Method for making catalyst for making vinyl acetate and method for making vinyl acetate

Abstract

Presented is a method for making a catalyst that can produce vinyl acetate with very high selectivity while ensuring high catalyst activity. A method for preparing a catalyst for the production of vinyl acetate comprising a carrier, copper, palladium, gold and acetate, the method comprising the following steps: Step 1) a step for impregnating the carrier with an alkaline solution; Step 2) a step for impregnating the carrier with a solution containing a copper-containing compound, a palladium-containing compound and a gold-containing compound; Step 3) a step for carrying out a reduction operation; and Step 4) a step for causing the carrier to carry acetate.

Description

Description Title Method for making catalyst for making vinyl acetate and method for making vinyl acetate Context

[0001] The present invention relates to a method for producing a vinyl acetate production catalyst used in the production of vinyl acetate using acetic acid, ethylene and oxygen as raw materials, as well as a method for producing vinyl acetate using such a catalyst. Background

[0002] Vinyl acetate is used as a raw material for vinyl acetate resins, a raw material for polyvinyl alcohol, and a monomer for copolymerization with ethylene, styrene, acrylates, and methacrylates in a wide range of fields such as paints, adhesives, and textile finishing agents, and is an important industrial material.

[0003] A palladium, gold, and potassium acetate catalyst supported on silica is widely used for the production of vinyl acetate using acetic acid, ethylene, and oxygen as raw materials. The active site in this reaction is considered to be palladium, and it is thought that gold, in addition to suppressing palladium aggregation, plays a role in reducing the production of carbon dioxide, which is a byproduct, thereby improving the selectivity of vinyl acetate. For this effect of gold to exist, gold atoms must be present in the vicinity of palladium. In Patent Reference 1, by devising a process for impregnating the carrier, palladium and gold are supported in a state in which their supported sites are in close proximity to each other.

[0004] In vinyl acetate production, increasing the selectivity of vinyl acetate is an important technical goal, and in terms of environmental impacts, suppressing carbon dioxide production is desirable.

[0005] In the patent source, the selectivity of vinyl acetate is improved by supporting copper in addition to palladium and gold. [Citation list] [Patent Resources]

[0006] [PTL 1] JP 2008-080326 A [PTL 2] JP 2002-516749 A Summary [Technical problem]

[0007] In Patent Reference 2, a palladium-containing compound, a gold-containing compound and a copper-containing compound are supported on a carrier in separate steps, and the effect of the copper-containing compound in the support step on the final states of metallic palladium and metallic gold is much less than that of the state supported in the same step. It is not known that a catalyst is produced by supporting a palladium-containing compound, a gold-containing compound and a copper-containing compound on a carrier in the same step, and the obtained catalyst is used, whereby the selectivity of vinyl acetate is improved.

[0008] An object of the present invention is to provide a method for producing a catalyst by which vinyl acetate can be produced with extremely high selectivity while ensuring high catalyst activity. [Problem Solution]

[0009] As a result of extensive research to solve the above problems, the present inventors have discovered a method for producing a catalyst in which, in addition to a palladium-containing compound and a gold-containing compound, a copper-containing compound is supported in the same step while reacting with an alkaline component, and have succeeded in producing vinyl acetate with an extremely high selectivity. Gold-containing compounds represented by chlorouric acid are generally slowly hydrolyzed and are supported on carriers at a slow rate. However, if a copper-containing compound is present simultaneously during the hydrolysis of a gold-containing compound, the copper-containing compound is rapidly hydrolyzed, whereby the copper-containing compound supported by the carrier absorbs the gold-containing compound in solution. As a result, the gold-containing compound remains in solution for a short time, whereby gold can be atomized compared to a case where the copper-containing compound is not added in the same step. Atomized gold significantly helps improve the selectivity of vinyl acetate.The catalyst produced by the method of supporting the copper-containing compound in a different step from the steps of supporting the palladium-containing compound and the gold-containing compound described in Patent Reference 2 did not exhibit exceptionally high selectivity, unlike the cases of the present invention.

[0010] Specifically, the present invention includes the following [1] to [6]. [1] A method for producing a vinyl acetate production catalyst comprising a carrier, copper, palladium, gold and an acetate, the method comprising the following steps, in order: Step 1: Soaking a carrier with an alkaline solution, Step 2: Contacting and impregnating the carrier with a solution containing a copper-containing compound, a palladium-containing compound, and a gold-containing compound, Step 3: Perform a resuscitation operation and Step 4: Acetate support on carrier. [2] The method according to [1] wherein a mass of supported metallic copper per kilogram of catalyst is 0.1 g or more and 1.6 g or less. [3] The method according to [1] or [2], wherein a mass of supported palladium metal per kilogram of catalyst is 8.0 g or more and 16.0 g or less. [4] The method according to any one of [1] to [3], wherein a mass of supported metallic gold per kilogram of catalyst is 4.0 g or more and 12.0 g or less. [5] The method according to any one of [1] to [4], wherein a mass of supported acetate per kilogram of catalyst is 40 g or more and 100 g or less. [6] A method for producing vinyl acetate using ethylene, oxygen and acetic acid as raw materials, wherein a vinyl acetate production catalyst obtained according to any one of [1] to [5] is used. [Beneficial effects of the invention]

[0011] According to the method of the present invention, a vinyl acetate production catalyst in which copper, palladium, and gold are supported on a carrier can be easily produced, and the selectivity of vinyl acetate can be significantly improved while ensuring high catalyst activity compared with conventional methods. Brief description of the maps

[0012] Figure 1 is a graph showing the relationship between the supported amount of copper and the selectivity of vinyl acetate in examples and comparative examples. Figure 2 is a graph showing the relationship between the supported amount of gold and the selectivity of vinyl acetate in the examples and comparative examples. Description of the visualizations

[0013] Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments only, and various changes can be made within the scope of the present invention.

[0014] [Method for producing catalyst for vinyl acetate production] A method for producing a vinyl acetate production catalyst according to one embodiment comprises the following steps in order: Step 1: Soaking a carrier with an alkaline solution, Step 2: Contacting and impregnating the carrier with a solution (hereinafter referred to as "solution A") containing a copper-containing compound, a palladium-containing compound, and a gold-containing compound, Step 3: Perform resuscitation and Step 4: Acetate support on the carrier.

[0015] In one embodiment, step 2 is performed after step 1 and the carrier is contacted and impregnated with solution A containing the copper-containing compound, the palladium-containing compound, and the gold-containing compound to form a catalyst precursor in which these compounds are supported on the carrier.

[0016] Although steps 1 to 4 are preferably performed in the order described above, other steps may be included to improve the performance of the catalyst. Solution A may include other components. Since the reduction operation of step 3 is to convert the copper-containing compound, the palladium-containing compound, and the gold-containing compound into metallic copper, metallic palladium, and metallic gold, respectively, it should be performed after step 2. Each step will be described in detail below.

[0017] <Step 1. Soaking the carrier with alkaline solution> In this step, the carrier is impregnated with an alkaline solution. This step can be performed at room temperature. After the impregnation operation is completed, the carrier may be dried or proceed to the next step without undergoing any drying or other operations.

[0018] The carrier is not particularly limited, and a porous material generally used as a carrier for catalysts can be used. The carrier is preferably silica, alumina, silica-alumina, diatomaceous earth, montmorillonite or titania, and is preferably silica. When a carrier containing silica is used as a main component, the silica content of the carrier is usually at least 50 mass%, and preferably at least 90 mass%, based on the mass of the carrier.

[0019] The specific surface area of ​​the carrier, measured by the BET method, is preferably at least 0.01 m2 / g, preferably in the range of 10-1000 m2 / g and particularly preferably in the range of 100-500 m2 / g. The bulk density of the carrier is preferably in the range of 50 to 1000 g / l and particularly preferably in the range of 300 to 500 g / l. The water absorption of the carrier is preferably in the range of 0.05 to 3 g water / g carrier and particularly preferably in the range of 0.1 to 2 g water / g carrier. With respect to the pore structure of the carrier, the average pore diameter is preferably in the range of 1 to 1000 nm and particularly preferably in the range of 2 to 800 nm. When the average pore diameter is 1 nm or more, gas diffusion can be facilitated. Conversely, when the average pore diameter is 1000 nm or less, the specific surface area of ​​the carrier can be ensured to obtain catalyst activity.

[0020] Mercury diffusion method and gas absorption method (BJH method) are widely used to measure the pore size distribution of carriers. According to the IUPAC (International Union of Pure and Applied Chemistry) pore classification, mercury diffusion method can measure macropores of 50 nm or more and mesopores of 2 nm to less than 50 nm, and gas absorption method can measure mesopores and micropores of 2 nm or less. The appropriate measurement method can be selected according to the pore diameter size.

[0021] In the present disclosure, carrier water absorption refers to a numerical value measured by the following measurement method. 1. Approximately 5 g of the carrier (W1 g) is weighed with a balance and placed in a 100 ml beaker. 2. Approximately 15 ml of pure water (ionized water) is added to the beaker to completely cover the carrier. 3. The beaker is allowed to stand for 30 minutes. 4. The contents of the beaker are placed on a wire mesh to drain the pure water. 5. Water adhering to the carrier surface is removed by gently pressing with a paper towel until the surface becomes matte. 6. The total mass of the carrier and pure water is measured (W2 g). 7. The carrier water absorption is calculated using the following formula: Water absorption (grams of water per gram of carrier) = (W2 - W1) / W1 Therefore, the amount of carrier water absorption (g) is calculated by multiplying the carrier water absorption rate (grams of water per gram of carrier) by the mass of carrier used (g).

[0022] The shape of the carrier is not limited. Specific examples include powder-like, spherical, and pellet-like, but the shape is not limited to these. The optimal shape can be selected according to the type of reaction and the reaction vessel used.

[0023] The size of the carrier particles is not particularly limited. When the carrier is spherical, the particle diameter thereof is preferably in the range of 1 to 10 mm, and more preferably in the range of 3 to 8 mm. In the case of gas phase reaction in a tubular reactor filled with a catalyst, when the particle diameter is 1 mm or more, excessive pressure increase during gas flow can be prevented, whereby the gas can be effectively circulated. On the contrary, when the particle diameter is 10 mm or less, the raw material gas can be easily diffused inside the catalyst, and thus the catalyst reaction can proceed effectively. In addition, since the number of catalyst particles accumulated in the tubular reactor is not excessively reduced, it is possible to ensure a sufficient total surface area of ​​the catalyst particles to provide amounts of metal components (copper, palladium, and gold) dispersed on the surface of the carrier suitable for the reaction.

[0024] As the alkaline solution, any alkaline compound can be used. Examples of the alkaline compound include alkali metal or alkaline earth metal hydroxides, alkali metal or alkaline earth metal bicarbonates, alkali metal or alkaline earth metal carbonates, and alkali metal or alkaline earth metal silicates. Lithium, sodium, or potassium can be used as the alkali metal. Barium or strontium can be used as the alkaline earth metal. Sodium metasilicate, potassium metasilicate, sodium hydroxide, potassium hydroxide, barium hydroxide, or strontium hydroxide are preferably used as the alkaline compound.

[0025] The solvent of the alkaline solution is not limited, examples thereof include water, methanol and ethanol, and water is preferred.

[0026] The excess alkali compound is used relative to the total copper, palladium and gold, as explained below. For example, the product of the molar amount of the alkali compound and the capacity of the alkali compound is preferably greater than 1.1 times and 3.0 times or less, and preferably greater than 1.5 times and 2.0 times or less, of the sum of the product of the molar amount of the palladium-containing compound and the palladium capacity, the product of the molar amount of the gold-containing compound and the gold capacity, and the product of the molar amount of the copper-containing compound and the copper capacity.

[0027] The method of impregnating the carrier with an alkaline solution is not limited. Examples thereof include (I) a method of immersing the carrier in a large amount of an alkaline solution for a period of time and then removing the carrier impregnated with the alkaline solution corresponding to the water absorption amount; and (II) a method of dissolving an alkaline compound in a solvent and diluting it to a level equivalent to the water absorption amount of the carrier and then impregnating the carrier with it. Method (II) is preferable in terms of waste liquid treatment.

[0028] The carrier is impregnated with an alkaline solution having an amount equivalent to, preferably 0.9 times or more and 1.0 times or less by weight of the water absorption amount of the carrier, and preferably 0.95 times or more and 1.0 times or less by weight of the water absorption amount of the carrier. When the amount of the alkaline solution is 0.9 times or more by weight of the water absorption amount of the carrier, uneven saturation of the alkaline solution occurs less. When the amount of the alkaline solution is 1.0 times or less by weight of the water absorption amount of the carrier, the entire amount of the alkaline solution can be reliably absorbed by the carrier. In the present disclosure, the water absorption amount of the carrier is an amount measured with pure water, which is significantly different from the amount of the alkaline solution, but is used for convenience.

[0029] <Step 2. Contacting and impregnating the carrier with solution A> In this step, the carrier impregnated with the alkaline solution is brought into contact with and impregnated with solution A. Solution A is a solution containing a copper-containing compound, a palladium-containing compound, and a gold-containing compound. Other components may be dissolved in solution A if required.

[0030] The raw material composition of each catalyst component in solution A is adjusted to obtain the desired catalyst composition. The concentration of the raw material composition of each catalyst component (copper, palladium, and gold) in solution A can be calculated from the amount of the raw material composition supported on the carrier and the amount of solution. In actual operation, the amount (grams) of the raw material composition supported on the carrier is weighed and dissolved in a solvent to obtain the desired amount of solution.

[0031] As the copper-containing compound in solution A, a copper precursor that can be converted into metallic copper can be used. Copper precursors that can be converted into metallic copper include, for example, copper chloride, copper acetate and copper nitrate, and copper chloride is preferably used.

[0032] As the palladium-containing compound in solution A, a palladium precursor that can be converted into palladium metal can be used. Examples of palladium precursors that can be converted into palladium metal include palladium chloride, palladium nitrate, palladium sulfate, sodium chloropalladate, potassium chloropalladate, barium chloropalladate, and palladium acetate, and sodium chloropalladate is preferably used.

[0033] As the gold-containing compound in solution A, a gold precursor that can be converted into metallic gold can be used. Examples of gold precursors include chlorouric acid, sodium chloroaurate, and potassium chloroaurate, and chlorouric acid is preferably used.

[0034] Examples of solvents for Solution A include water, alcohols, and organic acids. Water is preferred because it does not damage the carrier and does not react with the compounds in Solution A.

[0035] The amount of solution A is preferably 1.0 to 10.0 times, preferably 2.0 to 8.0 times, and particularly preferably 2.0 to 5.0 times the mass of the water absorption amount of the carrier.

[0036] By placing the carrier, which is impregnated with an alkaline solution, in contact with solution A, the metal compounds of the raw materials can be converted into water-insoluble materials to form a shell catalyst precursor in which metal components such as palladium, gold, and copper are unevenly distributed and deposited on the surface of the carrier.

[0037] The contact time is not particularly limited and is preferably 0.5 to 100 hours, and more preferably 3 to 50 hours. By setting the contact time to 0.5 hours or more, a desired amount of the catalyst component can be supported and sufficient catalyst performance can be obtained. By setting the contact time to 100 hours or less, the degradation of the carrier can be prevented.

[0038] The contact temperature is not limited and is preferably 10 to 80°C, and more preferably 20 to 60°C. By setting the contact temperature to 10°C or higher, the conversion reaction can proceed sufficiently. By setting the contact temperature to 80°C or lower, the accumulation of copper, palladium, and gold can be suppressed.

[0039] <Step 3. Resuscitation stage> It is desirable that the carrier containing the copper compound (copper chloride, etc.), the palladium compound (palladium salt, etc.) and the gold compound (chlorouric acid, etc.) are subjected to a reduction operation to convert the compounds into metallic palladium, metallic gold and metallic copper. In the present disclosure, the terms "metallic copper", "metallic palladium" and "metallic gold" refer to metal species with zero valence. The reduction operation can be by liquid phase reduction or gas phase reduction. All palladium, gold and copper may be reduced to the metallic state, i.e., zero valence, after the reduction operation.

[0040] Liquid phase reduction can be carried out in a non-aqueous system using alcohol or hydrocarbon or in an aqueous system. Examples of reducing agents that can be used include carboxylic acids and their salts, aldehydes, hydrogen peroxide, sugars, polyhydric phenols, boron compounds, amines and hydrazine. Examples of carboxylic acids and their salts include oxalic acid, potassium oxalate, formic acid, potassium formate, potassium citrate and ammonium citrate. Examples of aldehydes include formaldehyde and acetaldehyde. Examples of sugars include glucose. Examples of polyhydric phenols include hydroquinone. Examples of boron compounds include diborane and sodium borohydride. As the reducing agent, hydrazine, formaldehyde, acetaldehyde, hydroquinone, sodium borohydride and potassium citrate are preferred, and hydrazine is particularly preferred.

[0041] When liquid phase reduction is carried out, the temperature is not particularly limited, and the liquid phase temperature is preferably in the range of 0 to 200°C, and preferably in the range of 10 to 100°C. When the liquid phase temperature is 0°C or higher, a sufficient reduction rate can be obtained. Conversely, when the liquid phase temperature is 200°C or lower, the accumulation of copper, palladium and gold can be suppressed. The reduction time is not particularly limited, and the reduction time is preferably in the range of 0.5 to 24 hours, and preferably in the range of 1 to 10 hours. When the reduction time is 0.5 hours or more, the reduction can proceed sufficiently. Conversely, when the reduction time is 24 hours or less, the accumulation of copper, palladium and gold can be suppressed.

[0042] The reducing agent used for gas phase reduction can be selected from hydrogen gas, carbon monoxide, alcohols, aldehydes and olefins such as ethylene, propene and isobutene. The reducing agent is preferably hydrogen gas. In gas phase reduction, an inert gas may be added as a diluent. Examples of inert gases include helium, argon and nitrogen.

[0043] When gas phase reduction is carried out, the temperature is not particularly limited, and the impregnated carrier is preferably heated to a range of 30 to 350°C, and preferably in the range of 100 to 300°C. When the heating temperature is 30°C or higher, a sufficient reduction rate can be obtained. Conversely, when the heating temperature is 300°C or lower, the accumulation of copper, palladium and gold can be suppressed. The reduction time is not particularly limited, and the reduction time is preferably in the range of 0.5 to 24 hours, and preferably in the range of 1 to 10 hours. When the reduction time is 0.5 hours or more, the reduction can proceed sufficiently. Conversely, when the reduction time is 24 hours or less, the accumulation of copper, palladium and gold can be suppressed.

[0044] The gas phase regeneration pressure is not particularly limited and is preferably in the range of 0.0 to 3.0 MPaG (gauge pressure) and preferably in the range of 0.1 to 1.0 MPaG (gauge pressure) depending on the equipment.

[0045] The feed rate of the reducing agent when gas phase reduction is carried out is preferably in the range of space velocity (hereinafter referred to as SV) of 10 to 15,000 / h, and particularly preferably 100 to 8,000 / h under standard conditions.

[0046] The carrier that has undergone the regeneration process is washed with pure water, if necessary. The washing may be carried out continuously or in batches. The washing temperature is preferably in the range of 5 to 200°C, and more preferably in the range of 15 to 80°C. The washing time is not particularly limited, and conditions sufficient to remove residual undesirable impurities may be selected. For example, undesirable impurities include chlorine-containing compounds and chloride ions. After washing, the carrier may be dried by heating, if necessary.

[0047] <Step 4. Acetate support step in the carrier> Acetate can be supported by impregnating the carrier with a solution containing the required amount of acetate and drying. The amount of acetate solution used is preferably 0.9 to 1 times the mass of the water absorption amount of the carrier. Acetate support is usually carried out after the regeneration operation, but can also be carried out before the regeneration operation.

[0048] The acetate is preferably at least one compound selected from alkali metal acetates and alkaline earth metal acetates, and preferably alkali metal acetates. Examples of alkali metal acetates include lithium, sodium and potassium acetates. Sodium acetate and potassium acetate are preferred as acetates, and potassium acetate is particularly preferred.

[0049] [Catalyst for the production of vinyl acetate] The mass of supported copper metal per kilogram of catalyst (the sum of the mass of the carrier, the mass of the catalyst metal, the mass of acetate and the mass of other components) is preferably 0.1 g or more and 1.6 g or less, preferably 0.3 g or more and 1.4 g or less, and particularly preferably 0.6 g or more and 1.2 g or less.

[0050] The mass of supported palladium metal per kilogram of catalyst is preferably 8.0 g or more and 16.0 g or less, and preferably 10.0 g or more and 14.0 g or less.

[0051] The mass of supported metallic gold per kilogram of catalyst is preferably 4.0 g or more and 12.0 g or less, and preferably 5.0 g or more and 10.0 g or less.

[0052] The mass of supported acetate per kilogram of catalyst is preferably 40 grams or more and 100 grams or less, and preferably 50 grams or more and 70 grams or less.

[0053] The vinyl acetate production catalyst obtained by the method of the present disclosure has an eggshell structure in which a large portion of copper, palladium and gold is supported on the surface portion of the carrier. The thickness of the shell portion varies depending on the type of carrier, the alkaline solution and the mixed aqueous solution of the raw metal used. When spherical silica with a diameter of 5 mm is used as the carrier, the shell portion preferably has a thickness of 0.05 to 0.5 mm, and preferably 0.1 to 0.3 mm. When the thickness of the shell portion is 0.05 mm or more, the activity of the catalyst can be maintained even if the surface portion of the carrier is peeled off during the reaction. When the thickness of the shell portion is 0.5 mm or less, the catalyst concentration on the surface portion of the carrier can be sufficiently increased, so that the shell type support can bring economic benefits. Acetate does not require support in the form of a shell and may be present uniformly throughout the catalyst.

[0054] [Specific example of catalyst production] Specific examples of catalyst production are shown below. 1. The carrier is soaked in an alkaline solution in an amount proportional to the carrier's water absorption rate. 2. The carrier is immersed in solution A, which is obtained by diluting the metal compounds of the raw materials copper, palladium, and gold with pure water to twice the mass of the carrier's water absorption, to impregnate the carrier and form a catalyst precursor. 3. The reduction operation is carried out by adding a reducing agent to the dispersion containing the catalyst precursor obtained in step 2. 4. The catalyst precursor is washed with pure water after regeneration. 5. The washed catalyst precursor is dried. 6. A predetermined amount of acetate is placed on it. 7. The carrier is washed with the catalyst support.

[0055] [Vinyl acetate production] A method for producing vinyl acetate using a vinyl acetate production catalyst produced by the method of the present disclosure will be described below. The reaction for producing vinyl acetate uses acetic acid, ethylene and oxygen as reactants and is preferably carried out in the gas phase. The gas phase reaction may be in any conventional manner known and is preferably a fixed bed flow reaction.

[0056] The reaction formula is as follows. CH2CH2 + CH3COOH + 1 / 2O2  CH2CHOCOCH3 + H2O

[0057] The ratio of acetic acid, ethylene and oxygen in the raw material gas is preferably acetic acid:ethylene:oxygen = 1:0.08 to 16:0.01 to 4 as a molar ratio and preferably acetic acid:ethylene:oxygen is 1:0.2 to 9:0.07 to 2.

[0058] The feed gas contains ethylene, acetic acid (gas) and oxygen gas, and may contain nitrogen gas, carbon dioxide or a noble gas as a diluent if necessary. When ethylene, acetic acid and oxygen are defined as the reaction feed, the ratio of the reaction feed and the diluent is preferably a molar ratio of reaction feed:diluent = 1:0.05 to 9, and preferably reaction feed:diluent = 1:0.1 to 3.

[0059] When the reaction is carried out in a fixed bed flow reaction, the feed gas is preferably supplied to the reactor at a space velocity (SV) of 10 to 15,000 / h, and preferably 300 to 8,000 / h under standard conditions. By setting the space velocity to 10 / h or more, the heat of reaction can be removed appropriately. Conversely, by setting the space velocity to 15,000 / h or less, equipment such as a compressor can be of practical size.

[0060] Preferably, 0.5 to 20 mol%, and more preferably 1 to 18 mol%, of water is added to the feed gas in the form of water vapor. Although not being limited by theory, it is believed that the presence of water in the reaction system suppresses the removal of acetate from the catalyst. Since the addition of more than 20 mol% of water does not improve the effect described above and the hydrolysis of vinyl acetate may continue, it is not preferred that a large amount of water be present in the feed gas.

[0061] The reactor material is not limited and is preferably a material that is resistant to corrosion.

[0062] The reaction temperature is preferably in the range of 100 to 300°C, and more preferably in the range of 120 to 250°C. When the reaction temperature is 100°C or higher, a suitable reaction rate can be maintained. When the reaction temperature is 300°C or lower, the heat of reaction can be easily removed.

[0063] The reaction pressure is preferably in the range of 0 to 3 MPaG (gauge pressure), and more preferably in the range of 0.1 to 1.5 MPaG. When the reaction pressure is 0 MPaG or more, an appropriate reaction rate can be maintained. When the reaction pressure is 3 MPaG or less, it is not necessary to have equipment such as a reaction tube with high pressure resistance, whereby the cost of the equipment can be reduced.

[0064] Although it is preferred to use high-purity ethylene as the reaction feedstock, lower saturated hydrocarbons such as methane, ethane, and propane may be mixed in.

[0065] Oxygen gas is not particularly limited. Gas diluted with an inert gas such as nitrogen gas or carbon dioxide gas can be supplied, for example, in the form of air. When a reaction gas is circulated, high-concentration oxygen gas is usually used, and oxygen gas with a purity of 99% or higher is preferably used. Examples

[0066] The present invention will be further explained below through the following examples, but is not limited to these examples.

[0067] Example 1 - Preparation of Catalyst A A catalyst was prepared by the following method using a spherical silica support (sphere diameter: 5 mm, specific surface area: 155 m2 / g, water absorption: 0.85 g water / g support).

[0068] Step 1. 23.5 g of the carrier (water absorption value: 20.0 g) was soaked in an aqueous solution containing 2.3 g of Na2SiO3.9H2O and having an amount equivalent (0.95 times the mass) to the water absorption value of the carrier. The container containing the carrier and the aqueous solution was shaken until the solution was completely soaked and air-dried for 5 minutes. The water absorption value was calculated from the carrier amount of 23.5 g and the water absorption of 0.85 g water / g carrier (the same applies to the following examples and comparative examples).

[0069] Step 2. The carrier obtained in Step 1 was immersed in an aqueous solution containing 0.92 g Na2PdCl4, 0.28 g HAuCl4, and 0.04 g copper chloride dihydrate, having twice the mass of the carrier's water absorption, and was allowed to stand at room temperature for 20 hours.

[0070] Step 3. 1.9 g of 52 wt% aqueous hydrazine hydrate solution was added to the carrier dispersion obtained in Step 2, mixed gently and left at room temperature for 4 hours. In the next step, the palladium / gold / copper / carrier combination obtained in the previous step was washed with deionized water and the washing was continued until the water after washing was free of chloride ions. The washed palladium / gold / copper / carrier combination was dried at 110°C for 4 hours.

[0071] Step 4. The palladium / gold / copper / carrier combination was impregnated with an aqueous solution containing 1.7 g of potassium acetate and having an amount equivalent to 0.9 times the mass of the water absorption amount of the carrier and dried at 110°C for 4 hours to obtain Catalyst A.

[0072] Example 2 - Preparation of Catalyst B Catalyst B was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, the amount of copper chloride dihydrate used was changed to 0.07 g.

[0073] Example 3 - Preparation of catalyst C Catalyst C was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, the amount of copper chloride dihydrate used was changed to 0.09 g.

[0074] Example 4 - Preparation of Catalyst D Catalyst D was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, the amount of copper chloride dihydrate used was changed to 0.10 g.

[0075] Example 5 - Preparation of Catalyst E Catalyst E was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, the amount of copper chloride dihydrate used was changed to 0.11 g.

[0076] Example 6 - Preparation of Catalyst F Catalyst F was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, the amount of copper chloride dihydrate used was changed to 0.087 g and the amount of HAuCl4 used was changed to 0.20 g.

[0077] Example 7 - Preparation of Catalyst G Catalyst G was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, the amount of copper chloride dihydrate used was changed to 0.087 g and the amount of HAuCl4 used was changed to 0.27 g.

[0078] Comparative Example 1 - Preparation of H catalyst Catalyst H was obtained by repeating the procedure of Example 1, except that in Step 2, copper chloride dihydrate from Example 1 was not used.

[0079] Comparative Example 2 - Preparation of Catalyst I Catalyst I was obtained by repeating the operation of Example 1, except that in step 2 of Example 1, HAuCl4 was not used and the amount of copper chloride dihydrate used was changed to 0.14 g.

[0080] Comparative Example 3 - Preparation of Catalyst J Using a spherical silica carrier (sphere diameter: 5 mm, specific surface area: 155 m2 / g, water absorption: 0.85 g water / g carrier), a catalyst was prepared by the following method in accordance with the description of the examples of Patent Reference 2 (JP 2002-516749 A).

[0081] Step i. 23.5 g of the carrier (water absorption value: 20.0 g) was impregnated with an aqueous solution containing 0.32 g of Na2PdCl4 and 0.14 g of copper chloride dihydrate and having an amount equivalent (0.95 times the mass) to the water absorption value of the carrier. The container containing the carrier and the aqueous solution was shaken until the solution was completely impregnated.

[0082] Step ii. The carrier dispersion obtained in Step I was contacted with a mixed solution of 0.7 g of 50% by mass aqueous NaOH solution and 35.7 g of distilled water for 2.5 hours, and palladium and copper were immobilized on the carrier in the form of palladium (II) and copper hydroxide.

[0083] Step III. The palladium(II) / copper hydroxide / carrier combination obtained in the second step was washed with deionized water and the washing was continued until the water after washing was free of chloride ions. After washing with water, it was dried at 150°C under a nitrogen gas flow for 10 hours. Then, the reduction operation was carried out by contacting with ethylene (5 mol% in nitrogen gas) at 150°C for 5 hours in the gas phase. It was allowed to cool for 10 hours and washed with deionized water for 2 hours and then dried in an oven at 150°C for 5 hours.

[0084] Step iv. 0.2 g of gold hydroxide was mixed with 0.10 g of potassium hydroxide in 17 ml of water, the resulting orange suspension was heated to 85 °C and all solids were dissolved for 5 h to obtain a clear yellow solution of potassium urate. The yellow solution was added to the palladium / copper / support mixture obtained in step 3 and the support was allowed to soak in for 30 min. The mixture was then dried in an oven at 100 °C for 5 h under a stream of nitrogen gas. It was then reduced using ethylene (5 mol% in nitrogen gas) at 120 °C for 5 h to obtain free metallic gold on the support.

[0085] Step v. The palladium / gold / copper / support combination obtained in Step IV was impregnated with an aqueous solution containing 1.7 g of potassium acetate and an amount equivalent to 0.9 times the mass of the water absorption amount of the support and dried at 110°C for 4 hours to obtain Catalyst J.

[0086] Comparative Example 4 - Preparation of Catalyst K Catalyst K was obtained by repeating the operation of Example 1, except that copper chloride dihydrate was not used in Step 2 of Example 1, and Step 4 of Example 1 was changed so that 0.01 g of copper acetate monohydrate was dissolved together with 1.7 g of potassium acetate in water having an amount equivalent to 0.9 times the mass of the carrier water absorption amount.

[0087] [Catalyst Evaluation] <Measurement of metal (copper, palladium and gold) and potassium acetate support values> 3 g of the supported catalyst sample was powdered and pressed into a disk with an inner diameter of 3 cm. The metal contents in this disk were measured using a Philips PW2404 X-ray fluorescence spectrometer. For potassium acetate, the amount of potassium atoms was measured and converted to the amount of potassium acetate.

[0088] <Catalyst activity evaluation test> 6.7 mL of a catalyst was diluted with 75 mL of glass beads and filled into a reaction tube (made of SUS316L, inner diameter: 22 mm, length: 480 mm). Under the conditions of reaction temperature of 150 °C and reaction pressure of 0.6 MPaG, a gas with a gas composition of C2H4 / O2 / H2O / HOAc / N2= 45 / 6 / 5 / 23 / 21 (mol%) was flowed to stabilize the catalyst state at a flow rate of 66.7 NL / h for 240 h. After that, the gas flow rate was changed to 20.0 NL / h and the reaction temperature was also changed to 145 °C, 150 °C, 155 °C or 160 °C to evaluate the activity and selectivity of the catalyst. When the gas flow rate and reaction temperature were changed, the catalyst activity and selectivity were evaluated after the apparatus and catalyst conditions were stabilized for at least 4 h. In general, the higher the vinyl acetate (STY) activity (g / L-cath), the lower the vinyl acetate selectivity; therefore, the vinyl acetate selectivity at the same vinyl acetate activity was compared for each catalyst.For example, the vinyl acetate selectivity at a vinyl acetate activity of 550 (g / L-cath) was calculated by interpolation from a polynomial fitted curve consisting of plots of vinyl acetate activity and vinyl acetate selectivity at each reaction temperature.

[0089] The reactor exhaust gas was analyzed using the following method. 1. Oxygen Using the absolute calibration curve method, 50 mL of the exhaust gas was sampled and the entire amount was poured into a 1 mL gas sampler connected to a gas chromatography and analyzed under the following conditions. Gas chromatograph: Gas chromatograph (GC-14B manufactured by Shimadzu) with Shimadzu gas chromatography gas sampler (MGS-4: measuring tube: 1 ml) Column: Mesh MS-5A IS 60 / 80 (3 mm  3 m) Carrier gas: helium (flow rate: 20 ml / min) Temperature conditions: Detector temperature, evaporation chamber temperature: 110°C, column temperature: 70°C constant Detector: TCD (Helium pressure: 70 kPaG, current: 100 mA)

[0090] 2. Acetic acid Using the internal standard method, 1 mL of 4,1-dioxane was added as an internal standard to 10 mL of the reaction liquid, and 0.2 μL of it was injected as the analysis liquid and analyzed under the following conditions. Gas chromatograph: GC-14B, manufactured by Shimadzu. Column: Thermon-3000 packed column (length: 3 m, inner diameter: 0.3 mm) Carrier gas: Nitrogen (flow rate: 20 mL / min) Temperature conditions: detector temperature, evaporation chamber temperature: 180°C, column temperature: held at 50°C for 6 minutes from the start of analysis, then increased to 150°C at a rate of 10°C / min and held at 150°C for 10 minutes. Detector: FID (Hydrogen pressure: 40 kPaG, Air pressure: 100 kPaG)

[0091] 3. Vinyl acetate Using the internal standard method, 1 g of 4,1-dioxane was added as an internal standard to 6 g of the reaction solution, and 0.3 μL of it was injected as the analysis liquid and analyzed under the following conditions. Gas chromatograph: GC-9A manufactured by Shimadzu Column: TC-WAX capillary column (length: 30 m, inner diameter: 0.25 mm, membrane thickness: 0.5 μm) Carrier gas: Nitrogen (flow rate: 30 mL / min) Temperature conditions: Detector temperature, evaporation chamber temperature: 200°C, column temperature: 2 minutes from the start of analysis at 45°C, then increased to 130°C at a rate of 4°C / min and held at 130°C for 15 minutes. Then the temperature was increased to 200°C at a rate of 25°C / min and held at 200°C for 10 minutes. Detector: FID (Hydrogen pressure: 60 kPaG, Air pressure: 100 kPaG)

[0092] The results of the catalyst evaluation are shown in Table 1 and Figures 1 and 2. Note that in Figures 1 and 2, Comparative Examples 2, 3 and 4 are not plotted because their STYs were significantly low. The selectivity of vinyl acetate is based on ethylene.

[0093] [Table 1] Catalyst Example / Comparative Example Metal content in catalyst [g / kg] Vinyl acetate selectivity [%]1) Vinyl acetate activity [g / L-cath]2) Cu Pd Au Catalyst A Example 1 0.64 12.0 6.0 91.8 539 Catalyst B Example 2 0.86 11.6 5.6 92.1 525 Catalyst C Example 3 1.14 12.2 6.2 92.3 529 Catalyst D Example 4 1.32 11.8 6.2 91.9 492 Catalyst E Example 5 1.54 11.8 6.2 91.2 502 Catalyst F Example 6 1.32 12.2 7.4 93.8 534 Catalyst G Example 7 1.24 11.6 9.6 93.1 466 Catalyst H Comparative Example 1 0.00 12.2 6.0 90.9 546 Catalyst I Comparative Example 2 1.98 12.4 0.0 91.0 58 Catalyst J Comparative Example 3 1.12 12.0 6.2 90.5 358 Catalyst K Comparative Example 4 1.16 12.2 6.2 91.3 410 1) Values ​​at vinyl acetate activity (STY) [g / L-cath] 550 for catalysts A to H and due to the very low vinyl acetate activity, values ​​at reaction temperature of 150°C for catalysts I to K 2) Values ​​at reaction temperature of 150°C

[0094] By comparing Examples 1 to 7 with Comparative Example 1, with copper support, the vinyl acetate selectivity is improved by 0.3 to 2.9 units, which is a significant effect. Focusing on Examples 4 and 6, it can be seen that the vinyl acetate selectivity is further improved with increasing the amount of supported gold even with the same amount of supported copper. In Comparative Example 2, where gold was not supported and a combination of palladium and copper was supported, the vinyl acetate activity (g / L-cath) did not reach 550 even at a reaction temperature of 160°C, and the activity was very low. In Comparative Examples 3 and 4, catalysts to which the copper-containing compound was added at a different stage from the palladium-containing compound and the gold-containing compound were evaluated, and the vinyl acetate activity was clearly lower than in Examples 1 to 7 and the vinyl acetate selectivity was also lower than in all examples except Example 5.From the above, it can be understood that by using the preparation method of Examples 1 to 7 in which not only palladium, gold and copper are combined, but also the palladium-containing compound, the gold-containing compound and the copper-containing compound are supported during reaction with an alkali in the same step, it is possible to obtain an extremely high selectivity of vinyl acetate while ensuring high activity of vinyl acetate. From Examples 1 to 7, it can be shown that the amount of supported copper is preferably 0.1 to 1.6 g / kg and the amount of supported gold is preferably 4.0 to 12.0 g / kg. Industrial application

[0095] The present invention can provide a vinyl acetate production catalyst with excellent selectivity while ensuring high catalytic activity, and is industrially useful.

Claims

Amended Claims

1. A method for producing a vinyl acetate production catalyst comprising a carrier, copper, palladium, gold and acetate, the method comprising the following steps in order: Step 1: impregnating a carrier with an alkaline solution, Step 2: contacting and impregnating the carrier with a solution containing a copper-containing compound, a palladium-containing compound and a gold-containing compound, Step 3: performing a reduction operation, and Step 4: supporting acetate on the carrier, wherein a mass of supported copper metal per kilogram of catalyst is 0.1 g or more and 1.6 g or less, and a mass of supported gold metal per kilogram of catalyst is 4.0 g or more and 12.0 g or less.

2. The method according to claim 1, wherein a mass of supported palladium metal per kilogram of catalyst is 8.0 g or more and 16.0 g or less.

3. The method according to claim 1 or 2, wherein a mass of supported acetate per kilogram of catalyst is 40 grams or more and 100 grams or less.

4. A method for producing vinyl acetate using ethylene, oxygen and acetic acid as raw materials, wherein a vinyl acetate production catalyst obtained according to any one of claims 1 to 3 is used.

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