JP3267019B2 - Process for producing unsaturated aldehydes and unsaturated carboxylic acids - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for the production of the corresponding unsaturated aldehydes and acids by gas-phase catalytic oxidation of propylene, isobutylene or tertiary butanol with molecular oxygen. Specifically, the present invention relates to a method for reusing a catalyst degraded by a reaction.

[0002]

2. Description of the Related Art Production of acrolein and acrylic acid from propylene by gas phase catalytic oxidation using a so-called molybdenum-bismuth composite oxide catalyst, production of methacrolein and methacrylic acid from isobutylene, and acrylonitrile and methacrylic acid by ammoxidation The technology for producing lonitrile is well known. However, the present catalyst has a problem that if the reaction is continued for a long period of time, the reaction activity and selectivity decrease due to deterioration of the catalyst with the passage of time.

Some proposals have been made on the method of suppressing the deterioration rate of the catalyst and extending the life thereof, but they are not complete, and the catalyst needs to be replaced sooner or later. Therefore, several methods for regenerating and using a catalyst whose performance has deteriorated have been proposed.

For example, JP-A-55-67335 discloses that
Degraded catalyst in an inert gas atmosphere at 500-800 ° C
A method of heat treatment at a temperature of
No. 4 describes that a deteriorated catalyst is stored in a reducing gas atmosphere for 200 hours.
A method is disclosed in which a heat treatment is performed at a temperature of 550 to 700 ° C., and a firing is performed at a temperature of 550 to 700 ° C. in an atmosphere of a molecular oxygen-containing gas. All of them disclose only examples of catalysts used for ammoxidation of propylene, and catalysts used for partial oxidation of propylene, isobutylene or tertiary butanol are susceptible to sintering when calcined at such a high temperature, and the activity is low. It has the disadvantage of lowering.

The catalyst used for the partial oxidation of propylene or isobutylene is disclosed in JP-A-61-33234 in an atmosphere consisting essentially of air at 380 ° C. to 540 ° C.
Heat treatment at a temperature of
No. 55 discloses a method of performing heat treatment at a temperature of 300 ° C. to 500 ° C. under a flow of an oxidizing gas containing molecular oxygen and water vapor. Further, JP-A-5-184945 discloses that when a deteriorated catalyst is withdrawn from a reaction tube and regenerated, 2 to 10% by weight of a reaction gas inlet portion is removed and the remainder is removed at 300 to 500 ° C. in a molecular oxygen-containing gas atmosphere. Is disclosed.

[0006] The regeneration method by heat treatment as described above is explained as being based on the effect of reoxidizing metal ions in a reduced state or the effect of restoring the catalyst surface composition changed by volatilization of components such as molybdenum by diffusion from inside the solid. However, the effect of the reproduction by this is not sufficient.
As shown in JP-A-184945, a portion having a large degree of deterioration, such as a gas inlet portion, cannot be completely regenerated, and cannot be regenerated many times.

It has been well known that one of the causes of catalyst deterioration is due to the volatilization of molybdenum, and a method of replenishing molybdenum by some method has been proposed as a method of regenerating the deteriorated catalyst. JP-A-50-49201
No. 1 discloses a regeneration process in which a catalyst is contacted with fluidized bed particles consisting essentially of an inert carrier containing molybdenum in a fluidized bed reactor. JP-A-52-131989 discloses a method of regenerating a deteriorated catalyst by impregnating it with at least a solution of molybdenum and bismuth and calcining the impregnated catalyst.
JP-A-57-56044 discloses a regeneration method in which a molybdenum compound is added to a deteriorated catalyst and then heat-treated in a reducing atmosphere and an oxidizing atmosphere.

However, all of these embodiments relate to the regeneration of propylene ammoxidation catalysts used at high temperatures, and the catalysts used in the partial oxidation of propylene, isobutylene or tertiary butanol in fixed beds are used. In the treatment method disclosed, molybdenum oxide has an activity, and the regeneration is insufficient or the composite oxide catalyst causes sintering and the activity is reduced. Resulting in.

[0009]

It is an object of the present invention to provide gas phase catalytic oxidation of propylene, isobutylene or tertiary butanol with molecular oxygen in a fixed-bed multitubular reactor to obtain the corresponding unsaturated aldehydes and unsaturated aldehydes. It is an object of the present invention to provide a method for reusing a catalyst in which the performance of a composite oxide catalyst containing molybdenum, bismuth, iron, or the like used in producing a saturated acid has deteriorated.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, molybdenum oxide which is substantially inactive in the present reaction is mixed with a deteriorated catalyst and reused. As a result, it has been found that the same results as when a new catalyst is used can be obtained, and the present invention has been achieved.

That is, the present invention relates to the general formula Moa Bib
Fec Ad Be Cf Dg Ox (wherein, Mo, Bi, and Fe each represent molybdenum, bismuth, and iron, A represents nickel and / or cobalt, and B comprises manganese, zinc, calcium, magnesium, tin, and lead. C represents at least one element selected from the group, C represents at least one element selected from the group consisting of phosphorus, boron, arsenic, tellurium, tungsten, antimony and silicon, and D represents potassium, rubidium, cesium. And at least one element selected from the group consisting of
b ≦ 10, 0 <c ≦ 10, 1 ≦ d ≦ 10, 0 ≦ e ≦ 1
0, 0 ≦ f ≦ 10, 0 <g ≦ 2, and x is a value determined by the oxidation state of each element), using a fixed-bed multitubular reactor with propylene, In a process for producing the corresponding unsaturated aldehydes and unsaturated carboxylic acids by subjecting isobutylene or tertiary butanol to gaseous phase catalytic oxidation with molecular oxygen, a catalyst whose performance has deteriorated by the reaction is replaced with a molybdenum oxide which is substantially inert to the reaction. And reusing the resulting mixture as a catalyst.

In the present invention, the target catalyst is a gas-phase catalytic oxidation of propylene, isobutylene or tertiary butanol with molecular oxygen in a fixed-bed multitubular reactor to convert the corresponding unsaturated aldehyde and unsaturated carboxylic acid. It is a composite oxide catalyst used in the production and its composition is known (JP-B-47-32044, JP-B-47-42241).
No. etc.). When this catalyst continues the reaction for a long time, the reaction activity and selectivity decrease due to deterioration of the catalyst with the passage of time.
In the present invention, the deteriorated catalyst is once extracted from the reaction tube, mixed with molybdenum oxide which is substantially inert to the reaction, filled in the reaction tube, and reused.

Molybdenum oxide which is substantially inert to the reaction can be obtained, for example, by subjecting a commercially available ammonium molybdate to a heat treatment at 550 ° C. to 700 ° C. in air.
If the heat treatment temperature is lower than this, the obtained molybdenum oxide has a complete oxidizing activity of the olefin, and when it is used in combination with a catalyst, the selectivity of the reaction is deteriorated. Alternatively, a commercially available molybdenum trioxide that is inert to the reaction can be selected. In the conventional method of impregnating a deteriorated catalyst with a solution containing molybdenum, in order to make molybdenum oxide inert to the reaction, finally, in air,
It is necessary to calcine at a high temperature of 550 ° C. or more, and in the case of the catalyst used in the present reaction, the reaction activity is further reduced as compared with the deteriorated catalyst.

One of the methods of mixing the molybdenum oxide which is substantially inert to the reaction with the degraded catalyst and reusing it as a catalyst is to pulverize the degraded catalyst withdrawn from the reaction tube and to substantially reduce the reaction. Mix the powder of inert molybdenum oxide,
This is a method in which tableting, extrusion or carrier molding is performed, and the formed catalyst is filled in a reaction tube. Although the molded catalyst does not necessarily need to be calcined, when water or an organic substance is used as a molding aid, the calcining temperature of the original new catalyst is 400 ° C. to 5 ° C.
It is preferable to perform calcination in air or an inert gas in a temperature range of 50 ° C.

Another method is to form molybdenum oxide, which is substantially inert to the reaction, alone or together with an inert carrier such as silica by a method such as tableting, extrusion, impregnation, etc. This is a method of mixing with a molded product of a deteriorated catalyst extracted from a tube and refilling the mixture.

The amount of molybdenum oxide which is substantially inert to the reaction mixed with the deteriorated catalyst is not particularly limited. About 3-20 against deteriorated catalyst
In general, when mixed with a molded article, it is used in an amount of about 5 to 40% by volume based on the deteriorated catalyst, depending on the shape.

In this reaction using a fixed-bed multitubular reaction tube,
It is known that the deterioration of the catalyst is not uniform in all layers, is larger at the inlet side of the reaction gas, and is relatively healthy at the middle and outlet sides. However, most of the reaction proceeds on the entrance side, and the deterioration of this part governs the overall reaction performance. The main part where the catalyst deteriorates is about 5 to 50% of the reaction gas inlet side. Therefore, only this part is extracted, mixed with molybdenum oxide which is substantially inert to the reaction, and refilled. it can. Of course, it is also possible to use relatively healthy parts. At this time, excessive oxidation is suppressed by suppressing heat generation at the entrance due to the effect of dilution of the catalyst by coexisting molybdenum oxide, and an effect of improving selectivity or improving productivity per unit catalyst can be obtained.

In the present invention, it is not clear why the same performance as the new catalyst can be obtained only by mixing the deteriorated catalyst with molybdenum oxide which is substantially inert to the reaction and reusing it, but it is not clear. It is presumed that the mixed molybdenum oxide passes through the gas phase and a part of the molybdenum volatilizes to reach the surface of the deteriorated catalyst lacking molybdenum and is supplied to the catalyst.

In the present invention, as long as molybdenum oxide which is substantially inactive in the mixed reaction remains, the rate of performance deterioration is suppressed as compared with the original catalyst due to the steady molybdenum replenishing effect. .

[0020]

As described above, by using a mixture of a deteriorated catalyst and molybdenum oxide which is substantially inert to the reaction, the same reaction results as those obtained when a new catalyst is used can be obtained, and the performance of the catalyst can be improved as compared with the new catalyst. The deterioration rate is suppressed, and long-term use is possible.

[0021]

The present invention will be described in more detail with reference to the following examples. The reaction rate (%) and yield (%) in the present specification are defined as follows. Conversion (%) = (moles of reacted olefin / moles of supplied olefin) × 100 Selectivity (%) = (moles of product / moles of reacted olefin) × 100 Yield (%) = (Mol number of product / mol number of supplied olefin) × 100

Example 1 [Preparation of New Catalyst] Ammonium molybdate [(N
H_Four)₆Mo₇O_{twenty four}・ 4H_TwoO] 144 kg of hot water 47
0 liter and further 20% silica sol (SiO
_Two) 20.4 kg was added (this is referred to as solution A). nitric acid
Cobalt [Co (NO_Three)_Two・ 6H_TwoO] 138.5k
g and ferric nitrate [Fe (NO_Three)_Three・ 9H_TwoO]
55 kg and cesium nitrate (CsNO_Three) 0.66k
g in 250 liters of warm water (this is referred to as solution B).
). Add 9.4 kg of 60% nitric acid to 40 liters of pure water.
, Bismuth nitrate [Bi (NO _Three)_Three・ 5H_TwoO] 33
kg was dissolved (this is referred to as solution C). Next, liquid B and liquid C
Was mixed. A liquid mixture of liquid B and liquid C while stirring liquid A
Is added to obtain a slurry. After concentrating and drying this,
The salt was decomposed at 200 to 250 ° C. Then crush and outside
Punched into a cylinder with a diameter of 5mmφ, an inner diameter of 2mmφ, and a height of 5mmH
Tablets are formed and calcined in air at 470 ° C for 6 hours to obtain a catalyst.
Was. The catalyst composition excluding oxygen atoms is Mo₁₂Bi_OneFe_TwoC
o₇Cs_0.05Si_OneIt is.

10 ml of this new catalyst was filled in a glass reaction tube having an inner diameter of 18 mmφ, and propylene: air: steam =
A raw material gas having a molar ratio of 1: 7.5: 3 was applied to an SV = 1
The reaction was carried out by introducing at a flow rate of 100 / h (standard state). The reaction pressure is 2.0 atm. At a reaction temperature of 320 ° C., the reaction results were as follows: propylene conversion = 97.5%, total yield of acrolein and acrylic acid = 90.4%.

This new catalyst was charged into a reactor of an acrylic acid production plant and operated for three years, and then the catalyst in a part of the reaction tubes was extracted in three parts. When the reaction performance of the catalyst on the gas inlet side was evaluated in the same manner, the reaction rate was 96.8% and the yield was 8
7.3%, and the decrease in yield was large. The catalyst at the center and the outlet was almost the same as the reaction result of the new catalyst.

The deteriorated catalyst on the gas inlet side is replaced with the deteriorated catalyst A.
And 100 parts powder obtained by pulverizing deteriorated catalyst A, ammonium molybdate _{[(NH 4) 6 Mo 7 O} 24 · 4
H ₂ O] in air at 630 ° C. for 6 hours was mixed with 10 parts of molybdenum trioxide, and 5 mmφ × 2 mmφ × 5
It was tableted into a cylinder of mmH and calcined at 460 ° C for 3 hours.

When the reaction results of this catalyst were evaluated in the same manner, the conversion was 97.0% and the yield was 90.3%, which were equivalent to the new catalyst.

Example 2 To 100 parts of powder obtained by pulverizing the deteriorated catalyst A, 6 parts of commercially available molybdenum trioxide powder confirmed to be inactive in a propylene oxidation reaction test and 4 parts of ceramic fiber were mixed. Add water and methylcellulose, outer diameter 5m
m, 2 mm in inner diameter, and about 6 mm in length, and was baked in air at 460 ° C. for 3 hours.

When the reaction results of this catalyst were evaluated in the same manner as in Example 1, the conversion was 97.2% and the yield was 90.90%.
4%, equivalent to the new catalyst.

Comparative Example 1 The deteriorated catalyst A was directly used in an electric furnace in an air atmosphere at 460 ° C.
For 6 hours. When the reaction results of this catalyst were evaluated in the same manner as in Example 1, the conversion was 96.5% and the yield = 8.
8.7%, which is partially reproduced but not enough.

Example 3 The new catalyst of Example 1 was charged and a single tube test was conducted. Inner diameter 3
This catalyst was directly filled into a gas outlet 2.8 m of a 0 mm carbon steel reaction tube, and 70% by volume of the catalyst and 30% by volume of a magnetic Raschig ring having an outer diameter of 6.2 mm were filled in a portion 1.2 m on the inlet side. And a reaction was carried out by introducing a raw material gas having a molar ratio of propylene: air: steam = 1: 7.5: 3 so that SV = 1000 / h (standard state). Gas inlet pressure is 1.1kg
/ Cm ² G, and the heating medium temperature was 310 ° C. Analysis of the reaction results 7 days after the start of the reaction revealed that the conversion of propylene was 97.7%, the yield of acrolein was 83.5%, and the yield of acrylic acid was 8.3%.

With respect to the reaction gas composition and the SV, the reaction rate is 97.5% to 98.0 while keeping substantially the same reaction conditions.
%, The operation was continued while controlling the temperature of the heating medium so that the reaction result was 322 ° C. after 650 days.
Propylene conversion 97.6%, acrolein yield 80.
The yield was 2% and the yield of acrylic acid was 8.8%.

At this time, the reaction was stopped, and a 1.2 m portion of the gas inlet side diluted layer was extracted. The Raschig ring and the catalyst were sieved. 65% by volume of this catalyst and separately commercially available molybdenum trioxide were prepared with an outer diameter of 6 mm, an inner diameter of 2.5 mm, and a height of 6 mm.
The mixture was mixed with 35% by volume of a molded product obtained by compression molding at a temperature of 600 ° C. in the air, and the portion 1.2 m previously extracted was filled again. The reaction was restarted in this manner, and the reaction results after two days were observed. At a heating medium temperature of 313 ° C., the propylene conversion was 97.6%, and the yield of acrolein was 82.2.
%, And the yield of acrylic acid was 8.6%. If the reaction was further continued as it was, the heating medium temperature was 316 ° C. after 21 days.
Propylene conversion 97.8%, acrolein yield 8
The yield was 3.8% and the yield of acrylic acid was 8.1%, which was equivalent to that of the new catalyst. Continue the reaction further and refill after 26
The reaction results after 0 days at a heating medium temperature of 323 ° C. showed a propylene conversion of 97.6%, an acrolein yield of 83.6%, and an acrylic acid yield of 8.2%, showing almost no reduction in yield.

Example 4 [Preparation of a new catalyst]
Excluding Mo₁₂Bi_1.4Fe_TwoNi _FiveCo_FourTl_0.5
P_0.4Si_FifteenWas prepared. However, Ni raw material
Nickel acid Ni (NO_Three)_Two・ 6H_TwoO, Tl raw material
Thallium nitrate TlNO_Three, P raw material is phosphoric acid H_ThreePO_Four
And the powder after salt decomposition and pulverization is converted to α-Al_TwoO_Three(5m
mφ ball) to carry and mold (bearing rate 30% by weight)
The catalyst was calcined at 550 ° C. for 6 hours in air.

12 ml of this new catalyst was filled in a glass reaction tube having an inner diameter of 18 mmφ. At a reaction temperature of 420 ° C., an isobutylene: air: steam = 1: 20: 8 molar ratio and SV
An accelerated life test was performed under a reaction condition of = 1500 / H.

As a result, the reaction result after 5 days was 93.2% for isobutylene conversion and 79.3% for selectivity between methacrolein and methacrylic acid. After 200 days, the conversion was 94.0%. % And selectivity 70.2%.

The deteriorated catalyst was once taken out of the reaction tube, and the molybdenum trioxide molded body inert to the reaction used in Example 3 was pulverized to a size of 10 to 16 mesh.
ml and mixed again into the reaction tube. The operation was resumed under the same conditions and the reaction results were observed. Two days later, the reaction rate was 9%.
It was 3.5% and the selectivity was 75.6%, but after 10 days, the conversion was 93.0% and the selectivity was 79.1%, showing the same performance as the new catalyst.

Comparative Example 2 Ammonium molybdate was added to 200 ml of ion-exchanged water at 50 ° C.
Nium [(NH_Four)₆Mo₇O_{twenty four}・ 4H_TwoO] 123 g
Impregnated with 1000 g of deteriorated catalyst A
It was dried and further fired in air at 350 ° C. for 6 hours. Degraded catalyst
MoO against _ThreeIs 10% by weight. This catalyst
When the reaction results were evaluated in the same manner as in Example 1, the reaction
Rate was 97.3% and yield was 88.4%. Partly played
But not enough.

Comparative Example 3 In the same manner as in Comparative Example 2, only the firing temperature was 550 ° C.
When the reaction results of this catalyst were evaluated in the same manner as in Example 1, the conversion was 63.5% and the yield was 59.7%. The reaction activity is greatly reduced.

Reference Example 1 Ammonium molybdate [(NH ₄ ) ₆ Mo ₇ O _24.
4H ₂ O] in air at 350 ° C. for 3 hours,
Got _three . A small amount of water and 1.5% of stearic acid were mixed, tableted into a cylinder of 5 mmφ × 2 mmφ × 5 mmH, and fired at 630 ° C. for 6 hours in air. This is the inner diameter 1
An 8φ reaction tube is filled with 10 ml and a reaction temperature of 360 to 42.
At 0 ° C., the reaction was carried out at a molar ratio of propylene: air: steam = 1: 7.5: 3 and a condition of the cylinder speed SV = 1100 / H. As a result, in each case, the propylene conversion rate was 0.5
And no substantial reaction was observed.

Reference Example 2 In the same manner as in Reference Example 1, MoO ₃ was prepared, and
The same experiment as in Reference Example 1 was performed using MoO ₃ performed at 00 ° C. for 6 hours. Table 1 shows the results. Inactive Mo
Firing at 500 ° C. is incomplete for producing O ₃ .

[0041]

[Table 1]

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁷ Identification code FI C07C 45/32 C07C 45/32 45/35 45/35 51/25 51/25 57/05 57/05 // C07B 61/00 300 C07B 61/00 300 (56) Reference JP-A-55-113730 (JP, A) JP-A-50-49201 (JP, A) JP-A-57-56044 (JP, A) JP-A-59-76543 (JP, a) JP Akira 57-130546 (JP, a) JP flat 5-184945 (JP, a) JP Akira 59-76544 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) C07C 47/22 B01J 23/88 B01J 23/92 B01J 27/057 C07C 57/05 C07C 45/32 C07C 45/35 C07C 51/25

Claims (6)

(57) [Claims] 1. The formula Moa Bib Fec Ad Be C
f Dg Ox (wherein, Mo, Bi, and Fe each represent molybdenum, bismuth, and iron, A represents nickel and / or cobalt, and B is selected from the group consisting of manganese, zinc, calcium, magnesium, tin, and lead. C represents at least one element selected from the group consisting of phosphorus, boron, arsenic, tellurium, tungsten, antimony and silicon, and D represents potassium, rubidium, cesium and thallium. Represents at least one element selected from the group consisting of:
b ≦ 10, 0 <c ≦ 10, 1 ≦ d ≦ 10, 0 ≦ e ≦ 1
0, 0 ≦ f ≦ 10, 0 <g ≦ 2, and x is a value determined by the oxidation state of each element), using a fixed-bed multitubular reactor with propylene, In a process for producing the corresponding unsaturated aldehydes and unsaturated carboxylic acids by subjecting isobutylene or tertiary butanol to gaseous phase catalytic oxidation with molecular oxygen, a catalyst whose performance has deteriorated by the reaction is replaced with a molybdenum oxide which is substantially inert to the reaction. And producing a mixture of the aldehyde and the unsaturated carboxylic acid. 2. The method according to claim 1, wherein the molded body of the deteriorated catalyst is pulverized, mixed with a molybdenum oxide powder which is substantially inert to the reaction, and remolded for use. 3. The method according to claim 1, wherein the molded body of the deteriorated catalyst is mixed with a molded body containing molybdenum oxide which is substantially inert to the reaction. 4. The process of claim 2 wherein the amount of molybdenum oxide substantially inert to the reaction is 3-20% by weight of the degraded catalyst. 5. The process according to claim 4, wherein the amount of molybdenum oxide substantially inert to the reaction is 5 to 40% by volume of the degraded catalyst. 6. The process as claimed in claim 1, wherein 5 to 50% of the deteriorated catalyst on the inlet side of the reaction gas is mixed with molybdenum oxide which is substantially inert to the reaction.