Nitrogen fixation by titanium dioxide

Abstract

In various embodiments, the present disclosure provides a method of fixing nitrogen. An amount of titania catalyst is provided and contacted with a feed stream that includes nitrogen. The titania catalyst is heated. The heated titania catalyst fixes nitrogen in the feed stream to form nitrogen products, such as nitrates. The nitrogen products are then removed from the titania catalyst. In some examples, the titania catalyst is treated with a base. In further examples, the catalytic process is carried out in the absence of light for photochemically activating the titania catalyst.

What is claimed is: 
     
         1 . A nitrogen fixation method, comprising:
 providing an amount of titania catalyst;   contacting the titania catalyst with a feed stream comprising nitrogen;   heating the titania catalyst to fix nitrogen from the feed stream to form nitrogen products; and   removing the nitrogen products from the titania catalyst.   
     
     
         2 . The nitrogen fixation method of  claim 1 , wherein heating the catalyst comprises heating the catalyst at a temperature of between about 40° C. and about 600° C. 
     
     
         3 . The nitrogen fixation method of  claim 1 , wherein heating the catalyst comprises heating the catalyst at a temperature of between about 150° C. and about 350° C. 
     
     
         4 . The nitrogen fixation method of  claim 1 , wherein heating the catalyst comprises heating the catalyst at a temperature of between about 175° C. and about 275° C. 
     
     
         5 . The nitrogen fixation method of  claim 1 , further comprising treating the titania catalyst with a base. 
     
     
         6 . The nitrogen fixation method of  claim 1 , wherein heating the titania catalyst is carried out at least substantially in the absence of light for photochemically activating the titania catalyst. 
     
     
         7 . The nitrogen fixation method of  claim 1 , wherein heating the titania catalyst is carried out in a reactor, the reactor being at least substantially opaque. 
     
     
         8 . The nitrogen fixation method of  claim 1 , wherein heating the titania catalyst is carried out for an average time of at least about 2 hours. 
     
     
         9 . The nitrogen fixation method of  claim 1 , wherein heating the titania catalyst is carried out for an average time of at least about 4 hours. 
     
     
         10 . The nitrogen fixation method of  claim 1 , wherein heating the titania catalyst is carried out for an average time of at least about 6 hours. 
     
     
         11 . The nitrogen fixation method of  claim 1 , further comprising converting solar radiation into heat to heat the titania catalyst. 
     
     
         12 . The nitrogen fixation method of  claim 1 , further comprising enriching the feed stream in nitrogen. 
     
     
         13 . The nitrogen fixation method of  claim 1 , wherein removing nitrogen products from the titania catalyst comprises contacting the titania catalyst with water, the nitrogen products dissolving in the water. 
     
     
         14 . The nitrogen fixation method of  claim 13 , further comprising separating the water from the titania catalyst. 
     
     
         15 . The nitrogen fixation method of  claim 14 , further comprising removing the water to recover the nitrogen products. 
     
     
         16 . The nitrogen fixation method of  claim 13 , further comprising regenerating the separated titania catalyst. 
     
     
         17 . The nitrogen fixation method of  claim 1 , wherein the nitrogen products are formed in an amount proportional to the ratio of the surface area to the weight of the titania catalyst.