| abstract |
A catalyst, for use in carbon oxide conversion reactions, in the form of a shaped unit, e.g. cylindrical pellets, formed from an oxidic catalyst powder comprising 30-70 wt% copper oxide, zinc oxide, alumina and silica, with an Si:Al atomic ratio of 0.005-0.15:1, and a nitrogen physisorption BET surface area ≥ 105m2/g and a copper surface area > 37m2/g. The catalyst can be a methanol synthesis catalyst or water-gas shift catalyst which may contain 20-30 wt% zinc oxide with a CuO:ZnO weight ratio of 2:1 to 3.5:1. Alumina and silica can be present in an amount 5-20 wt% & 0.05-1.5 wt% respectively. The catalyst can further comprise 1-5 wt% promoter compounds e.g. Mg, Co, Mn, V, Ti, Zr or rare earths. Preferably the Si:Cu atomic ratio is 0.001-0.018:1. The method of preparation can comprise: forming a co-precipitate of copper and zinc, preferably as nitrates, with alumina, from an alumina sol e.g. colloidally dispersed boehmite, and silica e.g. from a silica sol; recovering, washing and drying; and calcining and shaping. An aqueous alkaline precipitant solution e.g. potassium carbonate, may be used in a precipitation vessel and the co-precipitate may be aged in a separate vessel. |