JP2011001304A - Process for producing primary amine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a primary amine from a nitrile in a high yield by inhibiting side reactions which give condensation products.SOLUTION: In producing a primary amine by reacting hydrogen with a nitrile in the presence of a hydrogenation catalyst containing at least one metal selected from nickel, cobalt, and iron, whenever the catalyst whose activity has been lowered by being used in the reaction is subjected to regeneration treatment by hydrogenolysis, the catalyst is pretreated in a gas phase with the use of a treating agent to constantly obtain the primary amine in a high yield.

Description

  The present invention relates to a process for producing primary amines by catalytic hydrogenation of nitriles.

A method for producing a primary amine by hydrogenating nitrile in the presence of a catalyst containing a metal selected from nickel, cobalt and iron is well known. In the production of primary amines by hydrogenation of nitriles, condensation products such as secondary and tertiary amines are by-produced by intermolecular condensation reaction, and the yield tends to decrease (see Non-Patent Document 1).
In addition, the condensation products attached to the catalyst not only cause a decrease in the activity of the catalyst, but can also cause clogging of the catalyst layer. Therefore, periodic regeneration operations are required to continuously perform these reactions.

  In order to suppress the formation of secondary and tertiary amines due to such a condensation reaction, a method using ammonia as a solvent (for example, see Patent Documents 3 to 6), an alkali metal or alkaline earth metal hydroxide is added. Thus, a method for carrying out the reaction (see, for example, Patent Documents 1, 2, 7, and 8) has been well known for a long time. However, when ammonia is used as a solvent, a high pressure apparatus is required because ammonia has a high vapor pressure. In addition, when an alkali metal is used, a waste liquid containing the alkali metal is generated, which makes it difficult to perform the treatment in industrial implementation. Furthermore, it is difficult for these methods to completely suppress side reactions, and further improvement means are required.

  As means for suppressing side reactions and improving the yield, a method of modifying the catalyst with formalin in a liquid dispersion medium (see Patent Document 9), a method of modifying the catalyst using methanol or ethylene (see Patent Document 10) , Etc. have been proposed. It is disclosed that these methods can be carried out in combination with the above-mentioned method using ammonia as a solvent or the method of performing a reaction in the coexistence of alkali metal or alkaline earth metal, and has a certain yield improving effect. ing. In the method of using these organic substances for the modification of the catalyst, it is shown that the organic substances are attached on the catalyst (Patent Document 11).

JP-A-7-518900 Japanese Patent Laid-Open No. 7-517801 Japanese Patent Publication No.53-20969 JP-A-8-299799 Special Table 2002-505192 Japanese Patent Laid-Open No. 51-6971 Japanese Patent Publication No. 38-8719 JP 54-41804 A JP 2001-212461 A JP 2008-63326 A Special table 2008-519677 gazette

Handbook of Heterogeneous Catalytic Hydrogenation for Organic Synthesis, Shigeo Nishimura, John Wiley & Sons, Inc., Chapter 7 Hydrogenation of Nitriles p254-285

  The method is not described in terms of the long catalyst life required industrially. In general, when the condensation product adheres to the catalyst, the activity of the catalyst is lowered, so that some kind of regeneration operation is required to continue the reaction. The hydrogenolysis process is generally used as the regeneration operation. However, the method of reforming the catalyst with formalin and the like, the method of reforming the catalyst with methanol and ethylene, and the method of using organic substances as a modifier, Since the surface modification product is removed, the yield improving effect is lost and the primary amine cannot be obtained in a high yield in a long-term reaction.

  Even with these conventionally known methods, it is difficult to completely suppress side reactions that give condensation products over a long period of time.

  The problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, to produce a primary amine from nitrile in a high yield by constantly suppressing side reactions that give a condensation product, and depending on the condensation product It is to provide a method for suppressing clogging of a catalyst layer.

  As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention regenerated a catalyst whose activity has been reduced by hydrogenolysis when using a hydrogenation catalyst used in a nitrile hydrogenation reaction. It has been found that the above-mentioned problems can be solved by performing pretreatment in a gas phase using a treatment agent every time the treatment is carried out, and the present invention has been achieved.

  That is, the present invention provides (1) regeneration of a catalyst when producing a primary amine by reacting hydrogen with a nitrile in the presence of a hydrogenation catalyst containing one or more metals selected from nickel, cobalt and iron. The catalyst pretreatment and (3) the nitrile hydrogenation reaction are carried out in this order, and the pretreatment is performed by contacting the catalyst in the gas phase with at least one treatment agent selected from hydrocarbon compounds, alcohols, ethers and esters. It is related with the manufacturing method of the primary amine characterized by being made to carry out.

  In the present invention, when using the hydrogenation catalyst used in the nitrile hydrogenation reaction, after regenerating the catalyst with reduced activity by hydrocracking, it is pretreated with a specific treating agent prior to the reaction. The production amount of the by-product condensation product is always kept low, and the primary amine as the target product is maintained in a high yield. From an industrial point of view, the pretreatment operation from the regeneration of the present invention is very simple, and the nitrile hydrogenation reaction can be carried out without complicated operations after the pretreatment. Furthermore, methanol, dimethyl ether, ethylene, natural gas, etc. that are easily available and inexpensive can be used as pretreatment agents. Therefore, the industrial significance of the present invention is great.

  In the present invention, a primary amine is produced by reacting nitrile with hydrogen in the presence of a catalyst. The target nitrile may be an aliphatic nitrile, an alicyclic nitrile, or an aromatic nitrile. Nitriles having a plurality of nitrile groups may also be used. Furthermore, it may have a functional group such as an amino group, a halogeno group, an alkyl group, a phenyl group, a hydroxyl group, an ester group or an ether group. Further, it may have a hydrogenatable functional group such as an aldehyde group, a ketone group or an imino group. In the nitrile hydrogenation reaction, these functional groups may be hydrogenated at the same time as the nitrile hydrogenation to be converted into a hydroxyl group or an amino group. Examples of aliphatic nitriles include acetonitrile, propionitrile, butanenitrile, pentanenitrile, hexanenitrile, heptanenitrile, octanenitrile, butanedinitrile (adiponitrile), pentanedinitrile, hexanedinitrile, heptanedinitrile, octanedi Nitriles, benzyl cyanides and the like can be mentioned. Examples of alicyclic nitriles include cyclohexane nitrile, cyclohexane dinitrile, 3-cyano-3,5,5-trimethylcyclohexanone, 3-cyano-3,5,5-trimethylcyclohexylimine, tricyclodecane dicarbonitrile and the like. Can do. Examples of the aromatic nitrile include benzonitrile, methylbenzonitrile, dicyanobenzene, tricyanobenzene, biphenylnitrile, cyanonaphthalene, dicyanonaphthalene and the like. Other examples include heterocyclic nitriles such as pyridinecarbonitrile and pyrimidinecarbonitrile. In particular, the present invention is suitable for hydrogenation of aromatic nitriles, particularly hydrogenation of dicyanobenzenes such as isophthalonitrile and terephthalonitrile. The corresponding primary amine is obtained by hydrogenation. In the dinitrile hydrogenation, the present invention is also applicable to the production of an aminonitrile in which only one nitrile group is converted to a primary amine, for example, the production of aminocapronitrile by hydrogenation of adiponitrile and the production of cyanobenzylamine by hydrogenation of dicyanobenzene. Is applicable.

  In the present invention, hydrogenation is carried out in the gas phase or in the liquid phase, but generally the reaction is often carried out in the liquid phase except in the case of nitriles having a relatively low boiling point such as acetonitrile. In the hydrogenation in the liquid phase, a reaction solvent can also be used. As the reaction solvent, various solvents which are stable under hydrogenation reaction conditions can be used. Specifically, hydrocarbon solvents such as toluene, xylene and trimethylbenzene; ether solvents such as tetrahydrofuran and dioxane; lower aliphatic amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; methanol, ethanol and propanol Alcohol-based solvents such as ammonia; Two or more of these solvents may be selected and used in combination. Since the yield of primary amine can be increased by using ammonia, it is preferable to select ammonia as a part of the reaction solvent. The amount of reaction solvent used depends on the type of nitrile and catalyst, but is preferably in the range of 0.5 to 99 parts by weight, more preferably 1 to 98 parts by weight, and still more preferably 1 to 30 parts per 1 part by weight of nitrile. Parts by weight.

  Hydrogen used for nitrile hydrogenation may contain impurities that do not participate in the reaction, such as methane, nitrogen, etc., but if the impurity concentration is high, the total reaction pressure needs to be increased to ensure the necessary hydrogen partial pressure. Since it is industrially disadvantageous, the hydrogen concentration is preferably 50 mol% or more.

  In the present invention, a primary amine is produced by reacting hydrogen with a nitrile in the presence of a hydrogenation catalyst. As the hydrogenation catalyst in the present invention, a catalyst containing at least one metal selected from nickel, cobalt and iron as an active metal component is used. Among them, a catalyst containing nickel and / or cobalt is preferably used, and a nickel-containing catalyst is particularly preferable. The catalyst is in the form of a supported catalyst (for example, US Patent Publication No. 2002-177735), a non-supported metal catalyst (for example, JP-A-8-299799, JP-T-2002-505192, etc.), sponge metal catalyst (Raney nickel, Raney cobalt). Etc.). In the case of a supported catalyst, the concentration of the active metal component is preferably 10 to 98% by weight, more preferably 20 to 90% by weight, and particularly preferably 30 to 80% by weight. In the case of a supported catalyst, examples of the carrier used include alumina, silica, diatomaceous earth, silica-alumina, magnesia, titania, zirconia, silica-zirconia, and carbon. Catalysts may be alkali metals (Li, Na, K, Rb, Cs), alkaline earth metals (Mg, Ca, Sr, Ba), B, Al, Si, P, Ti, V, Cr, Mn, as necessary. Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Sb, Te, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi and It can be modified by adding at least one component selected from the group consisting of Ce.

  In the present invention, in the hydrogenation reaction, a known promoter may be used in combination for the purpose of promoting the reaction or improving the yield. Examples of the cocatalyst include alkali metal or alkaline earth metal hydroxides and alcoholates. When these cocatalysts are used, the effect of increasing the selectivity may be obtained.

  The hydrogenation reaction can be either a fixed bed or a suspension bed, and can be either a batch type or a continuous type. However, especially when the reaction is carried out in the liquid phase, it is industrially fixed bed. An irrigated continuous flow system (use of a so-called trickle bed reactor) is convenient and suitable. Although depending on the type of catalyst and nitrile, the reaction temperature of the hydrogenation reaction is preferably 20 to 250 ° C., more preferably 20 to 200 ° C., and the reaction pressure is preferably 0 to 30 MPaG, more preferably hydrogen partial pressure. Is 0.2 to 20 MPaG, particularly preferably 0.5 to 15 MPaG. The amount of catalyst used depends on the type of catalyst and nitrile, but in the case of suspension bed batch hydrogenation, it is preferably 0.1 to 100 parts by weight per 100 parts by weight of the starting nitrile. If the amount of catalyst is less than this, the reaction does not proceed sufficiently, and if the amount of catalyst is more than this, the cost of the catalyst increases and it is not economical. In the case of fixed bed continuous hydrogenation, the raw material nitrile is preferably supplied at a rate of 0.01 to 1000 parts by weight / hour with respect to 100 parts by weight of the catalyst.

  In the present invention, the catalyst used in the above reaction is regenerated and then reused in the reaction. Hydrocracking treatment is used as the catalyst regeneration operation. The hydrocracking treatment is performed by supplying hydrogen or hydrogen diluted with an inert gas to the catalyst layer. The temperature of the hydrocracking treatment is specifically 150 to 500 ° C, preferably 180 to 400 ° C, particularly preferably 200 to 300 ° C. If the temperature is lower than this, the regeneration effect cannot be obtained, and if the temperature is higher than this, there is a possibility that the sintering of the catalyst is accelerated and the reaction activity is reduced. The end of the hydrocracking process can be determined from, for example, the amount of hydrocracking product (methane or the like) produced. Usually, it is carried out until the methane concentration in the outlet gas (processing gas) becomes 1% or less with respect to the hydrogen concentration in the supply gas. It is more preferable to perform the hydrocracking operation until no methane is detected in the outlet gas.

  In the present invention, it is preferable to perform a pretreatment of the hydrogenation catalyst with a specific treating agent prior to the nitrile hydrogenation reaction after catalyst regeneration. By carrying out the pretreatment, the side reaction giving the condensation product is suppressed, and the effect of improving the yield of primary amine is obtained. Examples of the treating agent used for the pretreatment include hydrocarbon compounds, alcohols, ethers and esters. Of these, hydrocarbon compounds and alcohols are preferred.

  Examples of the hydrocarbon compound as the treating agent in the present invention include alkanes having 12 or less carbon atoms, alkenes and alkynes. Among them, alkenes and alkynes which are compounds having a carbon-carbon unsaturated bond are preferable. Are particularly preferred. Examples of alkanes include methane, ethane, propane, butane, pentane, hexane, heptane, octane, skeletal isomers (isobutane, isopentane, etc.), cyclopentane, cyclohexane, methylcyclohexane, and the like. Natural gas can also be used. Examples of alkenes include ethylene, propylene, butene, butadiene, pentene, hexene, heptene, octene and their skeletal isomers (isobutene, isopentene, etc.), cyclopentadiene, cyclohexene, and methylcyclohexane. Examples of alkynes include acetylene, methyl acetylene, and ethyl acetylene. Examples of the aromatic compound include benzene, toluene, xylene and the like. Among these, ethylene, propylene and butene which are alkenes having 4 or less carbon atoms are particularly preferable, and ethylene is more preferable.

  The alcohol as the treating agent in the present invention is preferably an alcohol having 6 or less carbon atoms, specifically, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, ethylene glycol, allyl alcohol, etc. Is exemplified. Of these, methanol or ethanol is preferable, and methanol is particularly preferable. The alcohol preferably contains no carbonyl group, carboxyl group or amide group as a functional group other than a hydroxyl group.

  The ether as the treating agent in the present invention is preferably an ether having 12 or less carbon atoms, more preferably an ether having 6 or less carbon atoms. Specific examples include dimethyl ether, diethyl ether, methyl ethyl ether, ethylene glycol monomethyl ether, diglyme and the like. Among them, dimethyl ether or diethyl ether is preferable, and dimethyl ether is particularly preferable. The ether preferably does not contain a carbonyl group, a carboxyl group or an amide group as a functional group other than the ether group.

  The ester as the treating agent in the present invention is preferably a methyl ester or an ethyl ester, and specific examples include methyl formate, methyl acetate, and ethyl acetate. The ester preferably contains no carbonyl group, carboxyl group or amide group as a functional group other than the ester group.

  The above treatment agents are used alone or in combination of two or more.

  When the catalyst is a stabilized catalyst that has been stabilized with oxygen or carbon dioxide, the catalyst may be pre-reduced with hydrogen prior to the pretreatment.

  Further, since coexistence of oxygen deactivates the catalyst, the pretreatment is preferably performed in the absence of oxygen.

  When the pretreatment is performed in the gas phase, the vapor of the treatment agent is brought into contact with the catalyst. At this time, it is also possible to use a diluent gas such as nitrogen, argon, helium or water vapor. By using the dilution gas, the treatment agent concentration can be adjusted to an appropriate condition. In the case of a fixed bed type, a method of circulating a gas containing a gaseous treating agent in the catalyst layer is very simple, and the nitrile hydrogenation reaction can be carried out without complicated operations such as solvent replacement.

  The presence of a large amount of hydrogen after regeneration by hydrocracking not only weakens the effect of pretreatment, but also tends to generate heat due to reaction with hydrogen. Therefore, the coexistence of hydrogen during pretreatment is preferably low. Non-existing conditions are the most desirable. When the pretreatment is performed in the gas phase, the concentration ratio (molar ratio) of hydrogen and the processing agent in the gas phase is preferably 6 or less, more preferably 3 or less, and particularly preferably 1.5 or less. . In addition, if the hydrogen-containing gas and the catalyst are brought into contact with each other at a high temperature in the absence of a treating agent after the pretreatment operation, the effect of the pretreatment may be weakened. Therefore, after the pretreatment step, an operation procedure in which the catalyst is once cooled in the absence of hydrogen and then the nitrile hydrogenation reaction is started is preferable.

  The temperature during the pretreatment is preferably higher than the nitrile hydrogenation reaction temperature, although it depends on conditions such as the type of catalyst and the type of treatment agent. Specifically, it is 150-500 degreeC, Preferably it is 180-400 degreeC, Most preferably, it is 200-300 degreeC. If the temperature is lower than this, a sufficient effect cannot be obtained. If the temperature is higher than this, the activity and selectivity may be lowered.

  The pretreatment time is 5 seconds to 50 hours, preferably 1 minute to 20 hours, particularly preferably 5 minutes to 10 hours, although it depends on conditions such as the type of treatment agent and temperature. If the time is shorter than this, a sufficient effect cannot be obtained, and if the time is longer than this, the activity and selectivity may be lowered.

When the pretreatment is performed in the gas phase, the concentration of the treatment agent is preferably 0.1 to 100 vol%, more preferably 0.2 to 20 vol%, and particularly preferably 0.5 to 10 vol%. When the pretreatment is performed in a form in which the treatment agent-containing gas is circulated in the gas phase, the space velocity (GHSV) is 30 to 10000 h ⁻¹ , preferably 50 to 5000 h ⁻¹ , particularly preferably 50 to 3000 h ⁻¹ .

  Although the total amount of the treatment agent depends on conditions such as the kind of treatment agent and temperature, it is 0.1 to 100 mol, preferably 0.2 to 50 mol, particularly preferably 0.3 to 20 mol, per 1 kg of the catalyst. It is.

  The pressure at the time of pretreatment depends on conditions such as the type of treatment agent, but is usually selected from the range of normal pressure to the reaction pressure of the hydrogenation reaction, and is illustratively selected from the range of 0 to 30 MPaG. A sufficient effect can be obtained by treatment under low pressure conditions of normal pressure to 1 MPaG.

The catalyst subjected to such pretreatment is subjected to a nitrile hydrogenation reaction. Formation of condensation products such as secondary and tertiary amines due to intermolecular condensation reaction in nitrile hydrogenation is remarkably suppressed, and the selectivity of primary amine is improved. The amount of condensation product produced by the pretreatment is reduced by at least 15%, in a preferred example, by 30% or more, and even 50% or more, compared to the case where the pretreatment is not conducted.
Such pretreatment is also preferably performed when the new catalyst is subjected to a hydrogenation reaction.

The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to these examples. The reaction results were determined by analysis by gas chromatography equipped with a DB-1 column manufactured by Agilent (J & W). For high-boiling by-products, the yield was expressed in terms of (NH ₂ CH ₂ —Ar—CH (NH ₂ ) —) ₂ (where Ar is a phenylene group), which is the main product. Moreover, the methane analysis in the exit gas at the time of hydrocracking was performed by GC-TCD (detection lower limit: 100 ppm).

<Catalyst preparation>
Nickel nitrate hexahydrate Ni (NO ₃ ) ₂ .6H ₂ O 305.0 g, copper nitrate trihydrate Cu (NO ₃ ) ₂ .3H ₂ O 6.5 g and chromium nitrate 9 hydrate Cr (NO ₃ ) and ₃ · _9H 2 O 7.1g was dissolved in pure water 1kg of 40 ° C., was further stirred at 40 ° C. while suspending kieselguhr 29.6g to the aqueous solution. To this slurry, an aqueous solution in which 128.6 g of sodium carbonate Na ₂ CO ₃ was dissolved in 1 kg of 40 ° C. pure water was added with good stirring to prepare a precipitated slurry. The slurry was heated to 80 ° C. and held at the same temperature for 30 minutes. The precipitate slurry thus obtained was filtered and washed to obtain a precipitate. The precipitate was dried at 110 ° C. overnight and calcined at 380 ° C. for 18 hours in an air atmosphere. This fired powder was mixed with 3% by weight of graphite and tableted to 3.0 mmφ × 2.5 mm. This molded product was reduced at 400 ° C. in a hydrogen stream. The molded product after the reduction was stabilized by oxidizing overnight at a temperature of room temperature to 40 ° C. under a flow of dilute oxygen gas (oxygen / nitrogen = 1/99 (volume ratio)). Furthermore, this stabilized molded product was crushed to obtain a crushed catalyst having a uniform particle size of 60 to 80 mesh. This was designated Catalyst A. The stabilized molded product itself before crushing was used as catalyst B.

<Comparative Example 1>
0.6 g of catalyst A was packed in a stainless steel tubular reaction tube having an inner diameter of 4 mm. 100% hydrogen gas was circulated through the catalyst layer, and it was activated by reduction for 10 hours under the conditions of normal pressure, 250 ° C., and gas flow rate of 0.6 NL / h. After stopping the flow of hydrogen gas and cooling the reaction tube to 50 ° C., the reactor was pressurized to 10 MPaG with hydrogen, liquid ammonia was supplied to the catalyst layer, and the catalyst layer was wetted with liquid ammonia. The composition is IPN: PCM: NH3 = 8: 8: 84 (weight ratio) in a mixed solution of 0.6 NL / h of hydrogen, isophthalonitrile (IPN), pseudocumene (PCM), and liquid ammonia (NH3) from the upper part of the reaction tube. ) Was fed at 2 g / h, and the hydrogenation reaction was carried out continuously. The total pressure was 10 MPa and the reaction temperature was 80 ° C. As for the reaction results 24 hours after the start of the reaction, the conversion rate of isophthalonitrile was 100%, the yield of metaxylylenediamine was 92.1 mol%, and the yield of the high-boiling condensation product was 7.8 mol%. .
When the reaction was continued for a total of 320 hours, the differential pressure in the catalyst layer increased. Therefore, after washing the catalyst layer with liquid ammonia, 100% hydrogen was passed through the catalyst layer, hydrocracking treatment was performed for 13 hours under the conditions of normal pressure, 290 ° C., and gas flow rate of 0.6 NL / h, and the outlet gas Regeneration operation was carried out until no methane was detected. After regeneration, a hydrogenation reaction of isophthalonitrile was performed under the same conditions as described above. The reaction results 24 hours after the start of the reaction were 100% conversion of isophthalonitrile, 88.3 mol% of metaxylylenediamine, and 11.7 mol% of the high-boiling condensation product. .
After a cumulative time of 495 hours, the pressure difference in the catalyst layer was increased again, and thus the same regeneration operation as described above was performed. After regeneration, the hydrogenation reaction of isophthalonitrile was performed under the same conditions as described above. As a result, the reaction results at 24 hours after the resumption of the reaction showed that the conversion rate of isophthalonitrile was 100% and the yield of metaxylylenediamine was 88. The yield of 7 mol%, high-boiling condensation product was 11.2 mol%.

<Example 1>
(Ethylene as treatment agent)
0.6 g of catalyst A was packed in a stainless steel tubular reaction tube having an inner diameter of 4 mm. 100% hydrogen was circulated through the catalyst layer, and it was activated by reduction for 10 hours under the conditions of normal pressure, 250 ° C., and gas flow rate of 0.6 NL / h. Subsequently, the flow gas was switched to a mixed gas of ethylene: nitrogen = 4: 96 vol%, and pretreatment was performed. The circulation of the mixed gas was continued for 1 hour under the conditions of normal pressure, 250 ° C., and gas flow rate of 0.6 NL / h. After the gas flow was stopped and the reaction tube was cooled to 50 ° C., the reactor was pressurized to 10 MPaG with hydrogen, liquid ammonia was supplied to the catalyst layer, and the catalyst layer was wetted with liquid ammonia. The composition is IPN: PCM: NH3 = 8: 8: 84 (weight ratio) in a mixed solution of 0.6 NL / h of hydrogen, isophthalonitrile (IPN), pseudocumene (PCM), and liquid ammonia (NH3) from the upper part of the reaction tube. ) Was fed at 2 g / h, and the hydrogenation reaction was carried out continuously. The total pressure was 10 MPa and the reaction temperature was 80 ° C. 24 hours after the start of the reaction, the conversion rate of isophthalonitrile was 100%, the yield of metaxylylenediamine was 97.8 mol%, and the yield of the high-boiling condensation product was 2.1 mol%. .
When the reaction was continued for a total of 880 hours, the differential pressure in the catalyst layer increased. Therefore, after washing the catalyst layer with liquid ammonia, 100% hydrogen was circulated through the catalyst layer until methane in the outlet gas was not detected under the conditions of normal pressure, 290 ° C., and gas flow rate of 0.6 NL / h. A 13-hour hydrocracking treatment was performed and a regeneration operation was performed. After regeneration by hydrocracking, the pre-treatment in the gas phase is continued by switching the flowing gas to a mixed gas of ethylene: nitrogen = 4: 96 vol% under the conditions of atmospheric pressure, 250 ° C. and gas flow rate of 0.6 NL / h. did. After the pretreatment, a hydrogenation reaction of isophthalonitrile was performed under the same conditions as described above. The reaction results 24 hours after the resumption of the reaction were as follows: the conversion rate of isophthalonitrile was 100%, the yield of metaxylylenediamine was 99.2 mol%, and the yield of the high-boiling condensation product was 0.8 mol%. .
After a cumulative time of 1150 hours, an increase in the differential pressure in the catalyst layer was observed, and the same regeneration operation and pretreatment as described above were performed. After the pretreatment, an isophthalonitrile hydrogenation reaction was performed under the same conditions as described above. 24 hours after the start of the reaction, the conversion rate of isophthalonitrile was 100%, the yield of metaxylylenediamine was 97.0 mol%, and the yield of the high-boiling condensation product was 3.0 mol%. .
By adding gas phase pretreatment after catalyst regeneration treatment by hydrocracking, not only the target substance metaxylylenediamine can be always obtained in high yield, but also blockage of the catalyst layer by high boiling point compounds is suppressed. And we were able to operate continuously for a long time.

<Example 2>
(Methanol as treatment agent)
Except that the amount of catalyst is 0.6 g, the flow gas at the time of pretreatment is a mixed gas of methanol: nitrogen = 4: 96 vol%, the pretreatment conditions are normal pressure, 200 ° C., gas flow rate 0.18 NL / h, 3 hours. Were subjected to catalyst reduction, pretreatment, and nitrile hydrogenation under the same conditions as in Example 1. The reaction results 24 hours after the start of the reaction showed that the conversion of isophthalonitrile was 100%, the yield of metaxylylenediamine was 98.5 mol%, and the yield of the high-boiling condensation product was 1.5%. .
After a cumulative time of 1370 hours, an increase in the differential pressure in the catalyst layer was observed, so the catalyst layer was washed with liquid ammonia. Thereafter, the same reproduction operation as in Example 1 was performed. After regeneration by hydrocracking, the mixed gas is continuously passed at normal pressure, 200 ° C., and a gas flow rate of 0.18 NL / h, and pretreatment with a gas phase is performed for 3 hours. A hydrogenation reaction was performed. The reaction results 24 hours after resuming the isophthalonitrile hydrogenation reaction were as follows: the conversion of isophthalonitrile was 100%, the yield of metaxylylenediamine was 97.8 mol%, and the yield of the high-boiling condensation product was 2. It was 2 mol%.

<Comparative Example 2>
14 g of catalyst B was packed into a stainless steel tubular reaction tube (front stage) having an inner diameter of 17 mm, and 1.0 g of catalyst A was packed into a stainless steel tubular reaction tube (back stage) having an inner diameter of 4 mm. Two reaction tubes were connected, 100% hydrogen was circulated through the catalyst layer, and activated by reducing for 12 hours under conditions of normal pressure, 250 ° C., and gas flow rate of 3 NL / h. After the gas flow was stopped and the reaction tube was cooled to 50 ° C., the reactor was pressurized to 10 MPaG with hydrogen, liquid ammonia was supplied to the catalyst layer, and the catalyst layer was wetted with liquid ammonia. From the top of the previous reaction tube, 3NL / h of hydrogen, isophthalonitrile (IPN), pseudocumene (PCM), and liquid ammonia (NH3) are mixed in a composition of IPN: PCM: NH3 = 8: 8: 84 (weight ratio) ) Was fed at 15 g / h, and the hydrogenation reaction was carried out continuously. The total pressure was 10 MPa and the reaction temperature was 55 ° C. The average reaction results for 100 hours immediately after the start of the reaction were 99.7% conversion of isophthalonitrile, 93.6 mol% of metaxylylenediamine, and 5.8 mol of high-boiling condensation product. %Met.

<Example 3>
(Ethylene and methanol as treatment agents)
14 g of catalyst B was packed into a stainless steel tubular reaction tube (front stage) having an inner diameter of 17 mm, and 1.0 g of catalyst A was packed into a stainless steel tubular reaction tube (back stage) having an inner diameter of 4 mm. Two reaction tubes were connected, 100% hydrogen was circulated through the catalyst layer, and activated by reducing for 12 hours under conditions of normal pressure, 250 ° C., and gas flow rate of 3 NL / h. Subsequently, the flow gas was changed to a mixed gas of ethylene: nitrogen = 10: 90 vol%, and pretreatment was performed. The circulation of the mixed gas was continued for 8 hours under the conditions of normal pressure, 200 ° C., and gas flow rate of 1 NL / h. After the gas flow was stopped and the reaction tube was cooled to 50 ° C., the reactor was pressurized to 10 MPaG with hydrogen, liquid ammonia was supplied to the catalyst layer, and the catalyst layer was wetted with liquid ammonia. From the top of the previous reaction tube, 3NL / h of hydrogen, isophthalonitrile (IPN), pseudocumene (PCM), and liquid ammonia (NH3) are mixed in a composition of IPN: PCM: NH3 = 8: 8: 84 (weight ratio) ) Was fed at 15 g / h, and the hydrogenation reaction was carried out continuously. The total pressure was 10 MPa, and the reaction temperature was adjusted in the range of 55 to 70 ° C. so that the conversion rate of isophthalonitrile at the outlet of the previous reaction tube was 95% or more. The average reaction results for 100 hours immediately after the start of the reaction are 99.8% conversion of isophthalonitrile, 95.8 mol% of metaxylylenediamine, and 3.4 mol of high-boiling condensation product. %Met.
When the reaction was continued for a total of 100 hours, the catalyst layer was washed with liquid ammonia, and then 100% hydrogen was circulated through the catalyst layer, under conditions of normal pressure, 290 ° C., and gas flow rate of 3 NL / h. Hydrocracking treatment was performed for 13 hours until no methane was detected, and a regeneration operation was performed. After regeneration by hydrocracking, the pre-treatment in the gas phase is continued for 3 hours by switching the flowing gas to a mixed gas of ethylene: nitrogen = 6: 94 vol% under the conditions of atmospheric pressure, 250 ° C. and gas flow rate 2 NL / h did. After the pretreatment, a hydrogenation reaction of isophthalonitrile was performed under the same conditions as described above. The average reaction results in the first 100 hours (cumulatively 100 to 200 hours) immediately after the resumption of the reaction are: conversion of isophthalonitrile is 99.9%, yield of metaxylylenediamine is 96.7 mol%, high boiling point condensation product The yield of the product was 3.1 mol%.
When the reaction was continued for a total of 200 hours, the catalyst layer was washed with liquid ammonia, then 100% hydrogen was passed through the catalyst layer, and hydrogenation was performed for 13 hours under conditions of normal pressure, 290 ° C., and gas flow rate of 3 NL / h. A decomposition process was performed and a regeneration operation was performed. After regeneration, the hydrogenation reaction of isophthalonitrile was carried out under the same conditions as described above without performing pretreatment. As a result, the average reaction result at 100 hours (cumulative 200 to 300 hours) immediately after the reaction was resumed was that of isophthalonitrile. The conversion was 99.7%, the yield of metaxylylenediamine decreased to 92.3 mol%, and the yield of the high-boiling condensation product increased to 7.5 mol%.
When the reaction was continued for 300 hours, the catalyst layer was washed with liquid ammonia, then 100% hydrogen was passed through the catalyst layer, and hydrogenation was performed for 13 hours under conditions of normal pressure, 290 ° C., and gas flow rate of 3 NL / h. A decomposition process was performed and a regeneration operation was performed. After regeneration by hydrocracking, the pre-treatment in the gas phase was continued for 10 hours by switching the flowing gas to a mixed gas of methanol: nitrogen = 4: 96 vol% under the conditions of atmospheric pressure, 250 ° C. and gas flow rate 2 NL / h did. After the pretreatment, a hydrogenation reaction of isophthalonitrile was performed under the same conditions as described above. The average reaction results in the first 100 hours (cumulative 300 to 400 hours) immediately after the resumption of the reaction show that the conversion rate of isophthalonitrile is improved to 100%, the yield of metaxylylenediamine is increased to 98.2 mol%, and high-boiling condensation The product yield was reduced to 1.8 mol%.

  The primary amines obtained in the present invention are industrially useful as raw materials for polyamide resins, epoxy curing agents and the like, and as intermediate materials for isocyanates, organic solvents, agricultural chemicals, pharmaceuticals, detergents and the like.

Claims (12)

  In the production of a primary amine by reacting hydrogen with a nitrile in the presence of a catalyst containing one or more metals selected from nickel, cobalt and iron, (1) regeneration of the catalyst, (2) pretreatment of the catalyst and ( 3) The nitrile hydrogenation reaction is carried out in this order, and the pretreatment is carried out by contacting the catalyst in the gas phase with at least one treatment agent selected from hydrocarbon compounds, alcohols, ethers and esters. A process for producing a primary amine characterized by   The process according to claim 1, wherein the treating agent is selected from hydrocarbon compounds and alcohols.   The method according to claim 1 or 2, wherein the hydrocarbon compound is an alkene having 4 or less carbon atoms.   The process according to claim 1 or 2, wherein the hydrocarbon compound is ethylene.   The method according to claim 1 or 2, wherein the alcohol is an alcohol having 6 or less carbon atoms.   The process according to claim 1 or 2, wherein the alcohol is methanol.   The method according to claim 1, wherein the pretreatment is performed under a gas phase condition of 150 to 500 ° C.   When the regeneration of the catalyst is in the range of 150 to 500 ° C., hydrogen or hydrogen diluted with an inert gas is supplied to the catalyst layer, and the methane concentration in the outlet gas becomes 1% or less with respect to the hydrogen concentration in the supply gas. The method according to any one of claims 1 to 7, wherein the method is performed.   The method according to claim 1, wherein the hydrogenation catalyst is a nickel-containing catalyst.   The method according to claim 1, wherein the nitrile is an aromatic nitrile.   The method according to any one of claims 1 to 9, wherein the nitrile is dicyanobenzene.   The method according to any one of claims 1 to 11, wherein the nitrile hydrogenation reaction is carried out in a fixed bed continuous flow system.