JPS59142852A - Preparation of catalyst for manufacture of acrylic acid - Google Patents

Abstract

PURPOSE:To prepare a catalyst having a high yield of acrylic acid by mixing phosphomolybdic acid and compds. containing other catalytic component elements in the presence of water, drying the mixture so as to have a specified water content and subjecting it to a heat-treatment at the specified temp. CONSTITUTION:Phosphomolybdic acid and compds. containing other catalytic elements (e.g. phosphoric acid, arsenic acid, copper oxide or the like) are mixed in the presence of water for the preparation of a heteropolyacid-type catalyst for acrylic acid manufacture which contains phosphor, molybdenium, copper and arsenic as catalytic component elements and is used for manufacturing acrylicacid by allowing acrolein to react with molecular oxygen in the presence of the catalyst at a high temp. and in vapor phase. After the obtd. solution or slurry is concentrated or dried to adjust so as to have 5-20wt% water content of the concentrated or dried substance, a heat treatment is carried out at 100- 300 deg.C. By using the catalyst obtd. in this manner, acrylic acid can be manufactured over a long period in a high yield at comparatively low reaction temp. and in a short contacting time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a heteropolyacid-based catalyst for producing acrylic acid containing phosphorus, molybdenum, and copper arsenic as catalyst component elements, which can produce acrylic acid in high yield. This relates to a new manufacturing method.

A method for producing acrylic acid by reacting acrolein with molecular oxygen in a high-temperature gas phase in the presence of a heteropolyacid catalyst containing phosphorus, molybdenum, copper, and arsenic as catalytic elements is already known. Acid-based catalysts are generally produced by starting with a suitable compound containing the catalyst component elements, such as an oxide or a phosphate, adding a carrier if necessary, and mixing these in the presence of water or the like. It is produced by making a solution into a slurry, drying it, generally evaporating it to dryness, and baking it as necessary without shaping or molding (Japanese Patent Laid-Open No. 56-501)
No. 16='USP, '4110-69° JP-A-51194, JP-A-50-41811, etc.).

heteropolyacids (which still commonly contain phosphorus and molybdenum)
-18 Takeso salt) has a Keggin structure as a skeleton structure, and the skeleton is said to be surrounded by protons, eyes, cations, and water of crystallization. It is in the range of 0 molecules.

The present inventors conducted intensive research on the production of acrylic acid using a heteropolyacid catalyst containing phosphorus, molybdenum, copper, and arsenic as catalyst components, and as a result, improved the method for producing the catalyst.

The inventors discovered that the yield of acrylic acid can be increased more than when using a catalyst obtained by a conventional method for producing a heteropolyacid catalyst, leading to the present invention.

The present invention is a heteropolyacid-based acrylic acid containing phosphorus, molybdenum, copper, and arsenic as catalyst component elements, which is used to produce acrylic acid by reacting acrolein with molecular oxygen in the presence of a catalyst in a high-temperature gas phase. In a method for producing a catalyst for production.

A compound containing phosphomolybdic acid and other catalyst component elements is mixed in the presence of water, the resulting solution or slurry is concentrated or dried, and the concentrate is strained until the water content in the dried material is 5. After adjusting it to be ~20 weight, 10
The present invention relates to a method for producing a catalyst for producing acrylic acid, which is characterized by heat treatment at a temperature of 0 to 300°C.

The present invention is effective for producing a heteropolyacid-based catalyst for producing acrylic acid containing phosphorus, molybdenum, copper, and arsenic as catalyst component elements.

Besides molybdenum, copper and arsenic, tungsden, iron, bismuth, antimony, cobalt zinc, zirconium, calcium,
Chromium, boron, tin, titanium, palladium, tantalum, cerium, vanadium, magnesium, silver, aluminum, potassium.

The present invention can be applied to the production of catalysts for producing acrylic acid containing catalyst component elements such as niobium and lead.

Mo12 PaCubAsCXd06 [In the formula, MO is molybutenic acid di ASi, I arsenic, and X are tungsten, iron, and bismuth.

Antimony, for Koba +-. Zinc, boron, chromium.

One or more elements selected from the group consisting of zirconium, vanadium, titanium and tin, and ○ represent oxygen, and the subscripts a''-e represent the number of atoms.

When the number of atoms of Mo is 12, + a-1], 9 to 2
+ Preferably 1 to 1.6. b-0,005 to 0, preferably 0.01 to 1. c=0.01~2. Preferably 0
．． 1-1.5. d=0-21 preferably 0.001-1
1O is a value determined by the valence of each component. ]
When applied to the production of a catalyst for producing acrylic acid expressed by A catalyst is obtained.

In the present invention, it is necessary to use phosphomolybdic acid as a source of molybdenum. When a molybdenum-containing compound other than phosphomolybdic acid, such as ammonium molybdate, is used as a molybdenum source, an ammonium salt of a heteropolyacid is formed, and a catalyst exhibiting sufficient selectivity cannot be obtained.

When crushed molybdenum oxide, molybtenic acid, etc. are used, it takes a long time to produce a stable phosphomolybtenic acid compound, and it is difficult to obtain a catalyst that exhibits sufficient catalytic performance.

As the molybdenum source used in the present invention, phosphomolybtenic acid has an atomic ratio of phosphorus to molybdenum (P/Mo) of 1.
It is not limited to P/Mo (atomic ratio) of /12, and the generally known P/Mo (atomic ratio) is 1/11, 1/i Q, 1
It may also be phosphomolybdic acid such as /9, 2/17.

In the present invention, first, a solution or slurry is prepared by mixing a compound containing phosphomolybdic acid and other catalyst component elements in the presence of water. Typical compounds containing other catalyst component elements include phosphoric acid, arsenic acid, arsenic oxide, copper oxide, etc., as well as oxides, hydroxides, carbonates, etc. of other catalyst component elements. be able to.

When mixing compounds containing catalytic component elements, including phosphomolybdic acid, in the presence of water, the mixing order is not particularly limited, but if possible, the phosphomolybdic acid should be dissolved first, and then the other catalytic component elements should be dissolved. It is desirable to mix the contained compounds.

In the present invention, after mixing, it is preferable to age the mixed solution or slurry at a temperature of 20 to 100 DEG C., preferably 0 to 80 DEG C., for a period of at least 5 to 30 hours, with stirring. Aging provides a catalyst with higher acrylic acid yield. The reason why the acrylic acid yield is increased by aging is not fully clear.

It is speculated that this aging causes a change in the crystal structure of the heteropolyacid of phosphomolybdic acid, forming a new heteropolyacid containing other catalyst component elements.

In the present invention, the organic reducing substance 2, such as oxycarboxylic acids such as glycolic acid, glyokyful acid, and lactic acid, is added to the mixed solution or slurry.

The reproducibility of the catalyst is improved by adding glycols such as ethylene glycol, fluoropylene gelcol, and polyalkylene glycol, and sugars such as textolin, starch, aldose, and lactose.

Catalyst performance is also improved. What is the amount of organic reducing substances used?

Although it varies depending on the type of organic reducing substance used, the appropriate amount is 0.3 to 12 parts by weight, preferably 0.5 to 9 parts by weight, relative to the catalyst to be obtained. If the amount of organic reducing substance used is too large or too small, the yield of acrylic acid will be low. There is no significant difference in the catalytic performance of the resulting catalyst whether one type or multiple types of organic reducing substances are used.

In the present invention, compounds containing phosphomolybdic acid and other catalyst component elements are mixed in the presence of water, the resulting solution size or slurry is concentrated or dried, and the water content in the concentrate or dried product is The content is adjusted to be 5 to 20% by weight, preferably 7 to 18% by weight. Concentration is conveniently carried out by concentrating the concentrate until the water content falls within the above range, or by drying it by evaporation to dryness, spray drying, etc., and then adding water to the dried product. It is appropriate that the material or solid material be allowed to stand at room temperature for 2 to 30 hours until the heteropolyacid becomes a stable crystalline form, and then subjected to heat treatment.

Concentrates or dry products with adjusted moisture content.

This is heat treated at a temperature of 100-300°C, preferably 17) 0-250°C, with or without molding.

In the present invention, adjustment of moisture content and heat treatment temperature are particularly important.

If the water content is not adjusted within the above range, a catalyst that exhibits a high yield of acrylic acid cannot be obtained.

Furthermore, when molding a dried product, moldability is poor if the water content is too high or too low. Further, even if the water content is adjusted within the above range, if the heat treatment temperature is too high/hard or too low, a catalyst showing a high yield of acrylic acid cannot be obtained.

In the present invention, it is necessary to carry out the heat treatment at the above-mentioned temperature, but in order to effectively carry out the heat treatment, the concentrate or dried product with adjusted moisture content must be prepared in advance at a temperature of 100 to 300%.
It is desirable to dehydrate the concentrate or dry product whose moisture content has been adjusted by rapid heat treatment in a heater heated to .degree. The heat treatment time is generally 1 hour or more, and even 1 hour or more.
~20 hours is suitable, and the heat treatment is generally suitably carried out under an atmosphere of an oxygen-containing gas, such as air.

A heteropolyacid catalyst containing phosphorus, molybdenum, copper and arsenic as catalyst component elements produced by a conventional manufacturing method by adjusting the moisture content and heat treatment, preferably or rapidly at the above temperature. The desired catalyst can be obtained without showing a higher yield of acrylic acid than in the case of the present invention. The reason for the improvement in acrylic acid yield is not fully clear, but it is believed that changes in the crystal structure of heteropolyacids are caused by adjusting the moisture content of 1' ft and heat treatment, as well as by aging, use of organic reducing substances, etc. This appears to further enhance the catalytic activity.

Each catalyst component element in the catalyst obtained by the present invention includes a mixture of heteropolyacids such as phosphomolybdic acid and their copper salts, a composite oxide in which multiple catalyst component elements are combined with oxygen, and each catalyst component element alone. It exists as a mixture of oxides of

In the present invention, the desired catalyst may be produced by adding 41-isomer during the production of the catalyst. When the catalyst obtained according to the present invention is used in the production of acrylic acid, it may be used together with a phase.

As the phase, any of those conventionally known as supports for catalysts for producing acrylic acid can be used, such as diatomaceous earth, alumina, silica, silica silicon carbide, and graphite.

When producing acrylic acid by reacting acrolein with molecular oxygen in the high-temperature gas phase in the presence of the catalyst obtained by the present invention, the molecular oxygen used in the two reactions may be pure oxygen gas, but particularly There is no need for purity, so
Generally, it is economical and convenient to use air. It is still advisable to use a diluent gas in conjunction with molecular oxygen and acrolein in the reaction. The diluting residue may be one that does not adversely affect this reaction9, such as nitrogen gas.

Carbon dioxide gas, water vapor, etc. can be used, and water vapor not only has the effect of improving the selectivity of acrylic acid, but also
It is preferable to carry out the reaction in the presence of water vapor, as this has the effect of sustaining the catalytic activity.

Like molecular oxygen, acrolein used in the single-stage reaction does not need to be of particularly high purity.

The catalyst obtained by the present invention can be used in any reactor such as a fluidized bed, moving bed, or fixed bed reactor, but the catalyst obtained by the present invention can react with acrolein at a relatively low reaction temperature and short contact time. It is generally advantageous to use a fixed bed reactor, since it has the advantages of high reaction rate and selectivity for acrylic acid, and the ability to maintain catalytic activity over a long period of time.

The reaction may be carried out under normal pressure, increased pressure, or reduced pressure, but it is generally convenient to carry out the reaction under normal pressure. The reaction temperature is still 200-400℃, preferably 250-400℃.
0'C, especially 260-320C is suitable. The contact time was 01 to 10 seconds.

Preferably, 0.5 to 5 seconds is appropriate. The reaction involves acrolein and molecular oxygen, generally air.

It is preferable to use a mixed gas to which water vapor is further added, and the composition of the mixed gas is 1 mole of acrolein to 1 mole of acrolein.
It is preferred that the molecular oxygen is 0.5 to 7 moles, preferably 1 to 5 moles, and the water vapor is 0.5 to 30 moles, preferably 1 to 10 moles.

In addition, to recover the desired product, acrylic acid, 1
Conventionally known methods 1 include condensation.

Methods such as solvent extraction are applied.

Next, Examples and Comparative Examples will be shown. Reaction rate (person) 1 in the example
Selectivity (%) and yield (correspondence) follow the following definitions.

Example 1 [Production of catalyst] Phosphomolybutenic acid CH3PIMO1□04o・29H2
0] 1007 was dissolved in 300 ml of water (approximately 25°C), and cupric oxide [Cub] 0.34 Y and arsenic acid [
A 6-Oy aqueous solution of IH3AsO4) was added and mixed, ethylene glycol 17 was added, and the mixture was stirred at 50°C for 20 hours.

Next, this mixed solution was concentrated under reduced pressure using a rotary evaporator until the water content became 15% by weight, and after being left at room temperature for 8 hours, the concentrate (water content was approximately the same) was heated at 150°C.
After putting it into a heater held at
$X 4. The atomic ratio of molybutenyline, copper and arsenic is 12:1:0.1:0.
6 catalyst was obtained.

[Manufacture of acrylic acid]

- The catalyst 9 m/f (16, 17) is 9', 8
A mixed gas containing 4 parts of acrolein, 10 parts of oxygen, 3 C% of water vapor, and 56 parts of nitrogen was poured into the tube at a flow rate of 400 m and e/min to conduct one reaction. The contact reaction was carried out at 00° C. for 1 hour. The contact time at that time was 1.4 seconds.

The results of the contact reaction are shown in Table 1.

Comparative Example 1 A catalyst was produced in the same manner as in Example 1, except that the moisture content was not adjusted and the mixture was dried in a loaf l) U2/- borator to form a dried product. A contact reaction was carried out under the reaction conditions.

The results of the contact reaction are shown in Table 1.

Comparative Example 2 Ammonium molybutenoate [(NH4)6MO7024.4H20:
]917 and 85 tyrinic acid [H3PO4] 4.9
A catalyst was produced in the same manner as in Example 1, except that No. 1 was used, and a catalytic reaction was carried out under the same reaction conditions as in Example 1.

The results of the contact reaction are shown in Table 1.

Table 1 Example 2 [Production of catalyst] Phosphormolybdic acid C83PI MO+2040・29H
20] Dissolve 1007 in 00rrd! water (approximately 25°C).

Cupric oxide (Cub) C1,68f, arsenic acid [H3AS
○4] and 0.62 y of antimony trioxide [5b2o3] were added and mixed, niretine glycol 27 was added, and the mixture was aged at 50°C for 20 hours with stirring.

Next, this mixed solution was concentrated under reduced pressure using a rotary evaporator until the water content became 10% by weight, and the concentrate with a water content of 10% by weight was allowed to stand at room temperature for 24 hours (the water content in the concentrate was Almost no change), 1
301 for 10 hours, then added 1 weight fraction of graphite and formed into pellets of 4 mm, IX 4 film H, and made of molybdenum phosphorus.

The atomic ratio of copper:arsenic:antimony is 12:1:0.20.
A catalyst of 6:0.1 was obtained.

[Manufacture of acrylic acid]

A catalytic reaction was carried out under the same reaction conditions as in Example 1 using the above catalyst.

The results of the contact reaction are shown in Table 2.

Example 13 A catalyst manufacturing method similar to that of Example 2 was used except that the catalyst component elements were changed to have the atomic ratios listed in Table 2.

A catalyst was produced in the same manner as in Example 2, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. In addition to the raw materials described in Example 2 as starting materials for catalyst production, bismuth oxide CB 1203 as a hismuth source + tungsten oxide [WO3] as a tungsten source; chromium oxide CCr2.03 as a chromium source + boron as a boron source. acid CH3BO3: ], ferric oxide CFe2O as iron source
3:] was used. The results of the contact reaction are shown in Table 2. In addition, when the atomic ratio of P was 1 or more, phosphoric acid was added.

Comparative Example A catalyst was produced in the same manner as in Example 2, except that the moisture content of the concentrate in Example 2 was changed from 10% by weight to 1% by weight, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. I did it.

The results of the contact reaction are shown in Table 3.

Comparative Example 4 A catalyst was produced in the same manner as in Example 2, except that the heat treatment temperature in Example 2 was changed from 0°C to 550°C.

A contact reaction was carried out under the same reaction conditions as in Example 1.

The results of the contact reaction are shown in Table 6.

Example 14 A catalyst was produced in the same manner as in Example 2, except that the aging at 50°C for 20 hours in Example 2 was changed to aging at 60°C for 15 hours, and the catalyst was contacted under the same reaction conditions as in Example 1. The reaction was carried out.

The results of the contact reaction are shown in Table 5.

Example 15 A catalyst was produced in the same manner as in Example 2, except that the water content of the concentrate in Example 2 was changed to i8 weight.
A contact reaction was carried out under the same reaction conditions as in Example 1.

The results of the contact reaction are shown in Table 5.

Example 16 A catalyst was produced in the same manner as in Example 2, except that the heat treatment temperature M and O'C in Example 2 were changed to 180°C.

A contact reaction was carried out under the same reaction conditions as in Example 1.

The results of the catalytic reaction are shown in Table V.

Table 1

Claims (1)

[Claims] 碩 Heteropolyacid-based acrylic acid production catalyst containing phosphorus, molybdenum, copper, and arsenic as catalyst component elements used to produce acrylic acid by reacting acrolein with molecular oxygen in the presence of a catalyst in a high-temperature gas phase. In a method for producing phosphomolybdic acid and other catalyst component elements, a compound containing phosphomolybdic acid and other catalyst component elements is mixed in the presence of water, the resulting solution or slurry is concentrated or dried, and the water content in the concentrate or dry product is A method for producing a catalyst for producing acrylic acid, which comprises adjusting the weight ratio to be 5 to 20% by weight, and then heat-treating the catalyst at a temperature of 100 to 500°C.