Method of storing and delivering ammonia and the use of electromagnetic radiation for desorption of ammonia from a chemical complex
A method of storing and delivering ammonia and the use of electromagnetic radiation for desorption of ammonia from a chemical complex. Solid metal ammine complexes are applied for safe and high-density storage of ammonia to be released for use as reducing agent in selective catalytic reduction of NO x in exhaust gases. The compositional formula of the metal ammine complexes is M(NH 3 ) n X z , where M 2+ represents one or more metal ions capable of binding ammonia, X represents one or more anions, n is the coordination number (from 2 to 12), and z the valency of the metal ion (and thus the total number of compensating anion charges). Ammonia is released non-thermally by photon-activation using electromagnetic irradiation of the complex bond between ammonia coordinated to the metal ion.
1. A method of storing and delivering ammonia, said method comprising the steps of:
(a) providing a container;
(b) placing an ammonia containing material in said container, said ammonia containing material being a chemical complex in the form of an ionic salt of the general formula: M a (NH 3 ) n X z , wherein M is one or more cations selected from alkali metals, alkaline earth metals, Al and transition metals or combinations thereof, X is one or more anions selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulphate, molybdate and phosphate ions, a is the number of cations per salt molecule, z is the number of anions per salt molecule, and n is the coordination number of 2 to 12;
(c) irradiating said ammonia containing material with electromagnetic radiation having a wavelength or wavelengths in the infrared region between 1 and 15 micrometers for photon-activated release of ammonia to the gas phase, wherein the wavelength spectrum of said radiation is chosen to match one or several absorption peaks of said ammonia containing material; and
wherein the released ammonia is used in selective catalytic reduction of NOx in exhaust gases from combustion processes.
2. A method according to claim 1 , wherein the ammonia containing material is saturated with ammonia.
3. A method according to claim 1 , wherein the ionic salt is MgCl 2 , CaCl 2 , SrCl 2 or mixtures thereof.
4. A method according to claim 1 , wherein the ammonia containing material is compacted to a dense block, rod, cylinder ring or a cube.
5. A method according to claim 1 , wherein the radiation is emitted from one end of an elongated container.
6. A method according to claim 1 , wherein the radiation is emitted from a cylindrical source inside the container surrounded by ammonia storage material.
7. A method according to claim 1 , wherein the radiation is emitted from several surfaces of the container.
8. A method according to claim 1 , wherein the release of ammonia is controlled by valves.
9. A method according to claim 1 , wherein the released ammonia is used in NOx emission reduction from stationary or mobile combustion engines fuelled by fossil fuels.
10. The method of claim 9 , wherein the fossil fuel is selected from diesel, petrol, and natural gas.
11. The method according to claim 1 , wherein the released ammonia is used in NOx emission reduction from stationary or mobile combustion engines fuelled by synthetic fuels.
12. The method of claim 11 , wherein the synthetic fuel is selected from methanol, ethanol, hydrogen, methane, or ethane.
13. The method according to claim 1 , wherein the released ammonia is used in NOx emission reduction from stationary or mobile power plants fuelled by fossil fuels.
14. The method of claim 13 , wherein the fossil fuel is selected from coal or natural gas oil.
15. The method according to claim 1 , wherein the released ammonia is used in NOx emission reduction from stationary or mobile power plants fuelled by synthetic fuels.
16. The method of claim 15 , wherein the synthetic fuel is selected from methanol, ethanol, hydrogen, methane or ethane.