JPS5820942B2 - Method for producing acrolein or methacrolein - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing acrolein or methacrolein, which comprises using a specific catalyst in producing acrolein or methacrolein by oxidizing propylene or isobutylene with molecular oxygen. It is something.

Many catalysts have been proposed as catalysts for gas phase catalytic oxidation reactions of propylene or imbutylene.

However, from an industrial standpoint, there are still problems that need to be improved.

For example, the selectivity of acrolein or methacrolein is low in the reaction, and isobutyraldehyde is produced as a by-product, and the boiling point of isobutyraldehyde (72.2°C) is very close to the boiling point of methacrolein (73.5°C). Therefore, it is difficult to separate and purify the two, and purified methacrolein cannot be used as a raw material for polymers that require it.Also, methacrylic acid, etc. are generated as by-products, making it difficult to separate and purify the two, and it is difficult to use the purified methacrolein as a raw material for producing unsaturated esters directly from unsaturated aldehydes. For example, it cannot be provided as a

Therefore, a catalyst system is desired that produces as few by-products as possible, such as isobutyraldehyde and methacrylic acid.

The present invention overcomes these drawbacks.

That is, the present invention has a general composition Sma, Feb%Nic, Bid, Xe, Qf
, Zg, Mol 2 , Oh (tanishi X is Rb,
Cs, Q are B, Co, Si, Z are Sc, Gd,
Hg = at least one element selected from Nd and Dy, e, f, and g each have X, Q, and Z of 2
When representing more than one element, it represents the sum of those elements, a is a value from 0.05 to 5, and b is a value from 0.05 to 1.
Value up to 0, C is a value from 0-05 to 5, d is 0.1
to 10, e is a value from 0.01 to 3, f is a value from 0 to 8, g is a value from 0.01 to 3, h satisfies the valence of other atoms present. It is the number of atoms of oxygen.

) is a method for producing acrolein or methacrolein, characterized by using a catalyst composition having the following.

In the catalyst composition of the present invention, the activity can be significantly improved by adding a small amount of Ni.

When the amount added is further increased, an increase in activity is observed, but on the other hand, the selectivity of methacrolein decreases and the amount of by-product of isobutyraldehyde increases.

As mentioned above, isobutyraldehyde is difficult to separate from methacrolein, and when methyl methacrylate is produced using methacrolein containing a large amount of isobutyraldehyde as a raw material, methyl isobutyrate is also produced at the same time, and the polymerization raw material It is not a sufficient standard.

Therefore, it is extremely important for industrial catalysts to suppress the by-product of isobutyraldehyde as low as possible.

In the catalyst composition of the present invention, the addition of Sm has the effect of significantly improving the selectivity of acrolein and methacrolein.

On the other hand, the Z component is at least one element selected from Gd, Sc, Hg, Nd, and Dy, preferably Gd and/or Sc.

By using this Z component together with Sm, there is an effect of suppressing the production of methacrylic acid, which is a byproduct.

Methyl acrylate (MMA) directly from methacrolein
When producing methacrylic acid, good results cannot be obtained if methacrylic acid is mixed in the raw material methacrolein.

Therefore, the result of suppressing the by-product of methacrylic acid as low as possible by adding the Z component to both Sm and \ has extremely important significance as an industrial catalyst.

The X components are Rb and Cs.

Component X is an essential component in this present catalyst composition.

Systems that do not contain X component and other alkali +) (Na,
In the system with the addition of Li ), a significant decrease in the selectivity of acrolein and methacrolein is observed.

As the carrier for the present catalyst composition, known carriers such as silica sol, silica gel, silicon carbide, and alumina can be used, and silica sol and silica gel are particularly excellent.

The present catalyst composition can be prepared, for example, as follows.

Water-soluble bismuth, iron, nickel, rubidium (or/and cesium) compounds and water-soluble samarium were added to an aqueous solution of ammonium molybdate, silica sol was added as a carrier, and the mixture was evaporated to dryness on a hot water bath. , Preliminary firing and main firing are performed in the presence of air or oxygen.

Usually, the pre-firing temperature is 100-500℃, preferably 2
The main firing temperature is 400 to 100℃.
It is carried out at 0°C, preferably 500-700°C, more preferably 500-630°C.

As the raw materials for each element used in the preparation of the present catalyst composition, not only oxides but also any material can be used as long as it forms the catalyst of the present invention by calcination.

For example, ammonium salts, nitrates, carbonates of each element,
Examples include organic acid salts, free acids, and condensed acids.

The catalyst can be used in the form of granules, tablets or powder.

The reactor may be either a fixed bed or a fluidized bed.

The reaction is carried out at 250-550°C, preferably 350-450°C.
It is carried out at a temperature in the temperature range of 0.degree. C. and a pressure of 0.5 to 10 atm, preferably normal pressure to 2 atm.

propylene or imbutylene, air (or oxygen),
The contact time between the mixed raw material gas of water vapor and inert gas and the catalyst is 0.1 to 15 seconds at normal pressure, preferably 0.2 to 10 seconds.
Seconds.

Also, the composition of the gas mixture is 0.5 to 4 moles of oxygen per mole of propylene or imbutylene, preferably 1,4
~2.5 mol, water vapor from 1 to 30 mol, preferably 2 to 30 mol
It is 15 moles.

Other active gases (e.g. N2, He, Ar, CO
2 etc.) can be freely changed depending on changes in other compositions.

The catalyst composition used in the present invention has characteristics such as a much higher selectivity for acrolein or methacrolein than conventionally proposed catalysts, and the production of isobutyraldehyde and methacrylic acid is suppressed to trace amounts. .

Therefore, it is ideal for producing raw materials for directly producing unsaturated esters from unsaturated aldehydes.

Further, the present catalyst composition does not contain highly toxic arsenic, tellurium, etc., and is found to be an extremely excellent catalyst composition as an industrial catalyst from the viewpoint of safety and economy.

Examples will be shown below, but the present invention is not limited to the scope of these Examples.

Example 1 200 m of ammonium paramolybdate 21.2f
1 of distilled water, add and dissolve 0.31 f of rubidium nitrate.

This is called solution A. 200m of nickel nitrate 2.91
Dissolve A in distilled water, and further dissolve 4.04 P of ferric nitrate, 4.44 P of samarium nitrate, and 1.35 P of gadolinium nitrate.

This was mixed with the previously prepared solution A, and silica sol (Ca
Add taloid S 20H) 32.779.

A nitric acid aqueous solution containing 4.48 g of bismuth nitrate is added to this solution while stirring.

This solution was then evaporated to dryness on a water bath and then heated to 300°C.
Temporary firing was carried out in the air for 2 hours, and the fired product was heated to 10
It was crushed into ~28 meshes and main firing was performed in air at 600°C for 4 hours.

This catalyst composition is Mol2BilFelNil SmlRb6.2Gd□
-30x.

Example 2 A Pyrex reaction tube with an inner diameter of 5 mm was filled with the catalyst 51 prepared in Example 2, and the molar ratio of imbutylene 10□/H20/N2 was 2- at a reaction temperature of 380 to 480°C.
A mixed gas of 1/4.2/20/72.7 was reacted for a contact time of 2.5 seconds.

The results are shown in Table 1. Example 3 A reaction was carried out under the same reaction conditions as in Example 2 using a catalyst prepared by adding samarium nitrate and gadolinate and simultaneously adding boric acid under the same preparation conditions as in Example 1.

The results are shown in Table 1. Example 4 Under the same preparation conditions as in Example 1, a reaction was carried out under the same reaction conditions as in Example 2 using a catalyst to which scandium nitrate was added instead of gadolinium nitrate.

The results are shown in Table 1.

Example 5 Under the same preparation conditions as in Example 4, Example 2 was prepared for a catalyst in which scandium nitrate was added and boric acid was added at the same time.
The reaction was carried out under the same reaction conditions.

The results are shown in Table 1.

Comparative Example 1 A reaction was carried out under the same preparation conditions as in Example 1 and under the same reaction conditions as in Example 2 using a catalyst to which gadolinium nitrate was not added.

The results are shown in Table 1. Comparative Example 2 A reaction was carried out under the same reaction conditions as in Example 2 using the same preparation conditions as in Example 3 and using a catalyst to which gadolinium nitrate was not added.

The results are shown in Table 1. Examples 6 to 16 Prepared under the same preparation conditions as Example 1 with different catalyst compositions,
The reaction was carried out under the same reaction conditions as in Example 2.

The catalyst composition and reaction results are shown in Table 2.

Comparative Examples 3 to 8 Prepared under the same preparation conditions as Example 1 with different catalyst compositions,
The reaction was carried out under the same reaction conditions as in Example 2.

The catalyst composition and reaction results are shown in Table 2.

Examples 17 to 19 and Comparative Examples 9 to 12 Catalysts prepared under the same preparation conditions as Example 1 but with different catalyst compositions were reacted under the same reaction conditions as Example 2, and the production of isobutyraldehyde and acetic acid was investigated. .

The results are shown in Table 3. Example 20 A reaction tube was filled with the catalyst 52 prepared in Example 1, and a raw material gas having a molar ratio of 0□ and propylene of 1.5 was reacted at a reaction temperature of 420°C for a contact time of 2.5 seconds. However,
The conversion rate of propylene was 94.5%, the selectivity of acrolein was 85.0%, and the selectivity of acrylic acid was 6.8%.

Claims (1)

[Claims] 1. When propylene or imbutylene is oxidized with molecular oxygen to produce acrolein or methacrolein, the general composition Sma, Feb, Nic, Bid, Xe, Qf, Zg
, Mo12, Oh (and X is Rb, Cs,
Q is B, Co, Si, X is Sc, Gd, Hg, Nd,
At least one element selected from Dy,
e, f, and g each represent the sum of those elements when X, Q, and Z represent two or more elements, and a is 0.05
b is a value from 0.05 to 10, C is a value from 0.05 to 5, d is a value from 0.1 to 10, e is a value from 0.01 to 3, f is a value from 0 to 8, g is a value from 0.01 to 3, and h is the number of oxygen atoms satisfying the other valences present. ) A method for producing acrolein or methacrolein, characterized by using a catalyst composition having the following. 2. The method for producing acrolein or methacrolein according to claim 1, wherein c is a value of 0.05 or more and less than 2.