CN107614476B - Method for producing allyl acetate - Google Patents

Abstract

An object of the present disclosure is to suppress degradation of the catalyst after a long-term reaction when allyl acetate is produced by the reaction of oxygen, acetic acid, and propylene, and to prolong the life of the catalyst. In one embodiment of the present disclosure, a 4th period metal compound containing (a) palladium, (b) gold, (c) at least one element selected from the group consisting of copper, nickel, zinc and cobalt, (d) Propylene, oxygen, and acetic acid are supplied to a fixed-bed tubular reactor of an alkali metal salt compound and (e) a supported catalyst for producing allyl acetate as raw material gases, and allyl acetate is produced by a gas-phase catalytic oxidation reaction, and In the above production method, in the reaction tube of the fixed-bed tubular reactor, the loading amount of the (d) alkali metal salt compound on the (e) carrier decreases sequentially from the inlet side to the outlet side of the fixed-bed tubular reactor. Mode: Two or more catalyst layers containing the catalyst for the production of allyl acetate are arranged along the flow direction of the raw material gas, and (d) the amount of the alkali metal salt compound in the catalyst for the production of allyl acetate contained in each catalyst layer is Quantities vary.

Description

The production method of allyl acetate

technical field

The invention relates to a method for producing allyl acetate from propylene, oxygen and acetic acid by gas-phase catalytic oxidation.

Background technique

Allyl acetate is one of important industrial raw materials that can be used as a solvent, a raw material for production of allyl alcohol, and the like.

As a method for producing allyl acetate, there is a method using propylene, acetic acid and oxygen as raw materials, and using a gas phase reaction or a liquid phase reaction. As a catalyst used for this reaction, a catalyst in which palladium is used as a main catalyst component and an alkali metal and/or alkaline earth metal compound is used as a co-catalyst and these are supported on a carrier is well known and widely used. For example, Japanese Patent Laid-Open No. 2-91045 (Patent Document 1) discloses a method for producing allyl acetate using a catalyst in which palladium, potassium acetate, and copper are supported on a carrier.

Although the product is different from the case of allyl acetate, for example, Japanese Laid-Open Patent Publication No. 2003-525723 (Patent Document 2) discloses a method for producing a catalyst for producing vinyl acetate in which ethylene, oxygen and In the production of vinyl acetate using acetic acid as a starting material, palladium is supported in the first step, gold is supported in the second step, and reduction treatment is performed, and then copper (II) acetate and copper acetate (II) and copper acetate are supported in the third step. potassium acetate, thereby suppressing the formation of carbon dioxide.

In the vinyl acetate production process using the above-mentioned catalyst, a gas-phase reaction using a catalyst uniformly packed in a fixed-bed multi-tubular reactor is usually used in many cases. On the other hand, US Pat. No. 8,907,123 (Patent Document 3) also discloses a method in which catalysts with different activities are removed from the reaction tubes of the reactor in order to suppress the generation of hot spots in the catalyst layers in the reaction tubes. The inlet is distributed in layers toward the outlet, and it is filled so that the catalyst activity increases sequentially toward the outlet of the reaction tube.

In addition, in a normal vinyl acetate production process using the above-mentioned catalyst, if a long-time continuous reaction for several thousand hours is performed, potassium acetate gradually flows out of the reaction tube during the operation of the process, so it is necessary to convert the acetic acid The continuous supply of potassium to the catalyst is described in Japanese Patent Application Laid-Open No. 2-91045 (Patent Document 1) and in the commentary on "Catalysts and Catalysts" by Sirius (Commentary on "Catalysts and Economy"), Vol.35, No.7 (1993 ), pages 467 to 470 (Non-Patent Document 1).

In the allyl acetate production process, the reaction is carried out at a lower acetic acid concentration than in the vinyl acetate production process. For example, Japanese Patent Laid-Open No. 2-91045 (Patent Document 1) and International Publication No. 2009/142245 (Patent Document 4) describe that the ratio of acetic acid in the raw material gas is preferably 6 to 10% by volume. On the other hand, in the vinyl acetate production process, as described in, for example, JP 2003-212824 A (Patent Document 5), the ratio of acetic acid in the raw material gas is preferably 7 to 40% by volume.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2-91045

Patent Document 2: Japanese Patent Publication No. 2003-525723

Patent Document 3: Specification of US Patent No. 8907123

Patent Document 4: International Publication No. 2009/142245

Patent Document 5: Japanese Patent Laid-Open No. 2003-212824

Non-patent literature

Non-Patent Document 1: Explanation of "Catalysts and Suspension" by Siri (an exposition of the series "Catalysts and Economics"), Vol.35, No.7 (1993), pp. 467-470 Changes and Prospects of Vinyl Ester Process")

SUMMARY OF THE INVENTION

The problem to be solved by the invention

However, in the conventional method described in Patent Document 1, there is a problem that the catalyst on the outlet side of the reactor deteriorates remarkably quickly.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to suppress degradation of the catalyst when the reaction proceeds for a long time when allyl acetate is produced by the reaction of oxygen, acetic acid, and propylene, and to prolong the life of the catalyst.

methods for solving problems

The inventors of the present application have studied and found that the outflow rate of alkali metal salt compounds such as potassium acetate depends on the acetic acid concentration in the reactor; and the acetic acid concentration in the reaction at the outlet side of the reactor is significantly lower than that at the inlet side of the reactor Therefore, the supplied alkali metal salt compound is accumulated in the catalyst on the outlet side of the reactor, and the deterioration of the catalyst is remarkably accelerated. In addition, it was found that for the catalyst for the production of allyl acetate, in contrast to the catalyst for the production of vinyl acetate, the more the supported amount of the alkali metal salt compound on the carrier, the higher the initial activity of the catalyst, and the higher the initial activity of the catalyst, the higher the initial activity of the catalyst through the fixed bed tube. In the reaction tube of the type reactor, two or more catalyst layers with different amounts of the alkali metal salt compound are arranged along the reaction direction so that the supported amount of the alkali metal salt compound on the carrier is from the inlet side to the outlet side of the fixed bed tube type reactor. By sequentially decreasing, the concentration gradient of the alkali metal salt compound is reduced, and local catalyst deterioration is suppressed, and as a result, the performance of the catalyst can be effectively exhibited. It should be noted that there is also an example in Patent Document 3 in which the concentration of the alkali metal salt compound is set so as to decrease sequentially toward the outlet side of the fixed-bed tubular reactor in the catalyst for vinyl acetate production, but this is not the case. The purpose is to increase the catalyst activity toward the reaction tube outlet side, and the technical idea behind this is contrary to the technical idea of the present invention for suppressing catalyst degradation on the reaction tube outlet side and achieving a longer catalyst life.

That is, the present invention relates to the following [1] to [8].

[1]

A method for producing allyl acetate, comprising filling a fourth element containing (a) palladium, (b) gold, and (c) at least one element selected from the group consisting of copper, nickel, zinc, and cobalt. A fixed-bed tubular reactor of a periodic metal compound, (d) an alkali metal salt compound, and (e) a supported catalyst for the production of allyl acetate supplies propylene, oxygen, and acetic acid as raw materials, and produces vinyl acetate by a gas-phase catalytic oxidation reaction Propyl ester, in the above-mentioned production method, in the reaction tube of the fixed-bed tubular reactor, the amount of the (d) alkali metal salt compound supported on the (e) carrier is removed from the fixed-bed tubular reactor. Two or more catalyst layers containing the catalyst for producing allyl acetate are arranged along the flow direction of the raw material gas in such a manner that the inlet side gradually decreases toward the outlet side, and among the catalysts for producing allyl acetate contained in each catalyst layer (d) The amount of the alkali metal salt compound is different.

[2]

The method for producing allyl acetate according to [1], wherein the supported amount of the (d) alkali metal salt compound per 1 g of the (e) carrier in the catalyst layer on the most inlet side of the reaction tube (g) is 1.2 to 3.0 times the supported amount (g) of the (d) alkali metal salt compound per 1 g of the (e) carrier in the catalyst layer on the most outlet side.

[3]

The method for producing allyl acetate according to [1] or [2], wherein the reaction tube is a straight tube, the catalyst layer is two layers, and the catalyst layer on the inlet side of the reaction tube and the outlet The ratio of the length of the catalyst layer on the side in the flow direction of the raw material gas is 4:1 to 1:4.

[4]

The method for producing allyl acetate according to any one of [1] to [3], wherein the fixed-bed tubular reactor is a multi-tubular type.

[5]

The method for producing allyl acetate according to any one of [1] to [4], wherein the (d) alkali metal salt compound is at least one selected from the group consisting of potassium acetate, sodium acetate, and cesium acetate.

[6]

The method for producing allyl acetate according to any one of [1] to [5], wherein the (c) fourth-period metal compound is a compound having copper or zinc.

[7]

The method for producing allyl acetate according to any one of [1] to [6], wherein the (c) fourth-period metal compound is copper acetate.

[8]

The method for producing allyl acetate according to any one of [1] to [7], wherein in all the layers of the catalyst layer, the catalyst for producing allyl acetate (a) palladium, The mass ratios of (b) gold, (c) the 4th period metal compound and (d) the alkali metal salt compound are all (a):(b):(c):(d)=1:0.00125～22.5:0.02～ 90: 0.2 to 450.

Invention effect

According to the production method of allyl acetate of the present invention, the catalyst life is extended. As a result, by using this manufacturing method, the manufacturing cost of allyl acetate can be reduced, and allyl acetate can be manufactured efficiently.

Description of drawings

FIG. 1A is a schematic view showing the filling position of the catalyst of Example 1. FIG.

FIG. 1B is a schematic diagram showing the filling position of the catalyst of Comparative Example 1. FIG.

FIG. 1C is a schematic diagram showing the filling position of the catalyst of Comparative Example 2. FIG.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments, and it is expected that various applications can be made within the spirit and scope of the embodiments.

In the present invention, in the reaction tube of the fixed-bed tubular reactor, two or more catalyst layers containing the catalyst for producing allyl acetate are arranged along the flow direction (reaction direction) of the raw material gas such that the alkali metal salt compound is supported on the carrier The loading amount on the fixed-bed tubular reactor decreases sequentially from the inlet side to the outlet side of the fixed-bed tubular reactor, wherein the amount of the alkali metal salt compound in the catalyst for producing allyl acetate contained in each catalyst layer is different.

<Catalyst>

The catalyst for producing allyl acetate used in the present invention contains the following components: (a) palladium, (b) gold, (c) a fourth element having at least one element selected from copper, nickel, zinc, and cobalt Periodic metal compound, (d) alkali metal salt compound and (e) carrier. Hereinafter, these components will be described.

(a) Palladium

In the present invention, (a) palladium may have any valence, but is preferably metal palladium. The "metal palladium" in the present invention refers to palladium having a valence of zero. Metal palladium can usually be obtained by reducing divalent and/or tetravalent palladium ions with hydrazine, hydrogen, or the like as a reducing agent. In this case, it may be that not all of the palladium is in the metallic state.

The raw material of palladium is not particularly limited, and metal palladium or a palladium precursor capable of being converted into metal palladium can be used. Examples of the palladium precursor include palladium chloride, palladium nitrate, palladium sulfate, sodium chloropalladate, potassium chloropalladate, barium chloropalladate, and palladium acetate. Preference is given to using sodium chloropalladate. As the palladium precursor, a single compound may be used, or a plurality of compounds may be used in combination.

The mass ratio of (a) palladium to (e) carrier in the catalyst for producing allyl acetate is preferably (a):(e)=1:10 to 1:1000, more preferably (a):(e)= 1:20～1:500. This ratio is defined as the ratio of the mass of the palladium element to the mass of the carrier.

(b) Gold

In the present invention, the (b) gold is supported on the carrier in the form of a compound containing a gold element, but it is preferable that substantially all of the gold is finally metallic gold. The "metallic gold" in the present invention refers to gold having a valence of zero. Metallic gold can be generally obtained by reducing monovalent and/or trivalent gold ions using hydrazine, hydrogen, or the like as a reducing agent. In this case, it may be that not all gold is in a metallic state.

The raw material of gold is not particularly limited, and metallic gold or a gold precursor capable of being converted into metallic gold can be used. Examples of the gold precursor include chloroauric acid, sodium chloroaurate, potassium chloroaurate, and the like. Preference is given to using chloroauric acid or sodium chloroauric acid. As the gold precursor, a single compound may be used, or a plurality of compounds may be used in combination.

The mass ratio of (b) gold to (e) carrier in the catalyst for producing allyl acetate is preferably (b):(e)=1:40 to 1:65000, more preferably (b):(e)= 1:550 to 1:32000, more preferably (b):(e)=1:750 to 1:10000. This ratio is defined as the ratio of the mass of the gold element to the mass of the carrier.

The amount of (b) gold in the catalyst for allyl acetate production is preferably 0.125 to 2250 parts by mass, more preferably 0.25 to 14 parts by mass, and even more preferably 0.8 to 10 parts by mass with respect to 100 parts by mass of palladium. The parts by mass of gold and palladium are based on the mass of the respective element. By setting such an amount of gold, the activity maintenance of the catalyst in the allyl acetate production reaction and the allyl acetate selectivity can be obtained in a balanced manner.

(c) Fourth-period metal compound having at least one element selected from copper, nickel, zinc, and cobalt

In the present invention, (c) soluble salts such as nitrates, carbonates, sulfates, organic acid salts, and halides of at least one element selected from the group consisting of copper, nickel, zinc, and cobalt can be used as the fourth-period metal compound. . The fourth-period metal compound is preferably a compound having copper or zinc from the viewpoint that the catalyst activity can be further improved. As an organic acid salt, acetate etc. are mentioned. Generally, readily available and water-soluble compounds are preferred. Preferable compounds include copper nitrate, copper acetate, nickel nitrate, nickel acetate, zinc nitrate, zinc acetate, cobalt nitrate, cobalt acetate, and the like. Among them, copper acetate is most preferable from the viewpoints of stability of raw materials and availability. As the fourth period metal compound, a single compound may be used, or a plurality of compounds may be used in combination.

The mass ratio of (c) the fourth-period metal compound to (e) the carrier in the catalyst for producing allyl acetate is preferably (c):(e)=1:10 to 1:500, more preferably (c): (e) = 1:20 to 1:400. This ratio is defined as the ratio of the total mass of copper, nickel, zinc and cobalt elements to the mass of the carrier.

(d) Alkali metal salt compound

In the present invention, as the (d) alkali metal salt compound, hydroxides, acetates, nitrates, bicarbonates and the like of lithium, sodium, potassium, rubidium, cesium and the like can be used. Preferred are potassium acetate, sodium acetate and cesium acetate, more preferably potassium acetate and cesium acetate. As the alkali metal salt compound, a single compound may be used, or a plurality of compounds may be used in combination.

The mass ratio of the (d) alkali metal salt compound to the (e) carrier in the catalyst for producing allyl acetate is preferably (d):(e)=1:2 to 1:50, more preferably (d):( e)=1:3 to 1:40. This ratio is defined as the ratio of the mass of the alkali metal salt compound to the mass of the support.

(e) Carrier

The (e) carrier used in the present invention is not particularly limited, and a porous material generally used as a catalyst carrier can be used. Examples of preferred supports can be exemplified by silica, alumina, silica-alumina, diatomaceous earth, montmorillonite, titania and zirconia. More preferably silica is used. When a substance containing silica as a main component is used as the carrier, the content of silica in the carrier is preferably at least 50% by mass, more preferably at least 90% by mass, based on the mass of the carrier.

The carrier preferably has a specific surface area measured by the BET method in the range of 10 to 1000 m ² /g, particularly preferably in the range of 100 to 500 m ² /g. The bulk density of the carrier is preferably in the range of 50 to 1000 g/L, particularly preferably in the range of 300 to 500 g/L. The water absorption rate of the carrier is preferably in the range of 0.05 to 3 g/g, and particularly preferably in the range of 0.1 to 2 g/g. Regarding the pore structure of the carrier, the average pore diameter is preferably in the range of 1 to 1000 nm, particularly preferably in the range of 2 to 800 nm. When the average pore diameter is less than 1 nm, gas diffusion may be difficult in some cases. On the other hand, if the pore diameter is larger than 1000 nm, the specific surface area of the carrier is too small, and the catalyst activity may decrease.

The water absorption rate of the carrier in the present invention refers to a value measured in the following order.

1. Precisely weigh about 5g of carrier with a balance and put it into a 100cc beaker. Let the mass at this time be w ₁ .

2. About 15 mL of pure water (ion-exchanged water) was added to the beaker to completely cover the carrier.

3. Set aside for 30 minutes.

4. Remove the upper clarified pure water from the carrier.

5. Gently press to remove the water adhering to the surface of the carrier with a paper towel, etc., until the surface is not shiny.

6. Precisely weigh the total mass of the carrier and pure water. Let the mass at this time be w ₂ .

7. Calculate the water absorption of the carrier from the following formula.

Water absorption (g/g-carrier)=(w ₂ -w ₁ )/w ₁

Therefore, the water absorption amount (g) of the carrier is calculated by the water absorption rate of the carrier (g/g-carrier)×the mass (g) of the carrier used.

The shape of the carrier is not particularly limited. Specifically, powder, spherical, granular, etc. are mentioned, but it is not limited to these. The most suitable shape can be selected according to the reaction form, reactor, etc. to be used.

The particle size of the carrier is also 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 2 to 8 mm. If the particle diameter is less than 1 mm when gas-phase reaction is performed by filling the catalyst in the tubular reactor, a large pressure loss occurs when the gas is circulated, and there is a possibility that efficient gas circulation cannot be performed. On the other hand, when the particle diameter is larger than 10 mm, the reaction gas is not easily diffused into the catalyst, and there is a possibility that the catalytic reaction cannot be efficiently performed.

(f) Alkaline solution

The (f) alkaline solution used in step 2 of the catalyst production step described below is not particularly limited, and any alkaline solution can be used. Examples of the raw material of the alkaline solution include alkali metal or alkaline earth metal hydroxides, alkali metal or alkaline earth metal bicarbonates, alkali metal or alkaline earth metal carbonates, alkali metal or alkaline earth metal silicates and the like. compound. The alkali metals are preferably lithium, sodium, and potassium, and the alkaline earth metals are preferably barium and strontium. Particularly preferable basic compounds include sodium metasilicate, potassium metasilicate, sodium hydroxide, potassium hydroxide, barium hydroxide, and the like. Part or all of the palladium compound and part or all of the gold compound can be converted into oxides or hydroxides by contacting with an alkaline solution.

The basic compound is appropriately used in excess on a molar equivalent basis relative to the total of (a) palladium and (b) gold. For example, the amount of the basic compound to be used is preferably 1 to 3 moles, more preferably 1.2 to 2.5 moles per mole of (a) palladium, and preferably 2 to 10 moles per mole of (b) gold. mole, more preferably a total of 3 to 8 moles.

The solvent used to form the alkaline solution is not particularly limited, and water, methanol, ethanol, and the like can be cited as preferred examples.

<Catalyst manufacturing process>

The production process of the catalyst is not particularly limited as long as each component of the above-mentioned (a) to (d) can be supported on the carrier (e), but the production is preferably carried out in the following steps.

Step 1. A step of preparing a homogeneous solution containing a palladium raw material and a gold raw material, and contact-impregnating the obtained homogeneous solution with the (e) carrier to support the above-mentioned palladium raw material and gold raw material on the carrier

Step 2. The step of contacting and impregnating the carrier obtained in the step 1 with the alkaline solution (f)

step 3. a step of subjecting the carrier obtained in step 2 to a reduction treatment, and

Step 4. Step of supporting (c) the fourth-period metal compound and (d) the alkali metal salt compound on the carrier obtained in Step 3

Next, each step will be described.

Process 1

In this step, a homogeneous solution containing a palladium raw material (metal palladium or a precursor thereof) and a gold raw material (metal gold or a precursor thereof) is prepared, and the obtained homogeneous solution is contact-impregnated into a carrier to carry out the support of these raw materials . The supported state of these raw materials on the carrier is preferably a so-called "egg shell type". In this case, the method for supporting the homogeneous solution containing the palladium raw material and the gold raw material on the carrier is not particularly limited as long as it is a method that results in an eggshell-type supported catalyst. The eggshell-type supported catalyst is related to the distribution state of the active ingredient (eg metal palladium) in the carrier particle or the shaped body, and refers to a supported catalyst in which most of the active ingredient is present on the outer surface of the carrier particle or shaped body. Specific examples of the method for producing an eggshell-type supported catalyst include dissolving the raw material in a suitable solvent such as water and acetone, or in an inorganic or organic acid such as hydrochloric acid, nitric acid, or acetic acid, or in a solution thereof, directly or indirectly. A method of supporting it on the surface layer of a carrier, and the like. As a method of directly supporting it, an impregnation method and a spraying method can be mentioned. As a method of indirectly supporting it, as described later, a uniform solution containing a palladium raw material and a gold raw material is uniformly supported on the carrier (step 1), and then impregnated by contact with the (f) alkaline solution ( Step 2), a method of moving the palladium raw material and the gold raw material inside to the surface, and then performing reduction (step 3), etc.

The support of the palladium raw material and the gold raw material on the carrier can be carried out by preparing a homogeneous solution containing the palladium raw material and the gold raw material, and contacting and impregnating the solution with an appropriate amount of the carrier. More specifically, a homogeneous solution is prepared by dissolving the palladium raw material and the gold raw material in a suitable solvent such as water and acetone, or an inorganic or organic acid such as hydrochloric acid, nitric acid, and acetic acid, or a solution thereof, and the obtained homogeneous solution is brought into contact with each other. The carrier is impregnated to obtain an impregnated carrier (A). Drying may be performed after impregnation, but it is preferable to proceed to step 2 by omitting the drying step, and thus the step can be omitted.

Process 2

This step is a step of contact-impregnating the impregnated carrier (A) obtained in the step 1 with the alkaline solution (f) to obtain the impregnated carrier (B). The alkaline substance used in the step 2 may be used as it is if it is a liquid, but it is preferably supplied in the form of a solution. The alkaline solution is preferably a solution of water and/or alcohol. The contact conditions of the impregnated carrier (A) and the alkaline solution are not particularly limited, but the contact time is preferably in the range of 0.5 to 100 hours, and more preferably in the range of 3 to 50 hours. If it is less than 0.5 hours, sufficient performance may not be obtained, while if it exceeds 100 hours, the carrier may be damaged.

The contact temperature is not particularly limited, but is preferably in the range of 10 to 80°C, and more preferably in the range of 20 to 60°C. When the contact is performed at a temperature lower than 10°C, there is a possibility that a sufficient switching speed cannot be obtained. On the other hand, when it exceeds 80 degreeC, there exists a possibility that aggregation of palladium or gold may be accelerated|stimulated.

Process 3

This step is a step of subjecting the impregnated carrier (B) obtained in the step 2 to a reduction treatment. The reduction method may use either liquid-phase reduction and gas-phase reduction. The metal-supported carrier obtained in this step was used as a metal-supported carrier (C).

The liquid-phase reduction can be performed in either a non-aqueous type or an aqueous type using alcohol or hydrocarbons. As the reducing agent, carboxylic acid and its salt, aldehyde, hydrogen peroxide, saccharide, polyhydric phenol, boron compound, amine, hydrazine and the like can be used. Examples of the carboxylic acid and its salt include oxalic acid, potassium oxalate, formic acid, potassium formate, potassium citrate, ammonium citrate, and the like. Examples of the aldehyde include formaldehyde, acetaldehyde, and the like. Glucose etc. are mentioned as a saccharide. Hydroquinone etc. are mentioned as an example of a polyhydric phenol. Examples of the boron compound include diborane, sodium borohydride, and the like. Among them, hydrazine, formaldehyde, acetaldehyde, hydroquinone, sodium borohydride, or potassium citrate is preferably used, and hydrazine is more preferably used.

When liquid phase reduction is performed, the temperature is not particularly limited, but the liquid phase temperature is preferably set in the range of 0 to 200°C, and more preferably in the range of 10 to 100°C. If the temperature is lower than 0°C, a sufficient reduction rate may not be obtained, and on the other hand, if it exceeds 200°C, aggregation of palladium or gold may occur. The reduction time is not particularly limited, but the reduction time is preferably in the range of 0.5 to 24 hours, and more preferably in the range of 1 to 10 hours. If it is less than 0.5 hours, the reduction may not proceed sufficiently, while if it exceeds 24 hours, aggregation of palladium or gold may occur.

The reducing agent used for the gas phase reduction is selected from, for example, hydrogen, carbon monoxide, alcohols, aldehydes, ethylene, propylene, isobutylene and other olefins, and the like. Preference is given to using hydrogen or propylene as reducing agent.

When the gas phase reduction is performed, the temperature is not particularly limited, but the impregnated carrier (B) is preferably heated in the range of 30 to 350°C, more preferably in the range of 100 to 300°C. When the temperature is lower than 30°C, a sufficient reduction rate may not be obtained, and on the other hand, if it exceeds 300°C, aggregation of palladium or gold may occur. The reduction time is not particularly limited, but the reduction time is preferably in the range of 0.5 to 24 hours, and more preferably in the range of 1 to 10 hours. If it is less than 0.5 hours, there is a possibility that reduction cannot be sufficiently performed. On the other hand, if it exceeds 24 hours, aggregation of palladium or gold may occur.

The processing pressure for gas phase reduction is not particularly limited, but from the viewpoint of equipment, it is preferably in the range of 0.0 to 3.0 MPaG (gauge pressure), and more preferably in the range of 0.1 to 1.0 MPaG (gauge pressure).

The supply of the reducing agent during gas phase reduction is preferably performed in the range of 10 to 15,000 h ⁻¹ , and particularly preferably in the range of 100 to 8000 h ⁻¹ , in a standard state with a space velocity (hereinafter referred to as SV).

The gas phase reduction can be carried out at various reducing substance concentrations, and an inert gas can also be added as a diluent as required. Examples of the inert gas include helium, argon, nitrogen, and the like. It is also possible to perform reduction in the presence of hydrogen gas, propylene, and the like in the presence of water that has been vaporized.

The catalyst before the reduction treatment may be filled in a reactor, reduced with propylene, and then oxygen gas and acetic acid may be introduced to produce allyl acetate.

The reduced carrier can also be washed with water as needed. Washing can be carried out in a flow-through mode or in a batch mode. The cleaning temperature is preferably in the range of 5 to 200°C, and more preferably in the range of 15 to 80°C. The cleaning time is not particularly limited. It is preferable to select conditions sufficient to remove the remaining unpreferable impurities. Unpreferable impurities include, for example, sodium, chlorine, and the like. After washing, heating and drying can also be performed as needed.

Process 4

This step is a step of supporting (c) the fourth-period metal compound and (d) the alkali metal salt compound on the metal-supported carrier (C) obtained in the step 3.

By contacting and impregnating the metal-supported carrier (C) with a solution containing necessary amounts of (c) the fourth-period metal compound and (d) the alkali metal salt compound, the mass of which is 0.9 to 1.0 times the water absorption capacity of the carrier Dry to support each compound. The solvent at this time is not particularly limited. Various solvents that can dissolve the alkali metal salt compound used in a solution having a mass of 0.9 to 1.0 times the water absorption capacity of the carrier can be used. The solvent is preferably water. In the present invention, the supported amount of the alkali metal salt compound can be adjusted by changing the concentration of this solution. The drying temperature and time are not particularly limited.

<Catalyst composition>

The mass ratio of (a), (b), (c) and (d) is preferably (a):(b):(c):(d)=1:0.00125-22.5:0.02-90:0.2-450, More preferably (a):(b):(c):(d)=1:0.0025-0.14:0.04-50:0.4-250, particularly preferably (a):(b):(c):(d ) = 1: 0.008 to 0.1: 0.04 to 50: 0.4 to 250. It is preferable that all catalyst layers satisfy the above-mentioned mass ratio. For (a), (b) and (c), it is based on the mass of the constituent elements, and for (d), it is based on the mass of the alkali metal salt compound.

The supported amount and composition ratio of the metal element contained in the catalyst for producing allyl acetate can be determined by a high-frequency inductively coupled plasma luminescence analyzer (hereinafter abbreviated as "ICP"), fluorescent X-ray analysis (hereinafter abbreviated as "XRF") ), atomic absorption spectrometry and other chemical analysis.

As an example of the measurement method, the following method can be mentioned: a predetermined amount of the catalyst is pulverized with a mortar or the like to obtain a uniform powder, and then the powdered catalyst is added to an acid such as hydrofluoric acid and aqua regia, and heated and stirred. This solution was dissolved to prepare a homogeneous solution. Next, the solution was diluted to an appropriate concentration with pure water, and the solution was quantitatively analyzed by ICP.

<Fixed Bed Tubular Reactor>

The "fixed bed tubular reactor" in the present invention is formed by filling a tubular reaction tube with a catalyst (a catalyst supported on a carrier) as a fixed bed. The reaction substrate is supplied to the reaction tube in the gas phase, and the reaction product is discharged from the outlet of the reaction tube. From the viewpoints of manufacture and maintenance of equipment, workability at the time of catalyst filling and replacement, removal of reaction heat, and the like, the tubular reaction tube is preferably a straight tube type. From the viewpoint of operability for filling and taking out the catalyst, the reaction tube is preferably installed in the vertical direction (vertical type). Since the gas-phase catalytic oxidation reaction of the present invention is an exothermic reaction, a system that removes reaction heat from the outside of the reaction tube is generally used. The inner diameter, outer diameter, length and material of the reaction tube, reaction heat removal equipment, reaction heat removal method, etc. are not particularly limited, but in consideration of the heat exchange area related to reaction heat removal and the pressure loss inside the reaction tube, the The inner diameter is preferably 10 to 50 mm, and the length is preferably 1 to 6 m. There is a limit to increasing the inner diameter of one reaction tube in order to remove the heat of reaction, and therefore, the reactor may be set to a multi-tube type. In an industrial manufacturing facility, throughput can be secured by setting the number of reaction tubes to several hundreds to several thousands. The reaction tube is not limited as long as it is made of a material having corrosion resistance and heat resistance. The material of the reaction tube includes, for example, SUS raw material, especially SUS316L.

Conventionally, the same catalyst was uniformly packed in the reactor, but in the present invention, the catalyst is mixed with (d) an alkali metal salt compound from the inlet side to the outlet side of the fixed-bed tubular reactor. The loadings are filled in a manner that decreases sequentially. That is, the catalyst layers having different supporting amounts of the alkali metal salt compounds are filled in the reaction tube in multiple layers so that the supporting amounts of the alkali metal salt compounds gradually decrease along the flow direction of the raw material gas. The number of catalyst layers may be two or more, or three or more. The supported amount of the alkali metal salt compound may be continuously decreased (gradually). From the viewpoint of the workability of catalyst filling in an actual factory, the number of catalyst layers is preferably two or three, and even two layers are sufficient to achieve the object of the present invention.

When the catalyst layers having different supported amounts of the (d) alkali metal salt compounds are filled in a reaction tube in multiple layers such that the supported amounts of the alkali metal salt compounds are sequentially decreased, the amount of alkali metal salt compound per 1 g of the (e) support is What is necessary is just to sequentially fill the catalyst with a smaller supported amount (g) of the metal salt compound so that the outlet side is filled. The supported amount (g) of the alkali metal salt compound in the catalyst layer on the most inlet side of the reaction tube per 1 g of the carrier is preferably the supporting amount (g) of the alkali metal salt compound in the catalyst layer on the most outlet side per 1 g of the carrier. The loading amount (g) is 1.2 to 3.0 times, more preferably 1.3 to 2.4 times, and still more preferably 1.3 to 2.1 times. The effect of the present invention can be enhanced by setting the above-mentioned loading amount ratio to 1.2 times or more, and on the other hand, by setting it to 3.0 times or less, deterioration of the catalyst can be suppressed.

The supported amount ratio of the (d) alkali metal salt compound in the catalyst layer is the ratio at the start of the reaction. The amount of the alkali metal salt compound in each catalyst layer changes during a long reaction period of hundreds to thousands of hours. In the case of a vertical reaction tube, the alkali metal salt compound in the upper (inlet side) catalyst layer may move to the lower (outlet side) catalyst layer, and may be gradually discharged from the reaction tube. In this case, it is preferable to supply the effluent portion of the alkali metal salt compound to the reactor.

(d) The supported amount of the components other than the alkali metal salt compound is usually the same in all the catalyst layers, but may be changed so as to improve the overall reaction efficiency.

When the catalyst layers are two, the ratio of the lengths of the catalyst layers is preferably reactor inlet side: outlet side=4:1 to 1:4, more preferably reactor inlet side: outlet side=3:2 to 1: 4, particularly preferably 3:2 to 2:3.

<Production of allyl acetate>

The reaction for producing allyl acetate is preferably carried out in the gas phase using propylene, oxygen and acetic acid as raw materials. It is preferable to employ a fixed-bed flow reaction in which the above-mentioned catalyst is filled in a reaction tube having corrosion resistance, which is practically advantageous. The reaction formula is shown below.

CH ₂ =CHCH ₃ +CH ₃ COOH+1/2O ₂ →

CH ₂ =CHCH ₂ OCOCH ₃ +H ₂ O

The raw material gas contains propylene, oxygen, and acetic acid, and as a diluent, nitrogen, carbon dioxide, rare gas, or the like can be used as necessary.

The raw material gas preferably has a composition in the range of acetic acid:propylene:oxygen=1:1 to 12:0.5 to 2 in terms of molar ratio.

In the reaction for producing allyl acetate, if water is allowed to exist in the reaction system, it is remarkably effective for the allyl acetate production activity of the catalyst and its maintenance. The water vapor is preferably present in the range of 0.5 to 25 vol % in the gas supplied to the reaction.

In the gas supplied to the reaction, it is preferable to use high-purity propylene, but lower saturated hydrocarbons such as methane, ethane, and propane may be mixed. Oxygen can also be supplied in a form diluted with an inert gas such as nitrogen and carbon dioxide gas, for example, in the form of air. When circulating the reaction gas, it is usually advantageous to use oxygen at a high concentration, preferably 99% by volume or more. .

The reaction temperature is not particularly limited. The range of 100-300 degreeC is preferable, and the range of 120-250 degreeC is more preferable. From the viewpoint of equipment, it is practically advantageous to have the reaction pressure in the range of 0.0 to 3.0 MPaG (gauge pressure), but it is not particularly limited. More preferably, it is the range of 0.1-1.5 MPaG (gauge pressure).

When the reaction is carried out by a fixed-bed flow reaction, the raw material gas is preferably supplied to the catalyst at a space velocity: SV=10 to 15000 hr ^-1 in a standard state, particularly preferably 300 to 8000 hr ^-1 .

Example

The present invention is further described below by way of Examples and Comparative Examples, but the present invention is not limited by these descriptions at all.

Production Example 1 Production of Catalyst A

Using a silica spherical carrier (sphere diameter 5 mm, specific surface area 155 m ² /g, water absorption 0.85 g/g, hereinafter abbreviated as "silica carrier"), Catalyst A was produced in the following procedure.

Process 1

4.1 L of an aqueous solution containing 199 g of sodium chloropalladate and 4.08 g of sodium chloroaurate tetrahydrate was prepared as an A-1 solution. To this, 12 L of a silica carrier (bulk density 473 g/L, water absorption 402 g/L) was added to impregnate the A-1 solution, and the entire amount was absorbed.

Process 2

427 g of sodium metasilicate nonahydrate was dissolved in pure water, and using a graduated cylinder, it was diluted with pure water so that the total amount was 8.64 L, and it was set as A-2 solution. The metal-supported carrier obtained in the step 1 was impregnated with the A-2 solution, and left to stand at room temperature for 20 hours.

Process 3

300 g of hydrazine monohydrate was added to the slurry of the alkali-treated silica carrier obtained in the step 2, and the mixture was slowly stirred, and then allowed to stand at room temperature for 4 hours. The obtained catalyst was filtered, moved to a glass column with a stop cock, and washed with pure water for 40 hours. Next, drying was performed at 110° C. for 4 hours under an air flow to obtain a metal-supported catalyst (A-3).

Process 4

624 g of potassium acetate and 90 g of copper acetate monohydrate were dissolved in pure water, and the total amount was 3.89 L by diluting with pure water using a graduated cylinder. The metal-supported catalyst (A-3) obtained in the step 3 was added thereto, and the entire amount was absorbed. Next, drying was performed at 110° C. for 20 hours under an air flow, and the catalyst A for producing allyl acetate was obtained. The mass ratio of (a), (b), (c) and (d) is (a):(b):(c):(d)=1:0.024:0.39:8.5. The mass ratio is based on the mass of the constituent elements for (a), (b) and (c), and based on the mass of the alkali metal salt compound for (d). (d) The supported amount (g) of the alkali metal salt compound per 1 g of the (e) carrier was 0.110 g/g.

Production Example 2 Production of Catalyst B

In step 4, except that the amount of potassium acetate was changed from 624 g to 396 g, the operation of Production Example 1 was repeated to produce catalyst B. The mass ratio of (a), (b), (c) and (d) is (a):(b):(c):(d)=1:0.024:0.39:5.4. The mass ratio is based on the mass of the constituent elements for (a), (b) and (c), and based on the mass of the alkali metal salt compound for (d). (d) The supported amount (g) of the alkali metal salt compound per 1 g of the (e) carrier was 0.069 g/g.

<Reference Examples 1 and 2> Performance Evaluation of Catalysts A and B

10.5 mL each of the catalysts A and B obtained in Production Examples 1 and 2 were uniformly diluted with 31.5 mL of ceramic balls, and then filled in a reaction tube (made of SUS316L, inner diameter 25 mm). Under the conditions of a reaction temperature of 150° C. and a reaction pressure of 0.8 MPaG (gauge pressure), the gas composition was introduced at a space velocity of 2070 hours ^-1 with a mixture of propylene:oxygen:acetic acid:water=35:6:8:23 (volume ratio) Gas, allyl acetate is formed from propylene, oxygen and acetic acid. Analysis of the reactants was carried out 200 hours after the start of the reaction.

As a method for analyzing the reactant, a method of cooling the total amount of the outlet gas passing through the catalyst packed layer, collecting the total amount of the condensed reaction liquid, and analyzing it by gas chromatography is used. For the uncondensed gas, the total amount of the uncondensed gas flowing out during the sampling time was measured, and a part of the uncondensed gas was taken out and analyzed by gas chromatography.

The analysis of the condensed reaction liquid was performed by the internal standard method using a FID detector, a capillary column TC-WAX (length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm) using GC-14B manufactured by Shimadzu Corporation.

For the analysis of uncondensed gas, GC-14B manufactured by Shimadzu Corporation (gas sampler MGS-4 for Shimadzu gas chromatography, with a 1 mL measuring tube) was used, and a TCD detector (He carrier gas, current value 100 mA) was used. , packed column MS-5A IS (3mmφ×3m, 60/80 mesh) and Unibeads (3mmφ×3m, 60/80 mesh), using the absolute calibration curve method for analysis.

The activity of the catalyst was calculated as the mass of allyl acetate produced in 1 hour per unit catalyst volume (L) (space-time yield: STY, unit: g/L-cat·hr).

The selectivity of allyl acetate was calculated|required by the following calculation formula.

Allyl acetate selectivity (based on propylene) (%) = [amount of allyl acetate produced (mol)/amount of consumed propylene (mol)]×100

The amount of potassium acetate in the catalyst was quantified as follows: The catalyst was pulverized to obtain a uniform powder, then molded, and analyzed by X-ray fluorescence (XRF), using the absolute calibration curve method to determine the content (mass %) of K (potassium) atoms. form quantification.

The results of Reference Examples 1 and 2 are shown in Table 1. In the evaluation after 200 hours from the start of the reaction, it was found that the catalyst A of Reference Example 1 had higher activity (STY) than the catalyst B of Reference Example 2. It can be said that in the production of allyl acetate, those with a large amount of potassium acetate supported show high catalyst activity.

Table 1

<Example 1>

In a reaction tube with an inner diameter of 34 mm, from the inlet side of the reaction gas to the outlet side, the inert balls are filled in order from the inlet side of the reaction gas to the upstream side of the catalyst to form a layer of 0.8m long, and the catalyst A with a large amount of potassium acetate and a high activity is loaded. The packed layer has a length of 3.3 m, and the catalyst B, which has a small amount of potassium acetate supported and low activity, is packed into a layer with a length of 2.2 m. The raw material gas having the composition shown in Table 2 was circulated at a space velocity of 2000 hours ^-1 , and the reaction was continued for 8000 hours under the conditions of a reaction temperature of 160°C and a reaction pressure of 0.75 MPaG (gauge pressure). After the completion of the reaction, the catalyst was divided into a ratio of 3:2 from the reaction gas inlet side and taken out so that the reaction tube inlet side was the catalyst C and the reaction tube outlet side was the catalyst D. FIG. 1A shows the filling position of the catalyst of Example 1. FIG. At the start of the reaction, the supported amount (g) of the (d) alkali metal salt compound (potassium acetate) per 1 g of the (e) carrier of the catalyst A (inlet side) was 0.1099 g/g, and the catalyst B (outlet side) The supported amount (g) of the (d) alkali metal salt compound (potassium acetate) per 1 g of the (e) carrier was 0.069 g/g, and the ratio of the supported amount of potassium acetate was 1.59 (=0.1099/0.069). For catalysts C and D, performance evaluation was performed after 8000 hours elapsed under the evaluation conditions described later. The result of Example 1 (whole) is shown in Table 4 together.

Table 2

Element Content (vol%) Acetic acid 8 acrylic 35 oxygen 6 water 18 Inert gases such as nitrogen 33

<Comparative Example 1>

The same reaction as in Example 1 was performed except that all the catalysts to be filled were catalyst A and the layer length of catalyst A was 5.5 m. After the completion of the reaction, the catalyst was divided into a ratio of 3:2 from the inlet side in the reaction direction and taken out so that the reactor inlet side was the catalyst E and the reactor outlet side was the catalyst F. FIG. 1B shows the filling position of the catalyst of Comparative Example 1. FIG. The results are shown in Table 4.

<Comparative Example 2>

The same reaction as in Example 1 was carried out, except that the catalyst B was packed with a layer length of 3.3 m and the catalyst A was packed with a layer length of 2.2 m from the reaction gas inlet side. After the completion of the reaction, the catalyst was divided into a ratio of 3:2 from the inlet side in the reaction direction and taken out so that the reactor inlet side was the catalyst G and the reactor outlet side was the catalyst H. FIG. 1C shows the filling position of the catalyst of Comparative Example 2. FIG. The results are shown in Table 4.

<Performance evaluation of catalysts C to H>

10.5 mL each of catalysts C to H obtained in Example 1 and Comparative Examples 1 and 2 were uniformly diluted with 31.5 mL of ceramic balls, and then filled in a reaction tube (made of SUS316L, inner diameter 25 mm). The raw material gas having the composition shown in Table 3 was circulated at a space velocity of 2070 hours ^-1 , and the oxidation reaction was carried out for 4 hours under the conditions of a reaction temperature of 160°C and a reaction pressure of 0.8 MPaG (gauge pressure). The results are shown in Table 4.

table 3

Element Content (vol%) Acetic acid 8 acrylic 35 oxygen 7 water twenty three nitrogen 27

Table 4

As can be seen from Table 4, in Example 1, compared with Comparative Example 1 in which the catalyst was uniformly filled in the reaction tube, and Comparative Example 2 in which the supported amounts of potassium acetate were reversed, the overall allyl acetate after the reaction for 8000 hours. The ester STY was large, and the catalyst performance of the whole reaction tube decreased less than that at the beginning of the reaction (200 hours). In addition, it was found that the catalyst D of Example 1 had a smaller amount of potassium acetate supported than the catalyst F of Comparative Example 1, and that the allyl acetate activity was high. As can be seen from these, compared with the case where the catalyst of the same specification is uniformly filled to carry out the reaction, as in the present invention, the catalyst is filled so that the potassium acetate supporting amount of the catalyst is sequentially decreased from the inlet side to the outlet side of the reactor. In the case of the reaction, the distribution of potassium acetate in the flow direction of the raw material gas in the reaction tube can be controlled to be more uniform, and the decrease in catalyst activity over time can be suppressed.

Industrial Availability

The present invention provides a method for producing allyl acetate with improved catalyst life, and is industrially useful because it can be used for efficient production of allyl acetate.

Claims (8)

1. A process for producing allyl acetate, characterized by supplying propylene, oxygen and acetic acid as raw material gases to a fixed-bed tubular reactor packed with an allyl acetate-producing catalyst comprising (a) palladium, (b) gold, (c) a 4 th-cycle metal compound having at least 1 element selected from the group consisting of copper, nickel, zinc and cobalt, (d) an alkali metal salt compound and (e) a carrier, and producing allyl acetate by a vapor-phase catalytic oxidation reaction,

in the above production method, 2 or more catalyst layers containing the catalyst for producing allyl acetate are disposed along the flow direction of the raw material gas in the reaction tube of the fixed-bed tubular reactor so that the amount of the (d) alkali metal salt compound supported on the (e) carrier decreases in the order from the inlet side to the outlet side of the fixed-bed tubular reactor, and the amounts of the (d) alkali metal salt compound in the catalysts for producing allyl acetate contained in the respective catalyst layers are different.

2. A process for producing allyl acetate according to claim 1, wherein the amount of (d) the alkali metal salt compound supported on 1g of the (e) carrier in the catalyst layer on the entry side of the reaction tube is 1.2 to 3.0 times the amount of (d) the alkali metal salt compound supported on 1g of the (e) carrier in the catalyst layer on the exit side, wherein the amount of (d) the alkali metal salt compound is in g.

3. The method for producing allyl acetate according to claim 1 or 2, wherein the reaction tube is a straight tube, the catalyst layer is 2 layers, and the ratio of the length of the catalyst layer on the inlet side to the length of the catalyst layer on the outlet side of the reaction tube in the flow direction of the raw material gas is 4:1 to 1: 4.

4. The method for producing allyl acetate according to claim 1 or 2, wherein the fixed-bed tubular reactor is a multitubular type.

5. The method for producing allyl acetate according to claim 1 or 2, wherein the alkali metal salt compound (d) is at least 1 selected from the group consisting of potassium acetate, sodium acetate, and cesium acetate.

6. The method for producing allyl acetate according to claim 1 or 2, wherein the (c) 4 th cycle metal compound is a compound having copper or zinc.

7. The method for producing allyl acetate according to claim 1 or 2, wherein the (c) 4 th cycle metal compound is copper acetate.

8. The method for producing allyl acetate according to claim 1 or 2, wherein the catalyst for producing allyl acetate has a mass ratio of (a) palladium, (b) gold, (c) the 4 th cycle metal compound to (d) the alkali metal salt compound in all the catalyst layers that is (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.00125-22.5: 0.02-90: 0.2 to 450.

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