Solid ammonia storage and delivery material

Abstract

A solid ammonia storage and delivery material A solid ammonia storage material comprising: an ammonia absorbing salt, wherein the ammonia absorbing salt is an ionic salt of the general formula: M a (NH 3 ) n X z , wherein M is one or more cations selected from alkaline earth metals, and/or one or more transition metals, such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions, a is the number of cations per salt molecule, z is the number of anions per salt molecule, and ri is the coordination number of 2 to 12, wherein M is Mg provides a safe, light-weight and cheap compact storage for ammonia to be used in the automotive industry.

1 . A solid ammonia storage and delivery material capable of absorption/desorption of ammonia and comprising:
 an ammonia absorbing salt, wherein the ammonia absorbing salt is an ionic salt of the general formula:
   M a (NH 3 ) n X z , 
   
       wherein M is one or more cations selected from alkaline earth metals, and/or one or more transition metals, such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions, 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, wherein M is Mg, and wherein the ammonia storage and delivery material has been saturated with ammonia and compressed to a density of 0.9 to 1.3 g/cm 3  and a bulk density above 70% of the skeleton density. 
     
     
         2 . A solid ammonia storage material as claimed in  claim 1  wherein the anion is selected from fluoride, chloride, bromide, iodide, nitrate, thiocyanate, sulphate, molybdate, and phosphate ions. 
     
     
         3 . A solid ammonia storage material as claimed in  claim 2  wherein the anion is the chloride. 
     
     
         4 . A solid ammonia storage material as claimed in  claim 3  wherein the salt is Mg(NH 3 ) 6 Cl 2 . 
     
     
         5 . A solid ammonia storage material as claimed in  claim 1 , wherein the solid storage material has a density of 0.9 to 1.3 g/cm 3 . 
     
     
         6 . A solid ammonia storage material as claimed in  claim 1 , wherein the solid storage material has a density of 1.1 to 1.3 g/cm 3 . 
     
     
         7 . A solid ammonia storage material as claimed in  claim 1 , wherein the solid storage material has bulk density above 85% of the skeleton density. 
     
     
         8 . A method of producing a solid ammonia storage material capable of absorption/desorption of ammonia and comprising:
 an ammonia absorbing salt, wherein the ammonia absorbing salt is an ionic salt of the general formula:
   M a (NH 3 ) n X z , 
   
       wherein M is one or more cations selected from alkaline earth metals, and/or one or more transition metals, such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions, 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, said method comprising the steps of
 1) providing the solid salt, 
 2) saturating the salt fully with ammonia, and 
 3) compressing the saturated ammonia salt complex to a bulk density above 70% of the skeleton density. 
 
     
     
         9 . A method as claimed in  claim 8 , wherein the ammonia salt complex is compressed to a bulk density above 80% of the skeleton density. 
     
     
         10 . A method as claimed in  claim 9 , wherein the ammonia salt complex is compressed to a bulk density above 85% of the skeleton density. 
     
     
         11 . A method for selective catalytic NO x  reduction in waste gases containing oxygen, using ammonia and a reduction catalyst wherein gaseous ammonia is provided by heating a solid storage medium capable of absorption/desorption of ammonia and comprising one or more ionic ammonia absorbing salts of the general formula:
   M a (NH 3 ) n X z ,   
       wherein M is one or more cations selected from alkaline earth metals, and transition metals such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions such as chloride or sulphate 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, wherein M is Mg, wherein the ammonia storage and delivery material has been saturated with ammonia and compressed to a bulk density above 70% of the skeleton density and wherein the release rate of ammonia is controlled in consideration of the content of NO x  in the waste gases. 
     
     
         12 . A method for selective catalatic reduction (SCR) of NO x  in exhaust gases from combustion processes comprising contacting an exhaust gase with a solid ammonia storage material capable of absorption/desorption of ammonia and comprising:
 an ammonia absorbing salt, wherein the ammonia absorbing salt is an ionic salt of the general formula:
   M a (NH 3 ) n X z , 
   
       wherein M is one or more cations selected from alkaline earth metals, and transition metals such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions such as chloride or sulphate 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, wherein M is Mg and wherein the ammonia storage and delivery material has been saturated with ammonia and compressed to a bulk density above 70% of the skeleton density as a source of ammonia as the reducing agent in selective catalytic reduction (SCR) of NO x  in exhaust gases from combustion processes. 
     
     
         13 . An ammonia delivery device comprising a container comprising
 an ammonia absorbing salt capable of absorption/desorption of ammonia, wherein the ammonia absorbing salt is an ionic salt of the general formula:
   M a (NH 3 ) n X z , 
   
       wherein M is one or more cations selected from alkaline earth metals, and/or one or more transition metals, such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions, 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, wherein M is Mg and wherein the ammonia storage and delivery material has been saturated with ammonia and compressed to a bulk density above 70% of the skeleton density, said container being provided with one or more closable outlet opening(s) connected to a pipe and further being provided with means for heating the container and the ammonia absorbing salt for release of gaseous ammonia. 
     
     
         14 . An ammonia delivery device as claimed in  claim 13 , wherein the closure of the closable outlet opening(s) is (are) in the form of one or more valve(s). 
     
     
         15 . An ammonia delivery device as claimed in  claim 13 , wherein the heating means is in the form of an electrical resistive heating device. 
     
     
         16 . An ammonia delivery device as claimed in  claim 13 , wherein said means for heating is provided by a heat produced by chemical reactions. 
     
     
         17 . An ammonia delivery device as claimed in  claim 13 , wherein the release rate of ammonia is controlled by accurate control of the heating of the container and the ammonia absorbing salt for release of gaseous ammonia. 
     
     
         18 . An ammonia delivery device as claimed in  claim 13 , where the release of ammonia is further controlled by reduction valves, flow controllers or similar. 
     
     
         19 . A method for selective catalytic reduction (SCR) of NO x  in exhaust gases from combustion processes comprising contacting an exhaust gase with an ammonia delivery device comprising a container comprising an ammonia absorbing salt capable of absorption/desorption of ammonia, wherein the ammonia absorbing salt is an ionic salt of the general formula:
   M a (NH 3 ) n X z ,   
       wherein M is one or more cations selected from alkaline earth metals, and/or one or more transition metals, such as Mn, Fe, Co, Ni, Cu, and/or Zn, X is one or more anions, 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, wherein M is Mg and wherein the ammonia storage and delivery material has been saturated with ammonia and compressed to a bulk density above 70% of the skeleton density, said container being provided with one or more closable outlet opening(s) connected to a pipe and further being provided with means for heating the container and the ammonia absorbing salt for release of gaseous ammonia as a source for ammonia in selective catalytic reduction of NO x  in exhaust gases from combustion processes. 
     
     
         20 . A solid ammonia storage and delivery material capable of absorption/desorption of ammonia and comprising:
 an ammonia absorbing salt, wherein the ammonia absorbing salt is 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, and transition metals such as Li, Na, K, Cs, Mg, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn or combinations thereof such as NaAl, KAl, K 2 Zn, CsCu, or K 2 Fe, 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, said storage and delivery material having been saturated with ammonia and compressed to a bulk density above 70% of the skeleton density and a density of 0.9 to 1.3 g/cm 3 . 
     
     
         21 . A solid ammonia storage material as claimed in  claim 20 , wherein the solid storage material has a density of 1.1 to 1.3 g/cm 3 .