JP3028327B2 - Method for producing methacrolein and methacrylic acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing methacrolein and methacrylic acid by subjecting isobutylene or tertiary butanol to gas-phase catalytic oxidation with molecular oxygen.

[0002]

2. Description of the Related Art Conventionally, catalysts used for producing methacrolein and methacrylic acid by subjecting isobutylene or tertiary butanol to catalytic oxidation in a high-temperature gas phase are disclosed in, for example, JP-A-56-2926, 56-16134
No. 1, JP-A-59-31727, JP-A-60-31727
Many proposals have been made, such as Japanese Patent No. 28824. These mainly relate to the components constituting the catalyst and the ratio thereof. However, various difficulties are involved when industrially producing methacrolein and methacrylic acid using these known catalysts.

[0003] Since the above-mentioned oxidation reaction is an exothermic reaction, heat storage in the catalyst layer is large. Industrially, it is necessary to increase the productivity of the target product. However, if the concentration of isobutylene or tertiary butanol in the raw material gas is increased carelessly, hot spots (local abnormalities) near the raw material gas inlet of the catalyst layer will occur. (High temperature zone). In general, when a hot spot occurs, the sequential oxidation is promoted, and the yield of the target product often decreases. Furthermore, in a hot spot, the catalyst deteriorates and deteriorates due to a heat load, which may have a great adverse effect on the catalyst life. For this reason, at present, reaction conditions are considerably restricted, such as lowering the concentration of isobutylene or tertiary butanol in the raw material gas to some extent.

[0004] Suppressing the heat storage at the hot spot enables the production of methacrolein and methacrylic acid in a high yield industrially, and also enables the stable operation for a long period of time by suppressing the deterioration of the catalyst. It is also very important above.

As a measure for preventing the generation of hot spots, a method of diluting a catalyst which generates a large amount of heat, specifically, a catalyst near an inlet of a raw material gas, with an inert carrier is known. Generally, when the reaction is carried out in a fixed-bed multitubular reactor, the outer diameter is usually 3
A molded catalyst or a supported catalyst having a size of about 10 to 10 mm is used. It is very difficult to mix these catalyst bodies and the inert carrier uniformly. When uneven catalyst dilution occurs in each reaction tube, the heat generation behavior differs for each reaction tube, and therefore, stable operation becomes extremely difficult. Therefore, from an industrial point of view, this usage is not very favorable.

JP-A-3-200733 and 3-2
No. 15441 and 3-294238,
In a method for producing methacrolein and methacrylic acid by gas-phase catalytic oxidation of isobutylene or tertiary butanol with molecular oxygen using a fixed-bed multitubular reactor, a catalyst layer is divided to provide a plurality of reaction zones. A method is disclosed in which the plurality of reaction zones are filled with a catalyst whose activity is adjusted by changing the type and / or ratio of the constituent elements of the catalyst and the calcination temperature at the time of preparing the catalyst to carry out the oxidation reaction. .

However, in general, catalysts having different types and / or ratios of the catalyst constituent elements or different calcination temperatures at the time of preparation,
It shows different behavior not only in activity but also in various properties such as selectivity and catalyst life. Therefore, in order to adjust the activity of the catalyst by changing the types and / or ratios of the constituent elements, the selectivity of the target product and the life of the catalyst have to be sacrificed to some extent. Therefore, although this method can be expected to have a certain effect as a measure for preventing the generation of hot spots, it is not a preferable method for industrially producing methacrolein and methacrylic acid in a high yield over a long period of time.

JP-A-51-127003 discloses a method for producing an unsaturated aldehyde and an unsaturated carboxylic acid from propylene or isobutylene using a combination of a supported catalyst having essentially the same composition and a molded catalyst. A method is disclosed. However, the use of both a supported catalyst and a molded catalyst not only complicates the production of the catalyst, but also significantly increases the cost of the catalyst. As a result, the unsaturated aldehydes and unsaturated This is a factor that increases the production cost of the carboxylic acid. Therefore, it is not preferable to use this method industrially. As described above, the catalysts and reaction means known so far are hardly sufficient, and further improvement is desired from the industrial point of view in terms of practicability of the catalyst production process and the target product production process.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to provide a process for the advantageous synthesis of methacrolein and methacrylic acid from isobutylene or tertiary butanol.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a method for producing methacrolein and methacrylic acid by gas phase catalytic oxidation of isobutylene or tertiary butanol with molecular oxygen using a fixed-bed multitubular reactor. (1) As a catalyst, a general formula Moa Bib Fec Ad Xe Yf Zg O
h (wherein, Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, respectively, A represents nickel and / or
Or cobalt, X is at least one element selected from the group consisting of magnesium, zinc, manganese, tin and lead, Y is phosphorus, boron, sulfur, tellurium, silicon, selenium, germanium, cerium, niobium, aluminum,
Z represents at least one element selected from the group consisting of potassium, sodium, rubidium, cesium and thallium, and Z represents at least one element selected from the group consisting of titanium, zirconium, tungsten and antimony.
Here, a, b, c, d, e, f, g and h represent the atomic ratio of each element, and when a = 12, 0.1 ≦ b ≦ 5, 0.1
≤c≤5, 1≤d≤12, 0≤e≤10, 0≤f≤1
0,0.01 ≦ g ≦ 3, and h is the number of oxygen atoms necessary to satisfy the valence of each component. The catalytically active component comprising the composite oxide represented by
A supported catalyst supported such that the amount of the catalytically active component supported is 10 to 400 parts by weight with respect to parts by weight. (2) The catalyst layer in each tube is divided into two or more layers in the tube axis direction. In the plurality of reaction zones provided, (3) a plurality of supported catalysts prepared by changing the supported amount of the catalytically active component per unit weight of the carrier in the catalyst of (1) above from the raw material gas inlet to the outlet. And carrying out the reaction so as to increase the amount supported by the method, thereby producing methacrolein and methacrylic acid.

In the present invention, the raw materials of the elements constituting the catalytically active component are not particularly limited, but are usually oxides or chlorides, hydroxides, sulfuric acids which can be turned into oxides by heating. Salts, nitrates, carbonates, ammonium salts or mixtures thereof are used.

In the present invention, the type of the carrier is not particularly limited, and silica, alumina, silica-alumina,
Conventional carriers such as silicon carbide, zirconia, magnesia, and titania are used. Also, the shape is not particularly limited, and examples thereof include a sphere, a column, a ring, and a plate.

The catalytically active component used in the present invention is prepared by a known method. In general, a method for preparing a catalytically active component of a catalyst for synthesizing an unsaturated aldehyde and an unsaturated carboxylic acid often includes a step of performing a heat treatment at about 400 to 600 ° C. In the present invention, a supported catalyst may be produced by supporting the catalyst active component thus obtained on a carrier, or the catalyst precursor obtained before the heat treatment may be supported on a carrier, The supported catalyst may be produced by heat-treating the body at the temperature.

The means for supporting the catalytically active component on the carrier is not particularly limited, and a usual impregnation-supporting method, immersion-supporting method or the like is used. In addition, in the case of preparing a material having a relatively large carrying amount, a method in which a slurry in which a catalyst active component or a catalyst precursor is dispersed in a liquid material is attached to a carrier and the liquid material is simultaneously vaporized and evaporated is particularly preferable. The liquid used here is not particularly limited, and may be water, alcohols, ketones, esters, etc., as long as they are easily vaporized and evaporated by heating and harmless to the catalyst. Water is particularly preferred industrially.

As a method of simultaneously evaporating and evaporating a liquid material while attaching the slurry to the carrier, for example, the slurry is attached to the carrier in a flowing state in a rotating drum by spraying or spraying, and at the same time, externally of the drum. It is preferable to easily evaporate and evaporate the liquid material by heating the solution from above or directly irradiating the carrier with hot air or infrared rays. In this method, the shape of the carrier used is preferably spherical rather than plate-like.

Further, in order to control the specific surface area, pore volume and pore distribution of the catalytically active component layer with good reproducibility and to increase mechanical strength, inorganic salts such as barium sulfate and ammonium nitrate, celluloses, etc. Organic substances such as starch, polyvinyl alcohol, and stearic acid, hydroxide sols such as silica sol and alumina sol, whiskers, glass fibers, and inorganic fibers such as carbon fibers may be appropriately added.

According to the present invention, there are provided a plurality of reaction zones provided by dividing the catalyst layer in each reaction tube into two or more layers in the tube axis direction, by changing the amount of the catalytically active component supported per unit weight of the carrier. Is loaded so that the supported amount becomes higher from the raw material gas inlet toward the outlet.

In general, when supported catalysts having different amounts of the catalytically active component supported per unit weight of the carrier are prepared by the same method using the same type of the catalytically active component and the carrier, the catalytic activity per unit weight of the obtained supported catalyst is as follows. It increases with an increase in the content of the catalytically active component, that is, with an increase in the supported amount. Also,
The thickness of the catalytically active component layer in the supported catalyst also increases as the amount of supported catalyst increases.

In the present invention, a plurality of supported catalysts having different supported amounts are packed so that the supported amount becomes higher from the raw material gas inlet to the outlet in the reaction tube. That is, the supported catalyst having the lowest activity and the smallest thickness of the catalytically active component layer is disposed at the inlet, and the supported catalyst having the highest activity and the largest thickness of the catalytically active component layer is disposed at the outlet. At the inlet, the reaction frequency is likely to be high because the concentration of isobutylene or tertiary butanol as a reactant is high. By arranging a catalyst having relatively low activity in this portion, heat generation due to the oxidation reaction can be suppressed. Furthermore, by disposing a catalyst having a thin catalytically active component layer in this portion, it is expected that the heat removal of the catalyst is promoted and the heat storage is suppressed. On the other hand, by arranging a catalyst with a high loading on the outlet side, the catalyst activity and catalyst life as a whole process reach a sufficiently practical level.

The amount of the catalytically active component supported on the inert carrier is preferably 10 to 400 parts by weight of the catalytically active component per 100 parts by weight of the inert carrier. Specifically, in the case of the catalyst disposed at the raw material gas inlet, 10 to 200 parts by weight of the catalytically active component is used with respect to 100 parts by weight of the inert carrier. It is preferable that about 100 to 400 parts by weight of the catalytically active component is supported.

In the present invention, the number of reaction zones provided by dividing the catalyst layer in the reaction tube in the tube axis direction is preferably 2 to 4 layers. As the number of reaction zones increases, the effect of controlling the temperature distribution of the catalyst layer increases, but the production and packing of the catalyst become extremely complicated, so that division exceeding four layers is not preferred. Industrially, the intended effect can be sufficiently obtained by dividing into two to four layers. In addition, the splitting ratio cannot be specified unconditionally because it depends on the amount of the catalyst in each layer, and is appropriately selected so as to obtain optimum activity and selectivity as a whole.

In the production of methacrolein and methacrylic acid by gas-phase catalytic oxidation of isobutylene or tertiary butanol with molecular oxygen according to the present invention, the molar ratio of isobutylene or tertiary butanol to oxygen is 1: 0. 5-3
Is preferred. It is preferable that the raw material isobutylene or tertiary butanol is diluted with an inert gas before use. The molecular oxygen used for the oxidation may be pure oxygen gas, but air is industrially advantageous. The reaction pressure is from normal pressure to several atmospheres. The reaction temperature is preferably in the range of 200 to 450 ° C.

[0023]

Embodiments of the present invention will be described below. "Parts" in the description means parts by weight, and the analysis was performed by chromatography. The conversion of isobutylene or tertiary butanol as a raw material for the reaction, the selectivity of methacrolein and methacrylic acid to be produced, and ΔT are defined as follows.

[0024]

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

EXAMPLE 1 300 parts of ammonium paramolybdate were added to 6000 parts of water.
0 parts, 165.6 parts of cesium nitrate, 19.1 parts of tin oxide
, 85.1 parts of silicon dioxide, 1.1 parts of titanium dioxide and 103.2 parts of antimony trioxide, and the mixture was heated and stirred (Solution A). Separately, 450 parts of 60% nitric acid was added to 5000 parts of water to make the mixture uniform, and then 618.2 parts of bismuth nitrate was added and dissolved. 1430.2 parts of ferric nitrate, 823.3 parts of nickel nitrate, 2059.9 parts of cobalt nitrate, 290.5 parts of magnesium nitrate and 12.3 parts of cerium nitrate were sequentially added and dissolved (solution B). The solution B was added to the solution A to form a slurry, which was then heated and stirred to evaporate most of the water. After drying the obtained cake-like substance at 120 ° C. for 10 hours,
It was baked at 500 ° C. for 5 hours and pulverized to 24 mesh or less.

The composition of the thus obtained catalytically active component is as follows:
It is shown by the formula. Mo₁₂Bi_0.9Fe_2.5Ni₂Co₅Mg_0.8
Sn_0.1Si₁Ce_0.02  Ti_0.01Sb_0.5Cs_0.6Ox (where Mo, Bi, Fe, Ni, Co, Mg, Sn,
Si, Ce, Ti, Sb, Cs and O are each molybdenum
Den, bismuth, iron, nickel, cobalt, magnesium
, Tin, silicon, cerium, titanium, antimony,
Represents calcium and oxygen. The numbers on the right side of the element symbols are
X is the atomic ratio of the elements, and X satisfies the valence of each component.
Is the number of oxygen atoms required to ) Obtained in 450 parts of water
300 parts of catalyst active ingredient and average diameter 10 μm, average length
Mix 21 parts of glass fiber of about 200 μm
It was made into a rally (slurry C). Spherical Al with a diameter of 5mm
1000 parts of the mina carrier are fluidized in the rotating drum.
And slowly apply the slurry C to the carrier using a spray.
At the same time as the gas burner from outside the drum
Heat was applied to evaporate the water. Spraying the entire amount of slurry C
After the setting is completed, the obtained support is further heated at 130 ° C.
After drying for 3 hours, catalyst (1) was obtained.

Next, 800 parts of the catalyst active component obtained above, an average diameter of 10 μm and an average length of about 2 parts were added to 1200 parts of water.
56 parts of 00 μm glass fibers were mixed to form a uniform slurry (slurry D). While flowing 1000 parts of a spherical alumina carrier having a diameter of 5 mm in a rotating drum, slurry D is gradually sprayed on the carrier using a spray, and at the same time, the water is vaporized by heating from the outside of the drum by a gas burner. Evaporated. After spraying the entire amount of the slurry D was completed, the obtained support was further dried at 130 ° C. for 3 hours to obtain a catalyst (2).

Separately, 3000 parts of water were mixed with 2000 parts of the catalytically active component obtained above and 140 parts of glass fibers having an average diameter of 10 μm and an average length of about 200 μm to form a uniform slurry (slurry E). While flowing 1000 parts of a spherical alumina carrier having a diameter of 5 mm in a rotating drum, a slurry E is gradually sprayed on the carrier by using a spray, and at the same time, the water is vaporized by heating from the outside of the drum by a gas burner. Evaporated. After the spraying of the entire amount of the slurry E was completed, the obtained support was further cooled at 130 ° C. for 3 hours.
After drying for an hour, catalyst (3) was obtained. Table 1 shows the composition of the catalytically active components of the catalysts (1), (2) and (3) and the amount of the catalytically active components carried per unit weight of the carrier.

A stainless steel reactor having a diameter of 25.4 mm is charged with 300 ml of catalyst (1) at the inlet of raw material gas, 400 ml of catalyst (2) at the center of the reactor, and catalyst (3) at outlet of raw material gas. Was charged to 500 ml. A raw material mixture gas containing 5% by volume of isobutylene, 12% by volume of oxygen, 10% by volume of steam and 73% by volume of nitrogen was introduced from the inlet of the reactor, and the reaction was carried out at a reaction temperature of 345 ° C. and a space velocity of 1400 hr ⁻¹ . Table 2 shows the results.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1, except that only 1200 ml of the catalyst (1) was charged. Table 2 shows the results. Comparative Example 2 A reaction was carried out in the same manner as in Example 1, except that only 1200 ml of the catalyst (2) was charged. Table 2 shows the results. Comparative Example 3 A reaction was carried out in the same manner as in Example 1 except that only 1200 ml of the catalyst (3) was charged. Table 2 shows the results.

From the results of Example 1 and Comparative Examples 1 to 3, the activity of the catalyst (1) is remarkably low, and the activity of the catalyst (2) is slightly lower, while the activity of the catalyst (3) is sufficiently high. Since the difference (ΔT) between the reaction temperature and the hot spot temperature becomes very large, the selectivity is remarkably reduced, and the total single stream yield is low in any case.
It can be seen that the desired methacrolein and methacrylic acid can be obtained in high yield in the method of the present invention combining (2) and (3).

Example 2 Catalysts (4) and (5) having the catalytically active component composition shown in Table 1 and the amount of the catalytically active component supported per unit weight of the carrier were prepared in the same manner as in Example 1. The catalyst (4) 400 was placed at the raw material gas inlet of a stainless steel reactor having a diameter of 25.4 mm.
of the catalyst (5) at the outlet of the raw material gas.
And a raw material mixed gas of tertiary butyl alcohol 5% by volume, oxygen 12% by volume, steam 10% by volume and nitrogen 73% by volume is introduced from the reactor inlet, and the reaction is performed at a reaction temperature of 345 ° C. and a space velocity of 1400 hr ⁻¹ . Was done. Table 3 shows the results.

Comparative Example 4 A catalyst (6) was prepared in the same manner as in Example 2 except that a catalytically active component having the same composition as in Example 2 was used. Table 1 shows the amount of the catalytically active component carried per unit weight of the catalyst. The reaction was carried out in the same manner as in Example 2 except that only 1200 ml of the catalyst (6) was charged in Example 2. Table 3 shows the results. Example 3 A catalyst (7) and a catalyst (8) having the catalytically active component composition and the amount of the catalytically active component supported per unit weight of the carrier shown in Table 1 were prepared in the same manner as in Example 1. Diameter 25.4
A 600 mm catalyst (7) was charged into the raw material gas inlet of a stainless steel reactor having a diameter of 200 mm, and a 600 ml catalyst (8) was charged into the raw material gas outlet. Subsequently, the reaction was carried out in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 5 A reaction was carried out in the same manner as in Example 3 except that only 1200 ml of the catalyst (8) was charged. Table 2 shows the results. Example 4 A reaction was carried out in the same manner as in Example 3 except that the reaction was carried out for a long period of time up to 5000 hours. Table 2 shows the results. Comparative Example 6 The reaction was performed in the same manner as in Comparative Example 5, except that the reaction was performed for a long period of time up to 5000 hours. Table 2 shows the results.

From the results of Examples 3 and 4 and Comparative Examples 5 and 6, according to the method of the present invention, since ΔT is very low, the deterioration of the catalyst activity with time is small, and even after 5000 hours of reaction, the activity decreases very much. And the yield is hardly reduced. Therefore, according to the method of the present invention, stable continuous operation can be performed for a long time.

Example 5 In the same manner as in Example 1, the catalysts (9), (10) and (1)
1) was prepared. Table 1 shows the composition of these catalytically active components and the amount of the catalytically active components carried per unit weight of the carrier.
A stainless steel reactor having a diameter of 25.4 mm is charged with 300 ml of the catalyst (9) at the inlet of the raw material gas, 400 ml of the catalyst (10) at the center of the reactor, and the catalyst (11) at the outlet of the raw gas. 500 ml was charged, and the reaction was carried out in the same manner as in Example 1. Table 2 shows the results.

Example 6 A reaction was carried out in the same manner as in Example 5 except that the concentrations of isobutylene and nitrogen in the raw material mixed gas were changed to 6% by volume and 72% by volume, respectively. Table 2 shows the results. Comparative Example 7 A reaction was carried out in the same manner as in Example 5, except that only 1200 ml of the catalyst (10) was charged. Table 2 shows the results
Shown in

Comparative Example 8 A reaction was carried out in the same manner as in Example 6, except that only 1200 ml of the catalyst (10) was charged. Table 2 shows the results
Shown in From the results of Examples 5 and 6 and Comparative Examples 7 and 8, it can be seen that according to the method of the present invention, since ΔT is suppressed to a low level, the decrease in the yield when the concentration of isobutylene is increased is extremely small. Example 7 In the same manner as in Example 1, catalysts (12) and (13) were prepared. Table 1 shows the composition of these catalytically active components and the amount of the catalytically active components carried per unit weight of the carrier. Diameter 2
A 5.4 mm stainless steel reactor was charged with 500 ml of the catalyst (12) at the raw material gas inlet and 700 ml of the catalyst (13) at the raw gas outlet, and then reacted in the same manner as in Example 1. Was done. Table 2 shows the results.

Comparative Example 9 Same as Example 7 except that the reactor was charged with 700 ml of the catalyst (13) at the raw material gas inlet and 500 ml of the catalyst (12) at the raw gas outlet. The reaction was carried out. Table 2 shows the results.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

According to the present invention, (1) a target product can be obtained at a high yield, (2) heat storage at a hot spot can be suppressed, and (3) side reactions such as sequential oxidation at a hot spot can be suppressed. (4) Methacrolein and methacrylic acid can be produced stably and safely at high yield over a long period of time due to a great effect of preventing deterioration of the catalyst due to heat load.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C07C 47/22 C07C 47/22 57/05 57/05 // C07B 61/00 300 C07B 61/00 300 (56) References Special Kaihei 3-200733 (JP, A) Japanese Patent Publication No. 53-30688 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 27/00 330 C07C 27/12-27/14 C07C 47/22 C07C 45/32-45/35 C07C 57/05-57/055

Claims (2)

(57) [Claims] 1. A method for producing methacrolein and methacrylic acid by subjecting isobutylene or tertiary butanol to gas-phase catalytic oxidation with molecular oxygen using a fixed-bed multitubular reactor, comprising the steps of: Formula Moa Bib Fec Ad Xe Yf Zg O
h (wherein, Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, respectively, A represents nickel and / or
Or cobalt, X is at least one element selected from the group consisting of magnesium, zinc, manganese, tin and lead, Y is phosphorus, boron, sulfur, tellurium, silicon, selenium, germanium, cerium, niobium, aluminum,
Z represents at least one element selected from the group consisting of potassium, sodium, rubidium, cesium and thallium, and Z represents at least one element selected from the group consisting of titanium, zirconium, tungsten and antimony.
Here, a, b, c, d, e, f, g and h represent the atomic ratio of each element, and when a = 12, 0.1 ≦ b ≦ 5, 0.1
≤c≤5, 1≤d≤12, 0≤e≤10, 0≤f≤1
0,0.01 ≦ g ≦ 3, and h is the number of oxygen atoms necessary to satisfy the valence of each component. The catalytically active component comprising the composite oxide represented by
A supported catalyst supported such that the amount of the catalytically active component supported is 10 to 400 parts by weight with respect to parts by weight. (2) The catalyst layer in each tube is divided into two or more layers in the tube axis direction. In the plurality of reaction zones provided, (3) a plurality of supported catalysts prepared by changing the supported amount of the catalytically active component per unit weight of the carrier in the catalyst of (1) above from the raw material gas inlet to the outlet. A method for producing methacrolein and methacrylic acid, characterized in that the reaction is carried out by filling the mixture so as to increase the amount supported. 2. The method for producing methacrolein and methacrylic acid according to claim 1, wherein the number of reaction zones is 2 to 4.