Improvements in or relating to the manufacture of formaldehyde

摘要

Formaldehyde is produced from carbon monoxide and hydrogen, freed from contact poison, by means of porous or finely-divided nickel, with a small proportion of a metal promoter, on a metal support. The support may be of nickel, chromium or aluminium gauze, and the promoter may be silver, vanadium, cobalt, copper, or cadmium or their alloys. The reaction temperature may be 180--225 DEG C., lower temperatures being used with higher proportions of hydrogen. The gases may be passed through two catalytic chambers or zones at different temperatures. The catalyst may be prepared by passing an organo-nickel compound such as nickel carbonyl over the heated support, or by placing nickel hydrate paste containing the promoter in the form of hydrate on the surface-oxidized support and reducing in hydrogen. The purification of the reaction gases may be effected by passing through tubes containing successive layers of iron, copper, and then nickel which may be in the form of wires or coiled strips or gauze, and may be mixed with a small amount of nickel paste. When two purifiers are used in series, the second may contain copper and carbon obtained by heating in situ cuprene obtained by treating copper or copper oxide with acetylene, and there may be added to the cuprene analogous compounds of nickel or cobalt; a small quantity of nickel paste may be added, the whole being mixed with wood charcoal as a carrier. During the process, frequent regeneration of the catalyst is necessary, this being effected by a current of a suitable gas such as nitrogen, oxides of nitrogen, hydrogen, carbon dioxides or steam, as described in Specification 371,377.ALSO:Formaldehyde is produced from carbon monoxide and hydrogen, freed from contact poison, by means of porous or finely-divided nickel, with a small proportion of a metal promoter, on a metal support. The support may be of nickel, chromium or aluminium gauze, and the promoter may be silver, vanadium, cobalt, copper, or cadmium or their alloys. The reaction temperature may be 180--225 DEG C., lower temperatures being used with higher proportions of hydrogen. The gases may be passed through two catalytic chambers or zones at different temperatures. The catalyst may be prepared by passing an organo-nickel compound such as nickel carbonyl over the heated support, or by placing nickel hydrate paste containing the promoter in the form of hydrate on p the surface-oxidized support and reducing in hydrogen. The purification of the reaction gases may be effected by passing through tubes containing successive layers of iron, copper, and then nickel, which may be in the form of wires or coiled strips or gauze, and may be mixed with a small amount of nickel paste. When two purifiers are used in series, the second may contain copper and carbon obtained by heating in situ cuprene obtained by treating copper or copper oxide with acetylene, and there may be added to the cuprene analogous compounds of nickel or cobalt; a small quantity of nickel paste may be added, the whole being mixed with wood charcoal as a carrier. During the process frequent regeneration of the catalyst is necessary, this being effected by a current of a suitable gas such as nitrogen, oxides of nitrogen, hydrogen, carbon dioxide or steam as described in Specification 371,377.