Regeneration of a silver catalyst useful in the preparation of ethylene oxide

• Main Author: SAFFER ALFRED
• Format: Patent
• Language: English
• Published: 24.08.1954
• Subjects: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; HETEROCYCLIC COMPOUNDS; METALLURGY; ORGANIC CHEMISTRY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; THEIR RELEVANT APPARATUS; TRANSPORTING

Silver surface catalysts used in the direct oxidation of olefins to olefin oxides are regenerated by contacting with olefin oxide in the absence of reactor feed gas containing olefin. The olefin feed may be interrupted, and inert gas such as nitrogen containing a small proportion of olefin oxide passed for a short time. If air is used as the carrier gas, the olefin oxide concentration is normally kept below 3 or 4 per cent. Subsequent introduction continuously or intermittently into the olefin feed of up to 0.1 per cent of olefin oxide is advantageous. The catalyst may be silver on alumina, silver activated by gold, copper or barium compounds, or silver deposited on spherical supports having roughened surfaces as disclosed in Specification 674,412. Dilute ethylenic gases may be directly oxidized as described in Specification 687,243. Inhibitors such as halogens may be present. Temperatures of 220-350 DEG C. and pressures of 5-25 atm. may be employed in the oxidation, and may be maintained for the activation step. In examples, a feed of 5 per cent ethylene and air is used with silver oxide on alumina particles or alumina spheres coated with silver and barium lactate, reactivation being effected with inert gas containing 4 per cent ethylene oxide.ALSO:Silver surface catalysts used in the direct oxidation of olefins to olefin oxides are regenerated by contacting with olefin oxide in the absence of reactor feed gas containing olefin. The olefin feed may be interrupted, and inert gas such as nitrogen containing a small proportion of olefin oxide passed for a short time. If air is used as the carrier gas, the olefin oxide concentration is normally kept below 3 or 4 per cent. Subsequent introduction, continuously or intermittently, into the olefin feed of up to 0.1 per cent of olefin oxides is advantageous. The catalyst may be silver on alumina, silver activiated by gold, copper or barium compounds or silver deposited on spherical supports having roughened surfaces as disclosed in Specification 674,412. Dilute ethylenic gases may be directly oxidized as described in Specification 687,243, [Group IV(b)]. Inhibitors such as halogens may be present. Temperatures of 220-350 DEG C and pressures of 5-25 atm. may be employed in the oxidation, and may be maintained for the activation step. In examples, a feed of 5 per cent ethylene and air is used with silver oxide or alumina particles or alumina spheres coated with silver and barium lactate, reactivation being effected with inert gas containing 4 per cent ethylene oxide.