JP2001347165A - Method for producing metal oxide catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a catalyst suitable for use in the preparation of acrylic acid from propane by vapor phase catalytic oxidation in a high yield. SOLUTION: The method for producing a metal oxide catalyst containing Mo, V and Sb has a step in which an Sb (III)-containing compound is reacted with an oxidizing agent in an aqueous medium to oxidize part of the Sb (III) to Sb (V) and a V (V)-containing compound is added to the resulting reacted liquid and heated at >=70 deg.C to convert the remaining Sb (III) to Sb (V). The method is suitable for the production of a metal oxide catalyst in which the ratio among the metal components is represented by the formula, MoV0.01-1.0 Sb0.01-1.0A0.01-1.0B0-0.1 (where A is Nb or Ta, B is one or more elements selected from the group comprising Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Cr, W, Mn, Fe, Ru, Co, Ni, Cu, Ag, Zn, Tl, Sn, Pb, P, As and Se and the atomic ratio of Sb to V is 0.3-1.0).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a metal oxide catalyst, and the metal oxide catalyst obtained by the present invention can be applied to the production of acrylic acid by gas phase catalytic oxidation of propane.

[0002]

2. Description of the Related Art In general, acrylic acid is produced by a contact reaction between propylene and molecular oxygen in the presence of a catalyst to produce acrolein, which is then subjected to a two-stage oxidation in which this is reacted with molecular oxygen. On the other hand, in recent years, because of the price difference between propane and propylene, a method of producing acrylic acid in a single step using propane as a starting material has been studied, and many proposals have been made regarding a catalyst to be used at that time. Representative examples include a [V, P, Te] -based catalyst [Catalysis Today (Catalysis Today), 1
3,679 (1992)], AgBiVMoO (JP-A-2-83348), BiMo12V5Nb0.5.
SbKOn (USP No. 5,198,580) and [M
o, Te, V, Nb] (JP-A-6-279351) and [Mo, Sb, V, Nb] (JP-A-9-3).
No. 16023, JP-A-10-137585, JP-A-1
0-230164). However, the above-mentioned catalyst has problems that the yield of acrylic acid, which is the target product, is insufficient and that the life of the catalyst itself is short. For example, the aforementioned 279351
According to the [Mo, Te, V, Nb] -based catalyst proposed in the above publication, acrylic acid can be obtained in high yield.
Easily evaporates, so that the activity of the catalyst is easily deteriorated with time.
[Mo, Sb, V, Nb] proposed by the present inventors.
The system catalyst (Japanese Patent Application Laid-Open No. Hei 10-137585) has room for improvement in terms of the yield of acrylic acid and the reproducibility of catalyst production.

In Japanese Patent Application Laid-Open No. Hei 10-137585, in order to obtain a metal oxide catalyst comprising Mo, V, Sb and Nb or Ta, a valence of 6 Mo [hereinafter referred to as Mo (V
I)], a compound having a valence of 5 (hereinafter referred to as V (V)) and a Sb having a valence of 3 (hereinafter Sb (III))
It has been proposed to apply a method of simultaneously reacting a contained compound in an aqueous medium with heating, adding an Nb compound or a Ta compound to the product, and calcining the product to convert it to a metal oxide. In the above method, it has been described that a redox reaction represented by the following formula (2) occurs in an aqueous medium as a main reaction, and as a result, a catalyst having high activity in a gas phase catalytic oxidation reaction of an alkane is obtained. V (V) + Sb (III) → V (III) + Sb (V) (2)

[0004]

Means for Solving the Problems The inventors of the present invention have proposed a method for oxidizing propane in a higher yield by oxidizing propane using a catalyst similar to the metal oxide catalyst as disclosed in JP-A-10-137585. As a result of studying to obtain a catalyst capable of producing the present invention, the present invention was completed. That is, the present invention relates to a method for producing a metal oxide catalyst containing Mo, V and Sb, wherein an Sb (III) -containing compound is reacted with an oxidizing agent in an aqueous medium to convert a part of the Sb (III). It is oxidized to Sb (V), and a V (V) -containing compound is added to the resulting reaction solution and the mixture is heated to 70 ° C.
By heating as described above, the remaining Sb (III) is converted to Sb (V).
A method for producing a metal oxide catalyst, comprising a step of converting the catalyst into a metal oxide catalyst. The production method of the present invention is preferably applied to the production of a metal oxide catalyst in which the proportion of a metal component is represented by the following formula (3). MoV _0.01-1.0 Sb _0.01-1.0 A _0.01-1.0 B _0-0.1 (3) (where A is Nb or Ta, and B is N
a, K, Rb, Cs, Mg, Ca, Sr, Ba, Cr,
W, Mn, Fe, Ru, Co, Ni, Cu, Ag, Z
At least one element selected from the group consisting of n, Tl, Sn, Pb, P, As, and Se. Also, Sb / V
(Atomic ratio) = 0.3 to 1.0) Hereinafter, the present invention will be described in more detail.

[0005]

DETAILED DESCRIPTION OF THE INVENTION In the above-mentioned JP-A-10-137585, in order to obtain a metal oxide catalyst comprising Mo, V, Sb and Nb or Ta, a Mo (VI) -containing compound,
A means is employed in which the V (V) -containing compound and the Sb (III) -containing compound are reacted simultaneously in an aqueous medium with heating. On the other hand, in the present invention, an Sb (III) -containing compound is first reacted with an oxidizing agent in an aqueous medium, and a part of the Sb (III) is oxidized to Sb (V) (hereinafter, this step will be referred to as “step”). The first step). Next, the remaining Sb (III) is converted to Sb (V) by adding a V (V) -containing compound to the obtained reaction solution and heating the mixture at 70 ° C. or higher (hereinafter, this step is referred to as a second step). ). According to this means, Sb (III) hardly remains in the obtained reaction product, and the metal oxide catalyst produced using this reaction product as an intermediate material has excellent performance. In the present invention, the Mo (VI) -containing compound may be added together with the Sb (III) -containing compound in the first step, or may be added after the first step or the second step. The Nb-containing compound or Ta-containing compound is preferably added after the completion of the second step. Further, in addition to the above-mentioned metals, Na, K, R
b, Cs, Mg, Ca, Sr, Ba, Cr, W, Mn,
Fe, Ru, Co, Ni, Cu, Ag, Zn, Tl, S
One or more metals selected from the group consisting of n, Pb, P, As, and Se can be added, but the preferred timing of adding these metals is the same as in the case of Mo (VI) described above. is there.

As the Sb (III) -containing compound used in the present invention, antimony trioxide is preferable, and V (V)
As the compound to be contained, ammonium metavanadate or vanadium pentoxide is preferable. Examples of the Mo (VI) -containing compound include ammonium molybdate, molybdenum oxide, molybdic acid, and the like. Preferably, ammonium molybdate is water-soluble. The above Sb (III) -containing compound, Mo (VI) -containing compound and V
(V) The preferred usage ratio of the compound is such that the atomic ratio of Mo, V and Sb constituting the resulting catalyst is such that the following composition formula is obtained. That is, Sb (III): V (V) =
(0.3-1): 1, and V (V): Mo (VI) =
(0.001-3): 1. If the ratio of Sb (III) is less than 0.3, the selectivity of acrylic acid is low, while if it exceeds 1, the conversion of propane is low. The preferred amount of the metal compound in the aqueous medium is 3 to 30 parts by weight in total of three metal compounds per 100 parts by weight of water. If the total amount of the three metal compounds exceeds 30, V
(V) A part of the compound or the Mo-containing compound becomes insoluble, and the reaction is likely to be incomplete.

Examples of the oxidizing agent used for oxidizing the Sb (III) -containing compound include an oxygen-containing gas such as air, oxygen, hydrogen peroxide, nitrates such as ammonium nitrate, nitric acid, and organic oxides. At least one of these oxides is added to an aqueous medium in which an Sb (III) -containing compound is dispersed or dissolved, and an oxidation reaction is performed. The oxidation reaction between the Sb (III) -containing compound and the oxidizing agent may be performed in the presence or absence of the Mo (VI) -containing compound. ) It is preferred to carry out in the presence of the containing compound. The preferred reaction temperature in this oxidation step is from room temperature to 100 ° C, more preferably from 70 to 100 ° C. The reaction time is
Depending on the type of the oxidizing agent, several minutes to several hours are appropriate. When the above-mentioned oxidizing agent is used, hydrogen peroxide or an aqueous solution of hydrogen peroxide is preferable in that it is easy to handle and the approximate amount of the Sb-containing compound to be oxidized is easily grasped. The preferable addition amount of hydrogen peroxide is usually 0.2 to 0.8 when Sb is 1 in a molar ratio. By using this amount of hydrogen peroxide, Sb (I
About 20 to 80% by weight of (II) is oxidized to Sb (V).
Further, a preferable oxygen gas concentration in the oxygen-containing gas is:
0.5 vol% or more, more preferably 1 to 2
0 vol%. The preferred blowing speed (flow rate) is
Although depending on the amount of the reaction solution, the amount of the reaction solution is 200 ml to 500
If it is about ml, 3 to 12 liters / Hr is preferable. The time for blowing the oxygen-containing gas into the reaction solution is preferably 4 hours or more. Further, it is preferable to stir the reaction solution while blowing the oxygen-containing gas. Instead of blowing oxygen-containing gas or adding hydrogen peroxide, or in conjunction with these operations, nitric acid or ammonium nitrate is used in a molar ratio of S
You may add the amount of about 0.1-2.54 with respect to b.

Next, a V (V) -containing compound is added to a reaction solution of the oxidation reaction (a dispersion of the Sb-containing compound or a dispersion of the Sb-containing compound and the Mo-containing compound) and heated at 70 ° C. or more. , S still remaining in the reaction solution
b (III) is converted to Sb (V). The preferred reaction temperature is from 95 ° C to the reflux temperature, and the reaction time may be from about 0.5 to 50 hours. The Nb-containing compound or the Ta-containing compound is further added to the dispersion containing Mo, V, and Sb obtained by adding the Mo-containing compound after the above-mentioned reaction or after the above-mentioned reaction, and the mixture is uniformly mixed. By calcining by a known method, a metal oxide catalyst is obtained.
Examples of the Nb-containing compound or Ta-containing compound include niobium oxide, niobic acid, tantalum oxide, and tantalic acid. The Nb-containing compound and the Ta-containing compound may be used in a form in which they are dispersed in water, but are more preferably used in the form of an aqueous solution of oxalate using oxalic acid or the like. The amount of the Nb-containing compound or Ta-containing compound used is
The amount is such that Nb or Ta is 0.001 to 3.0 when Mo is 1 in the atomic ratio of metal in the obtained catalyst. Nb or T when Mo in catalyst is 1
If the ratio of a is less than 0.001, the catalyst deteriorates. On the other hand, if it exceeds 3.0, the catalyst has low activity and the conversion of propane decreases.

The mixture of the metal compounds obtained by the above operation is dried by a method such as evaporation to dryness or spray drying, and then converted to a metal oxide having a specific crystal structure by baking treatment. The catalyst in the present invention is obtained by calcining the above mixture in the presence of oxygen at a temperature of 250 ° C. to 350 ° C. (preferably 280 ° C. to 320 ° C.) for 2 to 20 hours (preferably 4 to 10 hours). In the absence, the temperature is 500 to 660 ° C. (preferably 570 to 620
C.) for 0.5 to 6 hours (preferably 1 to 3 hours).

The metal oxide catalyst obtained by the above method is preferably pulverized to an appropriate particle size to increase the surface area. As the pulverization method, either a dry pulverization method or a wet pulverization method can be used. Examples of the crusher include a mortar, a ball mill and the like. In the case of wet pulverization, examples of the type of the solvent used as a pulverization aid include water and alcohols. The preferred particle size of the catalyst is
It is 20 μm or less, more preferably 5 μm or less. The metal oxide catalyst can be used in a carrier-free state, but diatomaceous earth having an appropriate particle size, silica, alumina,
It can be used in a state of being supported on a carrier such as silica alumina and silicon carbide. The metal oxide catalyst obtained by the present invention is suitable as a catalyst for the gas phase catalytic oxidation reaction of alkanes, and particularly suitable as a reaction catalyst for producing acrylic acid or acrolein from propane.

Hereinafter, a method for producing acrylic acid from propane using the present catalyst will be described. Propane and oxygen gas used for the production of acrylic acid 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. It is also preferable to supply oxygen gas through the wall (one side not open) of the porous ceramics tube inserted into the reaction tube. 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, more preferably 0.1% by volume.
The range is 2 to 20 times. Propane, an unreacted raw material obtained from the outlet of the reactor, and propylene, an intermediate product, can be used as fuel as they are, but after being separated from other components in the product, they are introduced into the reactor. It can be reused. Preferred reaction temperature is 300-600 ° C
And more preferably 350 to 500 ° C. The gas space velocity (hereinafter referred to as SV) is 300
５5000 / hr is appropriate.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. 1.0 ml (about 1.5 g) of the catalyst obtained in each example was filled in an 8 mmφ quartz reaction tube. The reaction tube was heated to 400 ° C., and 3.7% by volume of propane, 9.2% by volume of oxygen,
Acrylic acid was synthesized by supplying a mixed gas of 4.8% by volume and 52.3% by volume of steam at a rate of 2100 / hr. Based on the reaction products, the following conversions and selectivities were calculated, and the performance of the used catalyst was evaluated based on those values. The results are shown in Table 1 below. The propane conversion and the acrylic acid selectivity were calculated based on the following formulas (all calculated by moles). -Propane conversion (%) = (supply propane-unreacted propane) / supply propane-Acrylic acid selectivity (%) = formed acrylic acid / (supply propane-unreacted propane)-Acrylic acid yield (%) = propane Conversion x Acrylic acid selectivity

[0013]

Example 1 In a 300 ml glass flask which was sufficiently purged with nitrogen by flowing a large amount of nitrogen gas, 30.9 g of ammonium molybdate was added to 130 ml of distilled water, dissolved under stirring, and dissolved by heating. 5.87 g of antimony was added. The mixture consisting of the above components is
After heating for 1 hour in a nitrogen gas atmosphere while rotating the stirrer at a rate of rotation / minute, 40 g of 1.40% by weight of hydrogen peroxide solution was mixed and further heated at about 100 ° C. for 2 hours. Further, ammonium metavanadate is contained in the solution.
15 g was added, and the mixture was heated under reflux for 2.5 hours. The resulting blue colloidal dispersion was cooled to room temperature, and a room temperature aqueous solution in which 8.82 g of oxalic acid and 2.33 g of niobic acid were dissolved in 75 ml of distilled water was added. After vigorously stirring the resulting mixture for 30 minutes, ammonium nitrate 5.0
g, and then heat and concentrate.
And evaporated to dryness. The obtained solid was calcined at 290 ° C. for 5 hours, and then calcined at 590 ° C. for 2 hours in a nitrogen gas stream to obtain a metal oxide catalyst. The obtained catalyst was tablet-molded, further pulverized to 16 to 30 mesh, and used for an acrylic acid production reaction. The atomic ratio of this catalyst is Mo / V / Sb / Nb = 1.0 / 0.3 / 0.23
/0.08. The results of conducting an acrylic acid synthesis test using this catalyst are as shown in Table 1.

[0014]

Example 2 Example 1 was repeated except that 0.35 g of potassium bicarbonate was added together with ammonium molybdate.
A catalyst was produced under the same conditions as described above. The atomic ratio of this catalyst is
Mo / V / Sb / Nb / K = 1.0 / 0.3 / 0.23
/0.08/0.02. The results of conducting an acrylic acid synthesis test using this catalyst are as shown in Table 1.

[0015]

Example 3 5.87 g of antimony trioxide and 0.35 g of potassium hydrogencarbonate were added to 130 ml of distilled water and mixed in a 300 ml glass flask which was sufficiently purged with nitrogen by flowing a large amount of nitrogen gas. In the solution:
40 g of a 40% by weight aqueous hydrogen peroxide solution was mixed and heated under reflux for 1 hour. Furthermore, ammonium metavanadate 6.1
5 g and 30.9 g of ammonium molybdate were added, and the mixture was heated under reflux for 1 hour. The resulting blue colloidal dispersion was cooled to room temperature, and a room temperature aqueous solution in which 8.82 g of oxalic acid and 2.33 g of niobic acid were dissolved in 75 ml of distilled water was added. The resulting mixture was vigorously stirred for 30 minutes in a nitrogen gas atmosphere, and then ammonium nitrate was added.
After adding 0 g to homogenize and concentrating by heating, another 120 g was added.
Evaporated to dryness at ° C. The obtained dried product was fired, molded, and pulverized in the same manner as in Example 1 and used for an acrylic acid production reaction. The atomic ratio of this catalyst is Mo / V / Sb / Nb /
K = 1.0 / 0.3 / 0.23 / 0.08 / 0.02. The results of conducting an acrylic acid synthesis test using this catalyst are as shown in Table 1.

[0016]

[Table 1]

[0017]

According to the method of the present invention, a catalyst which is applied to a gas phase catalytic oxidation reaction of propane and can synthesize acrylic acid from propane in a high yield can be stably obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 51/215 C07C 51/215 57/05 57/05 // C07B 61/00 300 C07B 61/00 300 F Term (reference) 4G069 AA02 AA08 BB06A BB06B BC02A BC03A BC03B BC05A BC06A BC09A BC10A BC12A BC13A BC19A BC21A BC22A BC26A BC26B BC27A BC31A BC32A BC35A BC54A BC54B BC55A BC55B BC56ABC58ABCBCA BCBC BC BC AA02 AC46 BA02 BA05 BA06 BA07 BA09 BA11 BA12 BA13 BA14 BA15 BA16 BA19 BA20 BA21 BA23 BA30 BA35 BE30 BS10 4H039 CA65 CD10 CD30

Claims (3)

[Claims] 1. A method for producing a metal oxide catalyst containing Mo, V and Sb, comprising reacting an Sb (III) -containing compound with an oxidizing agent in an aqueous medium to convert a part of the Sb (III) into Sb.
(V), a V (V) -containing compound is added to the resulting reaction solution, and the mixture is heated at 70 ° C. or higher to obtain residual Sb (III).
A process for converting metal to Sb (V). 2. The method for producing a metal oxide catalyst according to claim 1, wherein the ratio of the metal component in the metal oxide catalyst is represented by the following formula (1). MoV _0.01-1.0 Sb _0.01-1.0 A _0.01-1.0 B _0-0.1 (1) (where A is Nb or Ta, and B is N
a, K, Rb, Cs, Mg, Ca, Sr, Ba, Cr,
W, Mn, Fe, Ru, Co, Ni, Cu, Ag, Z
At least one element selected from the group consisting of n, Tl, Sn, Pb, P, As, and Se. Also, Sb / V
(Atomic ratio) = 0.3 to 1.0) 3. The reaction of an Sb (III) -containing compound with an oxidizing agent in an aqueous medium oxidizes 20 to 80% by weight of Sb (III) to Sb (V), and then converts the V (V) -containing compound to Sb (V). The method for producing a metal oxide catalyst according to claim 1, wherein the metal oxide catalyst is added.