JP2022046942A - Method for producing catalyst - Google Patents

Abstract

To provide a method for producing catalysts that makes it possible to produce unsaturated aldehydes with a high invert ratio, selectivity and yield as catalysts used in a gas-phase catalytic oxidation reaction to produce unsaturated aldehydes, such as acrolein, methacrolein, cinnamaldehyde from unsaturated compounds such as propylene, isobutene, tertiary butanol, allyl benzene.SOLUTION: The present invention discloses a method for producing catalysts that subjects unsaturated compounds to a gas-phase catalytic oxidation with a molecular oxygen-containing gas to produce corresponding unsaturated aldehydes. The method includes the steps of: mixing a molybdenum-containing liquid with a pH of 7.0 or more with a liquid containing cobalt and iron to make a liquid mixture; drying the liquid mixture to make a powder; and mixing the powder with an organic bismuth compound.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a catalyst used in a vapor phase catalytic oxidation reaction for producing unsaturated aldehydes such as acrolein, methacrolein and cinnamaldehyde from unsaturated compounds such as propylene, isobutylene, tertiary butanol and allylbenzene.

Molybdenum-based catalysts are useful catalysts in vapor phase catalytic oxidation reactions to produce unsaturated aldehydes such as acrolein, methacrolein, and cinnamaldehyde from unsaturated compounds such as propylene, isobutene, tertiary butanol, and allylbenzene. It is well known and has been widely used industrially.

Many documents such as Patent Document 1 are known as patent documents relating to the composition and production method of the molybdenum-based catalyst in these various reactions.
In such documents, there is known a method for producing a catalyst that improves catalyst performance such as raw material conversion rate and selectivity by adjusting the pH of the raw material or the like in the catalyst manufacturing process. Examples of this production method include a method of simultaneously adding an aqueous solution of bismuth salt and aqueous ammonia to an aqueous molybdenum acid solution having a pH in the range of 6 to 8 (Patent Document 2), at least one of iron, bismuth and tellurium, and a molybdenum compound. A method of adjusting the slurry containing molybdenum to a range exceeding pH 7 (Patent Document 3), a method of adding a chelating agent to a molybdenum compound-containing slurry containing silica to adjust the pH to 6 or higher (Patent Document 4), and a molybdenum-containing slurry. A method of mixing a bismuth compound after setting the pH to 6 or higher (Patent Document 5), heat-treating a dried product of an aqueous solution containing molybdenum, iron, nickel or cobalt, and silica, and then mixing ammonia with bismuth and an aqueous medium. A method of adding water (Patent Document 6) and the like are disclosed.

Special Publication No. 39-3670 Special Publication No. 59-51848 Japanese Unexamined Patent Publication No. 2-59046 Japanese Unexamined Patent Publication No. 2-21453 Japanese Unexamined Patent Publication No. 2-251250 Japanese Patent Application Laid-Open No. 2003-205240

However, even with these methods, the desired yield of oxidation products was not always satisfactory.

Therefore, the present invention provides a conversion rate as a catalyst used in a gas phase catalytic oxidation reaction for producing unsaturated aldehydes such as achlorine, methacrolein and cinnamaldehyde from unsaturated compounds such as propylene, isobutene, tertiary butanol and allylbenzene. It is an object of the present invention to provide a method for producing a catalyst which has a high selectivity and can produce an unsaturated aldehyde in a high yield.

The present invention is a method for producing a catalyst for producing a corresponding unsaturated aldehyde by vapor-phase catalytic oxidation of an unsaturated compound with a molecular oxygen-containing gas in order to solve the above-mentioned problems.
A step of mixing a molybdenum-containing liquid having a pH of 7.0 or more and a liquid containing cobalt and iron to obtain a mixed liquid, a step of drying the mixed liquid to make a powder, the powder and an organic bismuth. It has been found that by including the step of mixing the compounds, a catalyst having high activity and giving the desired oxidation product in a high yield can be obtained.

Further, in the present invention, the organic bismuth compound is preferably triphenylbismuth.
Further, it is preferable to keep the mixed solution at 60 ° C. or higher and 100 ° C. or lower.
Furthermore, it is preferable to hold the mixed solution for 1 hour or more and 24 hours or less.

Further, it is preferable that the catalyst contains at least molybdenum, cobalt, iron and bismuth.
Further, it is preferable that the catalyst contains a composition represented by the following general formula (1).
Mo _a Bi _b Co _{c Fed} (1)
(In the formula, a to d represent the atomic ratio of each element, and when a = 12, they are in the range of 0.5 ≦ b ≦ 7, 0 <c ≦ 10, 0.05 ≦ d ≦ 5.)

According to the present invention, raw material conversion is used as a catalyst used in a gas phase catalytic oxidation reaction for producing unsaturated aldehydes such as acrolein, methacrolein and cinnamaldehyde from unsaturated compounds such as propylene, isobutene, tertiary butanol and allylbenzene. A catalyst capable of producing unsaturated aldehydes with high rate and selectivity and high yield can be obtained.

The method for producing the catalyst according to the present invention will be described in detail.
First, a solution containing a molybdenum component in which a molybdenum compound or the like is dissolved in a solvent such as water (hereinafter referred to as "molybdenum-containing liquid") is obtained. The pH of this molybdenum-containing liquid is adjusted to 7.0 or higher by adding an alkaline solution.

Then, a solution in which an iron compound and a cobalt compound are dissolved in a solvent such as water (hereinafter referred to as "cobalt / iron-containing liquid") is added to the pH-adjusted molybdenum-containing liquid to obtain a mixed liquid.

Examples of the molybdenum compound include ammonium paramolybdate, molybdenum trioxide, molybdic acid, ammonium phosphomolybdate, and phosphomolybdic acid. Examples of the iron compound include ferric nitrate, ferric sulfate, ferric chloride, ferric acetate and the like, and examples of the cobalt compound include cobalt nitrate, cobalt sulfate, cobalt chloride, cobalt carbonate and cobalt acetate. can give. Also, if necessary, before, at the same time as, or after the addition of the alkaline solution, as raw materials for other catalysts, nickel, sodium, potassium, rubidium, thallium, boron, phosphorus, arsenic, and / or ) Thallium compounds, preferably each water-soluble salt, may be added as is or as an aqueous solution thereof. Further silica may be added.
Examples of the alkaline solution include aqueous solutions such as ammonia and ammonium carbonate.

The amount of the alkaline solution added is such that the pH of the molybdenum-containing liquid obtained by adding the alkaline solution becomes 7.0 or more as described above.
By setting the pH value of the pH adjusting solution to 7.0 or more, the performance of the produced catalyst can be improved, and the raw material conversion rate and the selectivity can be improved. This pH value is preferably 7.2 or more, more preferably 7.8 or more. The upper limit of the pH value is not particularly limited, but is preferably 12.0 or less, more preferably 10.0 or less, from the viewpoint of ease of handling, safety, and economy.

Next, the first mixing step of mixing the molybdenum-containing liquid having the adjusted pH and the cobalt / iron-containing liquid to obtain a mixed liquid is performed.
In this first mixing step, it is preferable to keep at least one of the molybdenum-containing liquid and the cobalt / iron-containing liquid at a temperature of 60 ° C. or higher. By maintaining the temperature of 60 ° C. or higher, the solubility of the raw material dissolved in the obtained mixed solution can be maintained, the performance of the produced catalyst can be improved, and the raw material conversion rate and the selectivity can be improved. The lower limit of this temperature is more preferably 65 ° C, still more preferably 70 ° C. The upper limit is not particularly limited, but 90 ° C. is preferable. By setting the temperature of the mixed solution to 90 ° C. or lower, the complexity of the step of adding the alkaline solution is reduced, and the operability is improved. The upper limit of this temperature is preferably 90 ° C, more preferably 85 ° C.

Next, a holding step of holding the mixed solution at a predetermined temperature for a predetermined time is performed, and then the mixture is filtered to obtain a precipitate, and the obtained precipitate is dried to obtain a powder. I do.
The holding step is a step of heating the mixed solution to 60 ° C. or higher and 100 ° C. or lower, and then holding the temperature within a range of 1 hour or more and 24 hours or less.

By setting the holding temperature to 60 ° C. or higher, the solubility of the raw material dissolved in the mixed solution is maintained, the performance of the produced catalyst is improved, and the raw material conversion rate and the selectivity can be improved. The lower limit of this temperature is preferably 65 ° C, more preferably 70 ° C. Further, when the holding temperature is 100 ° C. or lower, the melting tank does not require a pressure-resistant container, the handling becomes simple, and the economy and operability are improved. When the holding temperature is 100 ° C., reflux can be applied by using a reflux device.

By setting the holding time to 1 hour or more, the effect of aging can be sufficiently obtained, the performance of the produced catalyst can be improved, and the raw material conversion rate and the selectivity can be improved. The lower limit of this time is preferably 1.5 hours, more preferably 2 hours. Further, the holding time may be longer than 24 hours, but since the aging effect is not increased, 24 hours is sufficient from the viewpoint of industrial implementation. The upper limit of this time is preferably 22 hours, more preferably 20 hours, and even more preferably 18 hours.

The solution subjected to the above-mentioned holding step may be subjected to a first drying step of drying the solution as it is in an air atmosphere to obtain a powder, or after filtering into a precipitate and a liquid portion by filtration, the air atmosphere The powder may be obtained by subjecting it to a first drying step of drying below. As this method for filtering, a well-known method can be used.

The drying method and the state of the obtained dried product are not particularly limited, and for example, a powdered dried product may be obtained using a normal spray dryer, slurry dryer, drum dryer, or the like, or usually. A block-shaped or flake-shaped dried product may be obtained by using a box-type dryer or a tunnel-type baking furnace.

If necessary, the obtained powder may be subjected to a first firing step of firing in an air atmosphere.
In this firing, a normal box-type heating furnace, a tunnel-type heating furnace, or the like may be used to heat the dried product in a fixed state, or a rotary kiln or the like may be used to heat the dried product while flowing it. .. The firing temperature is 180 ° C. or higher and 400 ° C. or lower. By setting the firing temperature within the above range, the performance of the produced catalyst can be improved, and the raw material conversion rate and the selectivity can be improved. The upper limit of the firing temperature is more preferably 350 ° C.

Furthermore, the firing time is preferably 1 hour or longer, preferably 3 hours or longer. By setting the firing time to 1 hour or more, the residual nitric acid in the dried product can be suppressed, the performance of the produced catalyst can be improved, and the raw material conversion rate and the selectivity can be improved. Further, the firing time may exceed 24 hours, but the effect of firing does not increase, and 24 hours is sufficient from the viewpoint of industrial implementation. The upper limit of the firing time is preferably 20 hours, more preferably 18 hours.
If the particles of the obtained calcined powder are not small, it is preferable to perform pulverization because the operability in the next step is improved.

Next, a second mixing step of mixing the organic bismuth compound with the powder obtained in the first drying step or the first firing step is performed.
The organic bismuth may be mixed as a solid, or may be mixed as a solution or a suspension. The organic bismuth solution or suspension may be one in which only the organic bismuth is dissolved or suspended in a solvent such as acetone or water, and the pH is adjusted to 7.0 or more with the alkaline solution. The molybdenum-containing liquid may be mixed with an organic bismuth compound or a solution or suspension thereof.

Further, the powder obtained in the first drying step or the first firing step may be mixed with an organic bismuth compound or a solution or suspension thereof as it is, and the powder may be mixed with the above-mentioned powder. A method may be used in which a molybdenum-containing solution having a pH adjusted to 7.0 or higher with an alkaline solution is added, and the organic bismuth compound or a solution or suspension thereof is mixed with the dried product by vacuum drying or the like.
By the way, examples of the organic bismuth compound include triphenyl bismuth, pentaphenyl bismuth, triphenyl carbonate bismuth, and triphenyl bismuth diacetate.

Next, the mixture obtained in the second mixing step is subjected to the second drying step.
In this second drying step, when the mixture is a powder, it is dried as it is, and when it is a solution or a suspension, it is evaporated to dryness. Then, the catalyst according to the present invention can be obtained by shaping it into an arbitrary shape as needed and subjecting it to a second firing step as needed.
The second drying step may be performed under normal pressure conditions under an air atmosphere or under reduced pressure conditions. Further, the drying method and the state of the obtained dried product are not particularly limited, and for example, a powdered dried product may be obtained by using an ordinary spray dryer, slurry dryer, drum dryer or the like, or usually. A block-shaped or flake-shaped dried product may be obtained by using a box-type dryer or a tunnel-type baking furnace.

Further, the second firing step can be performed by the same method as the second drying step.
The above-mentioned shaping can be performed by a method such as extrusion molding, tableting molding, or support molding.

The temperature in the second firing step is 450 ° C. or higher and 600 ° C. or lower. By setting the firing temperature to 450 ° C. or higher, the thermal decomposition of the raw material-derived component becomes sufficient, the performance of the produced catalyst is improved, and the raw material conversion rate and the selectivity can be improved. The lower limit of the firing temperature is preferably 480 ° C. Further, by setting the firing temperature to 600 ° C. or lower, the decrease in activity can be suppressed, the performance of the produced catalyst can be improved, and the raw material conversion rate and selectivity can be improved. The upper limit of the firing temperature is preferably 560 ° C.
Furthermore, the firing time is 0.1 hour or more and 24 hours or less. By setting the calcination time to 0.1 hours or more, the crystal growth by calcination becomes sufficient, the performance of the produced catalyst is improved, and the raw material conversion rate and the selectivity can be improved. The lower limit of the firing time is preferably 1 hour. Further, by setting the firing time to 24 hours or less, the catalytic activity is maintained, the performance of the produced catalyst is improved, and the raw material conversion rate and the selectivity can be improved. The upper limit of this firing time is preferably 10 hours.

The catalyst thus obtained contains at least molybdenum, cobalt, iron and bismuth, and specifically contains a composition represented by the following general formula (1).
Mo _a Bi _b Co _{c Fed} (1)
In the formula (1), a to d represent the atomic ratio of each element, and when a = 12, they are in the range of 0.5 ≦ b ≦ 7, 0 <c ≦ 10, 0.05 ≦ d ≦ 5. ..

The amount of each component used, the mixing ratio, and the like described above may be appropriately set so as to satisfy the conditions of the resulting general formula (1).

The catalyst produced in this manner is an unsaturated compound such as propylene, isobutene, tertiary butanol, allylbenzene, etc., which is vapor-phase catalytically oxidized with a gas containing molecular oxygen, and the corresponding unsaturated compound such as methacrolein, cinnamaldehyde, etc. is unsaturated. In the step of producing an aldehyde, it is possible to produce a catalyst having higher catalytic performance such as raw material conversion rate and selectivity, having high activity, and giving a target oxidation product in a high yield.

Hereinafter, a more specific method for producing the catalyst according to the present invention and the results of performing an oxidation reaction of allylbenzene using the obtained catalyst are shown below.
In the following, the definitions of allylbenzene conversion rate, cinnamaldehyde selectivity, and cinnamaldehyde yield are as follows.
-Allylbenzene conversion rate (mol%) = (number of moles of reacted allylbenzene / number of moles of supplied allylbenzene) x 100
Cinnamaldehyde selectivity (mol%) = (number of moles of produced cinnamaldehyde / number of moles of reacted allylbenzene) x 100
-Cinnamaldehyde yield (mol%) = (number of moles of produced cinnamaldehyde / number of moles of supplied allylbenzene) x 100

(Example 1)
<Catalyst preparation>
50 ml of pure water at room temperature was placed in a container, and 7.06 g of ammonium paramolybdate was added and dissolved to obtain a solution A. At this time, the pH of the solution A was 5.1.
50 ml of pure water at room temperature was placed in another container, and 1.41 g of ferric nitrate and 10.1 g of cobalt nitrate were added and dissolved to obtain a solution B. At this time, the pH of the solution B was 1.5.
Ammonia water was added to the solution A to adjust the pH to 8.0, the mixture was heated to 80 ° C., and then the solution B was added to prepare the solution C. At this time, the pH of the solution C was 6.0. It was further heated to reflux at 100 ° C. and kept for 3 hours with stirring. The resulting precipitate was filtered off and the filtered precipitate was dried at 110 ° C. in an air atmosphere. The dried product was further calcined at 300 ° C. for 6 hours in an air atmosphere to obtain powder D.
In another container, 50 ml of pure water at room temperature was placed, 0.617 g of ammonium paramolybdate was added to dissolve the solution, and aqueous ammonia was further added to adjust the pH to 8 to obtain a solution E. Powder D was added to solution E, mixed for 30 minutes, and then dried under reduced pressure to obtain powder F.
50 ml of acetone was placed in another container, 1.03 g of triphenylbismuth was added and dissolved to obtain a solution G. Powder F was added to the solution G, mixed for 30 minutes, dried under reduced pressure, and the dried product was further calcined at 500 ° C. for 2 hours in an air atmosphere to obtain a catalyst H. The composition of catalyst H is
It was Mo ₁₂ Bi _0.6 Co _9.6 Fe _0.96 .

<Phase contact oxidation reaction of allylbenzene>
A fixed-bed atmospheric pressure flow reactor was used for the gas-phase catalytic oxidation reaction of allylbenzene. A raw material mixed gas (allylbenzene 2.25 mL-liq / h, air 10.6 mL / min, nitrogen 44.6 mL / min) was supplied to 1.28 g of the catalyst H at a reaction temperature of 320 ° C. for 60 minutes. The entire product was recovered with an eye strap and gas bag and analyzed using gas chromatography.
As a result, the allylbenzene conversion was 3.5%, the cinnamaldehyde selectivity was 34%, and the cinnamaldehyde yield was 1.2%.

(Comparative Example 1)
<Catalyst preparation>
50 ml of pure water at room temperature was placed in a container, and 1.41 g of ferric nitrate and 10.1 g of cobalt nitrate were added and dissolved to obtain a solution b1. At this time, the pH of the solution b1 was 1.3.
After adding the solution b1 to the solution A obtained in Example 1, the solution was heated to 80 ° C., and then aqueous ammonia was added to prepare the solution c1. At this time, the pH of the solution c1 was 6.0.
For the subsequent steps, the same treatment as in Example 1 was carried out using the obtained solution c1 to obtain a catalyst h1. The composition of the catalyst h1 is
It was Mo ₁₂ Bi _0.6 Co _9.6 Fe _0.96 .

<Phase contact oxidation reaction of allylbenzene>
Using the catalyst h1, a gas phase catalytic oxidation reaction of allylbenzene was carried out under the same conditions as in Example 1. As a result, the allylbenzene conversion was 2.9%, the cinnamaldehyde selectivity was 34%, and the cinnamaldehyde yield was 1.0%.

(Comparative Example 2)
<Catalyst preparation>
Ammonia water was added to the solution A obtained in Example 1 to adjust the pH to 8.0, and then the mixture was heated to 80 ° C. (solution a2). Solution B obtained in Example 1 was added to solution a2 to obtain solution c2. When mixing was complete, the pH of solution c2 was 6.0.
The solution c2 was heated to reflux at 100 ° C. and held for 3 hours with stirring. The resulting precipitate was filtered off and the filtered precipitate was dried at 110 ° C. in an air atmosphere. The dried product was further calcined at 515 ° C. for 24 hours in an air atmosphere to obtain powder d2.
In another container, 75 ml of 10 wt% nitric acid at room temperature was placed, and 3.5 g of bismuth oxide was added and dissolved to obtain a solution p2. 50 ml of pure water at room temperature was placed in another container, and 3.98 g of ammonium paramolybdate was added to dissolve the mixture, which was then added to solution p2 to obtain solution q2. Ammonia water was added to the solution q2 to adjust the pH to 1.5, and then a hydrothermal synthesis treatment was carried out at 180 ° C. for 24 hours. The resulting precipitate was filtered off and the filtered precipitate was dried at 110 ° C. in an air atmosphere. The dried product was further calcined at 300 ° C. for 1 hour in an air atmosphere to obtain powder r2.
In another container, 50 ml of pure water was placed, 2.15 g of powder r2 was added, and the mixture was mixed for 60 minutes. Then, aqueous ammonia was added to adjust the pH to 7.0, and then the mixture was further mixed for 60 minutes. Then, 7.09 g of the powder d2 was added, mixed for another 30 minutes, evaporated to dryness, and then dried at 120 ° C. under an air atmosphere. The dried product was further calcined at 515 ° C. for 24 hours in an air atmosphere to obtain a catalyst h2. The composition of the catalyst h2 is
It was Mo ₁₂ Bi _1.0 Co _9.1 Fe _0.91 .

<Phase contact oxidation reaction of allylbenzene>
Using the catalyst h2, a gas phase catalytic oxidation reaction of allylbenzene was carried out under the same conditions as in Example 1. As a result, the allylbenzene conversion was 1.9%, the cinnamaldehyde selectivity was 32%, and the cinnamaldehyde yield was 0.6%.

Claims (6)

A method for producing a catalyst for producing a corresponding unsaturated aldehyde by vapor-phase catalytic oxidation of an unsaturated compound with a gas containing molecular oxygen.
A step of mixing a molybdenum-containing liquid having a pH of 7.0 or more and a liquid containing cobalt and iron to obtain a mixed liquid.
The process of drying the mixture into powder,
A method for producing a catalyst, which comprises a step of mixing the powder with an organic bismuth compound. The method for producing a catalyst according to claim 1, wherein the organic bismuth compound is triphenylbismuth. The method for producing a catalyst according to claim 1 or 2, wherein the mixed solution is held at 60 ° C. or higher and 100 ° C. or lower. The method for producing a catalyst according to any one of claims 1 to 3, wherein the mixed solution is held for 1 hour or more and 24 hours or less. The method for producing a catalyst according to any one of claims 1 to 4, wherein the catalyst contains at least molybdenum, cobalt, iron and bismuth. The method for producing a catalyst according to claim 5, wherein the catalyst comprises a composition represented by the following general formula (1).
Mo _a Bi _b Co _{c Fed} (1)
(In the formula, a to d represent the atomic ratio of each element, and when a = 12, they are in the range of 0.5 ≦ b ≦ 7, 0 <c ≦ 10, 0.05 ≦ d ≦ 5.)