JP2000051693A - Manufacture of catalyst for gas-phase catalytic oxidation for hydrocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the selection rate of an acrylic acid by catalytically oxidizing hydrocarbons in the gas phase with high catalytic activity by making a metallic oxide whose percentage of a metallic element is expressed by a specific composition formula or an inorganic mixture containing the oxide, come into contact with hydrogen peroxide. SOLUTION: A metallic oxide, the percentage of a metallic element of which is represented by the formula: MoViSbjAk (wherein, A is one or more kinds of metallic element selected from the group of Nb,Ta,Sn,W,Ti,Co and the like and Ce; (i) and (j) are each 0.01-1.5 and j/i = 0.3-1; k is 0.001-3.0) or an inorganic mixture containing the metallic oxide, is manufactured by dissolving or dispersing a chemical compound containing Mo, V, Sb and the other metallic part in water or an organic solvent and mixing each of these components as uniformly as possible. After mixing the components sufficiently, a liquid medium is removed and the remaining solid mixture is ground to the appropriate grain size. Further the grinds are brought into contact with a hydrogen peroxide solution and the powder of the metallix oxide or the inorganic mixture is obtained through a separation process. Thus it is possible to manufacture acrylic acid at a high yield by catalytically oxidizing hydrocarbons in the gas phase with high catalytic acitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a metal oxide-based catalyst used in gas phase catalytic oxidation of hydrocarbons.

[0002]

2. Description of the Related Art Metal oxides containing molybdenum (Mo), vanadium (V) and antimony (Sb) are known as catalysts for gas phase catalytic oxidation of hydrocarbons and will be described below. There are many suggestions. That is, the synthesis of acrylic acid from propane (JP-A-9-316)
023), acrylonitrile synthesis by reaction of propane and ammonia (JP-A-9-157241)
In a gas phase catalytic oxidation reaction such as the synthesis of methacrolein or methacrylic acid starting from isobutane and isobutane (JP-A-9-278680), Mo-V-Sb-
An Nb-based catalyst is used. The above-mentioned metal oxide-based catalyst is generally obtained by evaporating to dryness or depositing a solid from a solution containing a plurality of metal elements required for each catalyst, and then calcining the solid. Being manufactured. As another method, there is a method in which a plurality of inorganic compounds are mixed in a solid state without preparing the above-mentioned solution, and then fired.

[0003] However, the activity of the catalyst for gas phase catalytic oxidation of hydrocarbons obtained by the above-mentioned method slightly varies depending on the production conditions. Was not easy.
With respect to the Mo-V-Te catalyst, it has been proposed to treat the catalyst with oxalic acid, citric acid, hydrochloric acid, sulfuric acid or the like in order to solve the above problem (Japanese Patent Laid-Open No. 8-5).
No. 7319). The present inventors applied the same acid treatment to the Mo-V-Sb-based catalyst and applied the resulting catalyst to an acrylic acid production reaction from propane, as described in Comparative Example 2 below. The result was that the selectivity of acrylic acid was significantly reduced.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the present invention provides a method for producing a hydrocarbon gas comprising contacting a metal oxide having a metal element ratio represented by the following composition formula (I) or an inorganic mixture containing the oxide with a hydrogen peroxide solution. This is a method for producing a catalyst for phase contact oxidation. MoViSbjAk (I) (where A is Nb, Ta, Sn, W, Ti, Ni, F
At least one metal element selected from the group consisting of e, Cr, Co and Ce. i and j are each 0.01 to
1.5 and j / i = 0.3-1 and k is
It is 0.001-3.0. Hereinafter, the present invention will be described in more detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The composition formula (I) in the present invention
The metal oxide represented by the formula or an inorganic mixture containing the oxide has been conventionally used as a catalyst for gas phase catalytic oxidation of hydrocarbons, and can be produced by a conventionally known method.
That is, various compounds containing Mo, V, Sb and other metal components are dissolved or dispersed in water or an organic solvent, and the components are mixed so as to be as uniform as possible. Examples of the compound containing a metal component include oxides, chlorides, hydroxides, ammonium salts, nitrates, and alkoxides. Specific examples include molybdic acid, ammonium molybdate, molybdenum oxide, vanadium oxide, and antimony chloride. , Antimony acetate, niobate, niobium oxide and ammonium metavanadate.

[0006] The above-mentioned metal compound solution or dispersion is stirred to sufficiently mix each compound, and then the liquid medium is removed to obtain a solid mixture. As a method for removing the liquid medium, evaporation to dryness, spray drying, vacuum drying, or the like can be used. The obtained solid mixture is calcined at a temperature of 300 to 900C, more preferably 450 to 700C. As the firing atmosphere, nitrogen, argon or air can be adopted, and the firing time is preferably about 1 to 20 hours. The metal oxide catalyst obtained by the above method is preferably ground to an appropriate particle size. As a pulverizing method, either a dry type or a wet type can be used, and examples of the apparatus include a mortar and a ball mill.

In order to improve the mechanical strength of the metal oxide catalyst, Si, Al, Zr or Ti is added to the metal oxide.
After adding an oxide such as this, granulation may be performed. Preferred amounts of such diluents are from 1 to 9 based on the total mixture.
0% by weight.

In the present invention, the metal oxide powder obtained by the above method or the inorganic mixture powder obtained by mixing the powder with a diluent is brought into contact with a hydrogen peroxide solution by the following method or the like. The particle size of the metal oxide powder or the inorganic mixture powder to be brought into contact with the hydrogen peroxide solution is not particularly limited, but is 0.1 μm to 2 mm in that the activity of the catalyst can be improved by a relatively short contact. The degree is preferred. The above-mentioned metal oxide solid is pulverized with, for example, a ball mill or the like to obtain a particle having a particle size of about 0.1 to 20 μm. A particle having a particle size of about 2 mm is obtained. The aqueous hydrogen peroxide used is preferably one having a hydrogen peroxide concentration of 0.05 to 35% by weight. In the present invention, the metal oxide powder or the inorganic mixture powder is added to the aqueous hydrogen peroxide for 10 minutes. It is preferable to soak. A more preferred immersion time is 1 to 20 hours. During the immersion, the dispersion may be agitated as desired. The preferred temperature for bringing the metal oxide powder or the inorganic mixture powder into contact with the hydrogen peroxide solution is room temperature. As another contact method, there is a method of flowing a hydrogen peroxide solution into a tube filled with a metal oxide powder or an inorganic mixture powder.

After the above treatment, the metal oxide powder or the inorganic mixture powder is separated from the hydrogen peroxide solution. As a separation method, filtration, decantation, centrifugation or the like can be used. The obtained powder can be used as it is as a catalyst for gas phase catalytic oxidation of hydrocarbons, but it is more preferable to wash it several times with water and then dry it. The dried metal oxide powder or inorganic mixture powder may be further fired at 400 to 700 ° C. if desired. The resulting metal oxide-based catalyst can be used in the state of no carrier, but can also be used in the state of being supported on a carrier such as silica, alumina, silica-alumina and silicon carbide having an appropriate particle size. In the method for producing a catalyst of the present invention, a metal oxide-based catalyst whose activity has been reduced by being used in a gas phase catalytic oxidation reaction can also be used as a starting material.

The catalyst obtained by the present invention has an excellent activity in the partial oxidation reaction of alkanes having low reactivity among hydrocarbons, and produces acrylic acid from propane, acrylonitrile by ammoxidation of propane, and ethylene. The production of acrylic acid from propane is particularly effective. It is presumed that the catalyst of the present invention having such performance exhibits excellent effects even when applied to the oxidation of alkenes such as propylene. In order to produce acrylic acid by a gas phase catalytic oxidation reaction of propane, propane and an oxygen-containing gas are passed through a reactor filled with a catalyst at a temperature of 350 to 500 ° C at a gas space velocity of 300 to 5000 / hr.
As the oxygen-containing gas, air or oxygen gas is converted into steam,
Those diluted with carbon dioxide gas or nitrogen gas or the like can be used.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1 (Production of a composite metal oxide) 6.15 g of ammonium metavanadate was added to 130 ml of distilled water in a 300 ml glass flask, and dissolved under heating with stirring, and 5.87 g of antimony trioxide was added. And 30.9 g of ammonium molybdate. The mixture comprising the above components was heated and refluxed for 16 hours in a nitrogen gas atmosphere while rotating the stirrer at a rate of 360 rpm. Thereafter, while stirring, 40 g of 1.54% by weight aqueous hydrogen peroxide was added dropwise over 5 hours. The resulting blue colloidal dispersion was cooled to room temperature, and oxalic acid was added thereto.
A room temperature aqueous solution in which 82 g and 2.33 g of niobic acid were dissolved in 75 ml of distilled water was added. The obtained mixture is mixed with 30
After vigorous stirring for minutes, the mixture was evaporated to dryness at 120 ° C. The obtained metal compound mixture was fired at 290 ° C. for 5 hours, and then fired at 600 ° C. for 2 hours in a nitrogen gas stream to obtain a composite metal oxide. The atomic ratio of this oxide is
Mo / V / Sb / Nb = 1.0 / 0.3 / 0.23 /
0.08.

(Treatment of Composite Metal Oxide with Hydrogen Peroxide Solution) 5 g of the composite metal oxide produced by the above method is pulverized to a particle size of 20 μm or less, and then 5% by weight of hydrogen peroxide solution
0 ml and the resulting dispersion was stirred at room temperature for 2 hours. Next, the composite metal oxide was removed from the dispersion by centrifugation and washed twice with 50 ml of deionized water. Then, after drying in air at 120 ° C., the mixture was tableted, sized to 16 to 30 mesh, and used as a catalyst in the following acrylic acid production reaction.

(Acrylic acid production reaction) 1.5 ml of the above catalyst
(2.22 g) was charged into a 10 mmφ quartz reaction tube. The reaction tube was heated to 400 ° C., and propane 4.4 was added thereto.
%, Oxygen gas 7.0%, nitrogen gas 26.3%, and steam 62.3% as a SV = 1800 / hr.
Acrylic acid was synthesized by supplying at a speed of.
The results are as shown in Table 1. The conversion, the selectivity, and the yield were calculated by the following formulas (all calculated by the number of 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

[0014]

Comparative Example 1 Acrylic acid production reaction was carried out in the same manner as in Example 1 except that the composite metal oxide produced in Example 1 was used as a catalyst without treatment with aqueous hydrogen peroxide. The results are as shown in Table 1.

[0015]

Comparative Example 2 5 g of the composite metal oxide produced in Example 1 was pulverized to a particle diameter of 20 μm or less, added to 50 ml of a 10% by weight aqueous oxalic acid solution, and the resulting dispersion was stirred at 50 ° C. for 2 hours. did. Next, the composite metal oxide was removed from the dispersion by centrifugation and washed twice with 50 ml of deionized water. Then, after drying in air at 120 ° C., the mixture was tableted, sized to 16 to 30 mesh, and the acrylic acid production reaction was carried out in the same manner as in Example 1 except that this was used as a catalyst. The results are as shown in Table 1.

[0016]

[Table 1] The unit of each numerical value in the table is%.

[0017]

The metal oxide catalyst obtained by the present invention has a high activity as a catalyst for the gas phase catalytic oxidation reaction of hydrocarbons, and is particularly used for the gas phase catalytic oxidation reaction for producing acrylic acid from propane. Acrylic acid can be produced in high yield.

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Claims (2)

[Claims] A metal oxide having a metal element ratio represented by the following composition formula (I) or an inorganic mixture containing the oxide:
A method for producing a catalyst for gas phase catalytic oxidation of hydrocarbons, which is brought into contact with hydrogen peroxide water. MoViSbjAk (I) (where A is Nb, Ta, Sn, W, Ti, Ni, F
At least one metal element selected from the group consisting of e, Cr, Co and Ce. i and j are each 0.01 to
1.5 and j / i = 0.3-1 and k is
It is 0.001-3.0. ) 2. The method of claim 1, wherein said hydrocarbon is propane.
A process for producing the catalyst for gas phase catalytic oxidation of hydrocarbons according to the above.