JPH11226408A - Method for producing metal oxide catalyst - Google Patents

Abstract

(57) [Summary] [Objective] To obtain a metal oxide catalyst using a metal as a raw material. SOLUTION: In preparing an oxide catalyst containing an element M (M is one or more selected from tellurium, antimony and bismuth) and an element N (N is one or more selected from molybdenum, tungsten and vanadium). A method for producing a metal oxide catalyst, comprising using a solution containing an element M and an element N obtained by reacting an oxometalate containing the element N with a metal M in a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a composite oxide catalyst. More specifically, the present invention relates to a method for producing a composite oxide catalyst used in a gas phase catalytic oxidation reaction.

[0002]

2. Description of the Related Art A complex oxide containing tellurium, antimony, and bismuth as essential components has been widely known as a catalyst, particularly as a partial oxidation catalyst. The specification of Japanese Patent Application Laid-Open No. Hei 9-157241 is 4
Ammoxidation of propane to acrylonitrile at temperatures below 50 ° C. is disclosed.

In order to reproducibly prepare a catalyst for producing an industrially useful unsaturated nitrile or unsaturated carboxylic acid by subjecting an inert substance such as paraffin to gas phase catalytic oxidation at a relatively low temperature, It is important to select a catalyst raw material. In general, for preparing a metal composite oxide catalyst, a method of mixing a solution obtained by dissolving a raw material soluble in water or an organic solvent in a solvent, drying and calcining is used because it is necessary to uniformly mix the raw material salts. If this method is not used, a method of reacting the raw material metal or oxide at a high temperature in the solid phase is used, but physical properties such as surface area are compared with those prepared from a uniform aqueous solution. The performance as a catalyst is often inferior for reasons such as being different or the structure of the formed composite oxide being different. Therefore, conventionally, when producing a catalyst on an industrial scale, when it is difficult to obtain a raw material that is soluble in water or an organic solvent, it is often necessary to use the raw material metal by dissolving it in a mineral acid such as nitric acid. Was.

[0004]

In particular, although tellurium, antimony and bismuth are known as essential elements of a catalyst for a catalytic partial oxidation reaction, there are inexpensive and readily available soluble compounds on an industrial scale. In many cases, even if the performance of the catalyst is excellent, sufficient economic efficiency cannot be secured for industrial scale implementation, or the original activity may not be sufficiently exhibited. Also, the use of mineral acids corrodes catalyst manufacturing facilities,
It is not desirable because it combines with ammonium ions and the like present in the catalyst raw material to form an explosive compound, and generates harmful gas during heat treatment of the catalyst. After dissolving in mineral acid, there is a method of extracting only water-soluble compounds that do not contain nitrate groups, sulfate groups, etc. by ion exchange, separation and purification, etc., but this is performed as part of catalyst production in terms of equipment and cost required for implementation. It is very difficult.

[0005]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies on a method for producing a gas phase catalytic oxidation reaction catalyst using metal M as a raw material. The present inventors have found that a catalyst can be easily produced by using, as a raw material, a solution obtained by contacting with a solution in which a metalate is dissolved, and have reached the present invention. That is, the gist of the present invention is to provide an oxide catalyst containing an element M (M is at least one selected from tellurium, antimony and bismuth) and an element N (N is at least one selected from molybdenum, tungsten and vanadium). The preparation of a metal oxide catalyst, characterized by using a solution containing an element M and an element N obtained by reacting an oxometalate containing the element N with a metal M in a solvent. Be in the way.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the metal M, M represents at least one selected from tellurium, antimony and bismuth, and is preferably tellurium and antimony, more preferably tellurium or antimony. The element N is at least one selected from molybdenum, tungsten, and vanadium, and is preferably molybdenum or vanadium.

The oxometalates containing the element N include:
Ammonium paramolybdate, ammonium metavanadate, ammonium paratungstate, ammonium metatungstate, molybdic acid, vanadic acid, phosphomolybdic acid, phosphotungstic acid, silicomolybdic acid, silicotungstic acid, and the like, and ammonium paramolybdate, Ammonium metavanadate is preferably used.

[0008] As the solvent, water, ethylene glycol,
Examples thereof include alcohols such as ethanol and methanol, and oxygen-containing organic solvents such as acetone and ether. Water is preferably used. The reaction of the oxometalate containing the element N and the metal M in the solid state in a solvent is performed by first dissolving the oxometalate in the solvent, then charging the metal M in the solid state and heating the solution. As a result, a solution containing the element M and the element N can be obtained. Even if there is no oxidizing agent other than oxometallate,
The oxometalate itself becomes an oxidizing agent, and the metal M is oxidized and dissolved.

The oxometalate containing the element N and the metal M are added in a molar ratio of the metal M to the element N, usually 1:
0.01 to 1: 100. When no oxidizing agent other than oxometallate containing element N is used, the atomic ratio of metal M: element N is 1: 6 to 1: 100 when M is tellurium, and M
Is preferably antimony, the ratio is preferably in the range of 1: 5 to 1: 100. If the proportion of the element N is too small, a sufficient dissolution rate cannot be obtained, while if the proportion of the element N is too large, it becomes difficult to obtain a catalyst having a desired element ratio, which is not preferable.

In dissolving the oxometalate containing the element N and the metal M in a solvent, an oxidizing agent is added to the reaction system to increase the amount of the element M dissolved or to shorten the time required for dissolution. It is possible to do. Examples of the oxidizing agent include normal or pressurized air, normal or pressurized oxygen, ozone, inorganic peroxides such as hydrogen peroxide, and organic peroxides. Oxygen, hydrogen peroxide and ozone are preferred.

The reason why the presence of the oxometalate containing the element N significantly accelerates the oxidation and dissolution of the metal M is not fully understood, but it is understood that the oxygen of the oxometalate itself is activated, When the agent is added, the oxometalate is combined with the oxidizing agent to form an activated oxygen species, thereby rapidly oxidizing M. Further, ions M n + generated by the oxidation of M are rapidly formed. It is presumed that oxometallate and heteropolyoxometallate coexisting in the compound make the dissolution easy. For example, in the case of antimony, it is difficult to obtain an aqueous solution containing antimony by other methods because antimonic acid is very easily polymerized in an aqueous solution, and quickly precipitates an insoluble oxide or hydroxide. That's why. The present inventors oxidize a water-insoluble antimony material such as antimony metal and antimony trioxide in water with oxometalate to produce dissociated antimonic acid and the like, and before the polymer is changed into an insoluble solid substance by polymerization. It is believed that the coordination of an oxometalate such as molybdenum or vanadium makes it possible to obtain a stable and stable solution containing antimony suitable for catalyst production.

Although the structure of the antimony-containing substance in the solution state obtained in the present invention is not sufficiently clear, it is not clear from Y. Sasa
ki et al. (Acta Crystallographic)
aSection C: Crystal Struct
ure Communications, 1988, C
44 , 1879-1881), a heteropolyanion having antimony as a heteroatom and molybdenum as a polyatom, or J. Am. Lemerle et al. (Noveve
au Journal De Chimie, 198
7, 11 , 265-270 and Canadian
Journal of Chemistry, 199
0, 68 , 36-40), there is a possibility that antimony and vanadium or molybdenum oxo acid are condensed to form a water-soluble inorganic polymer.

The formation of a structure in which an oxyacid of a different metal element is condensed in an aqueous solution as described above facilitates the interaction between different elements, so that a highly active element such as that used in the catalytic oxidation reaction of alkanes is used. This is considered to be a very important condition in producing a metal oxide catalyst which is required to have a complex and complicated function. In the thus obtained solution containing the element M and the element N, a compound containing another catalyst component, a compound containing the element M, a compound containing the element N, and the like are dissolved so as to obtain a desired catalyst composition. Alternatively, the metal oxide catalyst is obtained by suspending and drying and calcining the obtained solution or slurry.

Compounds containing other catalyst components include oxo acid salts, carboxylate salts, ammonium halide salts, oxides, halides, acetylacetonates,
Alkoxides and the like can be used. Examples of the compound containing the element M include telluric acid, tellurium dioxide, tellurium trioxide, antimony trioxide, antimony pentoxide, bismuth trioxide, bismuth hydroxide, bismuth pentoxide, and the like.
Examples of the compound containing are oxo acid salts, oxides and the like.

Drying is performed by an evaporation to dryness method, a spray drying method, or a vacuum drying method. The firing is usually carried out in a nitrogen atmosphere at a temperature of 3
The reaction is performed at a temperature of 50 to 700 ° C. for a time of 0.5 to 30 hours. The catalyst obtained by the production method of the present invention comprises the element M
(M is one or more selected from molybdenum, tungsten and vanadium) and a metal oxide catalyst containing both elements N (N is one or more selected from tellurium, antimony and bismuth).

The metal oxide catalyst obtained by the production method of the present invention is used for producing an organic compound by a catalytic oxidation reaction of a hydrocarbon. The gas phase catalytic oxidation reaction of hydrocarbons is
It is a gas-phase catalytic oxidation of hydrocarbons with oxygen, but also includes reactions in which ammonia and water vapor are present in the reaction system in addition to oxygen, and includes various kinds of oxygen-containing organic compounds, dehydrogenated organic compounds, nitriles, etc. Used for production of organic compounds.

Among the metal oxide catalysts obtained by the production method of the present invention, in particular, a catalyst containing both molybdenum, vanadium, tellurium and / or antimony (Mo)
-V-Te (Sb) -containing catalyst) has excellent catalytic activity even in the partial oxidation reaction of alkane having low reactivity among hydrocarbons, and by appropriately selecting the conditions of the gas phase catalytic oxidation reaction, acrylonitrile and the like can be obtained. Of nitriles (JP-A-2-257, 5-148212, 5-20813)
6, 9-157241) and various reactions such as production of α, β-unsaturated carboxylic acids such as acrylic acid (JP-A-6-287184). In particular, the catalyst composition represented by the empirical formula (1) is preferably used.

[0018]

[Number 2] _{Mo a V b X c Y x} O n (1)

In the formula, X is at least one element selected from Te or Sb, and Y is Ti, Zr, Nb, Tb.
a, Cr, W, Mn, Fe, Ru, Co, Rh, Ir,
Ni, Pd, Pt, Cu, Ag, Zn, In, Sn, P
b, Bi, Ce, at least one metal element selected from alkali metals and alkaline earth metals;
When it is 1, 0.01 ≦ b ≦ 1, preferably 0.1 ≦ b
b ≦ 0.6, 0 <c ≦ 1, preferably 0.01 ≦ c ≦
0.4, 0 ≦ x ≦ 1, preferably 0.01 ≦ x ≦
0.6 and n are values determined by the oxidation state of other elements. Further, among the empirical formulas (1), those represented by the following empirical formulas (2) and (3) are preferably used for the alkane oxidation reaction.

[0020]

Equation 3] _{Mo a V b Te c Y x} O n (2) Mo a V b Sb c Y x O n (3)

The metal oxide obtained by the method of the present invention can be used alone as a catalyst, but the metal oxide obtained by the method of the present invention and one or more of Si, Al, Zr, Ti, and alkaline earth metals can be used. And a carrier component such as an oxide of the same may be used in the same particle. Further, the reaction may be performed in a state where particles containing a metal oxide and particles composed of one or more oxides of Si, Al, Zr, Ti, and alkaline earth metals are mixed.

Examples of the hydrocarbon as a raw material for the oxidation reaction include alkanes or alkenes having 3 to 8 carbon atoms, aromatic compounds having 6 to 12 carbon atoms, and the like. As an example of the reaction,
Production of nitriles by ammoxidation of alkanes or alkenes (eg production of acrylonitrile by ammoxidation of propane or propene, production of methacrylonitrile by ammoxidation of isobutane or isobutene, etc.), unsaturation by partial oxidation of alkanes or alkenes Simultaneous production of nitrile and unsaturated carboxylic acid by production of carboxylic acid (for example, production of acrylic acid from propane or propene, production of methacrylic acid from isobutane or isobutene), partial oxidation reaction of alkane or alkene in the presence of ammonia (Eg, simultaneous production of acrylonitrile and acrylic acid from propane), oxidative dehydrogenation of saturated carboxylic acids (eg, methacrylic acid from isobutyric acid), oxidative dehydrogenation of hydrocarbons (eg, ethane to ethylene, Production of propene from butene, butadiene from butene), production of acid anhydrides by partial oxidation of various hydrocarbons (eg, production of phthalic anhydride from naphthalene or xylene, maleic anhydride from butane or butene, etc.) There is.

The conditions for the gas phase catalytic oxidation reaction of hydrocarbons on the metal oxide catalyst represented by the formula (1) obtained by the production method of the present invention are as follows:
Since the catalyst has the property of high partial oxidation activity of alkanes even at a relatively low temperature of 500 ° C. or less, the reaction temperature is 300 to 500 ° C., preferably 350 to 480.
° C, gas hourly space velocity (SV) in gas phase reaction is 100 ~
10,000 hr ^-1 , preferably 300 to 6000 hr ^-1
And the pressure of the reaction is not particularly limited. In addition, an inert gas such as nitrogen, helium, or argon can be used as the diluting gas. For the reaction, either a fixed bed or a fluidized bed can be employed, but the temperature of the fluidized bed is more easily controlled. In addition, the removal of heat of reaction in the fluidized bed can be further facilitated by the presence of oxide particles inert to the reaction in the reaction system.

The metal oxide catalyst represented by the formula (1) obtained by the production method of the present invention is effective for producing nitriles by ammoxidation of alkanes, particularly for producing acrylonitrile from propane. In this case, in the reaction feed gas, oxygen is preferably in a range of 0.2 to 4 moles per mole of propane, and ammonia is preferably in a range of 0.1 to 3 moles per mole of propane.

The metal oxide catalyst represented by the formula (1) obtained by the production method of the present invention is capable of converting acrylic acid in a high yield by partial oxidation of unsaturated carboxylic acid, especially propane by partial oxidation of alkane. Obtainable. As the reaction raw material gas, propane and an oxygen-containing gas are used, and it is more preferable to use water vapor, and it is possible to suppress the generation of carbon dioxide and the like and further increase the selectivity of acrylic acid. In addition, the metal oxide catalyst represented by the formula (1) obtained by the production method of the present invention can be used under the reaction conditions of the partial oxidation reaction of propane in the presence of ammonia, in particular, the molar ratio of ammonia and oxygen to propane, the reaction temperature, and the like. Acrylonitrile and acrylic acid can be simultaneously produced by controlling the temperature.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded. The propane conversion (%), acrylonitrile selectivity (%), and acrylonitrile yield (%) in the following Examples and Comparative Examples are respectively represented by the following formulas. Propane conversion (%) = (moles of propane consumed / moles of propane supplied) × 100 Selectivity of acrylonitrile (%) = (moles of acrylonitrile formed / moles of propane consumed) × 100 Selectivity of acrylic acid (%) = (Mol number of produced acrylic acid / mol number of consumed propane) × 100

<Example 1> Experimental formula Mo₁V_0.3Nb_0.12
Te_0.23O_nThe metal oxide catalyst represented by
Made. 5.89 g of ammonium paramolybdate in water
Dissolve in 30 ml, tellurium powder (particle size about 150 micron
0.979 g was suspended at room temperature. 35% over this
2.28 g of an aqueous hydrogen oxide solution was added, and the mixture was stirred for 70 minutes.
Warmed to ° C. Solution turns colorless at the same time as hydrogen peroxide is added
It turned yellow. With continued heating and stirring, tellurium is completely
Upon dissolution, the solution became colorless. Metavanadate after dissolution
After adding 1.17 g of ammonium to make a homogeneous solution,
Dissolve 1.8 g of ammonium niobium oxalate in 20 ml of water
The mash was added and dried to give a dry solid. This dry
The dried solid is treated at about 300 ° C until no ammonia smell is present.
After calcination in a nitrogen stream at 600 ° C. for 2 hours, metal
An oxide catalyst was obtained. Metal oxide catalyst in fixed bed reactor
And the propane / ammonia / air molar ratio was 1 /
Under the reaction gas flow of 0.3 / 4, the space velocity (SV) is about
5000 hr ^-1Ammoxidation reaction of propane
Was. Table 1 shows the results.

<Embodiment 2> Experimental formula Mo₁V_0.3Nb_0.12
Te_0.23O_nThe metal oxide catalyst represented by
Made. 5.89 g of ammonium paramolybdate and
1.17 g of ammonium metavanadate and 60 ml of water
Dissolved in tellurium powder (particle size about 150 microns) 0.9
79 g were suspended. Reflux the suspension while stirring it.
went. The suspension is immediately molybdenum or vanadium
Blue color indicating the reduction of the oxometallate of the compound. this
While blowing air into the suspension at a flow rate of 100 ml per minute,
Reflux was performed. After 20 hours, all the tellurium powder has dissolved
After confirming that, 1.8 g of ammonium niobium oxalate
Was dissolved in 20 ml of water, and dried to dry solid.
I got a body. This dried solid has an ammonia odor at about 300 ° C.
After treatment until no longer occurs, 2 hours at 600 ° C in a nitrogen stream
After calcining for a time, a metal oxide catalyst was obtained. Metal oxide catalyst
Into a fixed bed reactor, propane / ammonia / empty
Empty under a reaction gas flow with a gas molar ratio of 1 / 0.3 / 4
Speed (SV) about 3300 hr ^-1Under the conditions of propane
An ammoxidation reaction was performed. Table 1 shows the results.

<Embodiment 3> Experimental formula Mo ₁ V _0.3 Nb _0.12
The metal oxide catalyst represented by Te _0.23 O _n was prepared as follows. Preparation was performed in the same manner as in Example 2 except that reflux was performed for 20 hours without blowing air. An ammoxidation reaction of propane was performed under the same reaction conditions as in Example 2. Table 1 shows the results.

<Embodiment 4> Experimental formula Mo ₁ V _0.3 Nb _0.05
The metal oxide catalyst represented by sb _0.15 O _n was prepared as follows. 5.89 g of ammonium paramolybdate are dissolved in 30 ml of water, and 0.61 g of antimony powder (particle size: about 100 microns) is suspended at room temperature. 3 g of a 35% aqueous hydrogen peroxide solution was added, and the mixture was heated to 70 ° C. with stirring. The solution changes from colorless to yellow at the same time as the dropwise addition of hydrogen peroxide, but with continued heating and stirring, all the antimony dissolves,
A completely homogeneous colorless solution resulted. After dissolution, 1.17 g of ammonium metavanadate was added to make a uniform solution, and 0.75 g of ammonium niobium oxalate was added to 10 m of water.
and dried to give a dry solid.
After treating the dried solid at about 400 ° C.,
It was calcined at 00 ° C. for 2 hours to obtain a metal oxide catalyst. The metal oxide catalyst is charged into a fixed bed reactor, and under a condition of a space velocity (SV) of about 3300 hr ^-1 under a reaction gas flow in which a molar ratio of propane / ammonia / air is 1 / 0.3 / 4. An ammoxidation reaction of propane was performed. Table 1 shows the results.

Comparative Example 1 Experimental formula Mo ₁ V _0.3 Nb _0.12
The metal oxide catalyst represented by Te _0.23 O _n was prepared as follows. 5.89 g of ammonium paramolybdate and 1.17 g of ammonium metavanadate were added to 60 ml of water.
Dissolved in tellurium powder (particle size about 150 microns) 0.9
79 g were suspended. Immediately after that, a solution prepared by dissolving 1.8 g of niobium ammonium oxalate in 20 ml of water was added, and dried immediately to obtain a dry solid. No discoloration of the solution as in Example 2 was observed. The dried solid is treated at about 300 ° C. until the smell of ammonia disappears, and then dried in a nitrogen stream for 6 hours.
It was calcined at 00 ° C. for 2 hours to obtain a metal oxide catalyst. The metal oxide catalyst is charged into a fixed bed reactor, and under a condition of a space velocity (SV) of about 3300 hr ^-1 under a reaction gas flow in which a molar ratio of propane / ammonia / air is 1 / 0.3 / 4. An ammoxidation reaction of propane was performed. Table 1 shows the results.

[0032]

[Table 1]

[0033]

According to the present invention, mineral acids and organic solvents that cause corrosion of production equipment and generation of harmful substances, or substances such as tartaric acid, which makes catalyst production difficult, can be used.
A metal oxide catalyst can be obtained using a metal as a raw material.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 23/64 B01J 23/64 Z 23/88 23/88 Z 23/89 23/89 Z C07B 61/00 300 C07B 61/00 300 // C07C 57/05 C07C 57/05 253/24 253/24 255/08 255/08

Claims (5)

[Claims] An oxide catalyst containing an element M (M is at least one selected from tellurium, antimony and bismuth) and an element N (N is at least one selected from molybdenum, tungsten and vanadium) is prepared. A method for producing a metal oxide catalyst, comprising using a solution containing an element M and an element N obtained by reacting an oxometalate containing the element N with a metal M in a solvent. 2. The method for producing a metal oxide catalyst according to claim 1, wherein an oxidizing agent is added when the oxometalate containing the element N and the metal M are reacted in the solvent. 3. The method for producing a metal oxide catalyst according to claim 1, wherein M is tellurium or antimony. 4. The method according to claim 1, wherein the oxometalate containing the element N is ammonium paramolybdate, ammonium metavanadate, ammonium paratungstate or ammonium metatungstate. A method for producing a metal oxide catalyst. 5. The method for producing a metal oxide catalyst according to claim 1, wherein the metal oxide catalyst is a composite oxide catalyst represented by empirical formula (1). . [Number 1] _{Mo a V b X c Y x} O n (1) ( In the formula, X, Te and / or Sb, Y is, Sb,
Ti, Zr, Nb, Ta, Cr, W, Mn, Fe, R
u, Co, Rh, Ir, Ni, Pd, Pt, Cu, A
g, Zn, In, Sn, Pb, Bi, Ce, at least one metal element selected from alkali metals and alkaline earth metals, and when a = 1, 0.01 ≦ b
≦ 1, 0 <c ≦ 1, 0 ≦ x ≦ 1, and n is a value determined by the oxidation state of another element.)