GB1319622A - Stabilized copper-zinc oxide catalyst and method for the production thereof - Google Patents

Abstract

1319622 Water-gas shift reaction catalysts CHEMETRON CORP 1 April 1970 [1 April 1969] 13734/70 Headings B1E and B1F [Also in Division C5] Pyrophoric catalyst comprising elemental copper and zinc oxide, which catalyst has been obtained by reduction of a composition comprising copper oxide and zinc oxide, is rendered non-pyrophoric, i.e. stabilised, by surrounding with a non-oxidising gas stream into which oxygen is introduced, the concentration of oxygen in the stream being increased gradually to a maximum of 5 volume per cent, whilst maintaining the catalyst at a temperature not greater than 150‹F, thereby partially to oxidise the elemental copper. Copper oxide and zinc oxide may constitute, respectively, from 25 to 40 weight per cent and, correspondingly, from 75 to 60 weight per cent of the copper oxide-zinc oxide content of the composition of which up to 25 weight per cent may be constituted by alumina. The composition may be prepared either by mulling and thereafter calcining a wet mixture comprising copper oxide, zinc oxide and, optionally, hydrated alumina or by treating a solution containing copper and zinc ions with alkali thereby to precipitate a mixture of copper and zinc hydroxides and/or oxides and thereafter calcining the mixture, optionally after addition thereto of hydrated alumina; details are given of the preparation of a composition consisting of 33.3 weight per cent CuO and 66.7 weight per cent ZnO from basic copper carbonate, zinc oxide and aqueous ammonia and of a composition comprising 26.3 weight per cent CuO, 53.5 weight per cent ZnO and 20.2 weight per cent Al 2 O 3 from an aqueous solution containing copper and zinc nitrates, aqueous ammonia and alumina trihydrate. An example relates to the reduction of a composition consisting of copper oxide and zinc oxide in a CuO:ZnO weight ratio of 1:2 and to the stabilization of the resulting pyrophoric catalyst to provide non-pyrophoric catalyst in which 93 per cent of the copper is in elemental form. Reduction of the comopsition and stabilization of the resulting catalyst may be effected in apparatus comprising reduction vessel 10 and interconnected stabilization vessel 26, which vessels are provided with respective wells 45, 46 for receiving thermocouples (not shown) to measure the temperature of material in the respective vessels. The reduction vessel, which is provided with funnel 11 and tube 12 controlled by valve 13 for introduction of the composition, is surrounded by heating jacket 16 connected to gas burner 14 via manifold 15 and to exhaust manifold 17 and exhaust stack 18 via conduits 19 equipped with dampers 20; line 30 and conduits 31 supply the reduction vessel with treatment gas which leaves the vessel via porous filter tubes 22 and manifold 21. Pyrophoric catalyst passes from the reduction vessel to the stabilization vessel by gravity via conduit 23, water-cooled valve 24 and conduit 25 provided with gas line 27 controlled by valve 27a; line 44 and conduits 41 supply the stabilization vessel with treatment gas which leaves the vessel via porous filter tubes 34 and manifold 33. Non- pyrophoric catalyst passes from the stabilization vessel via conduit 35 and valve 36 to separator 37 from whence fines-free material passes via line 39 to receptacle 47 for packaging.