| 摘要 |
Acrylonitrile and/or succinonitrile are produced by passing a gaseous mixture of hydrogen cyanide and ethylene oxide over a dehydration catalyst at 150-650 DEG C. In place of hydrogen cyanide any substance which will produce hydrogen cyanide under the reaction conditions may be used, e.g. formamide. The reaction may be carried out by passing liquid ethylene oxide and liquid hydrogen cyanide into a heating zone to vaporize the reactants simultaneously, before or after contact with the catalyst. Suitable catalysts are compounds of metals from the 3rd, 4th, 5th, 6th and 8th groups of the Periodic table, especially the oxides of aluminium, thorium, silicon, vanadium, molybdenum, titanium, tungsten and nickel, also a metal of the platinum group or salts such as alums, basic aluminium salts or metal phosphates may be used. The preferred catalyst is highly purified silica gel which may be prepared by neutralizing sodium silicate or by the hydrolysis of silicon halides or esters of orthosilicic acid. When acrylonitrile is required as the main product, the gas mixture should contain an excess of ethylene oxide over the equimolecular proportion, but when a large proportion of succinonitrile is required, the mixture should contain at least two molecular proportions of hydrogen cyanide for each molecular proportion of ethylene oxide. Inert diluent gases such as nitrogen, hydrogen or carbon monoxide may be added to the feed mixture. In examples: (1) a gaseous mixture of hydrogen cyanide and ethylene oxide (molar ratio of 1 : 2 1/2 ) is passed over alumina gel which has been previously dried in air at 400 DEG C. Nitrogen is added to the feed mixture to keep the catalyst temperature within the range 260-280 DEG C. The issuing vapours are condensed and the condensate separates into an aqueous layer and an organic layer. The latter is separated, dried and distilled to yield mainly acrylonitrile; (2) hydrogen cyanide and ethylene oxide in the molecular proportion of 2 : 1 are passed over silica gel at 350-400 DEG C. The liquid product is homogeneous and on distillation yields acrylonitrile and succinonitrile. |
