GB744049A - Revivification of poisoned metallic catalysts - Google Patents

Abstract

Catalysts containing metallic platinum, palladium, rhodium, iridium, ruthenium, osmium, nickel, cobalt, copper, or iron, which have been used in a liquid phase hydrogenation, dehydrogenation, or reduction process and have become poisoned by compounds of sulphur, selenium, tellurium, phosphorus, arsenic, or antimony or by sulphur or phosphorus in the free state, are revived by treatment with a liquid in which the poison is soluble and which does not attach chemically either the poison or the catalyst. The process may also be used for the revivification of metallic nickel, cobalt, copper, or iron catalysts which have become poisoned in gas phase hydrogenation, dehydrogenation, or reduction processes. The liquid preferably consists of or contains a substance having an ethylenic, acetylenic, or benzenoid bond, a carbonyl group, or an unsaturated bond between two nitrogen atoms or between carbon, and nitrogen. Water, alcohol, acetic acid, cyclohexene, benzene and acetone, are specified. A series of treatments with different liquids may be given. In examples (1) platinum black poisoned with thiophen is treated first with acetic acid and then with acetic acid containing 10 per cent cyclohexene (2) platinum black poisoned with zinc ions is treated with water (3) nickel poisoned with thiophen is treated with water, using four changes of liquid (4) platinum black poisoned with dimethylphenyl-arsine is treated three times with cyclohexene dissolved in acetic acid (5) platinum black poisoned with thionaphthen is treated twice with a 10 per cent solution of acetone in acetic acid. Specifications 437,659, 644,239, and 692,300 are referred to.