JPH1036311A - Production of alpha, beta-unsaturated carboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject compound useful as a raw material for synthetic resins, coating materials, plasticizers, etc., in high selectivity by vapor phase catalytic oxidation of the corresponding alkane under limitations of its concentration and conversion and the reaction gas composition ratio within respective specified ranges. SOLUTION: (A) A 3-8C aliphatic saturated hydrocarbon is subjected to vapor phase catalytic oxidation in the presence of (B) a multiple metal oxide catalyst under such controlled conditions that the concentration of the component A in the feedstock gases is 4-90vol.% the composition ratio of the reaction gases to be fed into the reaction vessel is 1:(0.1-1.9):0-20, and the conversion of the component A is <=70%. It is preferably that, after (C) the objective α,β-unsaturated carboxylic acid in the stream discharged from the reaction vessel is separated, a gas containing the unreacted component A is fed to the reaction vessel again; thereby improving the yield of the objective unsaturated carboxylic acid C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an α, β-unsaturated carboxylic acid. More specifically, the present invention employs specific reaction conditions in the production of α, β-unsaturated carboxylic acids by gas phase catalytic oxidation of aliphatic saturated hydrocarbons (hereinafter, may be abbreviated as alkanes). The present invention relates to a method for producing an α, β-unsaturated carboxylic acid with high selectivity. Α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid are industrially important as raw materials for various synthetic resins, paints, plasticizers and the like.

[0002]

2. Description of the Related Art Conventionally, the most common method for producing these α, β-unsaturated carboxylic acids is a method in which an olefin such as propylene or isobutene is contacted at high temperature in the gas phase with oxygen in the presence of a catalyst. Known as the method.
On the other hand, due to the price difference between propane and propylene, or the price difference between isobutane and isobutene, propane, a lower alkane such as isobutane as a starting material, and a gas phase catalytic oxidation reaction in the presence of a catalyst, Acrylic acid in one step,
There is increasing interest in developing methods for producing methacrylic acid.

As an example of a catalyst for producing acrylic acid in a single step by subjecting propane to a gas phase catalytic oxidation reaction, a Mo-Sb-PO catalyst (European Patent No. 000109)
02 specification), a VP-Te-O-based catalyst (Sai et al., Jo
urnal of Catalysis, 1986,
Vol. 101, p. 389), Bi-Mo-O catalyst (JP-A-3-170445), molybdophosphoric acid catalyst treated with pyridine (Ueda et al., Chemistry).
Letters, 1995, p. 541), Fe-
Cs-HPV-Mo-O based catalyst (Mizuno et al., Appl.
ied Catalyst A: General, 1
995, Vol. 128, p. L165) is known. On the other hand, as a catalyst for producing methacrylic acid in a single step by subjecting isobutane to a gas phase catalytic oxidation reaction,
Mo-VO catalyst (JP-A-2-42032) and related catalysts (JP-A-2-42033, JP-A-4-42033)
-59738, etc.), Cs-Ni-HP-Mo-
O catalyst (Mizuno et al., Journal of Chemical
al Society Chemical Commu
nication, 1994, p. 1411), a molybdophosphoric acid catalyst containing ammonium and potassium (F.
Cavani et al., Catalysis Letter.
s, 1995, Vol. 32, p. 215) are known. In addition to these, the present inventors have also considered that Mo-V-Nb-
Te-O-based catalysts (JP-A-6-279351 and JP-A-7-10801) are reported.

[0004]

However, all of these methods are not satisfactory because of low selectivity to the target α, β-unsaturated carboxylic acid. An object of the present invention is to provide a method for producing an α, β-unsaturated carboxylic acid with high selectivity in the production of an α, β-unsaturated carboxylic acid by gas phase catalytic oxidation of an alkane.

[0005]

Means for Solving the Problems The present inventors have proposed a process for producing an α, β-unsaturated carboxylic acid using an alkane such as propane or isobutane as a raw material, in order to increase the selectivity to an intended product. As a result of studying the characteristics of the catalyst and the reaction in detail, the ratio of the alkane: oxygen concentration in the supplied reaction gas was set to a specific range, particularly, the alkane concentration was set to a predetermined value or more. Producing an α, β-unsaturated carboxylic acid with a higher selectivity than the conventional method by suppressing the conversion of the alkane to a predetermined value or less;
After separation of the α, β-unsaturated carboxylic acid in the effluent from the reactor, the gas containing unreacted alkane is fed back into the reactor, thereby allowing substantially higher α, β from alkane.
The inventors have found that the yield of β-unsaturated carboxylic acid can be achieved, and have completed the present invention.

That is, the present invention provides a process for producing an α, β-unsaturated carboxylic acid by subjecting an aliphatic saturated hydrocarbon having 3 to 8 carbon atoms to a gas phase catalytic oxidation reaction in the presence of a composite metal oxide catalyst. In the above, the concentration of the hydrocarbon in the raw material gas is about 4 to
90 volume%, the composition volume ratio of the reaction gas supplied into the reactor is:

[0007]

## EQU3 ## The hydrocarbon: oxygen: diluent gas = 1: 0.1-
1.9: 0-20

Wherein the conversion of the supplied hydrocarbon is about 70% or less.
Production method of unsaturated carboxylic acid. Hereinafter, the present invention will be described in detail.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the target α, β is determined by setting the composition mole fraction of the raw material gas supplied to the reactor, particularly the alkane concentration, and the alkane conversion in the reaction within a predetermined range. States that the selectivity for unsaturated carboxylic acids is increased. Although the details of the reason are not clear, the rate of the formation and decomposition of α, β-unsaturated carboxylic acid was analyzed in detail using various catalysts.
It has been found that the rate of the sequential decomposition of the generated α, β-unsaturated carboxylic acid increases as the conversion of the alkane increases, and the sequential decomposition of the α, β-unsaturated carboxylic acid is suppressed, and In order to increase the conversion, the conversion of alkane of 70% or less proposed in the present invention is effective. In the present invention, since the operation is performed at an alkane conversion rate of 70% or less, the concentration of the alkane in the raw material gas supplied to the reactor is increased to increase the amount of α, β-unsaturated carboxylic acid produced in a single stream. Is more advantageous. Further, after the α, β-unsaturated carboxylic acid is separated from the effluent from the reactor as shown in FIG. 1, an unreacted alkane-containing gaseous substance is supplied to the reactor again, or , A plurality of reactors are provided, and unreacted alkanes are supplied to the second-stage reactor,
Providing a plurality of such reactors is advantageous because it increases the substantial amount of alkanes converted to α, β-unsaturated carboxylic acids.

As described above, the concentration of the alkane in the raw material gas is about 4 to 90% by volume, preferably 5 to 50% by volume, and the composition volume ratio of the reaction gas supplied to the reactor is alkane: Oxygen: diluent gas = 1: 0.1-1.9:
0-20, preferably 1: 0.2-1.8: 0-15
Here, the diluent gas is a gas that does not substantially participate in the gas phase catalytic oxidation reaction, and specifically, nitrogen, argon, helium, carbon dioxide, water vapor, or the like can be used.

The reactor used in the present invention is not particularly limited, and any of a fixed bed, a fluidized bed, a moving bed and the like can be employed.
Because of an exothermic reaction, the fluidized bed system is most commonly used because the reaction temperature is easily controlled. This reaction is generally carried out at atmospheric pressure, but can also be carried out under low pressure or reduced pressure. The reaction can be carried out at a reaction temperature of 300 to 500 ° C, and particularly preferably about 350 to 470 ° C. The gas hourly space velocity SV in the gas phase reaction is usually 100 to 10000 h ^-1 , preferably 300 to 2000 h ^-1 .
h- ¹ .

After separating the α, β-unsaturated carboxylic acid from the effluent from the reactor, when the gaseous substance containing unreacted alkane is supplied to the reactor again, C by-produced by the reaction is removed.
When O ₂ , CO and non-condensable diluent gas in the raw material gas supplied to the reactor, specifically, nitrogen or the like when air is removed, into the gas containing alkane supplied again to the reactor. Can prevent accumulation of inert gas. In other words, if a separator for selectively removing hydrocarbons effective for the reaction is provided, it is possible to substantially increase the amount of alkane converted to α, β-unsaturated carboxylic acid. Examples thereof include a pressure swing adsorption unit and the like. The alkene produced in a small amount by the reaction during this separation, specifically, propylene produced when propane is used as a raw material, can be supplied again to the reactor together with propane to be converted into acrylic acid.

Although the catalyst used in the present invention is not particularly limited, it is a composite metal oxide catalyst comprising molybdenum, vanadium, X, Y and O (X is at least one element selected from tellurium and antimony). Represents
Y is niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, bismuth, boron, indium, phosphorus, rare earth elements, alkali metals and alkaline earth metals Represents at least one element selected from the group consisting of), the proportion of each essential component to the total number of moles of the above essential components excluding oxygen is represented by the following formula:

[0014]

[Number 4] _{0.25 <r Mo <0.98 0.003 <} r V <0.5 0.003 <r X <0.5 0.003 <r Y <0.5

(Where r _Mo , r _V , r _X and r _Y are Mo, V, X with respect to the total number of moles of the above essential components excluding oxygen)
And a mole fraction of Y) are preferable, and it is particularly preferable that Y is at least one of Nb, Ta, Ti or Bi. This composite metal oxide catalyst has a higher α, β-unsaturated carboxylic acid than previously reported catalysts for producing α, β-unsaturated carboxylic acids.
Although the yield and selectivity of the β-unsaturated carboxylic acid are excellent and the reaction system proposed in the present invention is not used, for example, it is possible to carry out the conversion of the alkane at 70% or more,
Intensive studies have been made with a focus on the reaction characteristics in order to improve the performance of the catalyst. By adopting the method proposed in the present invention, the production efficiency of α, β-unsaturated carboxylic acid can be further increased. It has been found and led to the present invention.

[0016]

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 unless it exceeds the gist. The conversion (%), selectivity (%) and yield (%) in the following examples
Are represented by the following equations.

[0017]

## EQU5 ## Conversion of alkane (mol%) = (mol number of alkane consumed / mol number of supplied alkane) × 100

[0018]

## EQU6 ## Selectivity (mol%) of target α, β-unsaturated carboxylic acid = (mol number of target α, β-unsaturated carboxylic acid / formation)
Number of moles of alkane consumed) x 100

[0019]

## EQU7 ## Yield (mol%) of target α, β-unsaturated carboxylic acid = (mol number of target α, β-unsaturated carboxylic acid //
Number of moles of supplied alkane) x 100

Reference Example 1 Composite oxide catalyst (Mo ₁ V _0.3
The composite metal oxide having a Te _0.23 Nb _0.12 O _n prepared empirical formula _{Mo 1 V 0.3 Te 0.23 Nb 0.12} O n ) of was prepared as follows. 7 in 325 ml of hot water
8.9 g ammonium paramolybdate, 15.7
g of ammonium metavanadate and 23.6 g of telluric acid were dissolved to prepare a uniform aqueous solution. Further, 117.5 g of an aqueous solution of ammonium niobium oxalate having a niobium concentration of 0.456 mol / kg was mixed to prepare a slurry. The slurry was dried to remove water. Next, the dried product was heated at about 300 ° C. until the smell of ammonia disappeared, and then calcined at 600 ° C. for 2 hours in a nitrogen stream.
30 g of the composite metal oxide thus obtained was pulverized in a mortar, and the powder was dispersed in 100 ml of water to obtain a water-soluble slurry. This slurry was subjected to a heat treatment to obtain a powder solid. This solid was compressed to 5 mm using a tableting machine.
After molding into φ × 3 mmL, it was pulverized, sieved to 16 to 28 mesh, and fired at 600 ° C. for 2 hours in a nitrogen stream.

Example 1 A composite oxide catalyst Mo ₁ V _0.3 Te _0.23 Nb _0.12 O prepared as described in Reference Example 1 in a fixed bed flow type reactor
100 mg of _n and propane: air: water vapor = 1: 4: 12 (propane concentration: 5.
9% by volume), and the amount of propane supplied per unit weight of the catalyst was 1.
The gas phase catalytic oxidation reaction was performed so as to be 86 kg / kg-catalyst. As a result, the conversion of propane was 15.0 mol%, the yield of acrylic acid was 9.7 mol%, and propylene was produced at a yield of 4.1 mol%. The selectivity for acrylic acid is 64.7 mol% and the selectivity for propylene is 2
7.3 mol%. Here, acrylic acid and a small amount of acetic acid were absorbed in water and recovered in the product flowing out of the reactor, and then most of propane was separated and recovered from the discharged gas, and the above-described components were again described in the reactor. When gas phase catalytic oxidation reaction was performed by adding propane and air so as to obtain a reaction gas composition, almost the same reaction results as described above were obtained.

Examples 2 to 5 The gas phase catalytic oxidation reaction of propane was carried out in the same manner as in Example 1 except that the reaction temperature and the gas composition supplied to the reactor in Example 1 were changed as shown in Table 1. went. Table 1 shows the results.

[0023]

[Table 1] PPA: propane; PPY: propylene; AA: acrylic acid

Comparative Examples 1-3 Complex oxide catalyst M prepared as described in Reference Example 1 in a fixed bed flow reactor similar to that described in Example 1
the _{o 1 V 0.3 Te 0.23 Nb 0.12} O n was charged 610mg,
At temperatures of 380 ° C, 400 ° C, 420 ° C, propane:
Air: water vapor = 1: 15: 14 (propane concentration: 3.3
Volume%), and the propane supply amount per unit weight of the catalyst is 0.1%.
The gas phase catalytic oxidation reaction was performed so as to be 0 kg / kg-catalyst. Table 2 shows the results.

[0025]

[Table 2]

Reference Example 2 Complex oxide catalyst (Mo ₁ V _0.3
The composite metal oxide having a Te _0.15 Nb _0.06 O _n prepared empirical formula _{Mo 1 V 0.3 Te 0.15 Nb 0.06} O n ) of was prepared as follows. 7 in 325 ml of hot water
8.9 g ammonium paramolybdate, 15.7
g of ammonium metavanadate and 15.4 g of telluric acid were dissolved to prepare a uniform aqueous solution. Further, 58.8 g of an aqueous niobium ammonium oxalate solution having a niobium concentration of 0.456 mol / kg was mixed to prepare a slurry.
The slurry was dried to remove water. Next, this dried product is molded into a size of 5 mmφ × 3 mmL using a tableting machine, crushed and sieved to 16 to 28 mesh, and heat-treated at about 300 ° C. until the smell of ammonia disappears. For 2 hours.

[0027] Examples 6-9 with Example 2 in the composite oxide catalyst to be prepared in as noted _{(Mo 1 V 0.3 Te 0. 15} Nb 0.06 O n), the same amount of catalyst as in Example 1 The gaseous phase catalytic oxidation reaction of propane was performed at a reaction temperature of 400 ° C., 420 ° C., 430 ° C., and 440 ° C. under a supplied reaction gas ratio. Table 3 shows the results.

Example 10 The reaction gas composition ratio was changed to propane: air: steam = 1: 4: 1.
Example 7 except that the concentration was 2 (propane concentration: 20% by volume)
The gas phase catalytic oxidation reaction of propane was carried out under the same catalyst and reaction conditions as described above. Table 3 shows the results.

[0029]

[Table 3]

Reference Example 3 Composite oxide catalyst (Mo ₁ V _0.3
The composite metal oxide having a Te _0.23 Nb _0.12 Ce _0.08 O _n prepared empirical formula Mo ₁ V _0.3 Te _0.23 in) Nb _0.12 Ce _0.08 O _n was prepared as follows. 325 hot water
78.9 g of ammonium paramolybdate in ml,
15.7 g ammonium metavanadate, 23.6
g of telluric acid was dissolved to prepare a uniform aqueous solution. Further, 117.5 g of an aqueous niobium ammonium oxalate solution having a niobium concentration of 0.456 mol / kg and 8.08 g of cerium hydroxide (Ce (OH) ₄ .H ₂ O) were mixed to prepare a slurry. The slurry was dried to remove water. Next, this dried product was compressed to 5 mmφ × using a tableting machine.
After molding to 3 mmL, the mixture was pulverized, sieved to 16 to 28 mesh, heat-treated at about 300 ° C until the smell of ammonia disappeared, and then calcined at 600 ° C in a nitrogen stream for 2 hours.

[0031] Examples 11 to 15 and using Reference Example 3 in the composite oxide catalyst to be prepared in as noted _{(Mo 1 V 0.3 Te 0. 23} Nb 0.12 Ce 0.08 O n), in the same manner as in Example 1 Under the catalyst amount and feed reaction gas ratio,
The reaction temperature was 410 ° C, 420 ° C, 430 ° C, 440 ° C,
The gas phase catalytic oxidation reaction of propane was performed at 450 ° C.
Table 4 shows the results.

[0032]

[Table 4]

Reference Example 4 Composite oxide catalyst (Mo ₁ V _{0.3
Sb 0.15 Nb 0.05 Ce 0.02 O n} / SiO 2 10 % by weight)
Preparation empirical formula of _{Mo 1 V 0.3 Sb 0.15 Nb 0.05} Ce 0.02 O n / S
A composite metal oxide having 10% by weight of iO ₂ was prepared as follows. 15.7 g of ammonium metavanadate was dissolved in 325 ml of warm water, 9.75 g of antimony trioxide powder was added thereto, and the slurry was heated and aged for 6 hours. Then, 78.9 g of ammonium paramolybdate was added, and the mixture was cooled to about 15%. The concentration of Nb was 2.23 mol /
kg of an aqueous niobium ammonium oxalate solution, and 58.6 g of a silica sol having a silica concentration of 20% by weight.
Was added. The slurry was subjected to a heat treatment to remove water and obtain a solid. This solid was salt-decomposed in air at 400 ° C., molded into 5 mmφ × 3 mmL using a tableting press, pulverized, sieved to 16 to 28 mesh, and calcined at 600 ° C. for 2 hours in a nitrogen stream. . A homogeneous aqueous solution was prepared by dissolving 78.9 g of ammonium paramolybdate, 15.7 g of ammonium metavanadate, and 23.6 g of telluric acid. Further, the niobium concentration is 0.456.
mol / kg niobium ammonium oxalate aqueous solution 11
The slurry was prepared by mixing 7.5 g. The slurry was dried to remove water. Next, the dried product was heated at about 300 ° C. until the smell of ammonia disappeared, and then calcined at 600 ° C. for 2 hours in a nitrogen stream. 30 g of the composite metal oxide thus obtained was pulverized in a mortar, and the powder was dispersed in 100 ml of water to obtain a water-soluble slurry. This slurry was subjected to a heat treatment to obtain a pulverized solid.
This solid was molded into a size of 5 mmφ × 3 mmL using a tablet molding machine, pulverized, sieved to 16 to 28 mesh, and calcined at 600 ° C. for 2 hours in a nitrogen stream.

Examples 16 to 20 The composite oxide catalyst Mo ₁ V _0.3 Sb _0.15 Nb _0.05 C prepared in a fixed bed flow reactor as described in Reference Example 4
The e _0.02 O _n / SiO ₂ 10% by weight and 150mg fill,
Temperature 400 ° C, 410 ° C, 420 ° C, 430 ° C, 440
Gas phase catalytic oxidation reaction at a temperature of 0 ° C. so that propane: air: steam = 1: 4: 5 (propane concentration: 10% by volume), and the amount of propane supplied per unit weight of catalyst becomes 1.23 kg / kg-catalyst. Was done. The results are shown in Table-5.

[0035]

[Table 5]

COMPARATIVE EXAMPLES 4-5 Composite oxide catalyst M prepared as described in Reference Example 4 in a fixed bed flow reactor similar to that described in Example 1
_{o 1 V 0.3 Sb 0.15 Nb 0.05} Ce 0.02 O n / SiO 2 1
0 wt% 550mg, temperature 420 ℃, 430 ℃
Under the following conditions, propane: air: steam = 1: 15: 14 (propane concentration: 3.3% by volume), gas phase catalytic oxidation such that the propane supply per unit weight of the catalyst is 0.10 kg / kg-catalyst. The reaction was performed. The results are shown in Table-6.

[0037]

[Table 6]

[0038]

According to the present invention, α, β-unsaturated carboxylic acids can be produced with good selectivity in the production of α, β-unsaturated carboxylic acids by gas phase catalytic oxidation of alkanes. Efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing one embodiment of the present invention using one reactor.

FIG. 2 is a flow sheet showing another embodiment of the present invention using a plurality of reactors.

[Explanation of symbols]

 1 gas phase oxidation reactor 2 product recovery 3 gas separation

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location B01J 23/652 B01J 23/88 X 23/88 27/198 X 27/198 27/30 X 27 / 30 2115-4H C07C 51/215 C07C 51/215 C07B 61/00 300 // C07B 61/00 300 B01J 23/64 103X

Claims (4)

[Claims] 1. A gas phase catalytic oxidation reaction of an aliphatic saturated hydrocarbon having 3 to 8 carbon atoms in the presence of a composite metal oxide catalyst,
In the method for producing an α, β-unsaturated carboxylic acid, the concentration of the hydrocarbon in the raw material gas is about 4 to 90% by volume, and the composition volume ratio of the reaction gas supplied into the reactor is as follows: ## EQU1 ## The hydrocarbon: oxygen: diluent gas = 1: 0.1-
1.9: 0 to 20 and a conversion of the supplied hydrocarbon of about 7
A method for producing an α, β-unsaturated carboxylic acid, wherein the content is 0% or less. 2. The method according to claim 1, wherein after separating α, β-unsaturated carboxylic acid and the like in the effluent from the reactor, the unreacted gaseous substance containing the hydrocarbon is supplied to the reactor again. the method of. 3. The composite metal oxide catalyst, wherein molybdenum, vanadium, X, Y and O (X represents at least one element of tellurium and antimony, and Y represents niobium, tantalum, tungsten, titanium, aluminum, zirconium, Chromium, manganese, iron, ruthenium, cobalt,
Rhodium, nickel, palladium, platinum, bismuth, boron, indium, phosphorus, rare earth elements, alkali metals and alkaline earth metals). the proportion of the essential components to the total number of moles of the components, the following equation ## EQU2 ## _{0.25 <r Mo <0.98 0.003 <} r V <0.5 0.003 <r X <0.5 0.003 <r _Y <0.5 (where r _Mo , r _V , r _X and r _Y represent the mole fractions of Mo, V, X and Y based on the total moles of the above essential components excluding oxygen) 2. A composite metal oxide that satisfies the following.
Or the method of 2. 4. The method of claim 1, wherein said hydrocarbon is propane.
4. The method according to any one of claims 3 to 3.