| 摘要 |
Mixed oxide active catalysts having the formula: AaMocWdCoeBbOx wherein: A is at least one of the metals nickel, manganese and/or lead; B is at least one of the metals iron, bismuth, chromium and/or thallium; a is the sum of the values indicating the amounts present of each of the metals A, and is a number ranging from greater than or equal to 0 to about 4; c and d are numbers each equal to or greater than 0 and ranging to 12, with the sum c+d being about 12; e is a number ranging from about 8 to about 12; b is the sum of the values indicating the amounts present of each of the metals B, and is a number ranging from greater than 0 to about 1.5 [(c+d)-(a+e)]; and x is a number satisfying all unbalanced valences, are prepared by, in a first stage, intimately admixing in aqueous phase the salts of all metals to comprise such active catalyst, with the salts of molybdenum and/or tungsten being ammonium salts and at least one salt of at least one of the metals A and B being a nitrate; and, in a second stage, drying and calcining. In the process, the problems of ammonium nitrate formation are avoided by, in the first stage, acidifying an aqueous solution comprising the ammonium salts of molybdenum and/or tungsten to a pH ranging from about 0.5 to 3, separating the molybdic and/or tungstic acid precipitates which thereby form and preparing an aqueous suspension thereof, and then admixing therewith aqueous solutions of the metal salts of the remaining metals comprising the catalyst. |
