| 摘要 |
1,188,737. Vinyl esters. FARBWERKE HOECHST A.G. 4 March, 1968 [3 March, 1967; 10 Aug., 1967], No. 10364/68. Heading C2C. Vinyl esters of carboxylic acids are prepared by a process which comprises passing ethylene, oxygen or gases containing oxygen, and carboxylic acids in the gaseous phase at an elevated temperature over a catalyst comprising a carrier, e.g. silicic acid, a salt of a noble metal of Group VIII of the Periodic Table, and also 0À01 to 200 grams, per litre of catalyst, of cadmium in the form of the cadmium salt of a carboxylic acid. The catalyst may contain a cadmium compound which forms the cadmium salt of a carboxylic acid under the reaction conditions. Advantageously the reaction may be carried out in the presence of an alkali metal salt of the carboxylic acid to be reacted, e.g. the potassium salt thereof, and/or in the presence of a redox system, e.g. an iron salt. Preferably, that part of the catalyst which first comes into contact with the reaction gases is exchanged either by a periodical reversal of the direction of flow of the gases over the catalyst, or by continuously or periodically removing part of the catalyst from the inlet of the reactor, and adding it at the outlet of the reactor, or alternatively by continuously or periodically thoroughly mixing the catalyst. |
