Process for producing titanium oxide

Abstract

A process for producing a titanium oxide is provided which comprises (i) a step of calcining a titanium compound in the presence of ammonia gas or (ii) steps of treating a titanium compound with heat in the presence of ammonia gas and calcining the heat-treated titanium compound. The titanium oxide obtained in the present invention exhibits a sufficiently high photocatalytic activity by irradiation of visible light.

What is claimed is:  
     
         1 . A process for producing a titanium oxide which comprises (i) a step of calcining a titanium compound in the presence of ammonia gas or (ii) steps of treating a titanium compound with heat in the presence of ammonia gas and calcining the heat-treated titanium compound.  
     
     
         2 . A process for producing a titanium oxide according to  claim 1 , wherein the titanium compound is treated with heat in the presence of ammonia gas before the calcination of the titanium compound.  
     
     
         3 . A process for producing a titanium oxide according to  claim 1 , wherein the titanium compound is a titanium hydroxide and a compound which generates ammonia in calcination is allowed to come in contact with said titanium hydroxide before and/or in calcining the titanium hydroxide.  
     
     
         4 . A process for producing a titanium oxide according to any one of  claims 1  to  3 , wherein the calcination is conducted at a temperature of from about 300° C. to about 600° C.  
     
     
         5 . A process for producing a titanium oxide according to any one of  claims 1  to  3 , wherein the titanium oxide has an amorphous phase.  
     
     
         6 . A process for producing a titanium oxide according to  claim 2 , wherein the heat treatment is conducted in the presence of steam.  
     
     
         7 . A process for producing a titanium oxide according to  claim 2  or  6 , wherein the titanium compound to be treated with heat has a bibrous shape.  
     
     
         8 . A process for producing a titanium oxide according to  claim 3 , wherein the compound which generates ammonia in calcination is ammonia or ammonia solution.  
     
     
         9 . A process for producing a titanium oxide according to  claim 3 , wherein the compound which generates ammonia in calcination is ammonium compound.  
     
     
         10 . A process for producing a titanium oxide according to  claim 3 , wherein the titanium hydroxide is allowed to come in contact with the a compound which generates ammonia in calcination in amount of from about 0.1% by weight to about 10% by weight in terms of nitrogen atom in the ammonia-generating compound based on the titanium hydroxide substantially containing no water.