PRODUCTION OF ALIPHATIC NITRILES FROM OLEFINS

摘要

Unsaturated aliphatic nitriles are prepared by heating a mixture of an olefin of formula: wherein R1 and R2 are hydrogen or C1-6 alkyl, with molecular oxygen, ammonia and added steam in the vapour phase at an elevated temperature in the presence of a molybdenum compound as catalyst. The preferred volumetric proportions in the mixture are: olefin 1-20%; oxygen 2-10%; ammonia 1-10% and steam 20-90%, more preferably 40-60%. The oxygen may be diluted with inert diluents. Temperatures of 300-600 DEG C. are preferred. The preferred catalyst is molybdenum oxide on a carrier; the carrier may be pretreated by heating or by impregnating it with an inorganic compound, e.g. an alkali metal compound, drying and heating to 1,000 DEG -1,500 DEG C. Preferably 1-10% by weight of a sodium compound or 1-20% by weight of a potassium compound is used. The product may be recovered by extracting it into water or other solvent and then distilling. The residual gases from the wash may be recycled with or without removing carbon dioxide byproduct. Unreacted olefin may be removed from the product by extraction with an oil and recycled. Again, part of the reaction product may be recycled together with fresh reactant.ALSO:A catalyst composition comprises molybdenum oxide on a carrier such as silica gel, kieselguhr or alumina. The carrier may be pretreated by heating or by impregnating it with an inorganic compound, e.g. an alkali metal compound, drying and heating to 1000 to 1500 DEG C. Preferably 1-10% by weight of a sodium compound or 1-20% by weight of a potassium compound is used. The alkali metal compound may be a hydroxide, chloride, sulphate, carbonate, aluminate, nitrate, phosphate or molybdate. In an example a catalyst is prepared by impregnating alumina (pretreated with sodium hydroxide) with an ammoniacal solution of ammonium molybdate, drying and heating at 380 DEG C. in a stream of air to form the molybdenum trioxide.