GB645754A - Production of nitriles - Google Patents

Abstract

Aromatic nitriles are manufactured by contacting an alkyl-substituted aromatic hydrocarbon with ammonia, in gaseous phase, at temperatures between about 900 DEG F. and the decomposition temperature of ammonia (preferably at 980-1030 DEG F.), in the presence of a catalyst comprising a molybdenum oxide (e.g. the sesquioxide, dioxide, pentoxide or especially the trioxide), preferably supported on alumina. The molecular proportion of hydrocarbon in the reaction mixture may vary widely (e.g. from about 20 to about 90 per cent), but it is preferable to use a molar excess of ammonia. If the catalyst becomes fouled it may be regenerated by careful oxidation, e.g. by passing a stream of air over it. The pressure at which the reaction is effected may be subatmospheric, atmospheric or superatmospheric. Examples describe the preparation of benzonitrile from toluene, tolunitriles from xylenes and xylylnitriles from trimethylbenzenes. Other starting materials specified are methylnaphthalenes, and hydrocarbon fractions containing mixed alkylbenzenes or alkylnaphthalenes. The Specification as open to inspection under Sect. 91 comprises also the use of catalysts containing a tungsten oxide (e.g. the dioxide or trioxide) and of catalyst supports other than alumina (e.g. silica gel, the material sold under the Registered Trade Mark "Carborundum," pumice or clays), the use of temperatures down to about 850 DEG F. (the preferred range being about 925-1075 DEG F.), and the use as starting materials of other hydrocarbons having at least two carbon atoms to at least one of which at least two hydrogen atoms are attached (including alkenyl substituted aromatic hydrocarbons, especially styrene). Reference is made to the use of air diluted with flue gases for the oxidation treatment for the regeneration of the catalyst, and it is stated that this treatment is preferably followed by a purging treatment, e.g. by passing over the catalyst a stream of nitrogen, carbon dioxide or hydrocarbon gases. This subject-matter does not appear in the Specification as accepted.