JP2997113B2 - Method for regenerating hydration catalyst of methacrylonitrile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for regenerating a hydration catalyst for methacrylonitrile . For more information, see Methacrylo.
The present invention relates to a method for regenerating a copper metal catalyst having reduced hydration activity in the production of methacrylamide by a nitrile hydration reaction.

[0002]

2. Description of the Related Art As a catalyst for a hydration reaction of a nitrile compound such as acrylonitrile or methacrylonitrile, a metal copper catalyst is known. For example, Japanese Patent Publication No. 49-30810
JP-A No. 55-4 discloses a method for producing acrylamide from acrylonitrile using a Raney copper catalyst.
Japanese Patent No. 4063 discloses a method for producing an unsaturated amide using a copper catalyst obtained by reducing a copper compound with borohydride, and Japanese Patent Publication No. 55-36658 discloses a method for producing a copper compound obtained by reduction with formaldehyde. A method for hydrating unsaturated nitriles using a catalyst is disclosed. These metal copper-based catalysts deteriorate as the hydration reaction of the nitrile compound continues, and the reaction activity decreases. As a method for regenerating the catalyst with reduced activity, Japanese Patent Publication No. 54-7754
Patent Literature 1, deactivated metal copper-based catalysts are alkali metal ions,
A method of treating with ammonium ion, chlorine ion, cyanide ion or the like is disclosed.

[0003]

However, even in the regeneration method according to the above-mentioned method, regeneration of the catalyst is not sufficient, and problems such as mixing of metal ions, corrosive ions and toxic ions into products, handling, and the like arise. is there. Therefore, an effective and easy method for regenerating the catalyst is desired.

[0004]

Means for Solving the Problems The present inventors have proposed methacrylic acid.
In the production of methacrylamide by the hydration reaction of Ronitoriru, results of investigations from the above and other aspect the reduced regeneration method of the catalyst hydration activity, the reduced catalyst hydration activity alcohol - le or alcohol - The present inventors have found that the hydration activity of a metallic copper-based catalyst is improved by contact with a copper aqueous solution, and thus completed the present invention.

[0005] That is, the present invention is a method for regenerating a methacrylonitrile hydration catalyst, which comprises contacting a metal copper catalyst having reduced hydration activity with an alcohol or an aqueous alcohol solution. Hereinafter, the present invention will be described. The metal copper-based catalyst having reduced hydration activity in the present invention is methacrylonitrile.
By using for the hydration reaction of tolyl , it means a catalyst whose reaction activity is lower than the reaction activity immediately after the start of use, and in order to effectively carry out the method of the present invention, the reaction activity immediately after the start of use When the reaction activity becomes 9/10 or less, contact with alcohol or an aqueous alcohol solution is preferably performed.

The alcohol used in the present invention includes methanol, ethanol, propanol, isopropanol and the like, and it is preferable to use methanol. Further, the alcohol may contain water, and a sufficient amount of alcohol is added to the metal copper-based catalyst to be treated.
The concentration of the alcohol is not particularly limited as long as it is present, but an alcohol aqueous solution of 1% by weight or more, preferably an alcohol aqueous solution of 10% by weight or more, more preferably an alcohol aqueous solution of 20% by weight or more is used. Good to use.

[0007] As a method of contacting these alcohols or an aqueous alcohol solution with a catalyst, a method of supplying an aqueous alcohol solution instead of water during the hydration reaction of methacrylonitrile , a method of taking out only the catalyst, Examples of the method include a method of treating with alcohol or an aqueous solution of alcohol. The treatment temperature is in the range of 0 to 160C, preferably 30 to 150C, more preferably 50 to 140C. The treatment time is arbitrarily set depending on the amount of the catalyst, the alcohol concentration and the like.
A range from 1 to 10 hours is preferred.

[0008] The metal copper-based catalyst regenerated by the method of the present invention may be any one as long as the main component of the catalyst is copper. For example, metal copper wire or powder, Raney copper alloy is developed with an aqueous alkali solution. Obtained Raney copper catalyst
No. 5-26910, JP-A-50-88022), a metal copper catalyst obtained by reducing a copper salt with formaldehyde, hydrazine, sodium borohydride or the like in an aqueous solution (JP-B-55-36658, JP-B-55-36658). 48-6
No. 8519, Japanese Patent Publication No. 54-27326, Japanese Patent Publication No. 55-44061), a metal copper catalyst obtained by reducing a copper salt with zinc, aluminum or the like (Japanese Patent Publication No. 55-2102).
No. 9), a metal copper catalyst obtained by thermally decomposing copper hydride in an aqueous alkali solution (Japanese Patent Publication No. 53-43923), and a metal copper catalyst obtained by thermally decomposing an organic acid salt such as formate. JP-B-55-44062, JP-B-55-44064) and the like, but it is preferable to use the method of the present invention for a Raney copper catalyst. These metal copper based catalysts,
It may be supported on a commonly used carrier such as activated carbon, silica, alumina, silica-alumina, zeolite, titania and the like. Further, metals other than copper, for example, silver, gold, iron, cobalt, nickel, ruthenium and the like may be contained.

It is desirable that the copper metal catalyst used in the hydration reaction of methacrylonitrile in the present invention avoids contact with oxygen and a gas containing oxygen before and during use. When these catalysts come into contact with oxygen, the reaction activity is reduced and by-products such as cyanhydrin increase. Therefore, a metal copper-based catalyst supplied to the reactor,
It is preferable that methacrylonitrile and water are stored while avoiding contact with oxygen, and that oxygen dissolved therein is removed in advance. Further, it is preferable that the inside of the reactor is kept in an atmosphere containing no oxygen.

[0010] methacrylic due to hydration reaction of methacrylonitrile with metallic copper-based catalyst regenerated by the method of the present invention
The production of luamide is preferably carried out in a suspension bed or a fixed bed in a liquid phase, but may be carried out by other methods, for example, in a gas phase. The reaction can be carried out either in a flow or batch mode.

Although the hydration reaction of methacrylonitrile proceeds with a small amount of catalyst, a sufficient amount of catalyst is required for the raw material methacrylonitrile to obtain a sufficient conversion. Specifically, when reacted in a suspended bed, meta
0.0 for 1 hour contact time with acrylonitrile
It is preferred to use from 1 to 100 g of catalyst. The weight ratio of methacrylonitrile and water to be subjected to the hydration reaction is substantially arbitrary, but is preferably in the range of 50:50 to 5:95.

The reaction temperature is 30 to 200 ° C., preferably 5 to 200 ° C.
The range of 0 to 150 ° C is good. If the reaction temperature is too low, the conversion of the hydration reaction is not sufficient, and if the reaction temperature is too high, the catalyst deteriorates greatly. In the reactor, the reaction temperature and the vapor pressure at the reaction solution composition or the pressure obtained by adding an inert gas such as nitrogen thereto are maintained, and the pressure is usually from normal pressure to normal pressure.
The range is 10 atm.

After the hydration reaction, the reaction solution taken out of the reactor is mainly composed of unreacted methacrylonitrile , water and methacrylamide which is a reaction product, and further contains by-products such as cyanohydrin and copper. . This reaction solution
Methacrylonitrile , usually unreacted by evaporation or distillation
A part of ril and water is recovered, and methacrylamide is concentrated. The recovered unreacted methacrylonitrile and water can be reused as raw materials.

[0014]

The present invention will be described in detail below with reference to examples.

[0015]

EXAMPLE 1 A 500 ml autoclave was used as a reactor, 50% by volume of a Raney-copper catalyst was charged into the reactor, and 8% by weight of methacrylonitrile and 92% by weight of water from which dissolved oxygen had been removed in advance. Was supplied, and methacrylonitrile was hydrated at a temperature of 130 ° C. for a contact time of 1 hour. Ten hours after the start of the reaction, the conversion of methacrylonitrile was 84%, and the selectivity of methacrylamide was 99.3.
%Met. After 36 hours, the conversion of methacrylonitrile was 42%, the selectivity of methacrylamide was 99.5%, and the reaction activity was reduced. Therefore, as a methanol treatment, a raw material of 20% by weight of methanol, 72% by weight of water, and 8% by weight of methacrylonitrile was supplied to the reactor for 5 hours to bring the catalyst into contact with methanol, and then returned to the original state. Returned to raw material. Six hours after returning to the original raw materials, the conversion of methacrylonitrile was restored to 80%, and the selectivity of methacrylamide was restored to 99.5%.

[0016]

Example 2 Using the same apparatus as in Example 1, 3
A 0% by volume Raney-copper catalyst was charged, a raw material of 30% by weight of methacrylonitrile and 70% by weight of water was supplied, and reacted at a temperature of 120 ° C. for a contact time of 1 hour. After the start of the reaction, 10
At the time, the conversion of methacrylonitrile was 70% and the selectivity of methacrylamide was 99.5%. After 66 hours, the conversion of methacrylonitrile was 58%, the selectivity of methacrylamide was 99.6%, and the reaction activity was reduced. Then, the raw material was stopped and the raw material was withdrawn from the reactor. Instead, a 30% by weight aqueous methanol solution was supplied and contacted at the same temperature for 2 hours. After the treatment, when the original raw material was supplied again, the conversion of methacrylonitrile gradually increased, and recovered to 65% after 20 hours.

[0017]

[Comparative Example 1] In Example 2, 48 hours after starting the supply of the raw material.
At the time, the conversion of methacrylonitrile was 60%. Here, the supply of the raw material was stopped, and water was supplied instead, and the water washing treatment was performed for 2 hours. After the treatment, the original raw material was supplied again to restart the reaction, but the conversion of methacrylonitrile was 60% and no improvement was observed.

[0018]

According to the present invention, the hydration activity of methacrylonitrile can be recovered by treating the metal copper catalyst having reduced hydration activity with an alcohol or an aqueous alcohol solution. Therefore, methacrylonitrile
It can increase the life of the metallic copper-based catalyst used in the hydration reaction of the Le.

Claims (1)

(57) [Claims] 1. A method for regenerating a hydration catalyst of methacrylonitrile , comprising contacting a metal copper catalyst having reduced hydration activity with an alcohol or an aqueous alcohol solution.