| 摘要 |
1350959 Preparation of ethylene oxide SOC ITALIANA RESINE SIR SpA 28 Oct 1971 [12 Nov 1970] 50223/71 Heading C2C [Also in Division B1] Oxidation of ethylene to ethylene oxide is effected in the presence of silver-containing catalyst which has been prepared by a process wherein inert support material impregnated with a decomposable silver compound and optionally with at least one other catalyticallyactive metal or compound thereof is brought to a temperature of 270-350‹ C., preferably 300- 310‹ C., over a period of not greater than one hour in an atmosphere of nitrogen free from or containing up to 0À5 volume per cent oxygen and is maintained at such temperature whilst in contact with a gaseous stream flowing at a rate of 0À1-30 litres of gas per gram of impregnated support material per hour, the gaseous stream consisting of nitrogen free from or containing up to 0À5 volume per cent oxygen for an initial period of from one to ten hours and thereafter the oxygen content thereof raised, for example by addition thereto of air, to about 20 volume per cent over a period of from three to twenty hours, preferably six to twenty hours. The catalyst may contain from 7 to 30 weight per cent (based on the weight of support material) of silver and optionally from 0À01 to 1 weight per cent (based on the weight of silver) of platinum, palladium, gold, barium or calcium. The support material may be selected from magnesia, alumina, silicon carbide and combinations thereof and may be in the form of spheres having a diameter of between 4 and 9 mm. The Specification gives details relating to the preparation of the impregnated support material by methods which are (or are similar to) those methods disclosed in Specifications 1,243,480, 1,243,105 and 1,263,594. As exemplified, ethylene oxide is prepared by contacting a gaseous mixture of ethylene, nitrogen, oxygen and ethane at 269‹ C. with a fixed bed of catalyst which has been prepared by a procedure wherein macroporous alpha-alumina in the form of microspheres having an average diameter of about 7À1 mm., a surface area of less than 1 m.<SP>2</SP>/g., a total porosity of 44% and an average pore diameter of 100 microns is impregnated with a suspension of platinum-carbon in a solution of silver lactate in lactic acid, heated up to 120‹ C. in air and either heated up to and at 300‹ C. in nitrogen and thereafter at 300‹ C. in nitrogen which gradually is replaced by air (as per inventive procedure) or heated up to and at 300‹ C. in air (as per prior-art procedure). |
