Nitrogen fixation by titanium dioxide
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.
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 at a temperature of between about 40° C. and about 600° C. to fix nitrogen from the feed stream to form oxidized nitrogen products; and
removing the oxidized nitrogen products from the titania catalyst, comprising contacting the titania catalyst with water, the nitrogen products dissolving in the water;
wherein heating the titania catalyst is carried out in the absence of light for photochemically activating 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 150° C. and about 350° C.
3. The nitrogen fixation method of claim 1 , wherein heating the catalyst comprises heating the catalyst at a temperature of between about 75° C. and about 600° 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 , wherein heating the titania catalyst is carried out in the presence of a base.
6. 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.
7. 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.
8. 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.
9. The nitrogen fixation method of claim 1 , further comprising converting solar radiation into heat to heat the titania catalyst.
10. The nitrogen fixation method of claim 1 , further comprising enriching the feed stream in nitrogen.
11. The nitrogen fixation method of claim 1 , further comprising separating the water from the titania catalyst.
12. The nitrogen fixation method of claim 11 , further comprising removing the water to recover the nitrogen products.
13. The nitrogen fixation method of claim 11 , further comprising regenerating the separated titania catalyst.
14. 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.
15. The nitrogen fixation method of claim 1 , wherein the oxidized nitrogen products comprise nitrates or nitrites.