| 摘要 |
Oxidation of olefins to olefin oxides, such as is described in Specifications 687,243 and 690,718 is effected in the presence of a catalyst consisting of a support containing a coating of silver oxide and an organic salt of an alkali or alkaline earth metal (see Group III). The oxidation may take place at 220-350 DEG C. under superatmospheric pressure. In examples, a gaseous stream containing 5 per cent ethylene, 6 per cent oxygen and 89 per cent nitrogen were passed by 245 DEG C. over the catalyst at 200 litres per hour; (2) a mixture of ethylene (5 per cent) and air at 100 litres per hour were reacted at 240 DEG C. Specifications 674,412 and 688,242 also are referred to.ALSO:A catalyst for the oxidation of olefins to olefin oxides comprises a support surface having a coating containing silver oxide and an organic salt of an alkali or alkaline earth metal. Barium lactate in an amount of 1-25 per cent. is preferred but barium and calcium acetates, strontium salicylate and lithium citrate are also referred to. The catalyst may be prepared be reacting silver nitrate with caustic soda and, after working, the precipitate of silver oxide is mixed with an aqueous solution of the organic salt. Support particles are added and the mixture evaporated to dryness. The catalyst may be stabilized by roasting for one half to twenty-four hours at 300-500 DEG C. in the presence of an inert atmosphere, a substantial amount of the silver oxide remaining after roasting. The catalyst may be regenerated with ethylene dioxide as disclosed in Specification 688,242. Support materials include silicon carbide, beryllium porcelain, mullite or aluminium oxide or mixtures thereof, preferably in the form of roughened spheres having a diameter of .20 to .50 inches as described in Specification 674,412. Specifications 687,243 and 690,718, [both in Group IV (b)], also are referred to. |
