Titanium Oxide Photocatalyst, Process For Producing The Same And Application

Abstract

Titanium oxide-based photocatalysts which contain a metal halide in titanium oxide and which are prepared from titanium oxide and/or its precursor, which may optionally be heat treated, by contact with a reactive gas containing a metal halide of the formula MX n or MOX n (wherein M=a metal, X=a halogen, and n=an integer) with heating stably develop a high photocatalytic activity with visible light irradiation. The photocatalysts may subsequently be stabilized by contact with water or by heat treatment, and/or promoted by contact with a heteropoly acid and/or an isopoly acid so as to include a metal complex in the titanium oxide. Photocatalysts prepared in this manner exhibit novel ESR features. The present invention also provides methods for preparing these photocatalysts, a photocatalyst dispersion and a photocatalytic coating fluid containing such a photocatalyst, and photocatalytic functional products and methods for their manufacture using the photocatalyst.

1 - 13 . (canceled) 
   
   
       14 . A method for the preparation of a titanium oxide-based photocatalyst characterized in that titanium oxide and/or its precursor is brought into contact with a reactive medium containing a metal halide of the formula MX n  or MOX n  (wherein M=a metal, X=a halogen, and n=an integer). 
   
   
       15 . The method for the preparation of a titanium oxide-based photocatalyst as set forth in  claim 14  which further includes subjecting the titanium oxide and/or its precursor to contact with water and/or heat treatment after the contact with the reactive medium. 
   
   
       16 . The method for the preparation of a titanium oxide-based photocatalyst as set forth in  claim 14  which further includes performing contact with a heteropoly acid and/or an isopoly acid after the contact with the reactive gas, or after subsequent contact with water and/or heat treatment. 
   
   
       17 - 24 . (canceled) 
   
   
       25 . A method for the manufacture of a photocatalytic functional product characterized by applying a coating fluid to a surface of a substrate, wherein said coating fluid is characterized by comprising a titanium oxide-based photocatalyst in a solvent, and wherein said titanium oxide-based photocatalyst is characterized by comprising a titanium oxide and an additional metal compound; and developing a photocatalytic activity by irradiation with visible light the additional metal compound comprising at least one metal halide. 
   
   
       26 . A method for the preparation of a photocatalytic coating fluid characterized by mixing a binder with a photocatalyst dispersion, wherein said photocatalyst dispersion characterized by comprising a titanium oxide-based photocatalyst dispersed in a solvent, wherein said photocatalyst has an average particle diameter of at most 500 nm, wherein said titanium oxide-based photocatalyst is characterized by comprising a titanium oxide and an additional metal compound in titanium oxide; and developing a photocatalytic activity by irradiation with visible light, and wherein the additional metal compound comprising at least one metal halide. 
   
   
       27 . A method for the manufacture of a photocatalytic functional product characterized by depositing titanium oxide and/or its precursor on a surface of a substrate followed by bringing the surface into contact with a reactive medium containing a metal halide of the formula MX n  or MOX n  (wherein M=a metal, X=a halogen, and n=an integer). 
   
   
       28 . The method as set forth in  claim 27  which further includes subjecting the surface of the substrate to contact with water and/or heat treatment after the contact with the reactive medium. 
   
   
       29 . A The method as set forth in  claim 27  which further includes bringing the surface of the substrate into contact with a heteropoly acid and/or an isopoly acid after the contact with the reactive gas, or after subsequent contact with water and/or heat treatment. 
   
   
       30 . The method as set forth in  claim 15  wherein the heat treatment is carried out in a temperature range of 373-873 K. 
   
   
       31 . The method as set forth in  claim 14  wherein the metal halide is at least one compound selected from TiCl 4 , VOCl 3 , SnCl 4 , SbCl 5 , SiCl 4 , WCl 6 , and BiCl 3 . 
   
   
       32 . The method as set forth in  claim 31  wherein the metal halide is TiCl 4 . 
   
   
       33 . The method as set forth in  claim 14  which further includes subjecting the titanium oxide and/or its precursor or the substrate to heat treatment in a temperature range of 323-823 K or to wet processing prior to the contact with the reactive gas. 
   
   
       34 . The method as set forth in  claim 14  wherein the contact with the reactive gas is performed in a temperature range of 323-873 K. 
   
   
       35 . The method as set forth in  claim 14  wherein the reactive medium is gaseous and its base gas is a nonoxidizing gas. 
   
   
       36 . The method as set forth in  claim 35  wherein the base gas comprises hydrogen and/or nitrogen. 
   
   
       37 . The method as set forth in  claim 14  wherein the titanium oxide and/or its precursor is prepared via a step of neutralizing at least one compound selected from titanium tetrachloride, titanium sulfate, and titanyl sulfate with a nitrogen-containing base.