JP3282849B2 - Regeneration method of deteriorated catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating a catalyst having a reduced catalytic activity in a catalyst used for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation.

[0002]

2. Description of the Related Art Regarding a catalyst used in producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation,
Many suggestions have been made. However, it is difficult to stably maintain the catalyst activity over a long period of time, either due to the fate of the catalyst. On the other hand, from an economic point of view, there is a strong demand for a method of repeatedly regenerating and using a catalyst having deteriorated catalytic activity. From such a viewpoint, some proposals have been made on the regeneration of the catalyst. For example, Japanese Patent Application Laid-Open No. Sho 60-232247 discloses a method in which a catalyst whose activity has been reduced is extracted from a reaction tube and then regenerated with a nitrogen-containing heterocyclic compound. Similarly, there has been proposed a method of performing a regenerating treatment with ammonia water, a nitrogen-containing heterocyclic compound, etc., after extracting from a reaction tube. However, the method using these compounds requires heat treatment when activating the catalyst. In this case, sintering of the catalyst by combustion of the nitrogen-containing heterocyclic compound and reduction of the catalyst by the nitrogen-containing heterocyclic compound are required. Etc., and handling is not easy. On the other hand, some methods for regenerating a catalyst whose activity has decreased in a reaction tube have also been proposed. For example, Japanese Patent Application Laid-Open No. 56-91846 proposes a method of activating a catalyst whose activity has decreased with a nitrogen-containing compound such as nitric acid or nitrous acid. This method using a compound such as nitric acid or nitrous acid for regeneration in a reaction tube is complicated, and a simpler method is desired. As such a method, Japanese Patent Application Laid-Open No. 58-156351 proposes a method in which a gas containing 10% by volume or more of water vapor is treated at a temperature of 70 to 240 ° C. Although this method is simple and preferable, it has a drawback that at a processing temperature as low as 70 to 240 ° C., the deteriorated catalyst cannot be sufficiently activated.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a method for regenerating a catalyst having a reduced activity containing at least phosphorus, molybdenum and vanadium, which is used in producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation. The purpose is to regenerate the deteriorated catalyst for the purpose.

[0004]

According to the present invention, methacrolein is subjected to gas-phase catalytic oxidation using molecular oxygen using a catalyst containing at least phosphorus, molybdenum and vanadium filled in a reaction tube to convert methacrylic acid. A method for regenerating a deteriorated catalyst used in the production, wherein at least 0.2% of molecular oxygen is added to ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate at 20% by weight or less based on the deteriorated catalyst.
An oxidizing gas containing a decomposition product of ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate obtained by contacting with an oxidizing gas containing 1% by volume is filled with a deteriorated catalyst after gas phase catalytic oxidation. The degraded catalyst in the reaction tube is passed through the reaction tube at a temperature of 300 to 410 ° C. for 0.5 to
A method for regenerating a deteriorated catalyst is characterized by performing a heat treatment for 50 hours.

[0005] It is desirable that the catalyst can maintain the catalyst activity stably for a long period of time from the industrial and economic viewpoints. For this reason, the catalyst preparation method, the catalyst composition, the composition ratio, and the like have been continuously improved, and efforts have been focused on the development of long-life catalysts. However, the catalyst for partial oxidation of methacrolein has its own limit on the service life of the catalyst. Therefore,
The present inventors have tried to analyze the cause of the deterioration of the catalyst activity, and have intensively studied a method that can use the catalyst for a long time. As a result, the inventors have found that the activity can be recovered by a simple operation of simply heat-treating the deteriorated catalyst with an oxidizing gas containing a decomposition product of an ammonia-containing compound at a high treatment temperature, and completed the present invention. That is, the present invention is a method for regenerating a deteriorated catalyst, which comprises regenerating a catalyst having deteriorated catalytic activity without extracting the catalyst in a reaction tube.

[0006] The regeneration processing gas passed through the reaction tube filled with the deteriorated catalyst after the gas phase catalytic oxidation is 20% by weight or less, preferably 2.5 to 15% by weight of ammonium nitrate or ammonium carbonate based on the deteriorated catalyst. And / or at least 0.1% by volume of molecular oxygen in ammonium bicarbonate,
An oxidizing gas containing a decomposition product of ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate, obtained by contacting an oxidizing gas containing preferably 1 to 30% by volume. If the amount of ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate is less than 2.5% by weight, the effect of addition is small. On the other hand, if it exceeds 20% by weight, the regenerating effect is not exhibited. If the molecular oxygen content of the oxidizing gas to be brought into contact with ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate is less than 0.1% by volume, the deteriorated catalyst cannot be regenerated. Further, it is not economically preferable that the content of molecular oxygen exceeds 30% by volume.

As a method for contacting ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate with an oxidizing gas containing at least 0.1% by volume of molecular oxygen, any method may be used as long as these ammonia-containing compounds are decomposed. It may be a method. As one of such methods, a method in which an oxidizing gas is added to the inside of a reaction tube at a reaction gas inlet to flow an oxidizing gas can be cited. The space velocity of the regeneration gas flowing through the reaction tube is 100 ml / hr / ml-cat.
All that is required is the above. The heat treatment temperature when flowing the regeneration treatment gas is 300 to 410 ° C., preferably 330 to 400 ° C.
° C. If the heat treatment temperature is lower than 300 ° C, regeneration of the deteriorated catalyst is not sufficient, and if it exceeds 410 ° C, decomposition of the catalyst occurs, which is not preferable. The heat treatment time is 0.5 to 50 hours, preferably 1 to 30 hours.

[0008]

Examples and Comparative Examples Hereinafter, the present invention will be described with reference to Examples and Comparative Examples. First, prior to describing the examples and comparative examples, reference examples necessary for performing mutual comparison will be described.

Reference Example 1 100 parts of ammonium paramolybdate, 2.8 parts of ammonium metavanadate and 4.8 parts of potassium nitrate were dissolved in 300 parts of pure water. A solution prepared by dissolving 8.2 parts of 85% phosphoric acid in 10 parts of pure water was added thereto, and 3.3% of telluric acid was further added.
The mixture was dissolved in 20 parts of pure water and 3.4 parts of antimony trioxide were added, and the mixture was heated to 95 ° C. with stirring. Next, 3.4 parts of copper nitrate and 5.7 parts of ferric nitrate were added to 30 parts of pure water.
The mixture was added to the solution, and the mixture was evaporated to dryness while heating and stirring at 100 ° C. The obtained solid was heated at 130 ° C. for 1 hour.
After drying for 6 hours, the mixture was molded under pressure, and heat-treated at 380 ° C. for 5 hours under air flow was used as a catalyst. The composition of the elements other than oxygen in the obtained catalyst (hereinafter the same) is P _1.5 Mo
₁₂ V _0.5 Fe _0.3 Cu _0.3 Sb _0.5 K ₁ Te
_{At 0.3} , the catalyst was filled into a stainless steel reaction tube having an inner diameter of 16.1 mm and a length of 600 mm, and reacted with a mixed gas of methacrolein 5%, oxygen 10%, steam 30% and nitrogen 55% (volume%). The temperature was 290 ° C. and the contact time was 3.6 seconds.
When the product was collected and analyzed by gas chromatography, the conversion of methacrolein was 87.5% and the selectivity of methacrylic acid was 87.3%.

Reference Example 2 The catalyst of Reference Example 1 was filled in a stainless steel reaction tube having a length of 2500 mm, and a continuous reaction was carried out for one year. After the catalyst degraded by the continuous reaction was recovered and mixed uniformly, the reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 20.5% and the selectivity of methacrylic acid was 90.2%.

Reference Example 3 100 parts of molybdic acid trioxide, 2.6 parts of vanadium pentoxide
Parts and 6.7 parts of 85% phosphoric acid were added to 800 parts of pure water.
The mixture was heated and refluxed at 00 ° C. for 6 hours. To this was added 1.2 parts of copper acetate, and the mixture was further heated under reflux at 100 ° C. for 3 hours. After the reflux, the temperature of the mixture was cooled to 40 ° C, 11.2 parts of cesium bicarbonate dissolved in 100 parts of pure water was added, and the mixture was further heated at 40 ° C to 5.6 parts of ammonium carbonate dissolved in 100 parts of pure water. Then, the mixture was evaporated to dryness while heating. The resulting solid was dried at 120 ° C. for 16 hours, and then molded under pressure.
A catalyst heat-treated at 380 ° C. for 5 hours under air flow was used as a catalyst. The composition of the obtained catalyst was P ₁ Mo ₁₂ V
_0.5 Cu _0.1 Cs ₁ . Using this catalyst, a reaction was performed at a reaction temperature of 285 ° C. under the same reaction conditions as in Reference Example 1. As a result, the conversion of methacrolein was 85.8%, and the selectivity of methacrylic acid was 83.9%.

Reference Example 4 The catalyst of Reference Example 3 was filled in a stainless steel reaction tube having a length of 2500 mm, and a continuous reaction was carried out for one year. After the catalyst degraded by the continuous reaction was recovered and mixed uniformly, the reaction was carried out in the same manner as in Reference Example 3. As a result, the conversion of methacrolein was 18.9%, and the selectivity of methacrylic acid was 87.7%.

Comparative Example 1 The deteriorated catalyst of Reference Example 2 was regenerated by heat treatment at 390 ° C. for 15 hours in an oxidizing gas flow containing 20% by volume of molecular oxygen.
Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 75.7%, and the selectivity for methacrylic acid was 90.8%.

Comparative Example 2 The deteriorated catalyst of Reference Example 2 was regenerated by heat treatment at 390 ° C. for 15 hours in an oxidizing gas flow containing 30% by volume of molecular oxygen.
Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 75.5%, and the selectivity of methacrylic acid was 90.8%.

Comparative Example 3 The deteriorated catalyst of Reference Example 2 was regenerated by heat treatment at 390 ° C. for 15 hours in an oxidizing gas flow containing 5% by volume of molecular oxygen. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 75.4%, and the selectivity of methacrylic acid was 90.9%.

Comparative Example 4 The deteriorated catalyst of Reference Example 2 was regenerated by heat treatment at 390 ° C. for 3 hours in a flow of an oxidizing gas containing 20% by volume of molecular oxygen. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 75.8%, and the selectivity of methacrylic acid was 90.7%.

Example 1 Ammonium nitrate was added to the deteriorated catalyst of Reference Example 2 in an amount of 10% by weight, based on the weight of the deteriorated catalyst, in a reaction tube at a reaction gas inlet portion.
Heat treatment was performed at 90 ° C. for 15 hours to regenerate. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 1. as a result,
The methacrolein conversion was 77.6% and the methacrylic acid selectivity was 90.7%.

Example 2 To the deteriorated catalyst of Reference Example 2, 8% by weight of ammonium carbonate was added based on the weight of the deteriorated catalyst. In the present embodiment, a preheating zone is created in front of the reaction gas inlet, a predetermined amount of ammonium carbonate is filled in the preheating zone, and the preheating zone is heated and maintained at 200 ° C. While the ammonium was decomposed in the flow, it was heated at 390 ° C. for 15 hours for regeneration. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 77.4% and the selectivity of methacrylic acid was 90.8%.

Comparative Example 5 The deteriorated catalyst of Reference Example 4 was regenerated by heat treatment at 350 ° C. for 3 hours in an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, the conversion of methacrolein was 74.3%, and the selectivity of methacrylic acid was 88.5%.

Comparative Example 6 The deteriorated catalyst of Reference Example 4 was regenerated by heat treatment at 330 ° C. for 3 hours in an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, the conversion of methacrolein was 74.1%, and the selectivity of methacrylic acid was 88.5%.

Comparative Example 7 The deteriorated catalyst of Reference Example 4 was regenerated by heat treatment at 390 ° C. for 3 hours in an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, the conversion of methacrolein was 74.7%, and the selectivity of methacrylic acid was 88.4%.

Example 3 Ammonium bicarbonate was added to the deteriorated catalyst of Reference Example 4 in an amount of 3% by weight, based on the weight of the deteriorated catalyst, in a reaction tube at a reaction gas inlet portion. 3
Heat treatment was performed at 90 ° C. for 3 hours for regeneration. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, the methacrolein conversion was 76.5% and the methacrylic acid selectivity was 8
8.5%.

Example 4 Ammonium carbonate and ammonium bicarbonate were added to the deteriorated catalyst of Reference Example 4 in an amount of 5% by weight, based on the weight of the deteriorated catalyst, and into the reaction tube at the inlet of the reaction gas. Heat treatment was performed at 390 ° C. for 3 hours under an oxidizing gas flow to regenerate. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, methacrolein conversion 7
6.6% and methacrylic acid selectivity was 88.4%.

EXAMPLE 5 Ammonium nitrate and ammonium carbonate were added to the deteriorated catalyst of Reference Example 4 in an amount of 3% by weight, based on the weight of the deteriorated catalyst, in a reaction tube at the inlet of a reaction gas. It was heat-treated at 390 ° C. for 15 hours under a gas flow to regenerate. Using this regenerated catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, methacrolein conversion 7
6.8% and methacrylic acid selectivity was 88.2%.

Comparative Example 8 The deteriorated catalyst of Reference Example 2 was heat-treated at 390 ° C. for 15 hours in an oxidizing gas flow containing 0.02% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion rate of methacrolein was 45.7% and the selectivity of methacrylic acid was 90.0%, and the recovery ratio of the catalyst performance was poor as compared with Examples 1-4.

Comparative Example 9 The deteriorated catalyst of Reference Example 2 was heated at 390 ° C.
Heat treatment was performed for 5 hours. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, methacrolein reaction rate 2
5.5% and methacrylic acid selectivity was 87.1%.

Comparative Example 10 The deteriorated catalyst of Reference Example 2 was heat-treated at 280 ° C. for 15 hours under an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 53.5% and the selectivity of methacrylic acid was 90.1%.

Comparative Example 11 The deteriorated catalyst of Reference Example 2 was heat-treated at 200 ° C. for 15 hours under an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 30.5% and the selectivity of methacrylic acid was 90.3%.

Comparative Example 12 The deteriorated catalyst of Reference Example 2 was heat-treated at 430 ° C. for 15 hours in an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 10.5%, and the selectivity for methacrylic acid was 82.3%.

Comparative Example 13 The deteriorated catalyst of Reference Example 2 was heat-treated at 390 ° C. for 0.1 hour under a flow of an oxidizing gas containing 20% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, the conversion of methacrolein was 55.5%, and the selectivity of methacrylic acid was 90.1%.

Comparative Example 14 Ammonium carbonate was added to the deteriorated catalyst of Reference Example 2 in an amount of 25% by weight based on the weight of the deteriorated catalyst. In this comparative example, a preheating zone was created in front of the oxidizing gas inlet, and after filling the preheating zone with ammonium carbonate, the preheating zone was heated and maintained at 200 ° C.
While decomposing ammonium carbonate under flow with an oxidizing gas containing 20% by volume of molecular oxygen, the deteriorated catalyst was treated at 390 ° C. for 15 minutes.
Heat treated for hours. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 1. As a result, methacrolein conversion 6
5.5% and methacrylic acid selectivity was 88.5%.

COMPARATIVE EXAMPLE 15 The deteriorated catalyst of Reference Example 4 was heat-treated at 350 ° C. for 3 hours in a flow of an oxidizing gas containing 0.05% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, the conversion of methacrolein was 43.6%, the selectivity of methacrylic acid was 88.3%, and the recovery ratio of the catalyst performance was lower than in Examples 7 to 9.

Comparative Example 16 The deteriorated catalyst of Reference Example 4 was heat-treated at 200 ° C. for 3 hours in an oxidizing gas flow containing 20% by volume of molecular oxygen. Using this catalyst, a reaction was carried out in the same manner as in Reference Example 3. As a result, the conversion of methacrolein was 30.3% and the selectivity of methacrylic acid was 88.3%.

[0034]

The regenerating method of the present invention is extremely simple, has a considerably high level of regenerating the deteriorated catalyst, and has a great economic effect for industrial applications.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI C07C 57/07 C07C 57/07 (58) Field surveyed (Int.Cl. ⁷ , DB name) B01J 21/00-38/74 C07C 57 / 07 C07C 51/235 C07C 57/055 C07C 57/07

Claims (1)

(57) [Claims] 1. A method for producing methacrylic acid by subjecting methacrolein to gas-phase catalytic oxidation using molecular oxygen using a catalyst containing at least phosphorus, molybdenum and vanadium filled in a reaction tube. A method for regenerating a catalyst, comprising contacting an oxidizing gas containing at least 0.1% by volume of molecular oxygen with 20% by weight or less of ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate based on a deteriorated catalyst. In addition, an oxidizing gas containing a decomposition product of ammonium nitrate, ammonium carbonate and / or ammonium bicarbonate is passed through a reaction tube filled with the deteriorated catalyst after the gas phase catalytic oxidation to remove the deteriorated catalyst in the reaction tube.
A method for regenerating a deteriorated catalyst, comprising performing heat treatment at a temperature of 00 to 410 ° C for 0.5 to 50 hours.