Process for producing tungsten oxide and tungsten mixed oxides

Abstract

Process for producing a tungsten oxide powder or a tungsten mixed oxide powder of general formula M x WO 3 , wherein M=Na, K, Rb, Li and/or Cs, 0.1≤x≤0.5, comprising the consecutive steps of: a) providing a solution comprising respectively at least one tungsten compound and optionally at least one M-comprising compound in a concentration corresponding to the stoichiometry M x WO 3 , b) atomizing the solution, thus forming an aerosol, into a reaction space, c) reacting the aerosol in the reaction space with a hydrogen/oxygen flame for which the expression 1<O 2,primary /0.5H 2 ≤3 applies, wherein the reaction space is configured such that it comprises two reaction zones with two different velocities of the reaction mixture v 1 and v 2 where v 2 =0.3-0.8 v 1 and 0.5≤v 1 ≤10 Nm/s, d) separating the solid from vaporous or gaseous substances and e) passing a reducing gas stream over the separated solid at a temperature of 450-700° C. Process for producing a tungsten oxide powder or a tungsten mixed oxide powder of general formula M x WO 3 , wherein M=Na, K, Rb, Li and/or Cs, 0.1≤x≤0.5, comprising the consecutive steps of: a) providing a solution comprising respectively at least one tungsten compound and optionally at least one M-comprising compound in a concentration corresponding to the stoichiometry M x WO 3 , b) atomizing the solution, thus forming an aerosol, into a reaction space, c) reacting the aerosol in the reaction space with a hydrogen/oxygen flame having a lambda value<1, wherein: lambda=total oxygen/0.5×hydrogen, d) separating the solid from vaporous or gaseous substances.

1 - 11 . (canceled) 
     
     
         12 . A process for producing a tungsten oxide powder or a tungsten mixed oxide powder of general formula M x WO 3 , wherein M=Na, K, Rb, Li and/or Cs, and 0.1≤x≤0.5, comprising the consecutive steps of:
 a) providing a solution comprising respectively at least one tungsten compound and optionally at least one M-comprising compound in a concentration corresponding to the stoichiometry M x WO 3 ; 
 b) atomizing the solution, thus forming an aerosol, into a reaction space; 
 c) reacting the aerosol in the reaction space with a hydrogen/oxygen flame for which the expression 1<O 2,primary /0.5H 2 ≤3 applies, and wherein the reaction space is configured such that it comprises two reaction zones with two different velocities of the reaction mixture v 1  and v 2  where v 2 =0.3−0.8 v 1  and 0.5≤v 1 ≤10 Nm/s; 
 d) separating the solid from vaporous or gaseous substances; and 
 e) passing a reducing gas stream over the separated solid at a temperature of 450-700° C. 
 
     
     
         13 . The process of  claim 12 , wherein total oxygen is such that 1.5≤O 2,ttl /0.5H 2 ≤5. 
     
     
         14 . The process of  claim 12 , wherein t 2 >0.5 t 1 , and wherein t 1  is the average residence time of the reaction mixture in reaction zone 1 and t 2  is the average residence time of the reaction mixture in reaction zone 2. 
     
     
         15 . The process of  claim 12 , wherein the thermal treatment is performed over a period of 1-10 hours. 
     
     
         16 . The process of  claim 12 , wherein hydrogen, hydrogen/nitrogen mixtures or hydrogen/noble gas mixtures are employed as the reducing gas stream. 
     
     
         17 . The process of  claim 12 , wherein the average residence time in the reaction space is 1-5 s. 
     
     
         18 . The process of  claim 17 , wherein atomization is effected by means of a single- or multimaterial nozzle and the mean droplet diameter of the aerosol is less than 120 μm. 
     
     
         19 . The process of  claim 18 , wherein the concentration of metals in the solution is 5-60 wt %. 
     
     
         20 . The process of  claim 12 , wherein atomization is effected by means of a single- or multimaterial nozzle and the mean droplet diameter of the aerosol is less than 120 μm. 
     
     
         21 . The process of  claim 12 , wherein the solution comprises inorganic metal compounds. 
     
     
         22 . The process of  claim 12 , wherein the solution is an aqueous solution. 
     
     
         23 . The process of  claim 12 , wherein the concentration of metals in the solution is 5-60 wt %. 
     
     
         24 . A process for producing a tungsten oxide powder or a tungsten mixed oxide powder of general formula M x WO 3 , wherein M=Na, K, Rb, Li and/or Cs, and X is 0.1≤x≤0.5, comprising the consecutive steps of:
 a) providing a solution comprising respectively at least one tungsten compound and optionally at least one M-comprising compound in a concentration corresponding to the stoichiometry M x WO 3 ; 
 b) atomizing the solution, thus forming an aerosol, into a reaction space; 
 c) reacting the aerosol in the reaction space with a hydrogen/oxygen flame having a lambda value<1, wherein: lambda=total oxygen/0.5×hydrogen; 
 d) separating the solid from vaporous or gaseous substances. 
 
     
     
         25 . The process of  claim 24 , wherein atomization is effected by means of a single- or multimaterial nozzle and the mean droplet diameter of the aerosol is less than 120 μm. 
     
     
         26 . The process of  claim 24 , wherein the average residence time in the reaction space is 1-5 s. 
     
     
         27 . The process of  claim 26 , wherein atomization is effected by means of a single- or multimaterial nozzle and the mean droplet diameter of the aerosol is less than 120 μm. 
     
     
         28 . The process of  claim 27 , wherein the concentration of metals in the solution is 5-60 wt %. 
     
     
         29 . The process of  claim 24 , wherein the solution comprises inorganic metal compounds. 
     
     
         30 . The process of  claim 24 , wherein the solution is an aqueous solution. 
     
     
         31 . The process of  claim 24 , wherein the concentration of metals in the solution is 5-60 wt %.