JP2005185977A - Method for manufacturing mixed metal oxide catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for simply manufacturing a mixed metal oxide catalyst having a orthorhombic phase. <P>SOLUTION: This method for manufacturing the mixed metal oxide catalyst comprises the steps of: preparing a mixture of water, a Mo-containing compound (a), a V-containing compound and an X-containing compound (wherein X is Te or Sb) and/or a Y-containing compound (wherein Y is Nb, W, Zr or Ti); separating the obtained mixture into a gel portion and a solution portion and; firing the gel portion. The mixed metal oxide catalyst manufactured by this method is suitable for producing acrolein and acrylic acid or methacrolein and methacrylic acid from propane or butane by a gas phase catalytic reaction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention produces an unsaturated oxygen-containing compound such as acrylic acid or methacrylic acid by vapor-phase catalytic oxidation from an alkane such as propane or butane, an alkene such as propylene or butene, or an unsaturated aldehyde such as acrolein or metaacrolein. The present invention relates to a method for producing a composite metal oxide catalyst suitable for the purpose.

The production of unsaturated oxygenated compounds such as acrylic acid and methacrylic acid is generally carried out by a two-stage oxidation reaction. That is, taking acrylic acid or methacrylic acid as an example, in the first stage reaction, first, acrolein or methacrolein is produced from propylene or isobutylene, which is a raw material gas, using a Bi-Mo composite oxide catalyst, and then the second stage reaction. In the eye reaction, Mo-V composite oxide catalyst is used to produce acrylic acid or methacrylic acid, respectively.
However, in recent years, interest in methods for efficiently producing unsaturated oxygenated compounds from raw materials of alkanes such as propane and isobutane, which are cheaper than propylene and isobutylene, has increased, and MoVTe catalysts and MoVSb catalysts have been used as catalysts for these processes. Has been reported. These MoVTe and MoVSb-based catalysts include several types of crystal structures, and typically have two crystal structures, an orthorhombic phase and a hexagonal phase. Among them, the crystal structure that controls the main reaction is an orthorhombic phase, and a method for selectively preparing this crystal structure is known.

  For example, in Patent Document 1, Mo—V—Sb—X—O (X is Ti, Zr, Nb, Ta, Cr, W, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu. , Ag, Zn, In, Sn, Pb, Bi, Ce, and one or more metal elements selected from alkaline earth metals) and complex oxides including orthorhombic and hexagonal phases In addition, a method for producing an orthorhombic phase by selectively removing the hexagonal phase by adding oxalic acid, ethylene glycol, or hydrogen peroxide is disclosed.

  In Patent Document 2, AVNXO (A is at least one element selected from the group consisting of Mo and W, and N is at least one selected from the group consisting of Te and Se. An insoluble substance after contacting a mixed metal oxide having an element, and X is at least one element selected from the group consisting of Nb, Ta, Ti, etc.) with an organic acid, alcohol, or inorganic acid Is collected to form an orthorhombic phase, and a method of producing an orthorhombic phase in a quantitative yield is disclosed by seeding a catalyst precursor solution with this material.

JP 10-330343 A JP2003-024787A

  In Patent Document 1, a catalyst having two or more crystals is washed with a solvent to dissolve and remove the hexagonal crystal phase and the like, and only the orthorhombic phase is recovered as a solid. The disadvantage is that the amount of catalyst having a tetragonal phase is reduced. In Patent Document 2, as in Patent Document 1, other than the orthorhombic phase is washed away with a solvent, and the remaining solid is used as a seed material in the catalyst precursor solution to selectively prepare the orthorhombic phase. . However, this preparation process is complicated and has a problem in workability. Further, in the above two patent documents, the cleaning liquid containing useful metal after cleaning requires treatment even when it is discarded or reused, and the manufacturing cost of the entire catalyst preparation becomes high.

  The inventors of the present invention provide a composite metal oxide catalyst that selectively contains an orthorhombic phase suitable for producing acrolein, acrylic acid and methacrolein, and methacrylic acid, respectively, from propane and isobutane by a gas phase catalytic oxidation reaction, Furthermore, various methods for producing a composite metal oxide catalyst selectively containing an orthorhombic phase suitable for producing acrylic acid and methacrylic acid from acrolein and methacrolein were investigated. As a result, it was found that by separating a solution part and a gel part by allowing a slurry containing molybdenum, vanadium and a specific metal to stand, an intended orthorhombic phase complex metal oxide catalyst can be selectively produced. Was completed.

That is, the present invention provides (1)
(A) Mo-containing compound, V-containing compound and (b) X-containing compound (X represents Te or Sb) and / or Y-containing compound (Y represents Nb, W, Zr or Ti).
A mixture of water and water is prepared, the obtained mixture is separated into a gel part and a solution part, and the gel part is subjected to a baking treatment, and the following general formula (1)
_{Mo 6 V a X b Y c} O d (1)
(Wherein Mo and V are molybdenum and vanadium, X is Te or Sb, Y is Nb, W, Zr or Ti, respectively, ad represents the composition ratio of each element, and 0.1 <a <6, 0 ≦ b <6, 0 ≦ c <6, but b and c are not 0 at the same time, and d is a number that varies depending on the oxidation state of other elements. )
A process for producing an orthorhombic phase complex metal oxide catalyst represented by:
(2) The production method according to (1), wherein a is 0.9 or more and 1.5 or less, b is 1 or more and 2 or less, and c is 0.5 or more and 1.5 or less,
(3) The production method according to (1) or (2), wherein the Y-containing compound is used in a state containing oxalate ions. ,
(4) The production method according to any one of (1) to (3), wherein a Te-containing compound and an Nb-containing compound are used.
(5) The above (1) to (4), wherein the orthorhombic phase complex metal oxide catalyst is a catalyst for producing acrolein and acrylic acid, or methacrolein and methacrylic acid from propane or butane by a gas phase catalytic reaction. The manufacturing method of any one of these.

  According to the present invention, an unsaturated compound such as acrylic acid or methacrylic acid is obtained by gas phase catalytic oxidation from an alkane such as propane or butane, an alkene such as propylene or butene, an unsaturated aldehyde such as acrolein or metaacrolein by a gas phase catalytic oxidation reaction A composite metal oxide catalyst suitable for producing an oxygen-containing compound can be easily produced.

Hereinafter, the present invention will be described in detail.
The catalyst obtained by the present invention is represented by the above formula (1). In the above formula (1), there are ranges where 1 <a <4, 0.5 <b <2, 0.1 <c <2. The ranges of 0.9 ≦ a ≦ 1.5, 1 ≦ b ≦ 2, and 0.5 ≦ c ≦ 1.5 are particularly preferable. These composition ratios can be measured by plasma emission analysis.

  In the present invention, first, (a) a molybdenum-containing compound and a vanadium-containing compound (hereinafter sometimes referred to as (a) group compound) and (b) an X-containing compound (X represents Te or Sb, and two types are used in combination. And / or a Y-containing compound (Y represents Nb, W, Zr, Ti, and two or more types can be used in combination) (hereinafter referred to as a group compound (b)) Prepare a mixture of water). These (a) group or (b) group compounds are not particularly limited as long as they can be decomposed into oxides by firing in air. For example, among the (a) group compounds, molybdenum-containing compounds include molybdenum. Examples of vanadium compounds include ammonium oxide, molybdenum trioxide, molybdic acid, sodium molybdate, and the like. Examples of vanadium compounds include vanadium oxide, ammonium vanadate, and vanadyl oxosulfate. Examples of the (b) group compound include metal X or Y oxides, chlorides, sulfates, nitrates, and oxalates. Among (b) group compounds, X-containing compounds include Sb-containing compounds such as antimony trioxide, antimony sulfate and antimony acetate, Te-containing compounds such as tellurium dioxide and telluric acid, and Y-containing compounds include niobium. Nb-containing compounds such as acid, niobium oxide, niobium hydrogen oxalate, W-containing compounds such as ammonium paratungstate, tungstic acid, tungsten oxide, Zr-containing compounds such as zirconium oxide, zirconium nitrate, zirconium acetate, titanium oxide, ammonium ammonium oxalate Ti-containing compounds such as titanium sulfate are preferred compounds. Among the (b) group compounds, at least one of the X-containing compound and the Y-containing compound is used, but it is preferable to use both in combination, and it is particularly preferable to use the Te-containing compound and the Nb-containing compound in combination.

  The (a) group compound and the (b) group compound are combined and dissolved and / or dispersed in water at room temperature to 100 ° C. to form a slurry. The amount of water used is not particularly limited as long as these raw material compounds can be dissolved or can be dissolved even if they cannot be dissolved. (B) When using together an X containing compound and a Y containing compound among group compounds, a Y containing compound is added to the slurry liquid which mixed the (a) group compound, X containing compound, and water. In this case, the Y-containing compound may be added in a solid state, or may be added after being dissolved or dispersed in various solvents, preferably water. In addition, when the Y-containing compound is added separately as described above, the Y-containing compound may be added as a solution containing oxalic acid, preferably dissolved and / or slurry by adding the Y-containing compound to an aqueous solution containing oxalate or oxalic acid. preferable.

When stirring is continued after slurry preparation, a gel-like substance is generated, and the slurry containing the gel-like substance is allowed to stand to separate into a solution part and a gel part. The standing time is not particularly limited, but is 5 minutes to 100 hours, preferably 30 minutes to 48 hours. Further, the temperature at the time of standing is preferably 50 ° C. or less. After standing, the solution part is removed and the gel part is separated. The method may be a general filtration method, for example, natural filtration or suction filtration.
In addition, it is also possible to add (a) group or (b) group compound to a solution part, and to use again as a slurry.

Subsequently, the taken-out gel part is preferably dried and fired.
The baking treatment is preferably performed at a two-stage temperature such that the temperature difference is about 150 to 400 ° C. The first baking treatment is performed in the presence of oxygen gas (for example, in the air) at a temperature of 250 ° C. or higher, preferably 250 to 350 ° C. for 0.5 to 12 hours, and the second baking treatment is nitrogen, helium, or the like. It is carried out in an inert gas at 400 ° C. or higher, preferably at 500 to 650 ° C. for 0.5 to 10 hours. In the calcination treatment carried out in two steps, the catalyst performance may be lowered if the calcination temperature and time deviate from the above ranges. In particular, the selectivity of unsaturated oxygen-containing compounds such as acrolein, acrylic acid, methacrolein, and methacrylic acid is not preferable.

  The oxide thus obtained usually has 6.6 °, 7.8 °, 9.0 °, 22.2 ° (± 0.3 each) on the 2θ value of X-ray diffraction (using Cu—Kα ray). °) is a complex metal oxide with an orthorhombic phase showing the main diffraction peaks.

  The composite metal oxide catalyst obtained by the production method of the present invention can be used as it is, but is preferably used after being pulverized. The catalyst obtained by the present invention can be applied to any reaction mode such as a fixed bed, a fluidized bed, and a moving bed. However, in the case of a fixed bed, it is preferably a powdery material on a spherical support such as silica, alumina, or silicon carbide. A coated catalyst obtained by supporting and molding the composite metal oxide catalyst of the invention or a catalyst obtained by molding a powdered composite metal oxide with a molding machine such as tableting molding is advantageous. In addition, for fluidized bed and moving bed reactors, it is advantageous to use a uniform catalyst of about several tens of microns prepared by adding a silica component or the like to the composite metal oxide catalyst in order to improve wear resistance. .

  The catalyst obtained by the present invention contains an unsaturated compound such as acrylic acid or methacrylic acid by gas phase catalytic oxidation from an alkane such as propane or butane, an alkene such as propylene or butene, or an unsaturated aldehyde such as acrolein or metaacrolein. It can be preferably used for producing an oxygen compound.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

Example 1
In 600 ml of distilled water, 50.00 g of ammonium molybdate was dissolved at room temperature. This aqueous solution was heated to 80 ° C., 9.39 g of ammonium metavanadate and 14.74 g of telluric acid were added and stirred for 10 minutes, and then allowed to cool to 40 ° C. or lower to obtain Formulation A. In another container, 29.47 g of niobium hydrogen oxalate (containing 15% by weight in terms of Nb ₂ O ₅ ) was added to 200 ml of distilled water and dissolved by boiling, and then allowed to cool to 40 ° C. or lower to obtain Formulation B . When the preparation liquid B was added to the preparation liquid A and sufficiently stirred, a gel was formed with time. When this gel slurry was allowed to stand for 24 hours, it separated into a solution part and a gel part. The gel part was collected and subjected to suction filtration, and the solid remaining on the filter paper was dried to obtain a solid. The solid was calcined at 300 ° C. for 2 hours in an air atmosphere, and subsequently calcined at 600 ° C. for 6 hours under a nitrogen flow to obtain a composite metal oxide catalyst.
FIG. 1 shows the result of X-ray diffraction (using Cu—Kα ray) for the obtained catalyst. The obtained solid was a composite metal oxide selectively containing an orthorhombic phase of 6.6 °, 7.8 °, 9.0 °, 22.2 ° (each ± 0.3 °) in terms of 2θ values. It was confirmed to be a thing. As a result of analyzing the composition of the obtained solid by plasma emission analysis, it was Mo ₆ V _1.1 Te _1.6 Nb _0.9 (excluding oxygen).

Comparative Example 1
The solution part separated after standing for 24 hours in Example 1 was dried by an evaporator to obtain a solid. The solid was calcined at 300 ° C. for 2 hours in an air atmosphere, and subsequently calcined at 600 ° C. for 6 hours under a nitrogen flow.
FIG. 2 shows the result of X-ray diffraction (using Cu—Kα ray) for the fired sample. It was confirmed that the obtained solid was a complex metal oxide containing a lot of hexagonal phases of 22.2 °, 28.2 °, and 36.2 ° (each ± 0.3 °) in terms of 2θ values. The results for each resulting solid was analyzed composition by plasma emission _analysis, was _{Mo 6 V 1.6 Te 0.9 Nb 0.04} ( excluding oxygen).

Comparative Example 2
The entire gel slurry prepared in Example 1 was immediately evaporated to dryness with an evaporator to obtain a solid. The solid was calcined at 300 ° C. for 2 hours in an air atmosphere, and subsequently calcined at 600 ° C. for 6 hours under a nitrogen flow.
FIG. 3 shows the result of X-ray diffraction (using Cu—Kα ray) for the fired sample.
The obtained solid had an orthorhombic phase of 6.6 °, 7.8 °, 9.0 °, 22.2 ° (each ± 0.3 °) in 2θ value, and 22.2 in 2θ value. It was confirmed to be a composite metal oxide containing both hexagonal crystal phases of °, 28.2 °, and 36.2 ° (each ± 0.3 °). As a result of analyzing the composition of the obtained solid by plasma emission analysis, it was Mo ₆ V _1.7 Te _1.3 Nb _0.7 (excluding oxygen).

Test Example Using a fixed bed flow type reactor, 1.2 ml of each composite metal oxide (catalyst) obtained in Example 1 and Comparative Examples 1 and 2 sufficiently ground in a heat-resistant glass tube having an inner diameter of 12 mm was silicon carbide. While being diluted with 3.6 ml of powder and filled with each, a raw material mixed gas consisting of propane / oxygen / water vapor / nitrogen = 4.5 / 10.1 / 31.5 / 23.6 (ml / min) is flowed, A reaction test was conducted at 400 ° C. The reaction product was analyzed by gas chromatography. The results are shown below.

Sample Propane conversion (%) Acrylic acid selectivity (%)
Example 1 44.9 52.4
Comparative Example 1 1.7 0.0
Comparative Example 2 33.6 41.7

  From the test results, the catalyst obtained in the present invention has an orthorhombic phase as a main component and thus is excellent in both propane conversion and acrylic acid selectivity, but the catalyst of Comparative Example 1 having a hexagonal phase as a main component is propane conversion. The rate is very low, the function as a catalyst is low, and the target product is not produced at all, so it is clear that it cannot be used as a catalyst.

X-ray diffraction spectrum of the catalyst obtained in Example 1 X-ray diffraction spectrum of the catalyst obtained in Comparative Example 1 X-ray diffraction spectra of the catalyst obtained in Comparative Example 2 In FIGS. 1 to 3, the horizontal axis represents the diffraction angle (°), and the vertical axis represents the intensity (cps).

Claims (5)

(A) Mo-containing compound, V-containing compound and (b) X-containing compound (X represents Te or Sb) and / or Y-containing compound (Y represents Nb, W, Zr or Ti).
A mixture of water and water is prepared, the obtained mixture is separated into a gel part and a solution part, and the gel part is subjected to a baking treatment, and the following general formula (1)
_{Mo 6 V a X b Y c} O d (1)
(Wherein Mo and V are molybdenum and vanadium, X is Te or Sb, Y is Nb, W, Zr or Ti, respectively, ad represents the composition ratio of each element, and 0.1 <a <6, 0 ≦ b <6, 0 ≦ c <6, but b and c are not 0 at the same time, and d is a number that varies depending on the oxidation state of other elements. )
The manufacturing method of the orthorhombic phase complex metal oxide catalyst represented by these. The manufacturing method according to claim 1, wherein a is 0.9 or more and 1.5 or less, b is 1 or more and 2 or less, and c is 0.5 or more and 1.5 or less. The manufacturing method of Claim 1 or 2 which uses a Y containing compound in the state containing an oxalate ion. The manufacturing method according to any one of claims 1 to 3, wherein a Te-containing compound and an Nb-containing compound are used. The orthorhombic phase complex metal oxide catalyst is a catalyst for producing acrolein and acrylic acid, or methacrolein and methacrylic acid from propane or butane by a gas phase catalytic reaction. The manufacturing method as described.

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