Method for materials recovery from catalysts comprising iron, cerium, molybdenum, and potassium

Abstract

A method for materials recovery from a catalyst comprising oxides of iron, cerium, molybdenum, and potassium, in which potassium and molybdenum are removed by treating the catalyst with an aqueous leachant, giving an aqueous solution S1 comprising potassium and molybdenum, and a solid residue R1 comprising cerium oxide and iron oxide, and recovering cerium in the form of a solid comprising a cerium(III) compound or cerium(IV) oxide from the solid residue R1.

1 .- 11 . (canceled) 
     
     
         12 . A method for materials recovery from a catalyst comprising oxides of iron, cerium, molybdenum, and potassium, in which potassium and molybdenum are removed by treating the catalyst with an aqueous leachant, giving an aqueous solution S1 comprising potassium and molybdenum, and a solid residue R1 comprising cerium oxide and iron oxide, and recovering cerium in the form of a solid comprising a cerium(III) compound or cerium(IV) oxide from the solid residue R1. 
     
     
         13 . The method according to  claim 12 , wherein the catalyst, before being treated with the aqueous leachant, is heated in an atmosphere comprising oxygen. 
     
     
         14 . The method according to  claim 12 , wherein the catalyst, before being treated with the aqueous leachant, is mechanically comminuted. 
     
     
         15 . The method according to  claim 12 , wherein the solid residue R1 comprising cerium oxide and iron oxide is treated with a mineral acid, to recover an iron-containing solution S2 and a solid residue R2 comprising cerium(IV) oxide. 
     
     
         16 . The method according to  claim 15 , wherein the solid residue R2 comprising cerium(IV) oxide is dissolved, with reduction of cerium(IV) to cerium(III), in a mineral acid, giving a solution S4, and cerium is precipitated in the form of a cerium(III) compound from the solution S4 by addition of a basic precipitant. 
     
     
         17 . The method according to  claim 16 , wherein an iron(II) compound or metallic iron is added as reducing agent to the mineral acid. 
     
     
         18 . The method according to  claim 16 , wherein an alkali metal carbonate or alkaline earth metal carbonate is used as basic precipitant, and cerium is precipitated in the form of cerium(III) carbonate hydrate. 
     
     
         19 . The method according to  claim 15 , wherein iron is precipitated in the form of iron oxide or iron hydroxide from the iron-containing solution S2 by addition of a basic precipitant. 
     
     
         20 . The method according to  claim 15 , wherein iron oxide is recovered from the iron-containing solution S2 by spray drying. 
     
     
         21 . The method according to  claim 15 , wherein the iron-containing solution S2 is introduced as a flocculant into a wastewater treatment plant. 
     
     
         22 . The method according to  claim 12 , wherein molybdenum is precipitated in the form of a solid R3 comprising an oxygen-containing molybdenum(VI) compound from the aqueous solution S1 comprising potassium and molybdenum by addition of an acid, leaving a solution S3 comprising potassium salts.