Method for recovering molybdenum and method for preparing catalyst
AssigneeMitsubishi Raycon Co., Ltd.
InventorsTomomasa Tatsumi, Hiroyuki Naitou, Toru Kuroda
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Abstract
A method for obtaining a material containing recovered molybdenum for use in producing a catalyst from a molybdenum-containing material comprising at least molybdenum, A element (phosphorus and/or arsenic) and X element (at least one selected from the group consisting of potassium, rubidium, cesium and thallium), in particular, from a spent catalyst; and a method for producing a catalyst using said material containing recovered molybdenum. A particularly preferred catalyst is a catalyst for use in producing methacrylic acid through gas-phase catalytic oxidation.
Claims10
A method for recovering molybdenum comprising the steps of:
- 1) dispersing a molybdenum-containing material which contains at least molybdenum, A element (phosphorus and/or arsenic) and X element (at least one selected from the group consisting of potassium, rubidium, cesium and thallium) in water and adding alkali to make pH of the resultant mixed liquid 8 or more;
- 2) adjusting pH of the resultant mixed liquid to fall within the range of from 6 to 12 followed by adding a compound containing magnesium and aqueous ammonia to form a precipitate containing at least magnesium and A element;
- and
- 3) separating the precipitate containing at least magnesium and A element formed in the step 2) from a solution containing at least molybdenum (recovered molybdenum-containing liquid).
A method for producing a catalyst by using a recovered molybdenum-containing liquid which has been recovered by the steps of:
- 1) dispersing a molybdenum-containing material which contains at least molybdenum, A element (phosphorus and/or arsenic) and X element (at least one selected from the group consisting of potassium, rubidium, cesium and thallium) in water and adding alkali to make pH of the resultant mixed liquid 8 or more;
- 2) adjusting pH of the resultant mixed liquid to fall within the range of from 6 to 12 followed by adding a compound containing magnesium and aqueous ammonia to form a precipitate containing at least magnesium and A element;
- 3) separating the precipitate containing at least magnesium and A element found in the step 2) from a solution containing at least molybdenum and/or
- a recovered molybdenum-containing precipitate which has been obtained by the further step of:
- 4) forming a precipitate containing at least molybdenum by adjusting the pH of the recovered molybdenum-containing liquid to 3 or less and separating the precipitate thus formed from the recovered molybdenum-containing (liquid expressed altogether as “recovered molybdenum-containing material”).
Dependencies are inferred from the claim text.