JPS6032608B2 - Method for producing unsaturated compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing the corresponding unsaturated carboxylic acid from a saturated aldehyde and molecular oxygen.

More specifically, the present invention relates to a method for producing acrolein and acrylic acid or methacrolein and methacrylic acid by contacting a mixed gas containing propionaldehyde or isoptyraldehyde and molecular oxygen with a catalyst in a high-temperature gas phase.

There are many proposals in the art regarding a method for producing methachlorene and/or methacrylic acid by oxidative dehydrogenation of isobutyraldehyde in the presence of a catalyst.

For example, a method using molybdenum and a lead oxide catalyst (Japanese Patent Publication No. 43-16202), a method using phosphomolybdic acid in which a portion of molybdenum may be replaced with vanadium and/or tungsten (Samurai Publication No. 48-78112) )
, a method using a catalyst containing phosphorus, molybdenum, antimony, zinc, and an N ratio group as essential components (JP-A-50-149
611) etc.

On the other hand, some of the present inventors have already reported a method using molybdenum and cobalt, molybdenum and tungsten, or molybdenum and tungsten and tellurium (Japanese Patent Application Laid-open No. 14085/1985) and a method using antimony and titanium and (or ) Method using tungsten (
Special Publication No. 46-28001) was proposed. However, in all of these proposed methods, the yield of the target products, methacrolein and/or methacrylic acid, is low or
Moreover, it has disadvantages such as the short life of the catalyst used, and is not practical from an industrial standpoint.

Therefore, the present inventors conducted intensive research on catalysts used to produce methacrolein and methacrylic acid from isobutyraldehyde in order to improve the above-mentioned drawbacks. They discovered a highly practical catalyst, and discovered that this catalyst is also effective in producing acrolein and acrylic acid from propionaldehyde, thereby completing the present invention.

That is, the present invention converts a mixed gas containing propionaldehyde or isobutyraldehyde and molecular oxygen into phosphorus,
Consisting of molybdenum and oxygen, and one or more selected from the group consisting of potassium, rubidium, and cesium, and optional components of phosphorus, copper, vanadium, tungsten, iron, manganese, tin, antimony, magnesium, aluminum, and silicon. , calcium, titanium, zirconium, silver, tellurium, barium, tantalum, chromium, niobium, cobalt, nickel, strontium, zinc, cadmium, germanium, lead, bismuth, selenium,
Ruthenium, rhodium, platinum, palladium, rhenium,
At least one selected from the group consisting of gold and hafnium
This is a method for producing acrolein and acrylic acid or methacrolein and methacrylic acid, which is characterized by bringing them into contact with a catalyst containing seeds in a high-temperature gas phase.

The first feature when using the catalyst according to the present invention is that 300
The conversion rate of saturated aldehyde is extremely high at a relatively low temperature of 0.00 or less, and the conversion rate of saturated aldehyde is substantially reduced to 100%.
%, the yield of the target products, unsaturated aldehyde and unsaturated acid, can be maintained at a high level.

The conversion rate of the saturated aldehyde, which is the raw material, was substantially reduced to 10
The fact that it can be increased to 0% means that there is no need to recycle unreacted raw materials, which makes it possible to downsize the equipment and reduce utilities, which is of extremely great industrial value.

The second feature is that the stability of the catalyst activity is extremely high.

Even if the catalysts proposed in the past exhibit high activity at the initial stage of the reaction, in many cases the catalytic activity decreases over time if the reaction is continued for a long period of time. However, in the catalyst according to the present invention, 5
Even after 00 hours of continuous reaction, the production activity of the target products, unsaturated aldehyde and unsaturated acid, remained almost unchanged. Considering that if the alkali metal, which is an essential component, is removed from the catalyst of the present invention, the yield of the target unsaturated aldehyde and unsaturated acid decreases, and the catalytic activity decreases significantly over time, the above-mentioned problems regarding the present invention are considered. Both of these characteristics are thought to be due to the alkali metal, which is an essential component in the catalyst. In the method according to the present invention, unsaturated aldehydes and unsaturated acids are usually co-produced, but by increasing the reaction temperature, the amount of unsaturated aldehydes produced can be reduced and the amount of unsaturated acids produced can be increased. Alternatively, the catalyst according to the present invention is packed into two connected reaction tubes, saturated aldehyde is supplied to the first reaction column to cause an oxidative dehydrogenation reaction, and the product gas containing unsaturated aldehyde is passed from the first reaction column. It is also possible to synthesize an unsaturated acid from a substantially saturated aldehyde in one step by supplying the aldehyde to a second reaction column maintained at a high temperature.

The production ratio of unsaturated aldehyde and unsaturated acid can also be changed by changing the catalyst composition.

For example, ruthenium, rhodium, platinum,
When rhenium, gold, palladium or hafnium is added, the production rate of unsaturated acids can be significantly increased. On the other hand, when calcium, titanium, zirconium, silver, tellurium, barium, tantalum or chromium is added, the production ratio of unsaturated aldehydes can be further increased. In the catalyst used in the present invention, the atomic ratio of phosphorus and metal elements can be varied over a relatively wide range, but the atomic ratio particularly suitable for practical use is 12 for molybdenum and 0 for phosphorus.
．． The total amount of potassium, rubidium and cesium is 0.2 to 6, and the total amount of metals added as optional components is 0.01 to 6. The method for preparing the catalyst does not need to be limited to a special method, and various conventionally well-known methods such as evaporation to dryness method, precipitation method, oxide mixing method, etc. can be used as long as the method does not involve significant uneven distribution of components. be able to.

A combination of nitrates, ammonium salts, halides, or oxides of each element can be used as a raw material compound for catalyst preparation. The heat treatment temperature of the catalyst is 30
The heat treatment time ranges from 0 to 650 q0, preferably from 350 to 600 q0, and the heat treatment time varies depending on the temperature, but is suitably from one hour to several tens of hours. The catalyst used in the method of the present invention is silica,
It can be used by supporting it on an inert carrier such as alumina, silica alumina, silicon carbide, or by diluting it with these.

Although the raw material gas composition can be varied within a wide range, it is preferable that the saturated aldehyde and oxygen are each in the range of 1 to 20 mol %, and the inert gas is in the range of 60 to 98 mol %. Usually, the reactant is diluted with an inert gas such as nitrogen, steam, carbon dioxide, etc., and then subjected to the reaction.

In particular, the presence of water vapor may improve the yield of the target unsaturated compound. The reaction may be carried out at normal pressure, but under a slight reduced pressure or pressure, for example 0.5 to 20 atm (absolute pressure).
You can do it.

The reaction temperature is 220-3200°, especially 240-3000°
0 is preferred. The content of the present invention will be specifically explained below using Examples and Comparative Examples.

All parts represent parts by weight. Example 42.4 parts of ammonium paramolybdate was dissolved in 20 parts of 60 qC pure water.

To this were added 2.3 parts of 85% phosphoric acid and 2.0 parts of potassium nitrate. The mixture was heated and evaporated to dryness while stirring.
The obtained solid was dried at 130 pm for an hour, pulverized, pressure molded, pulverized into 10 to 20 mesh, and then fired at 400 qo for 5 hours under air circulation. The composition of the catalyst is P, Mo, and 2K in atomic ratio.

The obtained catalyst was packed into a reactor, and a mixed gas of 4% isobutyraldehyde, 10% oxygen, 30% steam, and 56% nitrogen (all by volume) was heated at a reaction temperature of 260°C and a contact time of 0.
．． It passed through the catalyst layer in 9 seconds. When the product was collected and analyzed by gas chromatography, the conversion of isobutyraldehyde was 98.0% and the selectivity of methacrolein was 77.5.
%, and the methacrylic acid selectivity was 4.3%. In addition, acetic acid,
Acetone, carbon monoxide, carbon dioxide, etc. were generated. When reacted for 50 hours under the same conditions, the isobutyraldehyde conversion rate was 97.5% and the methacrolein selectivity was 77.3%.
, the methacrylic acid selectivity was 4.1%.

Example 2 Using the catalyst of Example 1, a mixed gas of 4% propionaldehyde, 10% oxygen, 30% water vapor, and 56% nitrogen was passed through the catalyst layer at a reaction temperature of 250 qC and a contact time of 0.9 seconds. Propionaldehyde conversion rate 81
%, Ak.

The rhein selectivity was 62% and the acrylic acid selectivity was 3%.
Examples 3 and 4 Compared to Example 1, 2.95 parts of rubidium nitrate or 3.95 parts of cesium nitrate was used instead of potassium nitrate.
The reaction was carried out in the same manner as in Example 1, except that 9 parts of the catalyst were added.

The results are shown in Table 1. Table 1 Comparative Examples A catalyst different from Example 1 except that potassium nitrate was not added was prepared and reacted in the same manner as in Example 1.

The results are shown in Table 2. Table 2 Examples 5 to 49 The following catalysts were prepared according to the method of Example 1 and reacted in the same manner as in Example 1, and the results are shown in Table 3.

Table 3 Comparative Examples 2 to 4 Catalysts were prepared in Examples 5, 41, and 48, except that no alkali metal was added, and the reactions were carried out in the same manner as in Example 1.

The results are shown in Table 4. Table 4 From the above results, it can be seen that the catalyst to which no alkali metal is added exhibits a selectivity decrease of 6 to 7% under the same conditions.

Claims (1)

[Claims] 1. A mixed gas containing propionaldehyde or isobutyraldehyde and molecular oxygen consisting of phosphorus, molybdenum and oxygen, and one or more selected from the group consisting of potassium, rubidium and cedium and optional components. As arsenic, copper, vanadium, tungsten, iron, manganese, tin, antimony, magnesium, aluminum, silicon, calcium, titanium, zirconium, silver, tellurium, barium, tantalum, chromium, niobium, cobalt, nickel, strontium, zinc, cadmium ,
Acrolein is brought into contact with a catalyst containing at least one member selected from the group consisting of germanium, lead, bismuth, selenium, ruthenium, rhodium, platinum, palladium, rhenium, gold, and hafnium in a high-temperature gas phase. Method for producing acrylic acid or methacrolein and methacrylic acid. 2. The method according to claim 1, characterized in that a catalyst containing 1 to 5 types of elements used as optional components is used. 3. The method according to claim 1, characterized in that a catalyst is used in which the elements used as optional components are selected from arsenic, vanadium, copper, silicon, magnesium, titanium, zirconium, chromium, tantalum, and calcium. 4. The method according to claim 1, wherein the reaction is carried out in a gas phase at a reaction temperature of 220 to 320°C.