JP2000351744A - Method for producing methacrolein and methacrylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for improving productivity and elongating a catalyst life by using a specific compound oxide catalyst in vapor phase contact oxidation of isobutylene or tert-butyl alcohol using a fixed bed multipipe reaction vessel. SOLUTION: A compound oxide catalyst of the formula MoaBibFecAdBeOx (A is Ni or Co; B is K, Rb, Cs or Tl; when a is 12, 0<b<=10, 0<c<=10, 1<=d<=10, 0<e<=2; x depends on the oxidation state of each element) is filled on a gas outlet side of each reaction pipe of a fixed bed multipipe reaction vessel and a catalyst of the formula: MoaBibFecAdBeSbfOx (when a is 12, 0.01<=f<=5) is filled on a raw material gas inlet side of each reaction pipe, and isobutylene or tert-butyl alcohol is oxidized by a vapor phase contact oxidation reaction using molecular oxygen. Reaction temperature is 300-400 deg.C, reaction pressure is normal pressure to 500 kPa, molar ratio (oxygen/isobutylene or the like) is 1-3, and space velocity(SV) is 500-5000/h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing methacrolein and methacrylic acid by gas-phase catalytic oxidation of isobutylene or tert-butyl alcohol with molecular oxygen using a fixed-bed multitubular reactor.

[0002]

2. Description of the Related Art The production technology of methacrolein and methacrylic acid from isobutylene by gas phase catalytic oxidation using a so-called molybdenum-bismuth composite oxide catalyst is well known.

[0003] The oxidation reaction is usually carried out using a fixed-bed multitubular reactor. However, since the reaction involves a large amount of heat, a hot spot tends to be generated particularly at the raw material gas inlet side. Therefore, there is a problem in that the yield is lowered and the catalyst life is shortened due to accelerated catalyst deterioration. In particular, to increase the raw material concentration in order to increase the productivity per unit catalyst,
This problem becomes more serious when trying to increase space velocity.

Several proposals have been made in the past to reduce hot spots and improve productivity and catalyst life. For example, Japanese Patent Publication No. 53-30688 proposes a method for producing acrolein and acrylic acid by diluting a catalyst in a portion where a hot spot easily occurs with a substance inert to the reaction and subjecting propylene to gas phase catalytic oxidation with molecular oxygen. Have been. In addition, a catalyst for synthesizing methacrolein and methacrylic acid by subjecting isobutylene to gas-phase catalytic oxidation with molecular oxygen, for example, JP-A-51-127003 discloses a so-called supported catalyst placed on the raw material gas inlet side, and an outlet. Japanese Patent Application Laid-Open No. 6-19214 discloses a method in which the side of the molded catalyst is used as a normal molded catalyst.
No. 4 proposes a method of filling a supported catalyst such that the supported amount becomes higher from the raw material gas inlet side toward the outlet side.

Further, Japanese Patent Application Laid-Open No. 4-217932 proposes a method of filling a plurality of types of catalysts having different occupied volumes, that is, different sizes, so that the occupied volumes become smaller from the inlet side of the raw material gas toward the outlet side. Have been.

Further, Japanese Patent Application Laid-Open No. 3-176440,
Japanese Patent Application Laid-Open No. 3-200733 discloses a plurality of molybdenum-bismuth based multi-component catalysts in which the activity is controlled by changing the types and / or amounts of alkali metals, thallium group elements, and alkaline earth metal elements. Japanese Patent Application Laid-Open No. 3-294238 discloses a method of preparing a kind of catalyst and filling a catalyst having a higher activity from the inlet side of the raw material gas toward the outlet side. A method is disclosed in which the activity is controlled by changing the type and / or the amount of the thallium group element and the calcination temperature at the time of preparing the catalyst, and filling is performed in the same manner as described above. In Japanese Patent Application Laid-Open No. 3-215441, a molybdenum-bismuth-based multi-component catalyst such as tungsten,
Iron, nickel and / or cobalt as an essential component,
In addition, phosphorus, tellurium, antimony, tin, cerium,
Disclosed is a method of controlling the activity of a catalyst essentially including at least one element of lead, niobium, manganese, arsenic, and zinc by changing the type and / or amount of the element and filling the same as above. Have been.

[0007]

As described above, when the gas-phase catalytic oxidation reaction is carried out using a fixed-bed multitubular reactor, productivity is improved by suppressing hot spots at the raw material gas inlet. As a method for extending the life of the catalyst, a method of controlling the catalyst activity by some method and dividing and filling the reaction tube is adopted. These are all effective methods, but the method using an inert diluent is not necessarily advantageous in terms of catalyst life since the amount of catalyst component that can be filled in the reaction tube is reduced and the load per unit catalyst is increased. Is not a good way.

In the method of changing the size of the catalyst, even if the shape is devised and, for example, a ring-shaped catalyst is used, the larger the size of the catalyst is, the lower the yield of methacrolein and methacrylic acid is. However, this method cannot be said to be advantageous in view of the reaction yield.

The method of controlling the activity by changing the composition of the catalyst is more excellent than that,
No. 40, JP-A-3-200733, JP-A-3-2007
In JP-A-215441 and JP-A-3-294238, the number of constituent components of the catalyst is as large as 7 to 11, so that the catalyst preparation step and the operation of recovering the metal component from the used catalyst become complicated, and the above-mentioned catalyst eventually costs less. It will be high.

[0010] In view of such circumstances, the present inventors have conducted a gas-phase catalytic oxidation of isobutylene or tert-butyl alcohol using a fixed-bed multitubular reactor to produce methacrolein and methacrylic acid. As a result of diligent studies aimed at providing a simpler and more reliable method for improving productivity and prolonging catalyst life by suppressing the hot spot on the inlet side, the raw material gas for each reaction tube was found. In the case of using an antimony-added molybdenum, bismuth-based multi-component composite oxide catalyst as a catalyst to be charged on the inlet side and using an antimony-free molybdenum-bismuth-based multi-component composite oxide catalyst on the gas outlet side, The inventors have found that the above object can be achieved, and have completed the present invention.

[0011]

That is, the present invention relates to a catalyst of the general formula (1) MoaBibFecAdBeOx (where Mo, B
i and Fe each represent molybdenum, bismuth and iron, A represents nickel and / or cobalt, B represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, and a = 1
When 0, 0 <b ≦ 10, 0 <c ≦ 10, 1 ≦ d ≦
10, 0 <e ≦ 2, and x is a value determined by the oxidation state of each element. Using a fixed-bed multitubular reactor packed with the composite oxide catalyst represented by
In a method for producing methacrolein and methacrylic acid by subjecting t-butyl alcohol to gas-phase catalytic oxidation with molecular oxygen, each reaction tube is divided into two layers, and a gas outlet side of each reaction tube is represented by the general formula (1). The composite oxide catalyst shown in the figure was filled, and the following general formula (2) M
oaBibFecAdBeSbfOx (where A, B, a, b, c, d, and e are the same as those in the above general formula (1), and Sb represents antimony;
When f = 12, 0.01 ≦ f ≦ 5, and x is a value determined by the oxidation state of each element. The present invention provides a process for producing methacrolein and methacrylic acid, characterized by using a fixed-bed multitubular reactor filled with the composite oxide catalyst described in (1).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method of the present invention will be described in more detail. A feature of the present invention is a method for producing methacrolein and methacrylic acid by gas-phase catalytic oxidation of isobutylene or tert-butyl alcohol with molecular oxygen using a fixed-bed multitubular reactor. Each reaction tube is divided into two reaction zones, that is, the reaction tube is divided into a gas inlet side and an outlet side, and the catalyst contains antimony on the raw material gas inlet side. Characterized in that, on the outlet side, a molybdenum-bismuth-based multi-component composite oxide catalyst containing no antimony is used.

In the present invention, the catalyst filled on the gas outlet side of each reaction tube is represented by the following general formula (1): MoaBibFecAd
BeOx (the symbols in the formula, the meaning is the same as described above) is a composite oxide catalyst, and the catalyst to be charged into the raw material gas inlet side of each reaction tube is represented by the general formula (2) MoaBibF
This is a composite oxide catalyst represented by ecAdBeSbfOx (the symbols and the meanings in the formula are the same as described above).

Specifically, the catalyst to be charged into the raw material gas inlet side of each reaction tube constituting the fixed-bed multitubular reactor includes:
For example, the following catalyst composition (excluding oxygen atoms): Mo ₁₂ Bi _0.1-5 Sb _0.1-5 Fe _0.5-5 Co _5-10 Cs
_0.01-1 Mo ₁₂ Bi _0.1-5 Sb _0.1-5 Fe _0.5-5 Co _5-10 K _0.01-1 Mo ₁₂ Bi _0.1-5 Sb _0.1-5 Fe _0.5-5 Ni _5-10 Tl
_{Examples of the} catalyst to be filled on the outlet side include the following catalyst composition (excluding oxygen atoms): Mo ₁₂ Bi _0.1-5 Fe _0.5-5 Co _5-10 Cs _0.01-1 Mo ₁₂ Bi _0.1-5 Fe _0.5-5 Co _5-10 K _0.01-1 Mo ₁₂ Bi _0.1-5 Fe _0.5-5 Ni _5-10 Tl _{0.01-1 and the} like.

The method for producing these composite oxide catalysts is not particularly limited, and is described, for example, in JP-A-59-4613.
No. 2, JP-A-60-163830 and the like can be adopted.

As the raw material of the catalyst component, oxides, nitrates, sulfates, carbonates, hydroxides, ammonium salts, halides and the like of each element can be used in combination. Specifically, for example, molybdenum raw material is molybdenum trioxide, molybdic acid, ammonium paramolybdate, etc., bismuth raw material is bismuth oxide, bismuth nitrate, bismuth sulfate, etc., and iron nitrate (II
I), iron (III) sulfate, iron (III) chloride and the like are used as antimony raw materials such as antimony (III) oxide, antimony chloride (I
II) etc. can be used.

The catalyst of the present invention is produced by converting these catalyst raw materials into an aqueous solution, mixing them, drying a mixed solution or an aqueous slurry containing the obtained catalyst components, and calcining the obtained dried product. . In the present invention, the order of mixing and the method of mixing the catalyst raw materials are not particularly limited, but when preparing the inlet-side catalyst, a method of adding a predetermined amount of the antimony raw material at the time of forming the outlet-side catalyst includes a preparation step. Is more preferable to make the above simpler.

In the present invention, if the content of antimony in the catalyst on the inlet side is too small, the effect of addition is not exhibited. If the content is too large, the catalytic activity is remarkably reduced. Therefore, when the amount of Mo atoms is 12 mol, the amount is preferably about 0.01 to about 5 mol.

In the present invention, the method for drying the mixed solution containing the catalyst component or the aqueous slurry thereof does not need to be limited to a special method, and is well known in the art unless the component is not significantly unevenly distributed. For example, various methods such as an evaporative drying method using a kneader, a box-type dryer, a drum-type through-air dryer, a spray dryer, and a flash dryer can be used.

The dried catalyst (catalyst precursor) is then finally calcined to obtain the final catalyst applied to the reaction tube. The final firing is usually performed at a temperature in the range of about 350 to about 700 ° C. for about 1 to about 40 hours.

At the time of calcination, the catalyst precursor is used as it is or after being crushed if necessary, and is usually molded into a desired shape and used. The molding is performed into a ring shape, a pellet shape, a spherical shape, or the like by tablet molding or extrusion molding. As described above, the molding of the catalyst is usually carried out by molding the catalyst precursor and then calcining, but the present invention is not limited to this. For example, the catalyst precursor is calcined in advance and then molded.

In practicing the present invention, the reaction zone of each reaction tube is divided into two layers and arranged so that the activity becomes higher from the inlet side to the outlet side of the raw material gas. It is carried out by a simple method that is carried out mainly based on the presence or absence of antimony in the catalyst component. The activity of the antimony-added catalyst is lower than that of the antimony-free catalyst, but the selectivity is improved. Therefore, by filling the inlet with the antimony-added catalyst, the hot spot is suppressed and the selectivity of the reaction is improved. Therefore, an antimony-added catalyst is used as the catalyst to be charged on the inlet side, and a highly active catalyst without antimony is charged on the outlet side. The filling ratio of the antimony-added catalyst and the antimony-free catalyst filled in each reaction tube is not unique depending on the catalyst composition, the reaction temperature, the gas flow rate of the reaction tube and the like, but is usually 1: 9 to 7: 3 by weight ratio. Preferably, the filler is used in the range of 2: 8 to 6: 4.

The gas-phase catalytic oxidation reaction of isobutylene or tert-butyl alcohol with molecular oxygen using the multitubular reactor thus adjusted can be carried out by a conventionally known method. For example, a reaction temperature of about 300 to about 4
Although the reaction pressure can be reduced to 00 ° C. and the reaction pressure can be reduced, usually from normal pressure to about 500 kPa, oxygen / isobutylene or tert-
Butyl alcohol (molar ratio) is 1-3, space velocity SV =
About 500 to about 5000 / h [Standard item]
quality and pressure (ST
P) Conditions].

[0024]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.
In the examples of the present invention, the conversion (%), the selectivity (%) and the yield (%) were defined as follows.

Reaction rate (%) = [(moles of isobutylene or tert-butyl alcohol supplied)-(moles of unreacted isobutylene or tert-butyl alcohol)]
{(Mol number of supplied isobutylene or tert-butyl alcohol) × 100 selectivity (%) = (mol number of product)} [(mol number of supplied isobutylene or tert-butyl alcohol) − (unreacted isobutylene or tert-butyl alcohol) (Moles of butyl alcohol)] × 100 Yield (%) = (moles of product) ÷ (moles of supplied isobutylene or tert-butyl alcohol) × 100

[0026] Example 1 Ammonium molybdate _{[(NH 4) 6 Mo 7} O 24 · 4
The H ₂ O] 12711.7g was dissolved in hot water 15000 g, to prepare a solution A. Iron (III) nitrate [Fe (NO ₃ ) ₃
• 9H ₂ O] 6060.0 g and cobalt nitrate [Co
_{(NO 3) 2 · 6H 2} O] 13096.4g and cesium nitrate (CsNO ₃₎ 701.7g dissolved in warm water 6000g, then bismuth nitrate _{[Bi (NO 3) 3 ·} 5H 2
O] 2910.4 g was dissolved to prepare solution B. While stirring the solution A, the solution B was added to obtain a slurry, which was subsequently spray-dried. The obtained dried product was calcined at 360 ° C. for 1 hour to obtain a catalyst precursor. The obtained catalyst precursor was molded into a ring shape having an outer diameter of 6 mm, an inner diameter of 2.5 mm, and a length of 6 mm, and was finally calcined at 530 ° C. for 6 hours to obtain a catalyst A. The composition of the catalyst excluding oxygen is Mo ₁₂ Bi ₁ Fe _2.5 Co _7.5 Cs
_0.6 . In the above method for preparing catalyst A, 3000.0 g of the obtained catalyst precursor was added to antimony trioxide (Sb
Catalyst B was prepared in the same manner as Catalyst A, except that 72.9 g of ₂ O ₃ ) was added and the calcination temperature was changed to 550 ° C. The catalyst composition except oxygen of the catalyst _{B, Mo 12 Bi 1 Sb 0.5} Fe 2 .5 Co
_7.5 Cs _0.6 . 3.48 g (30 wt%) of the above catalyst B on the raw material gas inlet side of a glass reaction tube having an inner diameter of 18 mm.
Together with 9 g of silicon carbide (14 mesh), and 8.12 g of the above catalyst A on the raw material gas outlet side.
(70 wt%) together with 21 g of silicon carbide (14 mesh). A raw material gas having a molar ratio of isobutylene: oxygen: nitrogen: steam = 1: 2.2: 6.2: 2 was supplied to the reaction tube at a flow rate of 158 ml / min (STP) to perform a reaction. Table 1 shows the results.

Example 2 In Example 1, 5.8 g of catalyst B was placed on the raw material gas inlet side.
(50 wt%) together with 15 g of silicon carbide (14 mesh), and catalyst A,
The reaction was carried out in the same manner as in Example 1 except that 5.8 g (50 wt%) was filled together with 15 g of silicon carbide (14 mesh). Table 1 shows the results.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1, except that 11.6 g of catalyst A alone was charged together with 30 g of silicon carbide (14 mesh) without using catalyst B. Table 1 shows the results.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1 except that 11.6 g of catalyst B alone was charged together with 30 g of silicon carbide (14 mesh) without using catalyst A. Table 1 shows the results.

Example 3 A catalyst C was prepared in the same manner as in Example 1, except that 874.8 g of antimony trioxide (Sb2O3) was added after dissolving ammonium molybdate. The catalyst composition of catalyst C excluding oxygen is Mo ₁₂ B
i ₁ is a _{Sb 1.0 Fe 2 .5 Co 7.5 Cs} 0.6. 18m inside diameter
m above the catalyst C on the raw material gas inlet side of the glass reaction tube
Fill 3.48 g (30 wt%) with 9 g of silicon carbide (14 mesh), while filling the raw material gas outlet side with 8.12 g (70 wt%) of the above catalyst A with 21 g of silicon carbide (14 mesh) did.
Thereafter, the reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 A reaction was carried out in the same manner as in Example 3 except that 11.6 g of the catalyst C alone was charged together with 30 g of silicon carbide (14 mesh) without using the catalyst A. Table 1 shows the results.

[0032]

[Table 1]

From the results of Examples 1 to 3 and Comparative Examples 1 to 3, the activities of the catalysts B and C are very low, and the activity of the catalyst A is high, but the total yield is low. On the other hand, in a catalyst system combining these catalysts A and B or A and C, the temperature difference between the reaction temperature and the hot spot temperature (Δ
T) is smaller than that of catalyst A alone, the hot spots are suppressed, and the total yield is high.

[0034]

According to the present invention, isobutylene or tertiary terephthalate is prepared using a fixed-bed multitubular reactor filled with a composite oxide.
In a method for producing methacrolein and methacrylic acid by subjecting t-butyl alcohol to gas-phase catalytic oxidation with molecular oxygen, a molybdenum-bismuth-based composite oxide containing antimony added to a raw material gas inlet side of each reaction tube, a gas outlet side By using an extremely simple means of filling an antimony-bismuth-based composite oxide catalyst to which antimony is not added, hot spots are suppressed, and methacrolein and a target product can be obtained in high yield. It was found that methacrylic acid was produced, and its industrial utility value is extremely large.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C07C 47/22 C07C 47/22 A J 51/245 51/245 51/25 51/25 57/05 57/05 // C07B 61/00 300 C07B 61/00 300

Claims (1)

[Claims] 1. The catalyst of the general formula (1) MoaBibF
ecAdBeOx (wherein, Mo, Bi, and Fe each represent molybdenum, bismuth, and iron, A represents nickel and / or cobalt, and B is at least one member selected from the group consisting of potassium, rubidium, cesium, and thallium. 0 <b ≦ 10, 0 <c when a = 12
≦ 10, 1 ≦ d ≦ 10, 0 <e ≦ 2, and x is a value determined by the oxidation state of each element. ), A gas-phase catalytic oxidation of isobutylene or tert-butyl alcohol with molecular oxygen using a fixed-bed multitubular reactor packed with a composite oxide catalyst represented by the formula (1) to produce methacrolein and methacrylic acid. The gas outlet side of the reaction tube is filled with the composite oxide catalyst represented by the general formula (1), and the following general formula (2) MoaBib is provided on the raw material gas inlet side of each reaction tube.
FecAdBeSbfOx (where A, B, a, b, c, d, and e are the same as those in the above general formula (1), and Sb represents antimony;
When f = 12, 0.01 ≦ f ≦ 5, and x is a value determined by the oxidation state of each element. A method for producing methacrolein and methacrylic acid, characterized by using a fixed-bed multitubular reactor filled with the composite oxide catalyst represented by the formula (1).