JPH05213799A - Production of alpha,beta-unsaturated compound - Google Patents

Abstract

PURPOSE:To provide a paraffin-oxidation catalyst exhibiting a high activity and excellent in selectivity of an alpha,beta-unsaturated compound and stability. CONSTITUTION:In a process for producing a 3 to 5C alpha,beta-unsaturated aldehyde or a 3 to 5C alpha,beta-unsaturated carboxylic acid by a gas-phase catalytic reaction between a 3 to 5C paraffin and molecular oxygen there is employed a catalyst comprising the composition represented by the general formula XMoaAbBcCdOp [X is Ta or Nb; A is W, V, Sn, Sb, Fe, Al, Cr, Co, Ni, Cu, Mg, Ca, Sr or Ba; B is Li, Na, K, Rb or Cs; C is Ce, Pr or Tb; (a), (b), (c), (d) and (p) show atomic ratios of the respective elements based on X. (a) is 0.1 to 24 and (b) is 0 to 20. (c) is 0 to 0.4 and (d) is 0 to 0.4. (p) is the number of atoms required for satisfying the valencies of the respective component elements] and not containing P nor As.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is C₃~ C_FiveWith paraffin
In the gas phase catalytic oxidation reaction of molecular oxygen, C₃~ C _FiveΑ, β
-Unsaturated aldehyde and α, β-unsaturated carboxylic acid
It relates to a method of manufacturing.

[0002]

2. Description of the Related Art A number of catalysts for producing α, β-unsaturated compounds by vapor-phase catalytic oxidation of C ₃ -C ₅ paraffins have been proposed. Above all, several proposals have been made in recent years for methacrolein and methacrylic acid synthesis catalysts by vapor phase oxidation of isobutane. For example, JP-A-55-6
No. 2041, Mo-Sb-P-containing catalyst, JP-A-62-
132832, JP-A-63-145249 and JP-A-2-42034, Mo- (P or As) -containing catalyst; JP-A-2-42032, Mo-V- (P or As) -containing catalyst; JP-A-2-42033. Then, Mo-V
-Cu- (P or As) -containing catalyst, JP-A-3-20
In 237, a Mo-V-Cu-P-containing catalyst, and in JP-A-3-106839, Mo-P-alkali metal-
Mo-containing heteropolyacid catalysts such as (V or As) -containing catalysts have been proposed. These catalysts are known as gas phase oxidation catalysts for olefins. But,
Since paraffin is less reactive than olefin, the conversion of paraffin under olefin oxidation conditions is low. Therefore, in these catalysts, a relatively high reaction temperature is required for paraffin oxidation, and a concurrent gas phase radical reaction,
There has been a problem that the selectivity to unsaturated compounds is low due to sequential oxidation of the target unsaturated compounds. Also,
These Mo-containing heteropolyacids are poor in thermal stability and have a problem in stability when used as a catalyst.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a paraffin oxidation catalyst having high activity, high selectivity for α, β-unsaturated compounds, and high thermal stability.

[0004]

The present inventors have found that isobutane
Oxidization reaction and catalyst used therefor, especially Mo is essential
Regarding the catalyst contained as an ingredient, the activity,
It has excellent selectivity and thermal stability of methacrylic acid and methacrylic acid.
Catalyst component, composition, and preparation method in order to develop
As a result of intensive studies, Ta and Nb in addition to Mo
Contains one or more elements selected from among as essential ingredients
And a catalyst containing no P and As has a high activity,
Selectivity combining methacrolein and methacrylic acid
In addition to having much more than conventional heteropolyacid catalyst
It was found that the catalyst has excellent thermal stability, and
Reached the way. That is, the present invention is C₃~ C_FiveParafi
Gas and molecular oxygen are catalytically reacted in the gas phase to give C₃~ C
_FiveΑ, β-unsaturated aldehydes and α, β-unsaturated
In the method for producing rubic acid, a compound of the general formula XMo_aA_bB_cC_dO_p [In the formula, X is at least one selected from Ta and Nb.
Element, A is W, V, Sn, Sb, Fe, Al, Cr,
In Co, Ni, Cu, Mg, Ca, Sr and Ba
One or more elements selected from B, Li, Na, K, Rb
And one or more elements selected from Cs, C is C
one or more elements selected from e, Pr, and Tb
Represents a, b, c, d and p are based on X
Represents the atomic ratio of each element, a is 0.1 to 24, b is 0 to 2
0, c is 0 to 0.4, d is 0 to 0.4, p is each component element
It is the number of atoms required to satisfy the prime valence. ]
Containing the composition described above and containing neither P nor As.
C characterized by using a medium ₃~ C_FiveParaffin
And molecular oxygen are catalytically reacted in the gas phase to give C₃~ C_Fiveof
This is a method for producing an α, β-unsaturated aldehyde.

In order to obtain the effects of the present invention, it is important not to include P and As as catalyst components. As described in JP-A-3-106839, a heteropolyacid catalyst containing Mo, P or As as an essential component is industrially frequently used as an olefin oxidation catalyst.
Heteropolyacids or heteropolyacid salts containing
When it is used at about 40 ° C. for a long period of time, there is a problem that activity and selectivity are lowered. It is considered that this is because a part of the heteropolyacid or its heteropolyacid salt structure is decomposed. In the catalyst of the present invention containing, as an essential component, one or more elements selected from Ta and Nb in addition to Mo, when a component such as P or As that forms a heteropolyacid anion with Mo is added, the heat resistance of the catalyst is improved. Is reduced, which is not preferable.

The catalyst used in the method of the present invention can be prepared by a known method usually used in this field, for example, the following method. Ammonium molybdate is dissolved in pure water by heating, neutralized by adding a nitric acid aqueous solution, tantalum oxide is added, and this is stirred at about 100 ° C.,
Heat under reflux and, if necessary, W, V, Sn, Sb, F
e, Al, Cr, Co, Ni, Cu, Mg, Ca, Sr
And a compound of one or more elements selected from Ba,
For example, adding nitrate and, if necessary, SiO ₂
It is prepared by adding a carrier such as, and drying the resulting muddy suspension, calcining and firing. The raw material of the catalyst of the present invention is preferably a compound that can be decomposed into an oxide during the catalyst preparation process. Examples of such a compound include oxides, hydroxides, nitrates, ammonium salts, carbonates, chlorides, organic acid salts, metal acids, and ammonium salts of metal acids. As a raw material of SiO ₂ , silica sol, silica gel, silicate ester,
A silicate or the like is used. The catalyst is used in the fixed bed in the form of granules or shaped bodies, but it can also be used in the moving bed or the fluidized bed.

As the raw material gas for the gas phase catalytic oxidation reaction according to the present invention, C _{3 to} C ₅ paraffin and molecular oxygen are used. In addition to these raw material gases, a diluent gas can be used. Air is usually used as the molecular oxygen source, but pure oxygen may be used. An inert gas such as nitrogen or carbon dioxide is used as the diluting gas. A part of the non-condensable gas contained in the reaction gas may be circulated and used as a diluent gas. It is preferable to use water vapor together as a diluent gas in order to enhance activity and selectivity. The composition of the raw material gas is not particularly limited, but from the viewpoint of safety, the mixed gas composition is preferably outside the combustion range.
When water vapor is also used as a diluent gas, the water vapor in the raw material gas is usually added up to 60% by volume. The gas phase catalytic oxidation reaction according to the present invention is carried out by using the above-mentioned raw material gas,
A temperature range of 250 to 450 ° C., normal pressure to
It is carried out by introducing at a space velocity of 300 to 5000 / hr under a pressure of 10 atm.

[0008]

The present invention will be described in more detail with reference to Examples and Comparative Examples. The reaction rate, selectivity and yield are defined as follows.

Example 1 Ta ₂ O ₅ and H ₂ MoO ₄ were mixed at a Ta / Mo atomic ratio of 2/3.
To distilled water and stir at about 100 ° C for 16
The mixture was heated under reflux for a period of time and evaporated to dryness. The solid obtained is calcined at 600 ° C. for 4 hours in an air atmosphere to produce Ta ₂ Mo ₃
A catalyst having a composition of O ₁₄ was obtained. The obtained catalyst was filled in a normal flow reactor, and a raw material gas having a composition of an isobutane / oxygen / steam molar ratio of 3/2/2 was supplied at a space velocity of 3600.
/ Hr. The reaction temperature was kept at 320 ° C. to evaluate the performance of the catalyst. The evaluation results are shown in Table 1.

Example 2 Ammonium heptamolybdate and ammonium vanadate were dissolved in distilled water so that the V / Mo atomic ratio was 1/2, and a nitric acid aqueous solution was added to neutralize the mixture.
After adding tantalum oxide so that the / Mo atomic ratio becomes 1/1 and heating and refluxing at about 100 ° C. for 16 hours with stirring,
Evaporated to dryness. The solid obtained is calcined at 340 ° C. for 4 hours and then at 600 ° C. for 4 hours in an air atmosphere to give T
A catalyst having a composition of a ₂ V ₁ Mo ₂ O _x was obtained. The performance of the obtained catalyst was evaluated in the same manner as in Example 1. The results are shown in Table 1.
It was shown to.

Example 3 Ammonium heptamolybdate was dissolved in distilled water to prepare a solution A. Iron nitrate and cobalt nitrate were dissolved in distilled water so that the atomic ratio of Fe / Co was 3/7, and the solution was used as solution B. Fe / Mo
Solution B was added to Solution A so that the atomic ratio of was 3/12. Aqueous ammonia solution was added to this mixed solution to adjust to neutrality, then tantalum oxide was added to this so that the Ta / Mo atomic ratio was 1/12, and the mixture was heated under reflux at about 100 ° C. for 16 hours with stirring. , Evaporated to dryness. The solid obtained is 3
It was calcined at 40 ° C. for 4 hours and then calcined at 600 ° C. for 4 hours in an air atmosphere to obtain a catalyst having a composition of Ta ₁ Fe ₃ Co ₇ Mo ₁₂ O _x . The performance of the obtained catalyst was measured at a reaction temperature of 34
Evaluation was made in the same manner as in Example 1 except that the temperature was changed to 0 ° C. The results are shown in Table 1.

Example 4 In the same manner as in Example 3, Ta ₁ Fe ₃ Mg ₇ Ce _0.05 Mo
A catalyst having a composition of ₁₂ O _x was obtained. The performance of the obtained catalyst was evaluated in the same manner as in Example 3. The results are shown in Table 1.

Example 5 A catalyst having a composition of Nb ₂ Mo ₃ O ₁₄ was obtained in the same manner as in Example 1 except that Nb was used instead of Ta. The performance of the obtained catalyst was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 12 Molybdophosphoric acid (manufactured by Nippon Inorganic Chemical Co., Ltd.) was dissolved in distilled water, tantalum oxide was added thereto, and the mixture was stirred well.
After heating under reflux at about 100 ° C. for 16 hours, the mixture was evaporated to dryness. The solid obtained is calcined at 340 ° C. for 4 hours, then 4
Baked in a nitrogen atmosphere at 50 ° C. for 4 hours to produce Ta _0.1 P ₁ M
A catalyst having a composition of o ₁₂ O _x was obtained. The performance of the obtained catalyst was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0015]

[Table 1] Table 1 ─────────────────────────────────── Example Isobutane Methacrolein Methacrylic acid Conversion ( %) Selectivity (%) Selectivity (%) ──────────────────────────────────── Example 1 8.8 40 12 2 2 10.4 38 8 3 12.0 44 8 4 11.5 44 6 5 8.5 8.5 42 11 ────────────────────── ────────────── Comparative Example 1 2.1 18 24 ───────────────────────────── ────────

[0016]

The oxidation catalyst used in the present invention has a high activity and a high selectivity to α, β-unsaturated aldehydes or α, β-unsaturated carboxylic acids.
It is possible to efficiently produce α, β-unsaturated aldehydes and α, β-unsaturated carboxylic acids from C _{3 to} C ₅ paraffins.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C07C 47/21 9049-4H 57/05 7306-4H // C07B 61/00 300

Claims (2)

[Claims] 1. A C ₃ -C ₅ paraffin and molecular oxygen are catalytically reacted in the gas phase in the presence of a catalyst containing Mo as an essential component to give a C ₃ -C ₅ α, β-unsaturated aldehyde and In a method for producing an α, β-unsaturated carboxylic acid, a catalyst containing Mo and at least one element selected from Ta and Nb as an essential component and containing no P or As is used. C ₃ -C of ₅ alpha, beta-unsaturated aldehyde and alpha, method for producing beta-unsaturated carboxylic acids to. 2. A catalyst of the general formula XMo _a A _b B _c C _d O _p [wherein, X is at least one element selected from Ta and Nb, and A is W, V, Sn, Sb, Bi. , Fe, Al,
Cr, Co, Ni, Cu, Mg, Ca, Sr and Ba
One or more elements selected from among B, Li, Na,
One or more elements selected from K, Rb and Cs,
C represents one or more elements selected from Ce, Pr, and Tb. a, b, c, d and p represent atomic ratios of respective elements based on X, a is 0.1 to 24, b is 0 to 20, c is 0 to 0.4, d is 0 to 0.4. Yes, p is the number of atoms required to satisfy the valence of each component element. ] The composition shown by these is contained, P and As are not contained, The method of Claim 1 characterized by the above-mentioned.