JP2000354765A - Production of metal oxide catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a catalyst suitable for producing acrylic acid at high yield from propane by gas phase catalytic oxidation. SOLUTION: The metal oxide catalyst for producing acrylic acid is produced by depositing a compound comprising an element X (X is one or more elements selected from the group consisting of Na and K) as the main component on powder of a metal oxide containing a metal element Mo, V, Sb or A (A is Nb or Ta) and a B (B is one or more elements selected from the group consisting of Ag, Zn, Sn, Pb, As, Cu, Tl and Se) and sintering the mixture of the metal compounds at 400 deg.C or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a metal oxide catalyst used in a method for producing acrylic acid by gas phase catalytic oxidation of propane and a method for producing acrylic acid using the metal oxide catalyst. is there.

[0002]

2. Description of the Related Art Acrylic acid is conventionally produced by a two-stage oxidation method in which propylene and oxygen are contact-oxidized to produce acrolein, and then acrolein is contact-oxidized with oxygen. On the other hand, the present invention relates to the practical use of a single-stage oxidation method which can significantly reduce the production cost as compared with the above-described two-stage oxidation method, that is, a method of using acrylic acid as a starting material and producing acrylic acid by a one-step reaction with oxygen. Research is being conducted in various places. For example, JP-A-9-3160
No. 23 discloses that in a process for producing acrylic acid by a one-stage oxidation method of propane, Mo, V, and Sb are used as essential metals and selected from a metal group consisting of Nb, Ta, W, Ti, Cr, Fe, and the like. A four-component metal oxide catalyst comprising a metal has been proposed.
No. 5664 also discloses a four-component metal oxide catalyst made of a similar metal.

As a catalyst having a higher conversion and selectivity in an acrylic acid synthesis reaction than the above four-component metal oxide catalyst, JP-A-10-120617 discloses a catalyst disclosed in JP-A-9-316023. A basically five-component metal oxide catalyst in which a four-component metal oxide catalyst is further impregnated with a solution containing As, P or an alkali metal is disclosed. According to such a five-component metal oxide catalyst, the yield is about 20 to 2 by a one-step oxidation method of propane.
Acrylic acid can be synthesized at 5%. Also, JP-A-10-2
No. 8862 relates mainly to a catalyst for the catalytic oxidation reaction of alkane and ammonia for nitrile synthesis. In addition to the four-component metal oxide catalyst disclosed in the above-mentioned JP-A-10-45664, Mo, W , Zr, Cr, T
A metal oxide catalyst supporting one or more elements selected from i, Nb, Ta, Fe, P, Si, an alkali metal or an alkaline earth metal has been proposed.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides a metal element Mo, V, S formed by firing a mixture of metal compounds at 400 ° C. or higher.
b, A (A is Nb or Ta) and B (B is Ag, Z
The powder of the metal oxide containing at least one element selected from the group consisting of n, Sn, Pb, As, Cu, Tl and Se is added to the element X (where X is a group consisting of Na and K). A method for producing a metal oxide catalyst for producing acrylic acid, which comprises supporting a compound having at least one selected element (at least one selected element) as a constituent component, followed by firing. Less than,
The present invention will be described in more detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an element X (provided that X
Is a metal oxide that supports a compound having at least one element selected from the group consisting of Na and K) as a constituent. As the supporting oxide in the present invention, those obtained by the following production method can be preferably used. That is, in an aqueous medium, in the presence of a Mo ⁺⁶ compound having Mo ⁺⁶ as a constituent element, such as ammonium molybdate, molybdenum oxide or molybdic acid, a V ⁺⁵ compound such as ammonium monvanadate or vanadium pentoxide and After reacting an Sb ⁺³ compound such as antimony trioxide or antimony acetate at a temperature of 70 ° C. or higher (hereinafter, the above operation is referred to as step 1), a metal element A, ie, Nb or Ta is formed in the obtained reaction product. A compound containing a metal element B as a constituent element (hereinafter sometimes referred to as a metal B compound) is further added to a mixture produced by a step of adding and uniformly mixing the compound as a component (hereinafter, this operation is referred to as step 2). I do. The metal B compound is
Used together with the Mo ⁺⁶ compound in the step 1,
Alternatively, it is preferable to mix with other components by using together with a compound containing Nb or Ta as a component in step 2. Examples of the Nb compound include niobium oxide and niobate, and examples of the Ta compound include:
Examples include tantalum oxide and tantalic acid.

[0006] As the metal B compound, silver nitrate, silver acetate,
Silver compounds such as silver carbonate; zinc compounds such as zinc nitrate and zinc oxide; tin compounds such as stannous chloride and stannic chloride; lead compounds such as lead acetate and lead chloride; arsenic such as arsenic trioxide and arsenic oxide. Compounds; Copper compounds such as copper nitrate, cupric oxide, cuprous oxide; thallium compounds such as thallous nitrate and thallous nitrate; selenium compounds such as selenic acid, selenous acid, and selenic chloride; .

The metal elements Mo, V,
A preferable atomic ratio of Sb, A and B is such that in the following composition formula (1), g and h are each 0.01 to 1.5.
And h / g = 0.3 to 1, and i is 0.001 to
3.0 and j is 0.0001 to 0.05. MoVgSbhAiBj (1) When h / g is less than 0.3, the selectivity for acrylic acid is low. If i is less than 0.001, the catalyst is liable to deteriorate, while if i exceeds 3.0, the catalyst has low activity and the conversion of propane is poor. If j is less than 0.0001, the effect of adding the element B is not exhibited, while if it exceeds 0.05, the yield of acrylic acid decreases.

In the method for producing a supporting oxide, the reaction in step 1 is preferably carried out at around the boiling point of the aqueous medium for 10 to 30 hours. Further, in order to promote the redox reaction among the three members of Sb ⁺³ , V ⁺⁵ and Mo ⁺⁶ , oxygen gas is blown into the reaction solution in Step 1 or the reaction is carried out after the oxidation-reduction reaction has progressed to some extent. It is preferable to drop hydrogen peroxide into the liquid. Instead of oxygen gas, a gas containing oxygen gas such as air may be used. The preferred oxygen gas concentration in the oxygen gas-containing gas is 0.5 vol% or more, and more preferably 1 to 20 vol%. Particularly preferably, it is 2 to 15 vol% (hereinafter abbreviated as%). The time for blowing the oxygen gas-containing gas into the reaction solution is preferably 4 hours or more. In dropping the hydrogen peroxide, it is preferable to use a hydrogen peroxide solution having a hydrogen peroxide concentration of about 0.01 to 35% by weight, and a preferable dropping amount of the hydrogen peroxide is 1 mol of Sb to 1 mol of Sb. , 0.2 to 1.2. In this case, the preferable temperature of the reaction solution to be dropped is 80 to 10
0 ° C. Further, the dropping of hydrogen peroxide may be completed within a short time, or may be performed for a long time.

In step 2, an Nb compound or a Ta compound is added to a dispersion containing Mo, V and Sb, which are reaction products of the above reaction, or an evaporated to dryness thereof, and mixed uniformly. The Nb compound is preferably used in the form of an aqueous solution of oxalate, in which case it is preferable that ammonium ions coexist in the reaction solution obtained in step 1, and the ratio of ammonium ions and oxalate ions to Nb Is preferably an ammonium ion of 2 to 7 and an oxalate ion of 4 to 12 based on 1 of Nb in a molar ratio. As the compound that gives an ammonium ion, ammonia or an aqueous solution thereof is preferable. In the above step 1 or 2, as described above, a mixture containing Mo, V, Sb, A, and B is obtained by adding the metal B compound to the reaction solution, and firing the mixture at 400 ° C. or higher. Thus, the supporting oxide according to the present invention is obtained.

In the firing, first, in the presence of oxygen gas, for example, in the air, etc., at 250 to 350 ° C. for 4 to 10 minutes.
Heating for 500 hours and then 500-66 in inert gas.
It is preferable to perform firing at 0 ° C. for 1 to 3 hours. The content of the metal element in the metal oxide obtained by the calcination can be confirmed by fluorescent X-ray analysis. The supporting metal oxide obtained by the above method is pulverized to an appropriate particle size and used as a powder. As a pulverization method, any of a dry pulverization method and a wet pulverization method can be used, and examples of the pulverization device include a mortar and a ball mill. In the case of wet grinding, examples of the type of the solvent used as a grinding aid include water and alcohols. The preferred particle size of the catalyst is 20 μm or less, more preferably 5 μm.
μm or less.

In the present invention, a compound containing the element X (where X is one or more elements selected from the group consisting of Na and K) is carried on the metal oxide powder. The preferable loading amount of X is 0.001 to 0. 0 in the atomic ratio of element X based on Mo in the supporting oxide.
3, more preferably 0.002 to 0.1. The atomic ratio of the element X based on Mo is 0.00
If it is less than 1, the yield of acrylic acid is low. On the other hand, if it exceeds 0.3, the active surface of the supporting oxide is covered with the element X oxide, so that the conversion of propane decreases. Specific examples of the metal X compound include Na compounds such as sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, sodium nitrate and sodium oxide, and K compounds such as potassium hydroxide, potassium hydrogen carbonate, potassium nitrate and potassium oxide. .

As a method of supporting the metal X compound on the powder of the metal oxide, a method of mixing a solution in which the metal X compound is dissolved in water or an organic solvent with the powder of the supporting oxide is preferable. Further, the metal X compound may be dissolved in various solvents used in wet grinding of the above-mentioned oxide for support, and wet grinding may be performed using the metal X compound. The concentration of the metal X compound solution is suitably from 0.1 to 1.0 mol / l, and the ratio of the solution to the supporting oxide is 100 mol / l.
20 to 50 parts by weight per part by weight is preferred. After mixing the solution of the metal X compound and the powder of the supporting oxide, the mixture is stirred and mixed as uniformly as possible. By evaporating the solvent in the mixture by evaporating to dryness or the like, a metal oxide powder carrying the metal X compound is obtained.

The obtained metal oxide powder is optionally 3
Although firing may be performed at 00 to 500 ° C. for 1 to 5 hours, firing is not necessarily required. As the firing atmosphere, air, nitrogen gas, or the like can be used, but a nitrogen gas atmosphere is preferable. Confirmation of the amount of constituent metals in the obtained metal oxide catalyst can be performed by fluorescent X-ray analysis or the like. The metal oxide catalyst obtained by the above method (hereinafter sometimes simply referred to as a catalyst) can be used without a carrier, but is supported on a carrier having an appropriate particle size, such as silica, alumina, silica-alumina and silicon carbide. Can also be used in state

In the method for producing acrylic acid of the present invention, propane and oxygen gas as raw materials are supplied to a reactor in the presence of the catalyst to cause a reaction. Propane and oxygen gas may be separately introduced into the reactor and mixed in the reactor, or may be introduced into the reactor in a state where both are mixed in advance. Examples of the oxygen gas include pure oxygen gas or air, and a gas obtained by diluting them with nitrogen, steam, or carbon dioxide. When propane and air are used, the ratio of air to propane is preferably 30 times or less by volume, and more preferably 0.1 times or less. ~ 2
The range is 0 times. Preferred reaction temperatures are 300-600
° C, more preferably 350-500 ° C. The gas space velocity (hereinafter referred to as SV) is 300
５5000 ml / Hr is appropriate. Hereinafter, the present invention will be described more specifically with reference to Production Examples, Examples, and Comparative Examples.

[0015]

[Production Example 1] (Production of oxide for supporting a) 6.15 g of ammonium metavanadate was added to 130 ml of distilled water in a 300 ml glass flask, and dissolved by heating under stirring. 87 g, ammonium molybdate 30.9 g and thallium nitrate (divalent)
0.14 g was added. A mixture comprising the above components was added to 36
The mixture was heated and refluxed for 16 hours in a nitrogen gas atmosphere while rotating the stirrer at a rate of 0 rotation / minute. Thereafter, while continuing the heating and stirring, 40 g of a 1.54% by weight aqueous hydrogen peroxide solution was dropped into the reaction solution over 5 minutes. The resulting blue colloidal dispersion was cooled to room temperature, and a room temperature aqueous solution obtained by dissolving 8.82 g of oxalic acid, 2.33 g of niobic acid, and 3.0 g of 28% by weight aqueous ammonia in 75 ml of distilled water was added thereto. Was. After vigorously stirring the resulting mixture for 30 minutes, the water was gradually evaporated and finally dried at 120 ° C. The solid obtained by the above-mentioned operation was
After calcination for 2 hours, the mixture was calcined at 580 ° C. for 2 hours in a nitrogen gas atmosphere to obtain a supporting oxide a. The ratio of the constituent metals of the obtained supporting oxide b was Mo / V / Sb / Nb / Tl =
1.0 / 0.3 / 0.23 / 0.08 / 0.003.

[0016]

[Production Example 2] (Production of supporting oxide b) In Preparation Example 1, 0.317 g of a 82% by weight selenium solution was added instead of 0.14 g of thallium nitrate. In all other respects, the same operation as in Production Example 1 was carried out to obtain a supporting oxide b. The ratio of the constituent metals of the supporting oxide b is Mo / V / Sb / N
b / Se = 1.0 / 0.3 / 0.23 / 0.08 / 0.
008.

[0017]

Example 1 10 of the supporting oxide a obtained in Production Example 1
A solution prepared by dissolving 0.034 g of sodium carbonate in 7 g of distilled water was added to g, and the mixture was thoroughly mixed. The mixture was dried at 120 ° C. for 1 hour to obtain a metal oxide catalyst. The obtained catalyst was converted to fluorescent X
Line, Mo / V / Sb / Nb / Tl
/ Na (impregnated) atomic ratio is 1.0 / 0.3 / 0.23
/0.08/0.003/0.013. The obtained catalyst was pulverized to 16 to 30 mesh, and 1.5 ml
It was filled in a 0 mmφ quartz reaction tube. The reaction tube is 390
℃, propane 4.5%, oxygen gas 7.1
%, 25% of nitrogen gas and 63.4% of steam at a rate of SV = 2380 / Hr (contact time: 2 seconds) to synthesize acrylic acid. The conversion of propane is 59.5% and the selectivity for acrylic acid is 5
5.2% and acrylic acid yield was 32.8%. Incidentally, propane conversion and acrylic acid yield, etc.
It was calculated by the following formula (all calculated by the number of moles). ● Propane conversion (%) = (supply propane-unreacted propane) ÷ supply propane ● Acrylic acid selectivity (%) = produced acrylic acid ÷ (supply propane-unreacted propane) ● Acrylic acid yield (%) = propane Conversion x Acrylic acid selectivity

[0018]

Example 2 A metal oxide catalyst was prepared in the same manner as in Example 1 except that a solution prepared by dissolving 0.063 g of potassium hydrogen carbonate in 7 g of distilled water was added to 10 g of the supporting oxide b. I got As a result of analyzing the obtained catalyst by X-ray fluorescence, the atomic ratio of Mo / V / Sb / Nb / Se / K (impregnated) was 1.0 / 0.3 / 0.23 / 0.08 / 0.
008 / 0.014. Using this catalyst, the same acrylic acid production test as in Example 1 was performed. as a result,
The conversion of propane is 59.6% and the selectivity for acrylic acid is 5
7.8% and acrylic acid yield was 34.4%.

[0019]

Comparative Examples 1 and 2 Acrylic acid production test was carried out in the same manner as in Example 1 using the supporting oxides a (Comparative Example 1) and b (Comparative Example 2). The results of the acrylic acid production test of each of the above examples are as shown in Table 1 (units of numerical values in the table are%).

[0020]

[Table 1]

[0021]

According to the present invention, acrylic acid can be produced from propane in high yield by using the acrylic acid producing catalyst obtained by the production method of the present invention.

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[Procedure amendment]

[Submission date] August 2, 2000 (2008.2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides a metal element Mo, V, S formed by firing a mixture of metal compounds at 400 ° C. or higher.
b, A (A is Nb or Ta) and B (B is Ag, Z
The powder of the metal oxide containing at least one element selected from the group consisting of n, Sn, Pb, As, Cu, Tl and Se is added to the element X (where X is a group consisting of Na and K). it is selected one or more elements) method for producing a metal oxide catalyst for producing acrylic acid, characterized in that for supporting the compound as a constituent component. Hereinafter, the present invention will be described in more detail.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C07C 57/05 C07C 57/05 F term (Reference) 4G069 AA01 AA03 AA08 BC02A BC02B BC03A BC03B BC19A BC19B BC21A BC22A BC26A BC26B BC27A BC31A BC32A BC35A BC54A BC54B BC55A BC55B BC56A BC59A BC59B BD09A BD09B CB17 DA06 EA01Y EB18Y FA02 4H006 AA02 AC46 BA02 BA30 BA55 BA81 BC13 BE30 BS10 4H039 CA65 CC30

Claims (2)

[Claims] 1. A metal element Mo, V, Sb, A (A is Nb or Ta) and B (B is Ag, Zn, Sn, Pb, A) obtained by firing a mixture of metal compounds at 400 ° C. or higher.
a metal oxide powder containing at least one element selected from the group consisting of s, Cu, Tl and Se).
(Where X is at least one element selected from the group consisting of Na and K) on a metal oxide catalyst for acrylic acid production, characterized by supporting a compound having a constituent component and then calcining the compound. Production method. 2. A method for producing acrylic acid by a catalytic oxidation reaction of propane in a gas phase, comprising using a metal oxide catalyst obtained by the production method according to claim 1.