JPS584693B2 - Method for producing methacrolein - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for producing methacrolein in high yield by catalytically reacting isobutylene with molecular oxygen in the presence of a catalyst with excellent mechanical strength in a high temperature gas phase. be.

More specifically, the invention provides molybdenum, bismuth,
The present invention aims to provide a method for producing methacrolein from isobutylene in high yield by improving a catalyst containing iron, cobalt, and an alkali metal.

Conventionally, olefins such as propylene and isobutylene are catalytically reacted with molecular oxygen in the presence of a catalyst in a high-temperature gas phase.
Many methods for producing unsaturated aldehydes such as acrolein and methacrolein and catalysts used therein are already known.

However, it is generally said that it is more difficult to produce methacrolein from imbutylene than to produce acrolein from propylene.

In fact, it is clear from the description in Japanese Patent Publication No. 47-42813 that acrolein is produced from propylene using a catalyst proposed for the production of unsaturated aldehydes, and methacrolein is produced from isobutylene. As such, the yield of unsaturated aldehydes is often low, and the yield of methacrolein is generally 5 to 10% lower than the yield of acrolein.

The difference in yield of unsaturated aldehyde between the production of acrolein and methacrolein is generally thought to be partly due to the branching (methyl group) of inbutylene. It is also said that it is necessary to use different catalysts when producing acrolein and when producing methacrolein.

The present invention relates to an industrially advantageous method for producing unsaturated aldehydes, particularly methacrolein, in high yield by oxidizing inbutylene.

Conventionally, catalysts containing molybdenum, bismuth, iron cobalt, and alkali metals used when producing methacrolein by catalytically reacting isobutylene with molecular oxygen in the presence of a catalyst in a high-temperature gas phase have been disclosed, for example, in 4281
Publication No. 3 (Co-Fe-Bi-W-Mo-Si-K-P
-O), Japanese Patent Publication No. 48-17253 (Ni-Co-
Fe-Bi-P-Cs, K-Mo-O), Special Publication 1977-
Publication No. 4441 (Ni-Co-Fe-Bi-P-K-M
o-O), Japanese Patent Publication No. 51-47684 (Co-Fe
-Bi-Cr-K-Mo-O), JP-A-48-5271
Publication No. 3 (Co-Fe-Bi-Cs, K-Mo-O),
JP-A-51-34107 (Mn-K-Ni-Co
-Fe-Bi-Mo-O).

These conventionally known catalysts containing molybdenum, bismuth, iron, cobalt, and alkali metals can produce methacrolein in relatively high yields, but in most cases, the yield is around 70%. .

The inventors conducted extensive research with the aim of developing an industrial catalyst that can produce methacrolein at a higher yield and has high mechanical strength and excellent durability.

As a result, cesium was selected as a catalyst component among alkali metals, and together with cesium, one or more elements selected from the group consisting of vanadium and palladium and one element selected from the group consisting of titanium, tin, and zirconium were selected. They learned that there was a catalyst that could achieve the objective by adding the above elements to a catalyst system consisting of molybdenum, bismuth, iron, cobalt, and oxygen, and as a result of further research, they arrived at this invention.

This invention relates to a method for producing methacrolein by catalytically reacting isobutylene with molecular oxygen in the presence of a catalyst in a high-temperature gas phase. represents cobalt, Fe represents iron, Bi represents bismuth, Cs represents cesium, X represents vanadium and/or palladium, Y represents one or more elements selected from the group consisting of titanium, tin, and zirconium, and the subscripts a, b , c, d, e, f, g and h indicate the number of atoms, and when a = 12 is fixed, b is 2 to 12, preferably 4 to 10, c is 0.5 to 7, preferably 1 to 5,
d is 0.1-5, preferably 0.5-4, e is 0.00
05-0.5, preferably 0.001-0.3, f is 0
．． 01-2, preferably 0.05-1.5, and g is 0.
1 to 5, preferably 0.5 to 4, and h is a numerical value naturally determined by the valence of each element.

The present invention relates to a method for producing methacrolein, which is characterized by using a composition represented by:

In this invention, when producing methacrolein by oxidizing isobutylene, cesium is particularly selected among alkali metals, and vanadium and/or palladium are added as catalyst components together with cesium to the Mo-Bi-Fe-Co system. It is important to use, as a catalyst, a composition represented by the above general compositional formula, in which one or more elements selected from the group consisting of titanium, tin, and zirconium are added as a catalyst component.

Among alkali metals other than cesium, such as potassium, rubidium, and sodium, the selectivity for methacrolein is generally low, and the yield of methacrolein is around 70% or less, which is about the same as that of conventionally known catalysts.
Achieving the objectives of this invention is quite difficult.

Furthermore, even if cesium is selected as the alkali metal and added as a catalyst component, vanadium and/or
Alternatively, with a catalyst to which palladium is not added, the yield of methacrolein becomes low.

Furthermore, when vanadium and/or palladium are added as catalyst components along with cesium, the yield of methacrolein is further improved, but there is still room for further improvement in terms of catalyst abrasion resistance, crushing strength, etc. Further improvement in the yield of rhein is also desired.

Furthermore, when vanadium and/or palladium is added to molybdenum, cobalt, iron, bismuth, and cesium, and one or more elements selected from the group consisting of titanium, tin, and zirconium are added as a catalyst component,
In particular, the abrasion resistance and crushing strength of the catalyst are improved, and the yield of methacrolein is further improved, albeit slightly, compared to a catalyst without the addition of an element selected from the group consisting of titanium, tin, and zirconium. .

The elements selected from the group consisting of titanium, tin and zirconium may be 2 or 3 as long as they are 1 or more,
Even if multiple types are added, there will be no significant difference in the yield of methacrolein, the abrasion resistance of the catalyst, the crushing strength, etc.

In addition, although the composition ratio of the catalyst components is as expressed by the above general composition formula, a catalyst having a composition outside the range expressed by the above general composition formula may result in a low reaction rate of isobutylene.
This is not suitable because the selectivity of methacrolein becomes low and the yield of methacrolein also becomes low as a result.

According to the method of this invention, both the reaction rate of isobutylene and the selectivity of methacrolein are high, so methacrolein can be produced in a very high yield. It has the advantage of being able to operate stably over a long period of time due to its excellent crushing strength, and making it possible to produce methacrolein industrially very advantageously.

Each catalyst component of the catalyst represented by the general compositional formula used in this invention is mainly a metal oxide in which each component element is combined with oxygen, an oxide in which a plurality of component elements are combined together with oxygen, and a mixture thereof in the catalyst. exists in

The catalyst represented by the general compositional formula used in the present invention can be prepared using conventionally known oxidation methods using compounds containing each component element constituting the catalyst, such as oxides and salts of each element, as starting materials for catalyst preparation. It can be easily prepared using a catalyst preparation method.

However, the firing temperature is 550-800°C, which is higher than the 400-500°C which was conventionally used for firing at the final stage of catalyst preparation.
A suitable method for preparing the catalyst used in the method of the present invention is to prepare the catalyst by calcining it preferably at a temperature of 600 to 750° C. for 1 to 20 hours, preferably 2 to 10 hours.

If the calcination temperature is too low or too high, the yield of methacrolein and the strength of the catalyst will be affected, so it is appropriate to perform the calcination at the above temperature.

Suitable firing is performed under an oxygen-containing gas, generally air atmosphere.

The catalyst used in this invention is generally prepared by first dispersing and mixing compounds containing each constituent element, such as salts and oxides, as uniformly as possible in the presence of water at a temperature of 100 to 150°C.
, preferably at a temperature of around 120°C to evaporate moisture, and then further evaporate by heating at a higher temperature of 150 to 300°C, preferably around 200°C, such as ammonium nitrate and nitrogen oxides. The dried product is generally dried for 3 to 20 hours until it evaporates, and then the dried product is shaped and sized according to the usage conditions, and the
800°C, preferably 600-750°C and 1-20°C
It is suitable to prepare by baking for a period of time, preferably 2 to 10 hours.

Compounds containing each constituent element that can be used as starting materials for catalyst preparation include, for example, molybdic acid, ammonium molybdate, molybdenum compounds such as molybdenum trioxide, cobalt carbonate, cobalt nitrate, cobalt oxide, tricobalt tetroxide, and cobalt chloride. , cobaltous hydroxide,
Cobalt compounds such as ferrous hydroxide, cobalt sulfide, ferrous nitrate, ferric nitrate, ferrous oxide, ferric oxide, ferrous carbonate, ferrous sulfide, ferrous chloride, ferrous chloride Two irons,
Iron compounds such as ferrous hydroxide, ferric hydroxide, ferrous sulfate, ferric sulfate, ferrous ammonium sulfate, ferric ammonium sulfate, bismuth nitrate, bismuth dichloride, bismuth trichloride, Bismuth compounds such as bismuth oxide, bismuth trioxide, bismuth tetroxide, bismuth nitrate oxide, bismuth hydroxide, bismuth subnitrate, and bismuth oxychloride; cesium compounds such as cesium nitrate, cesium chloride, cesium hydroxide, cesium carbonate, and cesium oxide , vanadium compounds such as vanadium chloride, ammonium metavanadate, vanadyl chloride, vanadyl sulfate, vanadium oxide,
Palladium nitrate, palladium hydroxide, palladium chloride,
palladium compounds such as palladium oxide; titanium compounds such as titanium dioxide, titanic acid, titanium trichloride, and titanium tetrachloride; tin compounds such as stannic oxide, tin hydroxide, stannic chloride, stannous oxide, and stannic acid; Examples include zirconium compounds such as zirconium oxide, zirconium nitrate oxide, and zirconium hydroxide.

Among the compounds containing these constituent elements, nitrates and ammonium salts are particularly suitable as starting materials.

Next, one example of the most suitable method for preparing the catalyst used in the present invention will be explained using a catalyst composed of molybdenum, cobalt, iron, bismuth cesium, vanadium, titanium, and oxygen.

First, predetermined amounts of ammonium molybdate, ammonium metavanadate, and titanium dioxide are suspended and dissolved in water, preferably hot water.

Next, a predetermined amount of a nitric acid solution of bismuth nitrate and a solution of predetermined amounts of ferric nitrate, cobalt nitrate, and cesium nitrate dissolved in water, preferably warm water, are prepared, and the acidic solution of these nitrates is added to the alkaline molybdic acid solution. The mixture is added dropwise to a solution in which ammonium, ammonium metavanadate, and titanium dioxide are suspended and dissolved while stirring.

The suspension obtained by dropwise mixing is 100-1
After once removing moisture by evaporation with a drum dryer or spray dryer at a temperature of 50°C, preferably around 120°C, the generation of ammonium nitrate, nitrogen oxides, etc. will stop at a temperature of 150 to 300°C, preferably around 200°C. The dried product obtained is shaped and sized as appropriate depending on the usage conditions, and heated to 550 to 800°C, preferably 600°C.
Firing is performed at 00 to 750°C in an oxygen-containing gas atmosphere.

The desired catalyst is obtained by calcination. When palladium is used instead of vanadium as a catalyst component, palladium nitrate is preferred as the starting material, and after suspending and dissolving a predetermined amount of ammonium molybdate and titanium dioxide in hot water, a predetermined amount of ammonium molybdate and titanium dioxide are added to this together with the nitrate. A solution of nitrate in which palladium nitrate is dissolved is mixed dropwise under stirring, and the catalyst is prepared in the same manner as described above.

Of course, the preparation method, starting materials, etc. of the catalyst used in this invention are not limited to the above-mentioned specific preparation method, but
Use nitrates and ammonium salts as possible as starting materials, mix in the presence of water and dry twice at different temperatures, then dry at 550-800°C, preferably at 600-800°C.
A preparation method in which the catalyst is calcined at 750° C. is preferable because it has excellent reproducibility of catalyst activity, catalyst strength (durability), and the like.

The catalyst used in 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, diatomaceous earth, and carborundum.

When the catalyst is supported on a carrier, the catalyst may be supported on the carrier during or after preparation of the catalyst.

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

In carrying out this invention, the raw material imbutylene does not necessarily have to be of high purity, and is produced as a by-product as a C4 fraction during the cracking of a hydrocarbon mixture containing n-butene together with isobutylene, such as petroleum naphtha.

Furthermore, a hydrocarbon mixture containing isobutylene and n-butene, which are by-produced as a residue after extracting and separating 1,3-butadiene from this C4 fraction, can also be used.

When a hydrocarbon mixture containing isobutylene and n-butene is used as a raw material, isobutylene is converted to methacrolein and n-butene is converted to 1,3-butadiene, so methacrolein and 1,3-butadiene are simultaneously converted. It has the advantage that it can also be manufactured.

The hydrocarbon mixture containing isobutylene and n-butene may contain isobutane, n-butane, propane, etc., but generally the total amount of isobutylene and n-butene in the hydrocarbon mixture is 50 mol. % or more, preferably 70 mol% or more is suitable.

Further, in carrying out the present invention, a gas that is substantially inert to this catalytic reaction can be used as a diluent gas.

Examples of the diluent gas include water vapor, nitrogen gas, carbon dioxide gas, n-butane, isobutane, and propane.

Among these, water vapor is preferably present in the reaction system, since its presence in the reaction system improves the selectivity of methacrolein and sustains the catalytic activity.

The amount of water vapor is 0.1 to 10 per mole of isobutylene.
Moles, preferably 1 to 8 moles are suitable.

Furthermore, the molecular oxygen used in the catalytic reaction of this invention does not need to be of particularly high purity, and it is generally economical to use an oxygen-containing gas, such as a gas prepared by diluting pure oxygen with the diluent gas mentioned above, or air. Among them, it is convenient to use air.

The amount of molecular oxygen used is 0 per mole of isobutylene.
．． 4 to 5 mol, preferably 0.5 to 3 mol is suitable.

When the method of the present invention is carried out in the presence of a catalyst represented by the above general compositional formula, the reaction temperature is generally 300 to 50°C.
A suitable temperature is 0°C, preferably 310-480°C, and a contact time of 0.2-20 seconds, preferably 0.3-10 seconds.

The reaction pressure may be normal pressure, low pressure, or reduced pressure, but normal pressure is generally suitable.

Further, the reaction can be carried out in a fixed bed, a moving bed, a fluidized bed, or the like.

When carrying out the reaction in a fluidized bed, it is appropriate to use particles of 30 to 100 microns as a catalyst, and the water produced by the reaction fulfills the above role without intentionally adding water vapor to the reaction system, so the reaction does not proceed. proceed smoothly.

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

In each example, isobutylene reaction (%), methacrolein selectivity (%) and methacrolein yield (%)
) is the result measured 1 hour after starting the reaction, and follows the definition below.

The crushing strength (kg/tablet) of the catalyst can be determined by placing one catalyst tablet (diameter 5 mm x height 5 mm) on a sample stage and applying a load from above. ) was measured using a Kiya type hardness tester, and the average value of the results of testing 50 catalyst tablets was determined and this value is shown.

In addition, the abrasion resistance (wt%) of the catalyst was determined by dropping 50 catalyst tablets at once from the top of a glass tube with a diameter of 1 inch and height of 3 meters into the tube, and weighing the weight of the crushed catalyst particles broken into pieces of 6 mesh or less. , the value calculated by weight % is shown.

Example 1 Ammonium molybdate [(NH4)6Mo7O24.4H2O] 141 was added to 200 ml of water heated to 40°C.
．． 3g, titanium dioxide [TiO2] 6.39g and ammonium metavanadate [NH4VO3] 0.78g
was suspended and dissolved.

To this, bismuth nitrate [Bi(NO3)3.5H2O]
A solution of 38.8 g dissolved in 50 ml of 15% nitric acid and 64.6 g of ferric nitrate [Fe(NO3)3.9H2O],
A nitrate solution prepared by dissolving 0.078 g of cesium nitrate [CsNO3] and 186.2 g of cobalt nitrate [Co(NO3)2.6H2O] in 200 ml of water heated to 40°C was mixed and added dropwise under stirring. , and stirred to obtain a mixed solution.

The mixed liquid was dried with a drum dryer at a temperature of 120°C to obtain a dried product.The dried product was then dried at 200°C for 10 hours, and the dried product was made into tablets using a tablet machine (molding pressure 3kg/tablet). The tablet was molded into a size (diameter 5 mm x height 5 mm) and baked at 650°C for 5 hours in an air atmosphere.
A catalyst was prepared.

The atomic ratio of the catalyst composition (oxygen is omitted, the same applies hereinafter) of the catalyst thus obtained is Mo:Bi:Co:Fe
:Cs:V:Ti=12:1:8:2:0.05:0.
The ratio is 1:1.

The test results for the crushing strength and abrasion resistance of the catalyst are shown in Table 1.

Next, 10 ml of this catalyst was filled into a glass U-shaped reaction tube with an inner diameter of 8 mm, and 200 ml/m of a mixed gas of isobutylene:air:steam with a molar ratio of 1:10:6 was poured into the tube.
flow rate of in, contact time 3.0 seconds, reaction temperature 390
The contact reaction was carried out at °C.

The results are shown in Table 1.

Examples 2 to 5 In place of titanium dioxide in Example 1, zirconium oxide, stannic oxide, zirconium oxide and stannic oxide, or titanium dioxide and stannic oxide were used, and the compositions listed in Table 1 were prepared. Each catalyst was prepared using the same method as in Example 1, and the crushing strength and abrasion resistance of the catalyst were tested.

The results are shown in Table 1.

Table 1 also shows the results of a catalytic reaction using each catalyst under the same reaction conditions as in Example 1.

However, only in Example 3, the reaction temperature was changed to 370° C. and the catalytic reaction was carried out.

Example 6 A catalyst having the composition shown in Table 1 was prepared in the same manner as in Example 1 by adding palladium nitrate to the nitrate solution without using the ammonium metavanadate of Example 1, and the catalyst was crushed. Strength and abrasion resistance tests were conducted.

The results are shown in Table 1. Table 1 also shows the results of a catalytic reaction conducted under the same reaction conditions as in Example 1.

Examples 7 to 8 In place of titanium dioxide in Example 6, zirconium oxide or stannic oxide was used, and catalysts having the compositions listed in Table 1 were prepared in the same manner as in Example 1. The catalyst was tested for crushing strength and abrasion resistance.

The results are shown in Table 1. Table 1 also shows the results of a catalytic reaction using each catalyst under the same reaction conditions as in Example 1.

Examples 9-10 By further adding palladium nitrate to the nitrate solution of Example 1, and by adding palladium nitrate to the nitrate solution of Example 1, and using stannic oxide instead of titanium dioxide,
Catalysts having the compositions listed in Table 1 were prepared using the same method as in Example 1, and the crushing strength and abrasion resistance of each catalyst were tested.

The results are shown in Table 1.

Table 1 also shows the results of a catalytic reaction conducted under the same reaction conditions as in Example 1, except that each catalyst was used and the reaction temperature was changed to 370°C.

Comparative Example 1 A catalyst having the same composition as in Example 2 was prepared in the same manner as in Example 1 without using zirconium oxide, and the crushing strength and abrasion resistance of the catalyst were tested. I did this.

The results are shown in Table 1.

Table 1 also shows the results of a catalytic reaction conducted under the same reaction conditions as in Example 1.

Comparative Example 2 A catalyst having the same composition as in Example 10 was prepared in the same manner as in Example 1, except that it did not contain ammonium metavanadate and stannic oxide and did not contain vanadium or tin. Tests for crushing strength and abrasion resistance were conducted.

The results are shown in Table 1.

Table 1 also shows the results of a catalytic reaction conducted under the same reaction conditions as in Example 1, except that the reaction temperature was changed to 370°C.

Comparative Examples 3 to 9 Catalysts having the compositions listed in Table 2, which are outside the scope of this invention, were prepared using the same preparation method as in Example 1. The contact reaction was carried out under the following reaction conditions.

In Comparative Examples 4 and 9, the reaction temperature was changed to 370° C. and the contact reaction was carried out.

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 catalyst has the following general compositional formula: MoaCobFec
BidCseXfYgOh [In this formula, Mo is molybdenum, Co is cobalt, Fe is iron, Bi is bismuth, Cs is cesium, X is vanadium and/or palladium Y is one selected from the group consisting of titanium, tin, and zirconium. Indicates the above elements, subscripts a, b
, c, d, e, f, g and h indicate the number of atoms, a=1
If fixed as 2, b is 2 to 12, c is 0.5 to 7, and d is 0.
．． 1 to 5, e is 0.0005 to 0.5, f is 0.01 to
2. g is 0.1 to 5, and h is a numerical value naturally determined by the valence of each element. A method for producing methacrolein, which comprises using a composition represented by the following.