladium and gold, found on the media.

A known method of producing vinyl acetate by reaction of ethylene, oxygen and acetic acid as reactants, including the contact of these compounds with a catalyst containing a porous medium, the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, and the third metal in viive receipt of vinyl acetate with a relatively high level of performance, any tool that provides better performance, is highly desirable.

The following links are considered as significant in relation to the claimed invention.

U.S. patents 3775342, issued November 27, 1973, and 3822308, issued July 2, 1974, both in the name of Kronig and others, disclose a method of producing catalysts for vinyl acetate, including handling media simultaneously or sequentially with a solution containing dissolved salts of noble metals such as palladium and gold, and a solution containing a compound that can react to form salts of the noble metals to produce water-insoluble compounds, processing of water-insoluble compounds regenerating agent for the conversion of water-insoluble compounds of precious metals available in metals, washing of the catalyst to remove water-soluble compounds and the use of compounds of an alkali metal, such as alkali metal carboxylate, before or after treatment with reducing agent. The solution may also optionally contain salts of other metals, such as magnesium, calcium, barium and rare earth metals.

U.S. patent 5332710, issued July 26, 1994 in the name Nicolau et al., and acetic acid, including the impregnation of porous media, water-soluble salts of palladium and gold, the binding of palladium and gold in the form of insoluble compounds on the carrier, loading and processing in the drum impregnated carrier in the reactive solution for at least 1/2 hour for the deposition of these compounds, and then recovery of the compounds to their metallic form.

U.S. patent 5567839, issued October 22, 1996 in the name of Gulliver et al., describes a method of obtaining a vinyl acetate catalyst comprising a stage of application of the "salt" of barium, such as barium hydroxide, to precipitate water-insoluble compounds of palladium and gold on the media to restore the reducing agent. If the precipitating agents used barium hydroxide, in the finished catalyst is present residual barium.

The authors of the present invention has been reproduced disclosed in patent US 5567839 the catalyst carrier impregnated with palladium and gold with the use of BA(OH)2. It was found that the catalyst has a selectivity for CO211,92% and the activity of 2.1, whereas in the case of the catalyst according to the invention, where the third metal is used barium, the selectivity for CO2is 9,92% and Akti the persons (A) receipt of vinyl acetate by reaction of ethylene, oxygen and acetic acid as reactants, including the contact of these compounds with a catalyst containing a porous medium, the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, and the third metal in the form of its oxide or mixture of oxide and metal. The specified catalyst was prepared by the process comprising impregnation of the porous carrier with an aqueous solution of water-soluble salts of palladium and a third metal selected from the group consisting of magnesium, calcium, barium, zirconium and cerium, associates palladium and the third metal in the form of water-insoluble compounds by reaction with an appropriate alkaline compound, the subsequent impregnation of the catalyst with a solution of water-soluble gold salts, binding of gold in the solution used for the last impregnation in the form of water-insoluble compounds by reaction with an appropriate alkaline compound, and recovering the related palladium and gold to their metallic state, and the third metal in the form of its oxide or mixture of oxide and metal.

In another aspect the invention relates to method (B) receipt of vinyl acetate by reaction of ethylene, oxygen and acetic acid in the porous surfaces of which is deposited catalytically effective amounts of metallic palladium, gold and the third metal in the form of its oxide or mixture of oxide and metal, including phase rotation and/or rotation in the drum impregnated carrier at the time of his immersion in the solution of the corresponding alkali compounds. When this catalyst was prepared by the process comprising impregnation of the carrier with a solution of water-soluble salts of palladium, gold and a third metal selected from the group consisting of magnesium, calcium, barium and cerium, binding of palladium, gold, and the third metal in the final solution in the form of water-insoluble compounds by a process comprising a stage of rotation and/or rotation in the drum impregnated carrier at the time of his immersion in the solution of the corresponding alkali compounds, and recovery associated palladium and gold to their metallic state, and the third metal to its oxide or mixture of oxide and metal.

I believe that vinyl acetate catalysts in accordance with this invention, containing a catalytically effective amount of palladium, gold and any of these third metals, obtained by the method (A) or (B) act with more continuous high activity and/or a lower selectivity towards heavy fractions compared to rolled and therefore not included in the scope of the present invention, since the catalysts in accordance with this invention have a more consistent and predictable composition with a greater degree of homogeneity than the catalysts prepared by other methods. Such high activity and/or lower the selectivity to heavy fractions often leads to higher productivity vinyl acetate than in cases where the third metal is not applied.

Detailed description of the invention Upon receipt of the catalysts in accordance with this invention, by applying the method (A) or (B) the material of the catalyst carrier consists of particles having different regular or irregular, such as spheres, tablets, cylinders, rings, stars, etc. that may have dimensions such as diameter, length or width, approximately from 1 to 10 mm, preferably about 3 to 9 mm are Preferred areas, having a diameter of approximately 4 to 8 mm, the Material of the carrier may consist of any suitable porous material, for example silicon dioxide, aluminium oxide, silica - alumina, titanium dioxide, zirconium dioxide, silicates, aluminosilicates, titanates, spinel, silicon carbide, carbon, etc.,

Malepattern approximately from 100 to 200 m2/g; average pore size in the range of, for example, from about 50 to 2000 angstroms and a pore volume in the range of, for example, from about 0.1 to 2 ml/g, preferably about 0.4 to 1.2 mg/L.

When the soaking material of the carrier is a water-soluble salts alleged catalytically active metals palladium(II) chloride, sodium chloride-palladium(II), potassium chloride, palladium(II) nitrate, palladium(II) or sulfate, palladium(II) are examples of suitable water-soluble palladium compounds, while the alkali metals, for example sodium or potassium chloride, gold(III) or tetrachlorogallate(II) acid, are examples of water-soluble gold compounds, which can be used. Depending on the presence of a third metal is preferably in the catalyst, the following water-soluble salts are examples of compounds that can be used for impregnation of the third metal: magnesium sulfate (anhydrous or hydrated), magnesium acetate (anhydrous or hydrated), magnesium chloride (anhydrous or hydrated) or magnesium nitrate (hydrated); calcium chloride (anhydrous or hydrated), calcium acetate (anhydrous or hydrated), or neither is todny); the tetrahydrate of zirconium sulfate, zirconium chloride or zirconium nitrate (anhydrous or pentahydrate); or cerium nitrate (hydrated); cerium chloride (anhydrous), cerium sulfate (anhydrous or hydrated), or cerium acetate (anhydrous or hydrated).

Upon receipt of the catalyst (A) or (B) soaking the material of the carrier with solutions of water-soluble salts of the catalytically active metals can be carried out by any method known to specialists in this field. However, preferably such impregnation is conducted by the method of "initial humidity", in which the amount of solution a water-soluble salt used for impregnation is from about 95 to 100% of the absorption capacity of the material medium. Despite the fact that the amount of water-soluble salts of palladium and the third metal equivalent to the total amount of these metals in the finished catalyst may be present in the first impregnation carried out by the method (A) or (B), often it is preferable that a certain amount of water-soluble gold salts during the first impregnation carried out in method (C), or when the ground is saturated, containing a salt of gold after binding, as opvantage desirable in the final catalyst. In any case, after binding, as described below, part of the gold in the ground is saturated with a solution of water-soluble gold salts, further carry out impregnation with a solution of salts of gold, equivalent to the balance of gold whose presence is desirable in the final catalyst. The impregnation is conducted in such a way as to ensure, for example, from about 1 to 10 grams of elemental palladium and, for example, from about 0.5 to 10 grams of elemental gold per liter of the final catalyst, and the amount of gold is approximately from 10 to 125 wt.%, based on the weight of palladium. Depending on the presence of a third metal is preferably in the catalyst, and, assuming that there is only one third metal, the number of elementary third metal per liter of the catalyst provided by the impregnation may, for example, enter the following interval: magnesium: approximately from 0.1 to 2.0 g, preferably from about 0.3 to 1.0 g; calcium: approximately from 0.2 to 4.0 g, preferably about 0.5 to 1.5 g; barium: approximately from 0.2 to 5.0 g, preferably from about 0.6 to 3.0 g; zirconium: approximately from 0.4 to 7.0 g, preferably from about 1.0 to 3.0 g; CERI is osites aqueous solution of a water-soluble salt of a catalytically active metal "bind", i.e. precipitated in the form of water-insoluble compounds such as the hydroxide, reaction with an appropriate alkaline compound, for example an alkali metal hydroxide, silicate, borate, carbonate or bicarbonate, in aqueous solution. Of sodium hydroxide and potassium are the preferred alkali binding compounds. Alkaline compound should be present in excess, for example, from about 1 to 2 times, preferably from about 1.1 to 1.8 times the amount required for the complete precipitation of the cations present catalytically active metals.

In method (a) preparation of the catalyst, each binding of metal can be carried out by the method of initial moisture content at which the impregnated carrier is dried, for example at a temperature of approximately 150oWith in an hour, combined with a quantity of a solution of an alkali metal of approximately 95-100% of the pore volume of the carrier, and give him the opportunity to settle for from about 1/2 hour to 16 hours, either by topograghy, in which the impregnated carrier without drying immersed in a solution of alkaline material and rotate and/or rotate in the drum during at least the initial period sadogashima connection. In method (C) the binding of metals in the salts of palladium and other metals that are added during the first impregnation should be carried out by ratiograstim. However, the binding of gold in the water-soluble gold salts added any subsequent impregnation may be carried out by the method of initial humidity or protoparmelia. When the binding of metals by ratiograstim rotation and the rotation of the drum can be carried out, for example, within at least about 0.5 hour, preferably from about 0.5 to 4 hours. The proposed method of protoparmelia described in the aforementioned U.S. patent 5332710, given here in its entirety by reference.

Related, i.e., precipitated, the compounds of palladium, gold, and the third metal can be recovered, for example, in the vapor phase with ethylene, for example, 5% in nitrogen at 150oWith over 5 hours after the first washing of the catalyst containing compounds of the associated metal, the removal of anions such as halide, and drying, for example, if 150oC for approximately 1 hour, or such recovery can be carried out before washing and drying in the liquid phase at room temperature with an aqueous solution of hydrate gerasopoulos on the media, is in the range of, for example, from about 8:1 to 15:1, followed by washing and drying. Can be used and other reducing agents and tools for recovery related compounds of the metals present on the media, well-known in this field. Recovery of related compounds of palladium and gold mainly leads to the formation of the free metal, although there may be a small amount of oxide of the metal, while the recovery of the associated third metal leads to the formation of oxide or mixture of oxide and free metal depending on the conditions of recovery and what the third metal is present. In those cases, when using several stages of impregnation and binding, restoration can be performed after each stage of binding or after all the metal elements will be connected on the media.

In a preferred variant of the method (A), including the previously described specific procedures, the carrier is first impregnated with an aqueous solution of water-soluble compounds of palladium and the third metal by the method of initial moisture content, and then palladium and the third metal link processing alkaline binding solution by the method of starting icyhot solution of a soluble gold compounds, the number of elementary gold, which is desirable in the catalyst, and the gold is associated processing alkaline binding solution by the method of initial humidity or topograghy, preferably the initial moisture content. If gold is associated with the method of initial moisture content, such binding may be connected with the stage of impregnation through the use of a water solution of a soluble gold compounds and alkaline linking compound in the amount of the excess against the amount required to convert all the gold in the solution to the associated insoluble compound, such as gold hydroxide, gold. If as a reducing agent in the vapor phase is used hydrocarbon, such as ethylene or hydrogen, the catalyst containing compounds of related metals, washed to eliminate dissolved anions, dried and restore ethylene or other hydrocarbon, as described previously. If as a reducing agent in the liquid phase used hydrazine, the catalyst containing compounds of related metals, treated with an aqueous solution of an excess of hydrazine hydrate before washing and drying to recover metal compounds to free metals is or only part of the gold impregnated with palladium and a third metal during the first impregnation, metals bind reaction alkaline binding connection ratiograstim associated metal compounds reduced to the free metals, for example, ethylene or hydrazine hydrate, and the washing and drying are conducted before recovering ethylene or after reduction with hydrazine. Then the catalyst is impregnated with a balance of gold related to the catalyst by applying any of the previously described procedure. Preferably the wetting and binding takes place during one stage of the method of initial moisture content, using a single solution of water-soluble gold compounds and the corresponding alkali compounds. Added associated gold then restore, for example, ethylene or hydrazine, after or before washing and drying, as described earlier.

After you obtain a catalyst containing palladium and gold in metallic form and the third metal oxide or mixture of oxide and metal, deposited on a material carrier, any of the methods mentioned above, it is preferably optionally impregnated with a solution of acetate of an alkali metal, preferably potassium acetate or sodium, and most preferably potassium acetate. Then the catalyst is dried so chtoby, acetate of alkali metal per liter of the finished catalyst.

Although the catalysts in accordance with this invention have been described as containing only one "third" metal, may in fact be several such metals. If it is desirable to have the catalyst, at least two of these three metals, the original solution for impregnation should contain dissolved salts of these metals, in order to ensure the presence of these metals in the finished catalyst in the intervals, the upper and lower boundaries of each of which constitute a part of the above limit values, based on the presence of only one "third" metal, this part is the part that makes up a particular "third" metal from the total amount of the third metal in the catalyst.

If the vinyl acetate is obtained in use of the catalyst in accordance with this invention, the catalyst is passed a gas stream containing ethylene, oxygen or air, acetic acid, and preferably an alkali metal acetate. The composition of the gas stream can vary within wide limits, taking into account the explosion limits. For example, the molar ratio of ethylene to oxygen mo is blithedale from 100:1 to 1: 100, preferably from about 10:1 to 1:8, and the content of gaseous alkali metal acetate may range from 1 to 100 hours /million, based on the weight used is acetic acid. Acetate of an alkali metal may be added to the feed stream by spraying an aqueous solution of this acetate. The gas stream can also contain other inert gases such as nitrogen, carbon dioxide and/or saturated hydrocarbons. The reaction is carried out at elevated temperature, preferably in the range of approximately 150-220oC. the Pressure may be somewhat reduced, normal or increased, preferably to approximately 20 atmospheres.

The following, not limiting examples additionally illustrate the invention.

COMPARATIVE EXAMPLE a and EXAMPLES 1-5 These examples illustrate the obtaining of catalysts in accordance with this invention by the method (a) and the advantages of such catalysts for production of vinyl acetate from the point of view of higher activity and/or a lower selectivity towards heavy fractions.

In the comparative example And used as control material carrier comprising spheres of silicon dioxide Sud Chemie KA-160, having a nominal is the beginning impregnated by the method of initial humidity aqueous solution of sodium chloride-palladium (II), sufficient to provide about 7 grams of elemental palladium per liter of catalyst. Then palladium is associated with a carrier in the form of hydroxide, palladium(II) exposing the catalyst to notoperating with aqueous sodium hydroxide solution so that the molar ratio of Na/Cl amounted to about 1.2:1. Then the catalyst was dried at 100oC for 1 hour in a dryer fluidized bed, and then impregnate the method of initial moisture aqueous solution of tetrachloroaurate sodium in a quantity sufficient to provide 4 g/l of elemental gold, and sodium hydroxide so that the molar ratio of Na/Cl is approximately 1.8:1, to link gold on the media in the form of a hydroxide of gold. Then the catalyst is washed to remove chloride (about 5 hours) and dried at 150oC for one hour in a stream of nitrogen. After that, hydroxide, palladium and gold reduced to free metal by contact of the catalyst with ethylene (5% in nitrogen) in the vapor phase at 150oC for 5 hours. Finally, the catalyst was impregnated by the method of initial humidity aqueous solution of potassium acetate in a quantity sufficient to provide 40 g of potassium acetate per liter of catalyst, and dried in the dryer fluidized bed Ave is in the solution of sodium chloride-palladium (II) contains a variety of additional quantities of dissolved salts of the third metal, which is then connected to the carrier in the form of hydroxide together with palladium hydroxide(II) and restore the ethylene to the oxide or mixture of oxide and metal along with metallic palladium and gold. The third metal salts are magnesium sulfate (example 1), calcium chloride (example 2), barium chloride (example 3), zirconium sulfate (example 4) and cerium nitrate(III) (example 5).

The catalysts obtained as described in examples 1-5 are active upon receipt of vinyl acetate by reaction of ethylene, oxygen and acetic acid. To do this, about 60 ml of the catalyst of each type obtained in the examples are placed in a separate basket in stainless steel. The temperature of each basket is measured with a thermocouple at the bottom and the top. Each reaction basket is placed in a continuously mixed mixed Berty reactor recirculating type and support at a temperature of providing about 45% conversion of oxygen by means of the electric burner. A gas mixture containing about 130 l/h (measured at normal temperature and pressure) of ethylene, about 26 l/h of oxygen, about 128 lcares each basket. The reaction is stopped after about 18 hours. Analysis of the products is carried out using the non-Autonomous gas chromatographic analysis coupled with offline analysis of the liquid product, condensing the stream of products at approximately 10oFor optimal analysis of the final products.

Table 1 shows for each example, the identity and quantity in grams per liter of catalyst elementary third metal catalyst ("Third metal, g/l") in addition to 7 g/l of palladium and 4 g/l of gold, the results of the analysis of the reaction product from the point of view of the percentage selectivity of CO2("CO2, % selectivity) and heavy fractions (Heavy fraction, % selectivity), as well as the relative activity of the reaction, expressed as a ratio of activity ("activity rate"), calculated on the computer, as follows: a computer program uses a series of equations that correlate the activity coefficient with temperature of the catalyst during the reaction), the conversion of oxygen, as well as a series of kinetic parameters for the reactions that occur during the synthesis of vinyl acetate. In General, the activity coefficient is inversely proportional to the temperature, clean the ditch 1-5, each of which is obtained by the method (a) and contains one of said third metal in addition to continuous amounts of palladium and gold, and lead to reactions with higher activity than the catalyst of comparative example A, containing the same amount of palladium and gold, but not containing the third metal. Moreover, the catalysts of examples 1, 3 and 5, containing magnesium, barium and cerium, respectively, in the form of a third metal, also lead to reactions that have a significantly lower selectivity towards heavy fractions than the reaction of comparative example A, where the catalyst does not contain the third metal.

EXAMPLES 6, 7 and 8
These examples illustrate the obtaining of catalysts in accordance with this invention by the method (b) and the results of the use of such catalysts upon receipt of vinyl acetate under the same conditions as the conditions specified for the catalysts of examples 1-5.

The same media as in comparative example a and examples 1-5, first impregnated by the method of initial humidity with a solution of salts of palladium, gold, and the third metal sufficient to provide 7 grams of elemental palladium, 4 g of elemental gold and different number e and the third metal are magnesium sulfate in example 6, calcium chloride in example 7 and barium chloride in example 8. Then the metals associated with ratiograstim in an aqueous solution of about 120% of the amount of sodium hydroxide required for the deposition of palladium, gold and a third metal, the latter metal restore in the liquid phase using an aqueous solution of hydrazine hydrate under the excessive weight ratio of hydrazine to the metals constituting 12:1. After recovery of the catalyst is washed to remove chloride (about 5 hours), dried at 100oC for 1 hour in a dryer fluidized bed, and then impregnate the method of initial moisture aqueous solution of salt of gold, sufficient to provide the catalyst 3 more grams per liter of elemental gold (General 7 g), and sodium hydroxide so that the molar ratio of Na/Cl was approximately 1.8:1, to link additional gold. Then additional gold restore in the liquid phase with hydrazine hydrate as described previously, and the catalyst was washed, dried and impregnated with potassium acetate as described in comparative example A. Then, the catalysts examined for their function upon receipt of vinyl acetate, as described in the previous example.

Table 2 pocasie the results of the reaction terms of percentages, the selectivity of ethylene to CO2and heavy fractions and the activity coefficient.

The results in table 2 show that the catalysts containing the third metal of examples 6, 7 and 8 are in receipt of vinyl acetate from ethylene, acetic acid and oxygen is relatively high coefficients of activity and/or low selectivity towards heavy fractions.


Claims

1. The method of producing vinyl acetate by reaction of ethylene, oxygen and acetic acid as reactants, including the contact of these compounds with a catalyst containing a porous medium, the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, and the third metal in the form of its oxide or mixture of oxide and metal, characterized in that the catalyst was prepared by the process comprising impregnation of the porous carrier with an aqueous solution of water-soluble salts of palladium and a third metal selected from the group consisting of magnesium, calcium, barium, zirconium and cerium, associates palladium and the third metal in the form of water-insoluble compounds by reaction with an appropriate alkaline compound, the subsequent impregnation of the catalyst solution of the water-insoluble compounds by reaction with an appropriate alkaline compound, and recovery associated palladium and gold to their metallic state, and the third metal in the form of its oxide or mixture of oxide and metal.

2. The method of producing vinyl acetate by reaction of ethylene, oxygen and acetic acid as reactants, including the contact of these compounds with a catalyst containing a porous medium, the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, and the third metal in the form of its oxide or mixture of oxide and metal, including phase rotation and/or rotation in the drum impregnated carrier at the time of his immersion in the solution of the corresponding alkali compounds, characterized in that the catalyst was prepared by the process comprising impregnation of the carrier with a solution of water-soluble salts of palladium, gold and a third metal selected from the group consisting of magnesium, calcium, barium and cerium, the binding of palladium, gold, and the third metal in the final solution in the form of water-insoluble compounds by a process comprising a stage of rotation and/or rotation in the drum impregnated carrier at the time of his immersion in the solution of the corresponding alkali compounds, and recovery associated PAL whom/p> 3. The method according to p. 1 or 2, wherein the third metal is magnesium.

4. The method according to p. 1 or 2, wherein the third metal is calcium.

5. The method according to p. 1 or 2, wherein the third metal is barium.

6. The method according to p. 1 or 2, wherein the third metal is zirconium.

7. The method according to p. 1 or 2, wherein the third metal is cerium.

8. The method according to p. 2, characterized in that the rotation and/or rotation in the drum impregnated carrier immersed in a solution of the corresponding alkali compounds to bind palladium, gold, and the third metal lasts at least for about 0.5 hours

9. The method according to p. 1, characterized in that the catalyst contains the acetate of an alkali metal deposited on the catalyst after the restoration of all things palladium, gold, and the third metal in the catalyst.

10. The method according to p. 10, characterized in that the alkali metal acetate is the acetate of potassium.

 

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