JPS5835492B2 - Method for producing methacrolein - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for advantageously producing methacrolein by catalytically reacting imbutylene with molecular oxygen in the presence of an improved catalyst in the high temperature gas phase.

Conventionally, many methods for producing unsaturated aldehydes by catalytically reacting olefins with molecular oxygen in the presence of a catalyst in the high-temperature gas phase and catalysts used in this process are already known, but there are many known methods for producing acrolein from propylene. Compared to other methods, there are few proposals for producing methacrolein from isobutylene, and even if a catalyst can be used for both acrolein production and methacrolein production, if it is used for methacrolein production, it will not be used for acrolein production. In many cases, the catalyst performance is inferior to that when used.

The reason why there are few proposals for the production of methacrolein and the catalyst performance is inferior to that of acrolein is partly due to the branching of isobutylene. This shows that it is more difficult to produce methacrolein than it is to produce it.

Catalysts used when producing methacrolein by catalytically reacting isobutylene with molecular oxygen in the presence of a catalyst in the high temperature gas phase are disclosed, for example, in Japanese Patent Publication No. 4742241 (Co-F
e-Bi-W-Mo-8i-K), Special Publication No. 47-428
Publication No. 13 (Co-Fe-Bi-WMoSi
-KP), Special Publication No. 48-1645 (Co
-Fe -Bi -Cr -K -Mo ), Japanese Patent Publication No. 51-12604 (Co -Fe -W-Mo
-8i -TI-B i ), JP-A-48-514
No. (Co-Fe-Bi-MgK-Mo), JP-A-48-52713 (Co-Fe-Bi
-Mo-K), JP-A-5134107 (M
n -K -Co -Ni -Fe -Bi -Mo
), and these catalysts all have in common that they contain molybdenum, cobalt, bismuth, and iron as constituent elements.

Furthermore, although conventionally known Mo-Bi-Fe-Co catalysts have shown relatively high selectivity for methacrolein, the yield of methacrolein was often less than 80%.

There have also been proposals for catalysts that can achieve a yield of over 80% of methacrolein, but with such catalysts,
Requires a relatively high reaction temperature of around 400°C and a relatively long contact time of around 4 seconds, and the unit time of methacrolein
It has drawbacks such as a low production amount per unit catalyst volume (space-time yield), and there is still room for improvement as an industrial catalyst.

Although it is very difficult to develop a catalyst that can achieve a methacrolein yield of 80% or more, the inventors have succeeded in achieving a methacrolein yield of 80% or more using a lower reaction temperature and short contact time. With the aim of developing a catalyst that can produce methacrolein with a high space-time yield of more than %, intensive research was conducted on catalysts containing molybdenum, bismuth, iron, and cobalt.

As a result, the following general compositional formula is formed by combining one or more elements selected from the group consisting of vanadium, niobium, and tellurium. [In this formula, Mo is molybdenum, Co is cobalt, and Fe
is iron, Bi is bismuth, X is one or more elements selected from the group consisting of vanadium, niobium, and tellurium, and O is oxygen, and the subscripts a, b, c, d, e, and f indicate the number of atoms. and when 8 is fixed as 10, b is 3 to 10, preferably 4 to 9, C is 1 to 7, preferably 1.5 to 5,
d is 0.1-1.5, preferably 0.15-1.2, e
is 0.01 to 1, preferably 0.03 to 0.5, and f is a value naturally determined by the valence of each element other than oxygen, and usually takes a value of 34.6 to 54.1.

] When the composition represented by is used as a catalyst, 300
Not only does the yield of methacrolein reach more than 80% even at a reaction temperature of around 1.5°C and a contact time of around 1.5 seconds, but the space-time yield of methacrolein reaches more than 30 of/1-hr, and even more than 350? This invention was achieved after learning that it can reach even more than /1-br.

The present invention is characterized in that a composition represented by the above general compositional formula is used as a catalyst in a method for producing methacrolein by catalytically reacting isobutylene with molecular oxygen in the presence of a catalyst in a high temperature gas phase. The present invention relates to a method for producing methacrolein.

According to the method of the present invention, the reaction temperature is relatively lower than that of the conventional method, the yield of methacrolein is high even with a short contact time, and the space-time yield is also high. It has the great advantage of being manufacturable.

The catalyst used in the method of this invention is represented by the above general composition formula, but when molybdenum is fixed at 10 atoms, if cobalt, iron and bismuth are out of the above range, the selectivity of methacrolein will decrease. , the reaction rate of isobutylene will be low, and the yield and space-time yield of methacrolein will also be low, so it is not suitable, and vanadium,
When the proportion of one or more elements selected from the group consisting of niobium and tellurium is more than 1 atom per 10 molybdenum atoms, the selectivity of methacrolein in particular decreases,
It is not suitable because the yield and space-time yield of methacrolein are low.

The constituent elements of the catalyst used in the method of the present invention are mainly present in the catalyst as a metal oxide in which a single element is combined with oxygen, an oxide in which a plurality of elements are combined with oxygen, and a mixture thereof. There is.

In the catalyst used in the method of this invention, vanadium,
Even when two or three types of one or more elements selected from the group consisting of niobium and tellurium are present in the catalyst, no significant difference in catalyst performance is observed compared to when one element is present.

The catalyst used in the method of the present invention is prepared by using a compound containing each component element constituting the catalyst, such as an oxide or a salt of each element, as a starting material for preparing the catalyst. Although it can be easily prepared by a method, it can be prepared at a temperature of 500 to SOO℃, preferably 600 to 700℃, which is higher than the firing temperature conventionally used for catalyst preparation.
It is appropriate to prepare by baking for 20 hours, preferably 2 to 10 hours.

If the calcination temperature is too low or too high, the yield of methacrolein will decrease.

Catalysts can be made by mixing compounds such as oxides and salts of each element in the presence of water to form a paste, drying it, and then baking it at the above temperature to form a mixed solution or mixture of compounds of each element. By evaporating the suspension to dryness and then calcining it at the above temperature, or by producing a coprecipitate containing each component element from the mixed solution, separating it, drying it, and calcining it at the temperature mentioned above. It can be prepared.

Oxides of each element that can be used as starting materials for catalyst preparation,
Examples of compounds such as salts include molybdenum compounds such as molybdic acid, ammonium molybdate, and molybdenum dioxide, cobalt carbonate, cobalt nitrate, cobalt oxide, tricobalt tetroxide, cobalt chloride, cobaltous hydroxide, and cobaltous hydroxide. Cobalt, cobalt compounds such as cobalt sulfide, ferrous nitrate, ferric nitrate, ferrous oxide, ferric oxide, ferrous carbonate, ferrous sulfide, ferrous chloride, ferric chloride, water Iron compounds such as ferrous oxide, ferric hydroxide, ferrous sulfate, ferric sulfate, ferrous ammonium sulfate, ferric ammonium sulfate, bismuth nitrate, bismuth dichloride,
Bismuth compounds such as bismuth trichloride, hismuth pentoxide, bismuth trioxide, bismuth tetroxide, bismuth nitrate oxide, bismuth hydroxide, bismuth subnitrate, bismuth oxychloride, vanadium pentoxide, vanadium tetrachloride, ammonium metavanadate, vanadyl oxalate , vanadium compounds such as vanadyl nitrate and vanadium oxychloride, niobium compounds such as niobium chloride and niobium pentoxide, tellurium such as (ortho or meta) telluric acid, tellurium dioxide, tellurium dichloride, tellurium disulfide, and tellurium nitrate. Compounds such as cobalt molybdate and iron molybdate can also be used.

An example of a catalyst preparation method suitably used in the method of the present invention will be described below with respect to a catalyst consisting of molybdenum, cobalt, iron, bismuth, vanadium, and oxygen.

First, a predetermined amount of a water-soluble molybdenum compound such as molybdic acid, ammonium molybdate, etc., and a predetermined amount of a water-soluble vanadium compound such as ammonium metavanadate, vanadyl nitrate, etc. are added to hot water at 50 to 90°C. and a predetermined amount of a water-soluble cobalt compound such as cobalt nitrate, cobalt chloride, etc., and a predetermined amount of a water-soluble iron compound such as ferrous nitrate, ferric nitrate, etc. An aqueous solution containing each of these and a predetermined amount of a solution containing a bismuth compound soluble in nitric acid, such as bismuth nitrate or bismuth hydroxide, dissolved in nitric acid were added dropwise while stirring to form a slurry. After that, the slurry-like mixed solution was evaporated to dryness to obtain a solid, and then heated at 500 to SOO℃.
, preferably at 600 to 700°C for 1 to 20 hours, preferably 2 to 10 hours, to obtain the desired catalyst.

Although the catalyst preparation method is not limited to this one example, in order to prepare a catalyst that exhibits sufficient catalytic performance, each starting material must be sufficiently dispersed and mixed to ensure that the catalyst component elements are as uniform as possible. It is preferable to disperse the starting materials in water and calcinate them at the above calcination temperature. Generally, it is preferable to perform dispersion and mixing by dissolving each starting material in water, an acid such as nitric acid, an alkaline solution such as aqueous ammonia, etc. It is.

The catalyst used in the method of this invention may be used alone or supported on a carrier.

As the carrier, any of the carriers conventionally known as carriers for oxidation catalysts can be used, and examples thereof include silica, alumina, alumina-silica, titania, giesel earth, and carborundum.

When the catalyst is supported on a carrier, the ratio of the carrier to 1 g of catalyst is preferably 3.02 or less, preferably 0.01 to 2.02. It may be supported.

There is no particular difference in catalyst performance depending on the size, shape, presence or absence of a carrier, etc. of catalyst particles.

When carrying out the method of the present invention in the presence of the catalyst, in addition to imbutylene and molecular oxygen, a gas substantially inert to the oxidation reaction is mixed with the mixed gas as a diluent gas. be able to.

Examples of the diluent gas include water vapor, nitrogen gas, carbon dioxide gas, etc. Among them, water vapor, when present in the reaction system, has the effect of improving the selectivity of methacrolein and sustaining the catalytic activity. Therefore, it is preferable to have water vapor present in the reaction system.

The amount of water vapor is 0.1 to 1 mole of isobutylene.
The proportion is preferably 8 mol, preferably 1 to 5 mol.

In addition to the diluent gas, the reaction system also contains a hydrocarbon compound that is substantially inert to this reaction in an amount of 0.5 mol or less, preferably 0.1 mol or less, per 1 mol of isobutylene. If so, there is no problem even if they are mixed together.

Therefore, the raw material isobutibine does not necessarily have to be of high purity.

Furthermore, molecular oxygen does not need to be a particularly high-purity oxygen gas, and it is generally economical to use an oxygen-containing gas, such as a gas prepared by diluting oxygen gas with the diluent gas mentioned above, or air. It is convenient to use it as is.

The amount of molecular oxygen is 1 to 1 mole of isobutylene.
A suitable proportion is 4 mol, preferably 1.2 to 3 mol.

When the method of the present invention is carried out in the presence of the above catalyst, a particularly high methacrolein yield can be obtained at a reaction temperature of around 300°C and a contact time of around 1.5 seconds; There is no problem in implementing it within the scope of.

In the method of this invention, the reaction temperature is generally from 260 to
The optimal temperature is 370°C, preferably 280-350°C, more preferably 290-340°C, and the contact time is 0.2
~7 seconds, preferably 0.5-5 seconds, more preferably 1
The optimum time is about 2.5 seconds.

The reaction pressure may be normal pressure, low pressure, or reduced pressure, but it is generally appropriate to carry out the reaction under normal pressure.

The reaction can be carried out in a fixed bed, a moving bed, a fluidized bed, etc., but it is generally suitable to carry out the reaction in a fixed bed.

Next, the present invention will be explained in further detail by showing Examples and Comparative Examples.

On each side, the results were measured 1 hour after starting the reaction, and were as follows: isobutylene conversion (%), methacrolein selectivity (%), methacrolein yield (1 pass yield) (%). and the space-time yield (?/l-hr) of methacrolein follow the following definition.

Example 1 Ammonium molyftate ((NH4)6 ・Mo7024'' 4H20,l
356. IP and ammonium metavanadate [NH
Cobalt nitrate (Co 2 (NO3) 2
・6 H2O, 1234,9 and ferric nitrate (Fe (NO3)3-9H20) l 53.4 f
and bismuth nitrate CBi(NO3)s・5H20,l 88.
A solution of IP dissolved in 10'I'Ill of a 15% by weight nitric acid aqueous solution was dropwise mixed with stirring to form a slurry-like mixed solution.

Next, this slurry mixed solution was heated and evaporated to dryness to obtain a solid.

The solid material was formed into a 5 mm TFI tablet, and then slowly heated in an air atmosphere to a temperature of 650°C for 50 minutes.
A catalyst having an atomic ratio as shown in Table 1 was prepared by firing for a period of time.

A glass U-shaped reaction tube with an inner diameter of 8 mm was filled with 8 rrL of the catalyst thus obtained, and 30 liters of a mixed gas of inbutylene:air:steam with a volume ratio of 1:10:4 was poured into the tube.
0TLl/mi! The reaction temperature was 310°C.
The contact reaction was carried out under normal pressure for a contact time of 1.6 seconds.

The amount of oxygen in the mixed gas used in this reaction was about 2.0 mol per 1 mol of isobutylene supplied.

The results of the contact reaction are shown in Table 1.

Examples 2 to 6 Ammonium metavanadate (NH4VO3), cobalt nitrate (Co (NO3)2 ・6H20, l,
Ferric nitrate (Fe (NOa) s・9H20, l
, bismuth nitrate (Bi(NO3)3.5H20), etc., were used in the same manner as in Example 1, except that catalysts having the atomic ratios shown in Table 1 were prepared. A contact reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 1.

Examples 7 to 9 Telluric acid [H2TeO4.4H20] was used instead of ammonium metavanadate [NH4vO3],
A catalyst having a catalyst composition having the atomic ratio shown in Table 1 was prepared in the same manner as in Example 1, and a catalytic reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 1.

Examples 10 to 12 Ammonium molybdate ((
Using a solution in which NH4)6"MO7024・4H20) was dissolved and niobium pentoxide [Nb2O,] was dispersed and suspended, the catalyst composition was adjusted to the atomic ratio shown in Table 1 in the same manner as in Example 1. A catalyst was prepared and a catalytic reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 1.

Examples 13 to 14 A catalytic reaction was carried out under the same reaction conditions as in Example 1, except that the catalyst prepared in Example 2 was used and the reaction temperature was changed to the temperature listed in Table 1.

The results are shown in Table 1.

Example 15 A contact reaction was carried out under the same reaction conditions as in Example 1, except that the catalyst prepared in Example 2 was used and the contact time was changed to 2 seconds.

The results are shown in Table 1. Example 16 Instead of ammonium metavanadate [NH4vO3], ammonium metavanadate [NH4VO3] 1.2y and telluric acid CH2Te0. A catalyst having the atomic ratio listed in Table 1 was prepared in the same manner as in Example 1, except that 4 H2O]4.19 was used, and a catalytic reaction was carried out under the same reaction conditions as in Example 1. I did it.

The results are shown in Table 1.

Comparative Examples 1-2 Ammonium metavanadate [NH4vO3] was not used, but bismuth nitrate (B i (NO3)3.5H20) was used.
A catalyst having the atomic ratio shown in Table 2 was prepared in the same manner as in Example 1, except that the amount used was changed, and a catalytic reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 2. Comparative Example 3 A catalyst having the atomic ratio shown in Table 2 was prepared in the same manner as in Example 5, except that the amount of ammonium metavanadate [NH4vO3] used was met, and the catalyst was prepared in the same manner as in Example 1.
A catalytic reaction was carried out under the same reaction conditions.

The results are shown in Table 2. Comparative Example 4 A catalyst having the atomic ratio shown in Table 2 was prepared in the same manner as in Example 7 except that the amount of TeA/A/acid [H2TeO4.4H20] was changed. A contact reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 2.

Comparative example 5 Cobalt nitrate (Co (NO3)2 ・6 H20)7
0.0? and ferric nitrate (Fe (NO3)3 ・5 H2O, l 24.3
? A solution of bismuth nitrate (Bi (NO3)3 ・5H20, l 29.O
A nitric acid acid solution in which P was dissolved in 301 rL of water acidified with 6 ml of concentrated nitric acid was mixed.

This mixed solution was mixed with ammonium molybdate ((1'J
H4) 6 ・MO7024・4H20) 106.2S'
and ammonium paratungstate ((NH4)1
0W12041 ” 5 H2O) 32.49 to 30
Add thallium nitrate C'rlN0 to this mixed solution dropwise while stirring.
3) o, s 01? A solution prepared by dissolving 1 OrIll of silica gel in water and 24.49 g of 20% by weight silica gel were added and mixed, heated under stirring, and evaporated to dryness to obtain a solid.

The solid material was pulverized, formed into a tablet of 5 mπφ, and calcined at 450° C. for 6 hours in an air atmosphere to prepare a catalyst.

A catalytic reaction was carried out under the same reaction conditions as in Example 1 using 811 Ll of the catalyst thus obtained.

The results are shown in Table 2.

Comparative Example 6 Ammonium molybdate ((NH4)6-MO7024-4H20,l 63
．． 5? was dissolved in 601 njl of 80°C warm water, 0.21 njl of potassium nitrate (KNO3) was added and dissolved, and then cobalt nitrate [co(NO3)2.6H20
]61.2f? and a solution of ferric nitrate (Fe (NO3)3 ・9H20, + 36.69 The aqueous solution 25 and the vertically dissolved solution were mixed dropwise with stirring, and 20% by weight silica sol 90y was added and mixed, then heated to evaporate to dryness, and further heated to 300°C.
Heating was continued for 3 hours to obtain a solid.

The solid material was pulverized, formed into a 5-diameter tablet, and calcined at 700'C for 5 hours in an air atmosphere to prepare a catalyst.

Using the catalyst 87711 obtained in this way,
☆A contact reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 2.

Examples 17-18 115 ml of a 30% by weight silica sol aqueous solution (Example 1) was added to a slurry mixed solution prepared in the same manner as in Example 2.
7) or 236 ml (Example 18) is added and mixed,
Hereinafter, in the same manner as in Example 1, MOIOFe2 Bio,
g
A catalyst supported on a carrier consisting of the following was prepared, and a catalytic reaction was carried out under the same reaction conditions as in Example 1.

The results are shown in Table 3.

Claims (1)

[Claims] 1. In a method for producing methacrolein by catalytically reacting isobutylene with molecular oxygen in the presence of a catalyst in a high temperature gas phase, the following general compositional formula is used as a catalyst: [In this formula, Mo is molybdenum] , Co is copper/l/t, Fe is iron, Bi is bismuth, X is one or more elements selected from the group consisting of vanadium, niobium and tellurium, and 0 is oxygen, and the subscripts a, b, c , d, e and f indicate the number of atoms,
If a is fixed as 10, b is 3-101c is 1-7, d
is 0.1 to 1.5, e is 0.01 to 1, and f is a value naturally determined by the valence of each element other than oxygen, and usually takes a value of 34.6 to 54.1. A method for producing methacrolein, which comprises using a composition represented by the following.