WO2005065825A1

WO2005065825A1 - Method for preparing composite oxide catalyst and composite oxide catalyst

Info

Publication number: WO2005065825A1
Application number: PCT/JP2004/013972
Authority: WO
Inventors: Hisao Kinoshita; Isao Teshigahara
Original assignee: Mitsubishi Chemical Corporation
Priority date: 2003-12-26
Filing date: 2004-09-24
Publication date: 2005-07-21
Also published as: CN1697703A

Abstract

A method for preparing a composite oxide catalyst having the following formula (1): Mo12NbaVbSbcCudSieCfOg (1) [wherein each valuable has the following meaning, that is, a, b, c, d, e, f or g represents the atomic ratio of each element, and, relative to 12 of molybdenum atom, 0 < a ≤ 10, 0 < b ≤ 10, 0 < c ≤ 5, 0 < d ≤ 5, 0 < e ≤ 1000, 0 < f ≤ 1000, and g is a number which depends on oxidation degrees of the above respective components expect Si and C], which comprises providing raw material compounds for respective metal components constituting the catalyst and a raw material compound for Si and C having a chemical bond of Si and C, forming an aqueous solution or dispersion containing the above raw material compounds dissolved or dispersed in an aqueous medium, heating the aqueous solution or dispersion to 70°C or higher, blowing an ozone-containing gas into the aqueous solution or dispersion, drying the resultant aqueous solution or dispersion into a powder, and forming the powder followed by firing.

Description

Method for producing composite oxide catalyst, and composite oxide catalyst

Technical field

The present invention provides a composite oxide catalyst for producing a corresponding unsaturated carboxylic acid stably over a long period of time and in a high yield by subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas. And a method for producing the same.

Background art

[0002] Conventionally, various catalysts have been proposed for producing unsaturated carboxylic acids such as acrylic acid and methacrylic acid by subjecting unsaturated aldehydes such as acrolein and methacrolein to gas-phase catalytic oxidation with molecular oxygen. I have. From the viewpoint of effective utilization of unsaturated aldehyde raw materials produced in Olefinka and rationalization of the process in the reaction, these catalysts are required to select a high degree of conversion of unsaturated aldehydes and selection of unsaturated carboxylic acids as target products. Rate is required. For example, when the reaction to produce acrolein force acrylic acid is manufactured in a 60,000-ton Z-year scale plant, if the above conversion and selectivity improve even at 0.1%, the resulting product, acrylic acid Increases significantly at the level of hundreds of tons. Therefore, the improvement of the catalyst performance such as the conversion and the selectivity, even with a slight improvement, greatly contributes to the effective use of resources and the rationalization of the process.

[0003] Conventionally, various proposals have been made with the aim of improving the catalyst performance such as the raw material conversion and selectivity of these reactions. For example, Patent Document 1 discloses that Mo—V produced by a step of heating Mo, V, and Sb in an aqueous medium and adding hydrogen peroxide to the reaction solution during or after the reaction. — Sb— Nb (or Ta) -based catalysts are disclosed. Patent Document 2 discloses that Mo, V, and Sb are heated and reacted in an aqueous medium, and during or after the reaction, the reaction solution is reacted. A Mo—V—Sb—Nb (or Ta) -based catalyst produced through a step of blowing molecular oxygen or a gas containing the oxygen into the catalyst is disclosed!

[0004] However, these conventional composite oxide catalysts exhibit excellent performance, respectively, but have an even higher performance. ヽ Improvement in the conversion of raw material unsaturated aldehyde and the selectivity of unsaturated carboxylic acid. Is desired. Furthermore, in the case of the catalyst of Patent Document 1, the use of hydrogen peroxide is Consideration of integrity is indispensable, and in the case of the catalyst of Patent Document 2, it is necessary to inject molecular oxygen for a long time, and improvement has been required.

Patent Document 1: JP-A-11-343261

Patent Document 2: JP-A-11 343262

Disclosure of the invention

Problems to be solved by the invention

[0005] The present invention is highly safe in the production process when the unsaturated aldehyde is subjected to gas phase catalytic oxidation with a molecular oxygen-containing gas to produce an unsaturated carboxylic acid, and shortens the time required for gas injection. Provided is a method for producing a composite oxide catalyst which is capable of providing a high conversion of raw material unsaturated aldehyde and a high selectivity of unsaturated carboxylic acid, and exhibiting stable performance over a long period of time.

Means for solving the problem

[0006] The present inventor has conducted various studies to achieve the above object. As a result, the present inventors newly added a Cu component and a Si-C component as catalyst components, and contained Mo-Nb-V in an aqueous medium. — Sb—Cu—SiC Mo, V and Sb are heated and reacted in the presence of all the components, and the ozone-containing gas is blown during the reaction. Further, the present inventors have found that a method for producing a composite acid sulfide catalyst which gives a high conversion rate of the raw material unsaturated aldehyde and a high selectivity of the unsaturated carboxylic acid, and exhibits stable performance over a long period of time can be realized.

The present invention is characterized by the following points.

(1) A method for producing a complex oxide catalyst having the following formula (1), which is used in the production of a corresponding unsaturated carboxylic acid by gas phase catalytic oxidation of an unsaturated aldehyde with a molecular oxygen-containing gas. The aqueous solution or dispersion obtained by dissolving and / or dispersing the raw material compound of each metal component constituting the catalyst and the raw material compound of the Si and C components containing the chemical bond between Si and C in an aqueous medium at 70 ° C. A catalyst characterized by heating as described above, blowing an ozone-containing gas into the aqueous solution or dispersion, and then drying the aqueous solution or dispersion to form a powder, molding the powder, and calcining the powder. Manufacturing method. Mo Nb V Sb Cu Si CO (1)

12 a b c d e f g

(Wherein the variables have the following meanings: a, b, c, d, e, f, and g represent the atomic ratio of each element, and for molybdenum atom 12, 0 <a≤10, 0 < b≤10, 0 <c≤5, 0 <d≤5, 0 <e≤1000, 0 <f≤1000, g is the acidity of each component of (1) except Si and c. The number is determined by the degree of dagger)

(2) The method for producing a composite oxide catalyst according to the above (1), wherein the aqueous solution or dispersion is dried by spray drying.

(3) The method for producing a composite oxide catalyst according to the above (1) or (2), wherein the raw material of the Si and C components containing the chemical bond between Si and C is silicon carbide.

(4) The composite oxide catalyst as described in any one of (1) to (3) above, wherein the powder is molded using at least one binder selected from the group consisting of silica, graphite and crystalline cellulose. Manufacturing method.

(5) The composite oxide catalyst produced by the production method according to any one of (1) to (4) above.

(6) A method for producing corresponding acrylic acid by subjecting acrolein to gas-phase catalytic oxidation with a molecular oxygen-containing gas in the presence of the composite oxide catalyst according to (5).

The invention's effect

[0008] According to the present invention, in the case of producing an unsaturated carboxylic acid by subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas, it is possible to increase the safety and shorten the gas blowing time. Thus, the present invention provides a method for producing a composite acid catalyst which gives a high conversion of the raw material unsaturated aldehyde and a high selectivity of the unsaturated carboxylic acid, and shows stable performance over a long period of time.

[0009] In particular, the conversion rate of acrolein per catalyst unit is improved, the selectivity of acrylic acid for the catalyst is further improved, and a highly active complex oxide catalyst capable of efficiently performing a gas phase catalytic oxidation reaction of acrolein. Can be manufactured.

[0010] In the present invention, Cu, Si-C component is newly contained as a catalyst component, and Mo, V, and Mo are contained in an aqueous medium in the presence of all components of Mo-Nb-V-Sb-Cu-Si-C. Sb reacts by heating The reason why the above-mentioned excellent effects can be achieved by blowing the ozone-containing gas during the reaction is not necessarily clear, but is presumed as follows.

[0011] The active component structure of the present catalyst system is presumed to be an isopolyacid structure based on Mo and V. It has been found that the addition of Sb stabilizes the isopolyacid structure and has a great effect on the catalytic performance. ing. However, the incorporation of Sb into the isopolyacid structure greatly affects the process conditions for preparing active species precursors. In particular, keeping the Mo-V in the preparation process slurry solution in a reduced state is extremely important for generating a rigid Mo-V-Sb structure. However, the activity is remarkably reduced in the reduced structure of Mo-V-Sb, and it is important to return the reduced structure to an appropriate oxidized state. It is presumed that the control of the state of reduction by iridani is important.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] The composite oxide catalyst produced by the present invention is represented by the above formula (1). Where Mo is molybdenum, Nb is niobium, V is vanadium, Sb is antimony, Cu is copper, Si is silicon, C is carbon, O is oxygen, and a, b, c, d, e, f, and g are as described above, even if the force is strong, l≤a≤8, 0.5,5b, 5, 0.5,5c≤5, 0.5,5≤ d≤5, 5≤e≤500, 5≤; [≤500 is preferred 1 ヽ.

The composite oxide catalyst of the present invention comprises a raw material compound of each metal component constituting the catalyst composition represented by the formula (1) and a raw material compound of Si and C components containing a chemical bond between Si and C in an aqueous medium. An ozone-containing gas is blown into an aqueous solution or dispersion dissolved and / or dispersed in water, and then the aqueous solution or dispersion is dried to form a powder, and the powder is molded and fired. .

The raw material compound of each metal component in the composite oxide catalyst of the present invention is not particularly limited as to whether it is water-soluble or hardly water-soluble, as long as it is a compound that becomes an oxide upon firing. Specific examples of the raw material compound include halogenated compounds, sulfates, nitrates, ammonium salts, oxides, carboxylate salts, ammonium carboxylate salts, ammonium halide salts, hydrogen acid, acetyl acetate of each component. Nart, alkoxide and the like can be mentioned.

[0015] Further, as a raw material conjugate of Si and C components containing a chemical bond between Si and C, specific examples in which silicon carbide is preferred include green silicon carbide and black silicon carbide. Silicon carbide has a large thermal conductivity of 0.2 to 80 microns to reduce the heat storage of the large heat generated at the active site and to provide the function of optimizing the dispersibility and pore structure of the active ingredient. Fine powder is preferred! / ,. Unlike Si and C in the molding aid described below, the raw compound of the Si and C components containing a chemical bond between Si and C is a homogeneous dispersion of the catalyst constituent elements that does not disappear by firing and a hot spot during firing. It is an important component that contributes to control.

[0016] As these raw material compounds, those containing each component alone may be used, or raw material compounds containing two or more types of components may be used.

In the present invention, first, the raw material compound is dissolved and / or dispersed in an aqueous medium to prepare an aqueous solution or dispersion containing all the catalyst components. The aqueous medium is not particularly limited, but water can be preferably used. In many cases, some components do not dissolve, resulting in a slurry. The amount of water in the vigorous aqueous solution or dispersion is not particularly limited as long as the raw material compounds of each component can be completely dissolved or uniformly dispersed. It should be decided appropriately in consideration of the drying conditions! The amount of water is usually 100-2000 parts by weight based on 100 parts by weight of the raw material mixture. If the amount of water is less than the above-mentioned predetermined amount, the compound may not be completely dissolved or may not be mixed uniformly. In addition, if the amount of water is large, there is a fear that the energy cost during the heat treatment is increased. In many cases, the dispersion in the form of a slurry is preferably aged at room temperature—200 ° C. for 1 minute—24 hours.

Next, the above aqueous solution or dispersion is heated to a temperature of 70 ° C. or higher, preferably 80 to 100 ° C., and an ozone-containing gas is blown into the aqueous solution or dispersion. The ozone concentration in the ozone-containing gas is preferably at least 0.1% by volume, particularly preferably at least 0.5% by volume. If the flow rate of the ozone-containing gas depends on the volume of the aqueous solution or the dispersion, the volume is preferably 0.5 to 1 liter, and preferably 10 to 30 liters Z hours. Ozone-containing gas blowing is blown narrowing time until desirability instrument Mo + ⁵ that continue until Mo + ⁵ disappears so that discussed later disappears, depending on the liquid amount, usually 0.5 hour or more, particularly 2—10 hours. During the blowing of the ozone-containing gas, the aqueous solution or dispersion is preferably stirred.

[0018] In the aqueous solution or dispersion according to the present invention, in the presence of Sb ³⁺ , The oxidation-reduction reactions of formulas (I) and (II) proceed. v ⁵⁺ + Sb ³⁺ → v ³⁺ + Sb ⁵⁺ (I)

V ³⁺ + Mo + 6 → V ⁴⁺ + Mo ⁵⁺ (II)

In this process, a reduced structure of the Mo—V—Sb isopolyacid is generated, and the reduced structure is oxidized by blowing the ozone-containing gas to obtain a precursor of a highly active composite oxide catalyst. It is estimated to be. In the present invention, the valencies of Mo and V in the reaction solution are determined by analytical means such as an electron spin resonance spectrum, and it is preferable to continue blowing the ozone-containing gas until Mo ⁵⁺ disappears. .

Next, the aqueous solution or dispersion is dried to obtain a powder. Drying is not particularly limited as long as the aqueous solution or dispersion can be sufficiently dried and a powder can be obtained, and preferable examples thereof include drum drying, freeze drying, and spray drying. Spray drying is a method that can be preferably applied to the present invention because it can be dried into a homogeneous powder state in a short time in an aqueous solution or aqueous dispersion.

The drying temperature varies depending on the amount of the catalyst component and the amount of the aqueous solution or dispersion, but is usually 100 to 300. C, preferably 120-250. C, for 0.5-24 hours, preferably for 11-10 hours. The powder obtained by vigorous drying preferably has a particle size of 10 to 200 m. For this reason, the powder can be optionally ground after drying.

[0022] Next, it is preferable to heat-treat the dried powder obtained above. The temperature of the heat treatment is usually 160-450 ° C, preferably 200-350 ° C, and the heat treatment time is usually 120 hours, preferably 2-10 hours. In addition, as a specific heat treatment method, a known method can be used, and there is no particular limitation. By performing such a heat treatment, a catalyst with more excellent uniformity and less dusting can be obtained.

Next, the dried powder or the powder heat-treated after drying is formed. There is no particular restriction on the molding method, and molding is preferably performed using a binder. Preferred binders are also selected from silica, graphite and crystalline cellulose. The binder can be used in an amount of preferably about 110 to 50 parts by weight based on 100 parts by weight of the powder. Also, if necessary Inorganic fibers such as ceramic fibers and whiskers can also be used as a material for improving the mechanical strength of catalyst particles. However, fibers that react with catalyst components such as potassium titanate whiskers and basic magnesium carbonate whiskers are not preferred. Ceramic fibers are particularly preferred for improving the strength. The amount of these fibers used is preferably 1 to 30 parts by weight based on 100 parts by weight of the powder. The above-mentioned molding aid is usually used by mixing it with a powder in advance.

[0024] The powder mixed with a molding aid such as a binder is subjected to an appropriate method such as (A) tablet molding, (B) extrusion molding, (C) sphere or any other known well-formed carrier molding method. Can be adopted. An appropriate shape such as a spherical shape, a cylindrical shape, and a ring shape is preferably selected as the molded body.

[0025] In the next step, the molded article thus molded is calcined to obtain a composite oxide catalyst. The sintering temperature can be usually 250-500 ° C, preferably 300-420 ° C, and the sintering time is 150 hours. The calcination can be performed in an atmosphere in the presence of an inert gas or molecular oxygen. If the calcination temperature is too low, there is a problem of remaining ammonium salt derived from the raw material, and if it is too high, crystallization of the structure of the active ingredient and structural destruction are caused and catalyst performance is reduced. The molecular oxygen content in the atmosphere gas is preferably 10% by volume or less. If the content of molecular oxygen exceeds 10% by volume, the activity of the catalyst may be insufficient. The content of molecular oxygen may be 0% by volume, but is preferably 0.05% by volume or more.

[0026] Means for producing a corresponding unsaturated carboxylic acid by using a catalyst produced according to the present invention and subjecting an unsaturated aldehyde to gas-phase oxidation using molecular oxygen or a gas containing molecular oxygen can be produced by a conventional method. It can be done by a method. For example, the reaction is carried out using a fixed-bed tube reactor. In this case, the reaction can be carried out under a condition generally used for this type of reaction, whether it is a single flow method or a recycling method through a reactor.

[0027] For example, mixed gas such as acrolein 418% by volume, molecular oxygen 6-10% by volume, steam 10-20% by volume, inert gas such as nitrogen and carbon dioxide 62-80% by volume Is added to the catalyst layer packed in each reaction zone of each reaction tube having an inner diameter of preferably 15 to 50 mm. C, 0.1-1 Introduced at a space velocity (SV) of 300-5000hr- ¹ under the pressure of IMPa. In the present invention, it is possible to operate under a high load reaction condition, for example, a condition of a higher raw material gas concentration or a high space velocity in order to further increase the productivity. Effortlessly manufactured with the present invention Acrylic acid can be produced with high selectivity and high yield by using the obtained catalyst.

Example

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, it is needless to say that the present invention should not be construed as being limited to these Examples. The acrolein conversion, acrylic acid selectivity, and acrylic acid yield are defined by the following formulas.

Acrolein conversion ratio (mol%) = ιοο X (moles of reacted acrolein) Z (moles of supplied acrolein)

Acrylic acid selectivity (mol%) = 100 X (number of moles of acrylic acid generated) Z (number of moles of acrolein subjected to transfer)

Acrylic acid yield (mol ^_0/0) = 100 X (acrylic acid mol number generated) Z (Akurore Inmoru number of supplied)

Example

The composite metal oxide having a catalyst composition of Mo Nb V Cu Sb Si C excluding oxygen is as follows:

12 2 3.5 2 1 150 150

It was prepared as follows.

First, 1124 ml of pure water was heated to 80 ° C., and 298.7 g of ammonium paramolybdate and 57.94 g of ammonium metavanadate were dissolved with stirring. To this aqueous solution, an aqueous solution prepared by dissolving 32.45 g of oxalic acid-obammo-pum in 324 ml of pure water at 80 ° C was added, and 70.24 g of copper sulfate was dissolved in 95 ml of pure water at 80 ° C. The aqueous solution was added. To this aqueous solution, 20.54 g of Sanshidani antimony was added and stirred. This liquid has a maximum particle size of 63 microns or less, a particle size of 50% or less at a cumulative height of 3%, a particle size of 25 ± 2.0 microns at a cumulative height of 50%, and a particle size of 16 at a cumulative height of 94%. 848 g of silicon carbide powder having a particle size distribution of submicron or less was added, and the mixture was sufficiently stirred and mixed to obtain a slurry dispersion.

[0030] After the vigorous slurry-like dispersion was heated to 90 ° C, an ozone-containing gas was blown. The ozone concentration of the ozone-containing gas was 3% by volume, and the flow rate of the ozone-containing gas was 15 liters Z hours. The pentavalent Mo in the liquid was detected by the electron spin resonance spectrum, and the ozone-containing gas was blown continuously for 4 hours while stirring the liquid until the pentavalent Mo disappeared.

[0031] The slurry-like liquid obtained by pressing was heated to 90 ° C and dried. Heat treated at 200 ° C After that, 1.5 wt% of graphite is added and mixed, and the mixture is molded into a column having a height of 4 mm and a diameter of 5 mm using a small tableting machine. The catalyst was manufactured by firing for 3 hours.

[0032] In order to evaluate the obtained catalyst, 0.3 g of a powder crushed and sized to 20-28 mesh was filled in a U-shaped reaction tube having an inner diameter of 4 mm, and the reaction tube was heated in a night game bath ( temperature: 280 ° C) put, Akurorein: 3.4 volume ^_0/0, oxygen: 9.3 volume ^_0/0, a steam: 41.5 volume ^_0/0, and a nitrogen gas: 45.8% by volume of gas composition Was introduced, and SV (space velocity; flow rate of raw material gas per unit time Z apparent volume of filled catalyst) was reacted at 20000 Zhr- ¹ .

[0033] The night game bath is a salt bath in which a reaction tube is placed in a heat medium composed of an alkali metal nitrate to cause a reaction. This heating medium melts at 200 ° C or higher, and can be used up to 400 ° C and has good heat removal efficiency, making it a reaction bath suitable for oxidation reactions with a large amount of heat generation.

As a result of the reaction, acrolein conversion ratio was 99.0%, acrylic acid selectivity was 98.5%, and atalylic acid yield was 97.5%.

[0034] Comparative example

A catalyst having the same composition as in the example was obtained in the same manner as in the example except that the ozone-containing gas was not blown into the slurry dispersion in the catalyst production process.

This catalyst was used to produce acrylic acid under the same conditions as in the example. As a result of the reaction, the reaction bath temperature was 306 ° C., acrolein conversion = 99.0%, acrylic acid selectivity = 95.5%, and atalylic acid yield = 94.5%.

As described above, in the embodiment in which the ozone-containing gas was blown, the acrolein conversion rate, the acrylic acid selectivity, and the acrylic acid yield were lower than those in the comparative example in which the ozone-containing gas was not blown. Excellent, gas-phase catalytic oxidation reaction of acrolein was performed efficiently.

Industrial applicability

[0036] The catalyst produced by the method of the present invention is used for subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas to produce a corresponding unsaturated carboxylic acid in high yield. . Manufactured unsaturated carboxylic acids such as acrylic acid are widely used as raw materials for various chemicals, monomers for general-purpose resins, monomers for functional resins such as water-absorbing resins, flocculants, and thickeners. Used for

Claims

The scope of the claims

[1] A method for producing a composite oxide catalyst having the following formula (1), which is used in producing an unsaturated carboxylic acid by subjecting an unsaturated aldehyde to gas-phase catalytic oxidation with a molecular oxygen-containing gas. The raw material compound of each metal component constituting the catalyst and the raw material compound of Si and C components containing a chemical bond between Si and C are dissolved and / or dispersed in an aqueous medium, and an aqueous solution or dispersion is heated to 70 ° C or more. Then, an ozone-containing gas is blown into the aqueous solution or dispersion, and then the aqueous solution or dispersion is dried to form a powder, and the powder is shaped and calcined.

Mo Nb V Sb Cu Si C O (1)

12 a b c d e f g

(In the formula, each variable has the following meaning: a, b, c, d, e, f, and g represent the atomic ratio of each element, and 0 <a≤10, 0 for molybdenum atom 12) <b≤10, 0 <c≤5, 0 <d≤5, 0 <e≤1000, 0 <f≤1000, g is the acid of each of the above components of (1) except Si and c It is a number determined by the degree

2. The method for producing a composite oxide catalyst according to claim 1, wherein the aqueous solution or the dispersion is dried by spray drying.

3. The method for producing a composite oxide catalyst according to claim 1, wherein the raw material conjugate of the Si and C components containing a chemical bond between Si and C is a silicon carnoid.

[4] The method for producing a catalyst according to any one of [13] to [13], wherein the powder is formed using one or more binders selected from the group consisting of silica, graphite and crystalline cellulose. Method.

[5] A composite oxide catalyst produced by the production method according to claim 14.

[6] A method for producing a corresponding acrylic acid by subjecting acrolein to gas-phase catalytic oxidation with a molecular oxygen-containing gas in the presence of the composite oxide catalyst according to claim 5.