Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Reexamination Certificate
2000-07-11
2002-08-06
Dentz, Bernard (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
C558S323000
Reexamination Certificate
active
06429330
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing nitrile compounds by reacting carbocyclic or heterocyclic compounds with a mixed gas of ammonia and oxygen.
2. Description of the Prior Art
Aromatic nitriles produced by ammoxidation of carbocyclic compounds are useful as raw materials for manufacturing synthetic resins, agricultural chemicals, etc., and as intermediate materials for producing amines, isocyanates, etc. Heterocyclic nitriles produced by ammoxidation of heterocyclic compounds are also useful as intermediates of medicines, animal feed additives, food additives, etc.
Ammoxidation of carbocyclic or heterocyclic compounds to aromatic or heterocyclic nitrile compounds generates a larger amount of heat as compared to ammoxidation of olefins. Therefore, a vapor-phase fluid catalytic reaction has been advantageously used for the ammoxidation of carbocyclic or heterocyclic compounds because the heat of reaction can be easily removed and side reactions due to local heating can be avoided. Various catalyst systems comprising a metal oxide or comprising a metal oxide supported on a carrier such as silica and alumina have been proposed for use in the vapor-phase fluid catalytic reaction.
For instance, Japanese Patent Publication No. 49-45860 produces an aromatic nitrile by ammoxidation of an alkyl-substituted aromatic compound in the presence of a catalyst containing V, Cr and B. Japanese Patent Application Laid-Open No. 49-13141 conducts the similar reaction in the presence of a catalyst containing Fe, Bi and Mo. Japanese Patent Application Laid-Open No. 63-190646 discloses ammoxidation of an alkyl-substituted aromatic compound or an alkyl-substituted alicyclic compound using an Fe—Sb catalyst.
Japanese Patent Application Laid-Open No. 1-275551 discloses ammoxidation of an alkyl-substituted aromatic compound or an alkyl-substituted heterocyclic compound in the presence of a V—Cr—B—Mo catalyst. Japanese Patent Application Laid-Open No.
5-170724
conducts the similar reaction in the presence of an Mo—P catalyst. Japanese Patent Application Laid-Open No. 9-71561 produces dicyanobenzene by ammoxidation of xylene in the presence of an Fe—Sb—V catalyst.
These known processes are advantageous because aromatic or heterocyclic nitriles are produced in high yields. However, the catalysts used in the processes are decreased in their activity with time. Therefore, it has been demanded to produce nitrile compounds in high yields over a long period of time. To meet the demands, there have been proposed a method for inhibiting the catalyst deterioration in fluidized reaction, a catalyst with little activity change with time, etc. For instance, Japanese Patent Application Laid-Open No. 10-120641 teaches to prevent the deterioration of a metal oxide catalyst containing V and/or Mo by a controlled feeding of raw materials to a fluid reactor.
As described above, in the process for producing nitrile compounds by fluid catalytic ammoxidation of carbocyclic or heterocyclic compounds in vapor-phase, various attempts have been made to improve catalysts and apparatuses for preventing deterioration of the catalysts. However, it is still demanded to produce the nitrile compounds stably in high yields over a prolonged period of time.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an economical process for producing a nitrile compound by vapor-phase fluid catalytic reaction of a carbocyclic or heterocyclic compound with ammonia and an oxygen-containing gas in high yields with little lowering with time over a long period of time.
As a result of extensive researches and studies on the production of nitrile compounds in view of the above objects, the inventors have found that one of the attributing causes of the deterioration of catalyst activity is water accompanying unreacted ammonia during its recycle and reuse, and that the use of catalysts containing a specific amount of alkali metal enables the ammoxidation to be stably performed with little change with time in the yields over a long period of time. The present invention has been accomplished based on this finding.
Namely, in accordance with the present invention, there is provided a process for producing an aromatic or heterocyclic nitrile, comprising a step of subjecting a carbocyclic or heterocyclic compound, ammonia and an oxygen-containing gas to fluid catalytic reaction in vapor phase in the presence of a catalyst containing 0.10 to 0.40% by weight of alkali metal; and a step of recycling unreacted ammonia recovered from a reaction product gas.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
In the vapor-phase catalytic reaction of the present invention, a carbocyclic compound or a heterocyclic compound is reacted with an oxygen-containing gas and ammonia. To effectively remove heat of reaction and avoid side reactions due to local heating, the catalytic reaction is carried out in fluidized manner.
The carbocyclic compounds used as raw materials in the present invention has a carbon ring selected from the group consisting of benzene, naphthalene, anthracene, cyclohexene, cyclohexane, dihydronaphthalene, tetralin and decaline. The carbon ring has at least one nitrile-forming group selected from the group consisting of methyl, ethyl, propyl, formyl, acetyl, hydroxymethyl and methoxycarbonyl. Further, the carbocyclic compound may have another substituent such as halogen atom, hydroxyl, alkoxyl, amino, nitro, etc. Examples of the carbocyclic compounds include toluene, xylene, trimethylbenzene, ethylbenzene, methylnaphthalene, dimethylnaphthalene, methyltetralin, dimethyltetralin, chlorotoluene, dichlorotoluene, methylaniline, cresol and methylanisole.
The heterocyclic compounds used in the present invention have at least one hetero ring selected from the group consisting of furan, pyrrole, indole, thiophene, pyrazole, imidazole, oxazole, pyran, pyridine, quinoline, isoquinoline, pyrroline, pyrrolidine, imidazoline, imidazolidine, piperidine and piperazine. The hetero ring has at least one nitrile-forming group selected from the same group as described above for the carbocyclic compounds. Examples of the heterocyclic compounds include furfural, 2-methylthiophene, 3-methylthiophene, 2-formylthiophene, 4-methylthiazole, methylpyridine, dimethylpyridine, trimethylpyridine, methylquinoline, methylpyrazine, dimethylpyrazine and methylpiperazine.
The ammonia used as a raw material in the present invention may be of industrial grade. The amount of ammonia used is 1.5 to 10 moles, preferably 3 to 5 moles per one mole of the nitrile-forming group in the carbocyclic or heterocyclic compound. When the amount of ammonia used is less than the above range, the yield of the nitrile compound is lowered. When the amount of ammonia used exceeds the above range, the space time yield of the nitrile compound becomes small.
In the process of the present invention, the unreacted ammonia in reaction product gas is recovered and recycled to the reaction system for reuse. The method of recovering the unreacted ammonia from the reaction product gas is not particularly restricted. From an industrial viewpoint, it is suitable that the unreacted ammonia is absorbed in water, and then separated from by-products by distillation.
The oxygen-containing gas used in the present invention may be usually air. Alternatively, diluted air or oxygen with an inert gas such as nitrogen, carbon dioxide or waste gases may also be used as the oxygen-containing gas. The oxygen concentration in the oxygen-containing gas is preferably 10 to 20% by volume. The amount of oxygen used is 1.5 moles or larger, preferably 2 to 50 moles per one mole of the nitrile-forming group in the carbocyclic or heterocyclic compound. When less than the above range, the yield of the nitrile compound is lowered. When exceeding the above range, the space time yield of the nitrile compound becomes small.
The catalyst used in the present invention contains an alkali metal in an amount
Ebata Shuji
Kanamori Yoshinori
Ogino Hideaki
Okawa Takashi
Dentz Bernard
Mitsubishi Gas Chemical Company Inc.
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