Catalyst for the synthesis of vinyl acetate containing palladium, gold, copper and certain fourth metal

 

The invention relates to an improved process for the preparation of vinyl acetate by reaction of ethylene, oxygen and acetic acid, used as reagents, including contacting the above reactants with a catalyst containing a porous medium, the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, copper in the form of free metal or copper acetate, and the fourth metal selected from the group consisting of magnesium, calcium, barium and zirconium, in the form of its oxide or mixture of oxide and free metal, at a temperature of 150-220oC and pressure up to 20 atmospheres. The use of catalysts with high activity and/or low selectivity for CO2and/or high-boiling products, allows you to get more performance on acetate than using any of the catalysts known in the art. 7 C.p. f-crystals, 3 tables.

This invention relates to new and improved catalysts for production of vinyl acetate by the reaction between ethylene, oxygen and acetic acid.

It is known that to obtain a vinyl acetate by reaction of ethylene, oxygen and acetic acid used in the use of such a catalyst, you can get vinyl acetate at a relatively high performance, any suitable method that could provide even greater performance, it would be highly desirable.

The following links can be considered as material relating to the claimed here to the invention.

In U.S. patent 3775342 of 27 November 1973 and 3822308 July 2, 1974, issued by the Kronig et al., the described method of producing catalysts for the synthesis of vinyl acetate, includes treatment, 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 noble metals with the formation of water-insoluble compounds, the treatment of such water-insoluble compounds reducing agent to convert water-insoluble compounds of precious metals available in metals, leaching of the catalyst to remove water-soluble compounds and the use of compounds of an alkali metal, such as a carboxylate of an alkali metal before or after treatment with reducing agent. The solution may also optionally contain salts of other metals, such as magnesium, calcium, barium and copper.

In U.S. patent 533 is of racette by reaction of ethylene, oxygen and acetic acid, comprising the impregnation of porous media, water-soluble salts of palladium and gold, the fixation of palladium and gold in the form of insoluble compounds on the carrier by immersing and agitating the impregnated carrier in the reaction solution at least for 1/2 h to precipitate these compounds, and subsequent recovery of these compounds to the free metals.

In U.S. patent 5347046 September 13, 1994, issued to White et al., the described catalysts for production of vinyl acetate by reaction of ethylene, oxygen and acetic acid containing a metal of the group of palladium and/or its connection, as well as copper, Nickel, cobalt, iron, manganese, lead or silver or their compounds, preferably deposited on the media.

In U.S. patent 5567839 from October 22, 1996 issued by Gulliver et al., the described method of producing catalysts for the synthesis of vinyl acetate, including the state of use of the salt of barium, such as barium hydroxide, to precipitate water-insoluble compounds of palladium and gold on the media before restoring a reducing agent. When the precipitator is used hydroxide barium remaining barium remains in the finished catalyst.

According to this invention, proposed is Rashi porous media, on the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, copper in the form of free metal or copper acetate, and the fourth metal selected from the group consisting of magnesium, calcium, barium and zirconium, in the form of its oxide or mixture of oxide and free metal, and any of the latter metals later in this description is called the "fourth" metal.

It can be assumed that the catalysts for the synthesis of vinyl acetate proposed in this invention, containing a catalytically effective amount of palladium, gold, copper, and any fourth metal of the above, are characterized by high activity and/or low selectivity for CO2and/or high-boiling products, so the use of such catalysts often gives a great performance vinyl acetate than when using any of a variety of catalysts known in the art.

Upon receipt of the catalysts proposed in this invention, the material of the catalyst carrier consists of particles having any of various regular or irregular, such as spherical particles, tablets, cylinders, rings, stars or other form of particles, and the particles may have a p is. fricassee particles having a diameter of from about 4 to about 8 mm, are preferred. The carrier may consist of any suitable porous material, for example of silicon dioxide, aluminum oxide, mixtures of silicon dioxide with aluminum oxide, titanium dioxide, zirconium dioxide, silicates, aluminosilicates, titanates, spinel, silicon carbide or coal, etc.,

The material of the carrier may have a specific surface area within, for example, from about 10 to about 350, preferably from about 100 to about 200 m2/g, the average pore size in the range, for example, from about 50 to about 2000 angstroms (from 5 to 200 nm) and pore volume in the range, for example, from about 0.1 to 2, preferably from 0.1 to 2, preferably from about 0.4 to about 1.2 ml/g

Upon receipt of the catalysts of this invention, the material of the carrier may be treated to precipitate catalytic amounts of palladium, gold, copper and the fourth metal on the porous surface of the particle carrier. You can use any of the various ways to achieve this goal, all of which include simultaneous or separating the carrier impregnated with one or more aqueous solutions of water-soluble compounds of Catalytica is I (II) or sulfate, palladium (II) are examples of suitable water-soluble palladium compounds; salt of an alkali metal such as sodium or potassium chloride, gold (III), or tetrachlorogallate (III) acid can be used as a water-soluble gold compounds; and the trihydrate or uranyl nitrate of copper, copper chloride (anhydrous or dihydrate), monohydrate copper acetate, copper sulfate (anhydrous or pentahydrate), copper bromide or copper formate (anhydrous or tetrahydrate) can be used as a water-soluble copper compounds. Depending on what the fourth metal desired in the catalyst, the following water-soluble salts are examples of compounds that can be used for impregnation with the purpose of introducing such a fourth metal: magnesium sulfate (anhydrous or hydrated), magnesium acetate (anhydrous or hydrated), magnesium chloride (anhydrous or hydrated), magnesium nitrate (hydrated), calcium chloride (anhydrous or hydrated), calcium acetate (anhydrous or monohydrate) or calcium nitrate (anhydrous or hydrated), barium acetate (anhydrous or hydrated), or barium nitrate (anhydrous); or zirconium sulfate (tetrahydrate), zirconium chloride or zirconium nitrate (anhydrous or pentahydrate). Salt of alkaline metal tetrachlorogallate (Lami for impregnation compounds of gold, palladium and copper, respectively, due to their good solubility in water.

The preparation of the catalyst impregnation of the material of the carrier with solutions of water-soluble salts of the catalytically active metals can be accomplished by any method known to specialists in this field. However, preferably such impregnation is performed by the method of "capacity" in which the number of solution of water-soluble salt used for impregnation is from about 95 to 100% of the absorption capacity of the material medium. The concentration of the solution or solutions is chosen such that the number of catalytically active metals in solution or solutions which are absorbed on the media, were equal to the desired predetermined amount. If more than one such impregnation, the solution for each propeci may contain water-soluble compound, the amount of which is equivalent to the whole or only part of one or any combination of the four catalytically active metals whose presence is desirable in the finished catalyst, until the sum of the quantity of these metals in the absorbed solution for impregnation becomes equal to the desired quantities in the finished catalyst. In particular, m is described in more detail here below. Impregnation are such to provide, for example, content from about 1 to about 10 grams of elemental palladium; for example, from about 0.5 to about 10 g of elemental gold; and, for example, from about 0.5 to about 3.0 g of elemental copper per liter of the finished catalyst, and the amount of gold should be from about 10 to about 125 weight percent by weight of palladium. Depending on what the fourth metal should be present in the catalyst, and assuming that there is only one fourth the metal, the number of grams of elementary fourth metal per liter of the catalyst obtained by impregnation, may be, for example, within the following limits: magnesium: from about 0.1 to about to 2.0, preferably from about 0.3 to about 1.0; calcium: from about 0.2 to about 4.0; preferably from about 0.5 to about 1.5; barium: from about 0.2 to about 5,0; preferably from about 0.6 to about 3,0; zirconium: from about 0.4 to about 7.0 and preferably from about 1.0 to about 3,0.

After each impregnation of the carrier with an aqueous solution of water-soluble salt of a catalytically active metal, "fixed", i.e., precipitates as insoluble in water connection is the ikat, borate, carbonate or bicarbonate of an alkali metal in an aqueous solution. The hydroxides of sodium and potassium are the preferred alkali locking connections. The amount of the alkaline compound should be from about 1 to about 2, preferably from about 1.1 to about 1.8 in relation to the amount required for the complete precipitation of the cations of catalytically active metal present in the water-soluble salts. The fixation of the metal can be carried out by the method of the capacity in which the impregnated carrier is dried, for example, at a temperature of approximately 150oC for one hour, add the number of solution of the alkaline substance, approximately 95-100% of the pore volume of the carrier, and leave to stand for any period of time from about 1/2 hour to about 16 hours; or by immersion-rotation, in which the impregnated carrier without drying immersed in a solution of an alkaline substance and stirred by rotation and/or stirring of the mixture during at least the initial period of deposition, so that the surface or near the surface of the particles of the medium formed of a thin strip of precipitated water-soluble compounds. When carrying out the fixation of metals by the method of P10 rpm over a period of time, for example, at least about 0.5 h, preferably from about 0.5 to about 4 o'clock this method of immersion-rotation described in the above cited U.S. patent 5332710, the substance of which is included here by reference.

Fixed, i.e., precipitated compounds of palladium, gold, copper and the fourth metal can be recovered, for example, in the vapor phase with ethylene, such as ethylene content of about 5% in nitrogen at a temperature of approximately 150oC for about 5 h after the initial washing of the catalyst containing the fixed metal compounds, prior to the removal of anions as halogen, and drying, for example, at a temperature of approximately 150oC for about 1 hour, or such recovery can be carried out in liquid phase at room temperature in an aqueous solution of hydrazine hydrate is added to the washing and drying, and the excess hydrazine compared to the number that you want to restore all of the metal compounds present in the medium is from about 8: 1 to about 15:1, followed by rinsing and drying. To restore the fixed metal compounds present on the media, you can use other reducing agents and methods of recovery, which result in the formation of the free metal, although, there might also be a small amount of a metal oxide, while the recovery of the fixed fourth metal usually leads to the formation of oxide or mixture of oxide and free metal depending on the conditions of recovery and what the fourth metal undergoes reduction. In cases where the preparation of the catalyst used by more than one stage impregnation and fixation, the recovery can be performed after each stage of fixation or after all the metals are fixed on the carrier.

As an example, the above-described General methods can lead method "separate commit" used to capture the catalytically active metals on the carrier and recover the water-insoluble metal compounds to the desired form of the free metal. In this method, using certain techniques described above, the carrier is first impregnated with an aqueous solution of water-soluble compounds of palladium, copper and the fourth metal capacity, and then palladium, copper and the fourth metal is fixed by treatment with an alkaline fixing solution according to the method of capacity or immersion-rotation, preferably by the method of the submersible, containing such quantity of elemental gold, which is preferably in the catalyst, and the gold is fixed by treatment with an alkaline fixing solution according to the method of capacity or immersion-rotation, preferably by the method of capacity. If gold will be fixed according to the method of capacity, this fixation can be combined with the stage of impregnation with the use of a single aqueous solution of a soluble gold compounds and alkaline locking connection in the quantity of excess compared with the amount needed to convert all the gold in solution in a fixed insoluble compound, such as gold hydroxide, gold. If as a reductant use hydrocarbons, such as ethylene or hydrogen in the vapor phase, the catalyst containing the fixed metal compounds, washed up until it will not be dissolved anions, dried and restore ethylene or other hydrocarbon, or hydrogen, as described above. When in use as a reducing agent hydrazine in liquid phase, the catalyst containing the fixed metal compounds, process, before washing and drying, an aqueous solution of an excess of hydrazine hydrate is added with a what was described.

Another alternative method of preparation of the catalyst is modified method of immersion-rotation" in which the first impregnation with palladium, copper and the fourth metal only add part of the gold, the metal is fixed by reaction with alkaline locking connection by immersion-rotation, fixed metal compounds reduced to the free metals, for example, ethylene or hydrazinehydrate, and washing and drying is carried out before re-ethylene or after reduction with hydrazine. The catalyst was then impregnated with the rest of the gold, which is fixed on the catalyst, using any of the techniques described previously. Preferably the impregnation and fixation is carried out in one stage by capacity using a solution of water-soluble gold compounds and the appropriate alkaline compound. Added a fixed gold then restore, for example, ethylene or hydrazine after or before washing and drying, as described earlier.

Not wishing to be bound by theory, it is possible to assume that in an optimal embodiment, the catalyst of this invention contains porous media, porous surfaces of which is deposited a metal Diya, gold and the fourth metal, none of which are particularly mixed with the specified copper. This catalyst can be prepared using different impregnation methods, fixation and recovery as described here above. Using this catalyst, in which the area of copper surrounded by palladium, gold, and the fourth metal, and therefore copper is less susceptible to environmental conditions, reduces the copper losses in the result of the escape.

In another useful embodiment, the catalyst of this invention contains porous media, porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, the fourth metal oxide or mixture of oxide and free metal and copper as copper acetate. This catalyst was prepared as follows: first, prepare a catalyst precursor containing porous media, porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, and the fourth metal oxide or mixture of oxide and free metal, using any of the methods of impregnation, commit and recovery described above. Predecessor katalysatoren impregnation on capacity. Then the catalyst is dried so that the finished catalyst contained copper acetate in an amount equivalent to, for example, the amount of from about 0.3 to about 5.0 g, preferably from about 0.5 to about 3.0 g of elemental copper per liter of the finished catalyst.

After the catalyst containing palladium, gold and copper in the form of free metal and the fourth metal oxide or mixture of oxide and free metal deposited on a carrier prepared by any of the methods mentioned above, it is useful to impregnate 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 that the finished catalyst contains, for example, from about 10 to about 70, preferably from about 20 to about 60 g of the acetate of alkali metal per liter of the finished catalyst. When prepared variant of the catalyst in which copper is present as copper acetate, optional impregnation of the catalyst with alkali metal acetate, if it is held, can be done before or after impregnation with copper acetate. However, it is preferable that the impregnation with alkali metal acetate was combined with impregnation with copper acetate, i.e., the si oxide and free metal, soaked up at the same time a separate solution of copper acetate, and acetate of an alkali metal, to obtain the finished catalyst after drying will contain the desired number of both acetates.

Although the catalyst of this invention has been described as containing only one "fourth" metal, in fact, can be more than one such metal. When it is desirable that the catalyst was attended by at least two of these described "fourth" of the metal, the initial solution used for impregnation may contain dissolved salts of these metals, to ensure that the content of these metals in the finished catalyst in the intervals, upper and lower limits of each of which are a fraction of the limits described above, based on the assumption that there is only one "fourth" metal, and this share is the same as the proportion that an individual "fourth" metal is the total number of fourth metal in the catalyst.

Upon receipt of vinyl acetate using a catalyst according to the present invention, the gas stream, which contains ethylene, oxygen or air, acetic acid, and preferably an alkali metal acetate, pass over, for example, the molar ratio of ethylene to oxygen may range from about 80:20 to about 98:2, the molar ratio of acetic acid to ethylene may be from about 100:1 to about 1: 100, preferably from about 10:1 to about 1:10 and most preferably from about 1:1 to about 1:8, and the content of gaseous alkali metal acetate may be about 1-100 ppm relative to that used acetic acid. Acetate of an alkali metal, you can usually add to the flow of feedstock in the form of a sprayable aqueous solution of this acetate. The gas stream may also contain other inert gases such as nitrogen, carbon dioxide and/or saturated hydrocarbons. The reaction temperature that can be used is a high temperature, preferably in the range of about 150-220oC. the Pressure used for the reaction can be somewhat reduced pressure, normal pressure or increased pressure, and preferably uses a gauge pressure of about 20 atmospheres.

A preferred variant of the process of obtaining vinyl acetate using a catalyst of this invention is the introduction does not contain halogen compounds of copper in the stream Reagan is neither soluble in water or in acetic acid and may be represented as, for example, copper acetate (anhydrous or monohydrate), which is preferred, copper nitrate (trihydrate or uranyl), copper sulfate (anhydrous or pentahydrate) or formate, copper (anhydrous or pentahydrate), etc., the Number of copper compounds fed to the reaction, may be such as to obtain, for example, the content of elemental copper in relation to acetic acid in the stream of reactants fed to the reaction, from about 10 h/billion (ppb) to about 50 ppm (parts per million), preferably from about 20 h/bn up to about 10 h/million through this introduction of copper and the amount of copper in the copper acetate contained in the catalyst, which is lost by volatilization of the catalyst during long use, is reduced compared with when the flow of the reactant supplied to the reaction, do not enter any copper compounds.

The following not limiting the invention to the examples additionally illustrate this invention.

Comparative example a and examples 1-3.

These examples illustrate the preparation of catalysts proposed in this invention, the method of "separate fixing" and the advantages of such catalysts upon receipt of the vinyl acetate from the point of view And more, which serves as the control material carrier comprising spherical particles of silicon dioxide Sud Chemie KA-160, having a nominal diameter of 5 mm, the value of specific surface area of from about 160 to 175 m2/g and a pore volume of about 0.68 ml/g, were first soaked in water holding capacity with an aqueous solution of sodium chloride-palladium (II) and copper chloride, in a quantity sufficient to provide about 7 grams of elemental palladium and 1.39 g of elemental copper per liter of catalyst. Then palladium and copper are recorded on the media in the form of hydroxide, palladium (II) hydroxide copper (II) by treatment of the catalyst by immersion-rotation aqueous solution of sodium hydroxide, so that the molar ratio of Na/Cl was equal to about 1.2:1. The catalyst was then dried at 100oC for 1 h in the dryer fluidized bed, after which he soaked in water holding capacity water solution of tetrachloroaurate sodium in sufficient quantity to obtain a catalyst containing 4 g/l of elemental gold, and sodium hydroxide so that the molar ratio of Na/Cl amounted to about 1.8:1, to capture the gold on the media in the form of a hydroxide of gold. Then the catalyst was washed with water until no chloride (about 5 hours) and was dried at 150oIn takenaway catalyst with ethylene (5% in nitrogen) in the vapor phase at 150oC for 5 hours Finally the catalyst was soaked in capacity with an aqueous solution of potassium acetate in a quantity sufficient to obtain a content of 40 g of potassium acetate per liter of catalyst, and dried in the dryer fluidized bed at 100-150oC for one hour.

In examples 1-3 was used the method of comparative example A, except that a solution of sodium chloride-palladium (II) chloride copper additionally contained various quantities of dissolved salts fourth metal, which is then recorded on the media in the form of hydroxide together with hydroxides of palladium (II) and copper, and restored the to ethylene oxide or mixture of oxide and free metal along with a free metal palladium, copper and gold. Salt of the fourth metal represented respectively calcium chloride (example 1), barium chloride (example 2) and sulfate of zirconium (example 3).

The catalysts prepared as described in comparative example a and examples 1-3 were tested for activity in the synthesis of vinyl acetate by reaction of ethylene, oxygen and acetic acid. To conduct these tests, about 60 ml of the catalyst of each type prepared in examples was placed in a separate mesh baskets and the first basket of the catalyst was placed in the reactor Bertie continuous mixer recirculation type and kept at a certain temperature, which ensured the conversion of oxygen to about 45%, with an electric heating casing. A gas mixture consisting of about 130 l/h (measured under normal conditions) of ethylene, about 26 l/h of oxygen, approximately 128 l/h of nitrogen, approximately 130 g/h of acetic acid and about 2 g/h of potassium acetate was purged under a pressure of about 12 atmospheres through each basket. The reaction was interrupted after about 18 hours the product Analysis was performed by gas chromatography directly in the process in conjunction with the analysis of liquid products taken from the process by condensing the product stream at a temperature of about 10oTo get the best analysis of the final products.

In table. I shows for each example, the name and quantity in grams per liter of catalyst elementary fourth metal oxide or mixture of oxide and free metal in the catalyst (4th metal, g/l), in which in addition contains 7 g/l of palladium, 4 g/l of gold and 1.39 g/l of copper, and the results of the analysis of the reaction products in the form of percent selectivity for CO2(CO2, % selectivity) and the percent selectivity of the high-boiling products (EAP) (EAP, % selectivity) and the relative activity of the reaction, vyrajeniyem the program uses a series of equations, linking the activity coefficient with temperature of the catalyst during the reaction), with the conversion of oxygen and with a number of kinetic parameters for the reactions that take place during the synthesis of vinyl acetate. More generally, the activity rate is in inverse proportion to the temperature required to achieve permanent conversion of oxygen.

Comparative example b and examples 4-6.

In these examples used the method of comparative example a and examples 1-3, respectively, except that the nominal diameter of spherical particles of silicon dioxide, used as a carrier, was equal to 7, instead of 5 mm In the table. II shows the results of these experiments, each of which in the examples 4 and 5 is the average result of the two experiments with the same catalyst under identical conditions.

The results of the above experiments are shown in table. I and II, indicate that the addition of calcium, barium or zirconium identical in all other respects palladium-gold-copper catalyst obtained by the method of separate commit, reduces the selectivity for high-boiling products (EAP) and/or increases the activity coefficient of the catalyst previa.

Examples 7-12.

These examples illustrate the preparation of catalysts according to the present invention by the modified method of "immersion-rotation" and the results of the use of such catalysts in the synthesis of vinyl acetate in the same form as for the catalysts of examples 1-6.

The same media that used in comparative example a and examples 1-3, was first impregnated by the method of capacity with a solution of salts of palladium, gold, copper and the fourth metal sufficient to enter in the catalyst 7 grams of elemental palladium, 4 g of elemental gold, 1.9 grams of elemental copper and a variable number of elementary fourth metal. Used salt of palladium, gold and copper were the same as in the previous examples, and the salts of the fourth metal was a zirconium sulfate in examples 7 and 8, barium chloride in example 9, the calcium chloride in example 10 and magnesium sulfate in examples 11 and 12. Then the metals were fixed by immersion-rotation in an aqueous solution of sodium hydroxide containing about 120% of the amount of sodium hydroxide required for the deposition of palladium, gold, copper and the fourth metal, and these metals were restored or ethylene in the vapor phase (5% in nitrogen) at a temperature of the ATA excessive weight ratio of hydrazine to the metal, equal to 12:1. After recovery of the catalyst was washed until no chloride (about 5 h), was dried at 100oC for 1 h in the dryer fluidized bed and then soaked in water holding capacity water solution of salt of gold, sufficient to enter in the catalyst in addition, 3 g/l of elemental gold (total content was 7 g/l) and sodium hydroxide solution so that the molar ratio of Na/Cl was equal to about 1.8:1 to capture the added gold. More gold then restored the same reducing agent, which is used during the first restoration, as described above, and the catalyst was washed, dried and impregnated with potassium acetate as described in comparative example A. Then the catalyst was tested for its functional characteristics in the synthesis of vinyl acetate, as described in the previous examples.

In table. III shows the name and number of the fourth metal in the catalyst, which contains about 7 g/l of palladium and gold and 1.9 g/l of copper, the results of the reaction in the form of percent selectivity for CO2and high-boiling products (EAP) and the activity coefficient, as shown in the table. I and II, and, in addition, shows, whether as wossidlo example are average results from the two experiments, carried out with the same catalyst under identical conditions.

Results table. III show that contains the fourth metal catalysts of this invention, prepared by the modified method of dip-rotation, which were used to obtain the vinyl acetate from ethylene, acetic acid and oxygen, have a relatively low selectivity for CO2and high-boiling products.

Example 13.

This example illustrates the preparation of the catalyst modified by immersion-rotation and the results of the use of a catalyst containing magnesium as the fourth metal, which is similar to the catalyst of example 11, except that it contains about 4 g/l instead of about 7 g/l of gold.

To apply the methodology of example 11, using hydrazine as a reducing agent, except that in each of the two solutions for impregnation contained tetrachloroaurate in sufficient number to enter in the catalyst, 2 g/l of gold to the total gold content in the finished catalyst was 4 g/L. When tested catalyst in the synthesis of vinyl acetate, as described in the previous examples, the flow analysis of the product showed that the selectivity for Kim indicator and the activity coefficient is equal to 1.87.

Example 14.

This example illustrates the preparation and results of the application of the catalyst in which palladium, gold and magnesium besieged on containing metallic copper media modified by immersion-rotation so that there was practically no mixing copper with other metals. It can be assumed that the copper on the carrier surrounded by other metals and not mixed with them. This, in turn, minimizes copper losses in the result of the escape.

The material of the carrier, the same as that described in comparative example A, in which the spherical particles had a nominal diameter of 7 mm were impregnated according to the method of capacity with an aqueous solution of three-hydrate of copper nitrate in an amount sufficient to introduce the catalyst approximately 1.9 g/l of elemental copper. Without drying the copper recorded on the medium by processing the media by the method of immersion-rotation aqueous solution of sodium hydroxide containing about 120% of the amount of sodium hydroxide required for the conversion of copper hydroxide copper (II). Media containing a fixed copper hydroxide, then washed with water until the absence of anions, dried at a temperature of 100oWith in the course is an increase of approximately 18 h, and the hydroxide of copper recovered to metallic copper in the vapor phase by contact with ethylene (5% in nitrogen) at a temperature of approximately 150oC for about 5 hours Then copper-containing media were treated to precipitate approximately 7 g/l of palladium and gold and about 0,53 g/l of magnesium, modified by immersion-rotation using the impregnation technique, fixation and recovery described in examples 7-12, and impregnated with potassium acetate as described in comparative example A. test the functional characteristics of the catalyst in the synthesis of vinyl acetate, as described in comparative example A, the composition of the reaction products showed that the selectivity to carbon dioxide and high-boiling products are scored 8.38 and 1.07%, respectively. Activity coefficient equal to 2.1.

Claims

1. The method of producing vinyl acetate by reaction of ethylene, oxygen and acetic acid, used as reagents, including contacting the above reactants with a catalyst containing a porous medium, the porous surfaces of which is deposited catalytically effective amounts of metallic palladium and gold, copper in the form of free metal in the form of its oxide or mixture of oxide and free metal, at a temperature of 150-220oC and pressure up to 20 ATM.

2. The method according to p. 1, wherein said fourth metal is magnesium.

3. The method according to p. 1, wherein said fourth metal is calcium.

4. The method according to p. 1, wherein said fourth metal is barium.

5. The method according to p. 1, wherein said fourth metal is zirconium.

6. The method according to p. 1, wherein said catalyst contains the acetate of an alkali metal deposited on the catalyst.

7. The method according to p. 6, wherein said alkali metal acetate is the acetate of potassium.

8. The method according to p. 7, in which the potassium acetate is fed to the reaction with these reagents.

 

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