JP2614089B2 - Acrolein production method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing acrolein, in which propane is oxidized in the gas phase in the presence of a catalyst to produce acrolein in one step.

[Prior Art] Several methods have been proposed to produce acrolein in one step using propane as a raw material. For example, U.S. Pat.No. 4,472,314 uses a bismuth-based perovskite-type oxide catalyst, and German Patent No. 1903617 uses an antimony-based catalyst. 13
No. 47971 discloses a method for producing acrolein in one step by using a phosphorus-based catalyst.

[Problems to be disclosed by the invention] However, in the disclosed methods, side reactions are insufficiently suppressed, and an oxidation reaction must be performed at a high temperature in order to obtain sufficient activity. However, there was a problem in implementing the method, and in practice, it was not practical.

[Means for Solving the Problems] The present inventors have conducted intensive studies with the aim of providing an advantageous method for producing acrolein from propane in one step, and as a result, by using a specific catalyst, It has been found that acrolein can be produced with good selectivity while suppressing side reactions, and the present invention has been completed.

That is, the present invention relates to a method for producing acrolein by contacting propane with a molecular enzyme in the gas phase in the presence of a catalyst, wherein a general formula Bi _a V _b Mo _c Ag _d O _x (where a, b, c, d and x represent the atomic ratio of each element, and when a = 1, b = 0.001 to 1 and c = 0.001
And d = 0 to 0.1, and x represents the number of oxygen atoms satisfying the average valence of the element present. A process for producing acrolein, which is carried out in the presence of a catalyst represented by the formula:

[Specific Description of the Invention] (1) Raw Material In the method of the present invention, propane used as a raw material can be used in a raw material gas whose concentration is changed in a wide range. Appropriately, it is more than 60% by volume, especially 25% by volume.
As described above, the content is preferably set to 50% by volume or less.

As the oxygen used to oxidize the propane, oxygen gas or oxygen-containing gas is used, but air is generally used because of its low cost.

The source gas may be diluted by adding an inert gas such as nitrogen, steam, or carbon dioxide.

(2) As the catalyst used in the catalyst structure present process, a catalyst of the general formula _{Bi a V b Mo c Ag d} O x is used.

Here, in the above general formula, a, b, c, d and x
Represents the atomic ratio of each element, and when a = 1, b
= 0.001 to 1, preferably 0.3 to 0.7, c = 0.001 to 1, preferably 0.3 to 0.7, d = 0 to 0.1, preferably 0.005 to 0.
05, and x represents the number of oxygen atoms that satisfy the average valence of the element present.

In the above catalyst, a, which is an atomic ratio of each element in the formula,
When b, c, d, and x are out of the above ranges, acrolein selectivity deteriorates.

Catalyst preparation Such a catalyst is not limited to a special catalyst preparation method, and various methods such as a well-known evaporation-drying method and a precipitation method are not limited unless a significant uneven distribution of each catalyst component is involved. Can be prepared.

As the raw material compound used for preparing the catalyst, a nitrate, a carbonate, an ammonium salt, an oxide or the like of each element can be used in combination.

Carrier The catalyst used in the method of the present invention is very effective without a carrier. However, the catalyst may be supported on a carrier such as silica, alumina, silica / alumina, or silicon carbide, or may be diluted with these.

(3) Reaction Conditions In carrying out the method of the present invention, an oxidation reaction is carried out by adding molecular oxygen to the raw material propane and bringing it into gas phase contact in the presence of the above catalyst.

The reaction conditions are as follows: the amount of oxygen in the raw material gas used in the reaction is 0.05 to 10, preferably 0.1 to 3, in terms of molar ratio to propane, and the space velocity (SV) in the gas phase catalytic oxidation reaction 500 to 5000 hr ^-1 , preferably 1000 to 4
Performed by setting to 000hr ^-1 . If the molar ratio of oxygen and the space velocity of these raw materials to propane are outside the above ranges, acrolein selectivity decreases.

In addition, the reaction pressure is generally good from normal pressure to several atmospheres, and most preferably normal pressure to 3 atmospheres, and the reaction temperature is 400 to 5 atmospheres.
Although it can be selected within the range of 50 ° C., it is particularly preferable to carry out the reaction within the range of 450 to 500 ° C.

In addition, by recycling unreacted propane in the reaction gas to make effective use of the raw material propane,
The overall conversion of propane can also be improved.

EXAMPLES Hereinafter, the method for producing acrolein of the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

In addition, the reaction rate and the selectivity described in this specification are defined as follows.

Example 1 While heating and stirring 100 ml of distilled water, 25.4 g of ammonium molybdate and 20.2 g of ammonium metavanadate were added and dissolved to obtain a solution A.

Separate from the above solution A, 13.2 g of bismuth nitrate in 15 ml of distilled water
Was further added to prepare a nitrate solution acidified by adding 3 ml of concentrated nitric acid, and a nitrate solution obtained by dissolving 5.4 g of silver nitrate in 5 ml of distilled water. These two types of nitrate solutions were added to the above solution A.

After evaporating the mixture to dryness while heating and stirring,
Dry at 16 ° C. for 16 hours. Crush the obtained solid, diameter 5m
After pressure molding into pellets of m, the mixture was calcined at a temperature of 500 ° C. for 4 hours in an air flow.

As a result of analyzing the catalyst obtained by this calcination by an atomic absorption method, the atomic ratio of the elemental composition excluding oxygen of the catalyst oxide was Bi ₁ V _0.635 Mo _0.529 Ag _0.012 .

This catalyst is charged into a gas-phase contact reactor, and a mixed gas of 33% by volume of propane and 67% by volume of oxygen is supplied at a reaction temperature of 485 ° C and an SV of 3%.
The reaction was performed by passing the mixture under the reaction conditions of 000 hr ^-1 .

The obtained product was collected and analyzed by gas chromatography. As a result, the propane conversion was 10%, the acrolein selectivity was 62%, and the CO + CO ₂ selectivity was 35%.

Example 2 Using the same catalyst as in Example 1, space velocity SV = 2400 hr ^-1
The reaction was carried out under the same conditions, except that the propane conversion was 12%, the acrolein selectivity was 60%, and CO + CO
₂ Selectivity was 35%.

Example 3 The same catalyst was used as in Example 1 and the reaction was carried out under the same conditions except that the reaction temperature was 460 ° C. The propane conversion was 10%, the acrolein selectivity was 55%, and the CO + CO ₂ selectivity was 10%. Was 36%.

Example 4 A catalyst was prepared in the same manner as in Example 1 except that the elemental composition excluding oxygen was Bi ₁ V _0.65 Mo _0.53 . The catalyst was charged into a gas phase contact reactor, and propane was 48% by volume and oxygen was 52% by volume. The mixed gas of
The reaction was conducted by passing the mixture under the reaction conditions of a reaction temperature of 485 ° C. and an SV of 1800 hr ⁻¹ , and the propane conversion was 30%, acrolein selectivity was 30%, and CO + CO ₂ selectivity was 55%.

[Effects of the Invention] The process for producing acrolein of the present invention suppresses side reactions by performing a contact reaction with a specific catalyst under specific reaction conditions, and has good selectivity. Acrolein can be produced at low cost. Further, since the reaction can be carried out at a relatively low reaction temperature, it is industrially extremely advantageous.

Claims (2)

(57) [Claims] 1. A process for producing acrolein by contacting propane with molecular oxygen in the gaseous phase in the presence of a catalyst, to produce acrolein, wherein the general formula Bi _a V _b Mo _c Ag _d O _x (where a, b , C, d and x represent the atomic ratio of each element, and when a = 1, b = 0.001 to 1 and c = 0.001
And d = 0 to 0.1, and x represents the number of oxygen atoms satisfying the average valence of the element present. A process for producing acrolein, which is carried out in the presence of a catalyst represented by the formula: 2. The oxygen / propane molar ratio in the raw material gas is set to 0.
The method for producing acrolein according to claim 1, wherein the spatial abundance (SV) is from 500 to 5000 hr ^−1, and the acrolein is from 05 to 10.