Process for the Electrochemical Synthesis of Ammonia (NH3) and the Ammonia Produced Thereby

Abstract

This invention relates to a process for the electrochemical synthesis of ammonia (NH3) and the ammonia produced thereby. Ammonia is synthesized by the electrochemical reduction of nitrogenous materials such as nitrogen or nitrates (NO 3 - ) using metal phthalocyanine such as iron phthalocyanine (FePc) or β-cobalt phthalocyanine (CoPc) or iron phthalocyanine-molybdenum disulfide (FePc-MoS 2 ) or cobalt phthalocyanine- carbon nitride (CoPc-C 3 N 4 ) catalyst at very low pressure and room temperature by applying low potential.

1 . A process for the electrochemical synthesis of green ammonia in an electrochemical cell, comprising an electrolyte and a three-electrode system, said three-electrode system comprising:
 a working electrode loaded with an electrocatalyst selected from transition metal phthalocyanine and composites based on transition metal phthalocyanine,   a reference electrode of silver/silver chloride (Ag/AgCl) saturated with potassium chloride (KCl); and   an auxiliary or counter electrode being a platinum wire or foil;   the process comprising the steps of subjecting a nitrogen source to produce green ammonia by electrocatalytic reduction.   
     
     
         2 . The process as claimed in  claim 1 , wherein said nitrogen source is selected from nitrates (NO 3   -  ) and Nitrogen gas (N 2 ). 
     
     
         3 . The process as claimed in  claim 1 , wherein said working electrode is a glassy carbon electrode or a carbon paper. 
     
     
         4 . The process as claimed in  claim 1 , wherein the reference electrode is saturated with 3.5 M KCl. 
     
     
         5 . The process as claimed in  claim 1 , wherein when the nitrogen source is NO 3   - , the NO 3   -  is diffused into the catalyst surface for electrocatalytic reduction. 
     
     
         6 . The process as claimed in  claim 1 , wherein when the nitrogen source is N 2 , N 2  gas is diffused into the electrolyte for electrocatalytic reduction. 
     
     
         7 . The process as claimed in  claim 1 , wherein said transition metal catalyst is selected from nano-tubes and nano-rods. 
     
     
         8 . The process as claimed in  claim 1 , wherein said composite based on transition metal phthalocyanine comprises a composite of transition metal phthalocyanine and a compound selected from the disulfide and selenide of Molybdenum (Mo) and Tungsten (W), carbon nitride (C 3 N 4 ), boron nitride, graphene and Borophene. 
     
     
         9 . The process as claimed in  claim 8 , wherein said compound used in the composite is selected from molybdenum disulfide (MoS 2 ), molybdenum diselenide (MoSe 2 ), tungsten disulfide (WS 2 ), tungsten diselenide (WSe 2 ),), carbon nitride, boron nitride, reduced graphene oxide (RGO) and Borophene. 
     
     
         10 . The process as claimed in  claim 1 , wherein said transition metal phthalocyanine is selected from iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc), nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), chromium phthalocyanine (CrPc), manganese phthalocyanine (MnPc). 
     
     
         11 . The process as claimed in  claim 1 , wherein said composite is selected from FePc-MoS 2 , FePc-MoSe 2 , FePc-WS 2 , FePc-WSe 2 , CoPc-MoS 2 , CoPc-MoSe 2 , CoPc-WS 2 , CoPc-WSe 2 , NiPc-MoS 2 , NiPc-MoSe 2 , NiPc-WS 2 , NiPc-WSe 2 , CuPc-MoS 2 , CuPc-MoSe 2 , CuPc-WS 2 , CuPc-WSe 2 , CrPc-MoS 2 , CrPc-MoSe 2 , CrPc-WS 2 , CrPc-WSe 2 , MnPc-MoS 2 , MnPc-MoSe 2 , MnPc-WS 2 , MnPc-WSe 2 , FePc- C 3 N 4 , FePc-B 3 N 4 , FePc-RGO, FePc-Borophene, CoPc- C 3 N 4 , CoPc-B 3 N 4 , CoPc-RGO, CoPc-Borophene„ NiPc-C 3 N 4 , NiPc-B 3 N 4 , NiPc-RGO, NiPc-Borophene, CuPc- C 3 N 4 , CuPc-B 3 N 4 , CuPc-RGO, CuPc-Borophene, CrPc-C 3 N 4 , CrPc-B 3 N 4 , CrPc-RGO, CrPc-Borophene, MnPc-C 3 N 4 , MnPc-B 3 N 4 , MnPc-RGO and MnPc-Borophene. 
     
     
         12 . The process as claimed in  claim 1 , wherein the ammonia is green ammonia which is obtained from the electrolyte in liquid form. 
     
     
         13 . A process for the electrochemical synthesis of green ammonia by electroreduction of nitrate (NO 3   -  ) in an electrochemical cell, comprising an electrolyte and a three-electrode system, said three-electrode system comprising:
 a working electrode loaded with an electrocatalyst selected from transition metal phthalocyanine and composites based on transition metal phthalocyanine, 
 a reference electrode of silver/silver chloride (Ag/AgCl) saturated with potassium chloride (KCl); and 
 an auxiliary or counter electrode being a platinum foil; 
 
 the process comprising the steps of subjecting a nitrogen source to produce green ammonia by electrocatalytic reduction. 
 
     
     
         14 . The process as claimed in  claim 13 , wherein during the reduction process, the concentration of nitrate ion is 0.1-0.5 M. 
     
     
         15 . The process as claimed in  claim 13 , wherein the electro-reduction is effected for a period ranging from about 1-2 hours. 
     
     
         16 . A process for the electrochemical synthesis of green ammonia by electroreduction of nitrogen gas in an electrochemical cell, comprising an electrolyte and a three-electrode system, said three-electrode system comprising:
 a working electrode loaded with an electrocatalyst selected from transition metal phthalocyanine and composites based on transition metal phthalocyanine,,   a reference electrode of silver/silver chloride (Ag/AgCl) saturated with potassium chloride (KCl); and   an auxiliary or counter electrode being a platinum wire;   the process comprising the steps of subjecting a nitrogen source to produce green ammonia by electrocatalytic reduction.   
     
     
         17 . The process as claimed in  claim 16 , wherein during the reduction process, the rate of entry of nitrogen gas is 2-5 mL/min. 
     
     
         18 . The process as claimed in  claim 16 , wherein during the reduction process, nitrogen gas is purged in the cathode chamber. 
     
     
         19 . The process as claimed in  claim 16 , wherein the electro-reduction is effected for a period ranging from about 1-2 hours. 
     
     
         20 . The process as claimed in  claim 16 , wherein the electro-reduction is occurred in H-type cell as well as single cell. 
     
     
         21 . An electrochemical cell for the electrochemical synthesis of green ammonia, comprising an anodic chamber and a cathodic chamber in fluid connectivity with each other through a tubular structure configured to hold a membrane separating said anodic chamber and cathodic chamber,
 said anodic chamber and cathodic chamber being configured to comprise an electrolyte and a three-electrode system, said three-electrode system comprising,
 a working electrode comprising carbon paper loaded with iron phthalocyanine, iron phthalocyanine-molybdenum disulfide and cobalt phthalocyanine-carbon nitride 
 a reference electrode of silver/silver chloride (Ag/AgCl) saturated with potassium chloride (KCl); and 
 an auxiliary or counter electrode being a platinum wire. 
   
     
     
         22 . The system as claimed in  claim 20 , wherein the cathodic chamber and anodic chamber are separated by Nafion 117 membrane for H-type cell. 
     
     
         23 . The system as claimed in  claim 20 , wherein the cathodic chamber comprise at least one inlet for the entry of gases and at least one outlet for the exit of gases for nitrogen reduction to green ammonia. 
     
     
         24 . The process as claimed in  claim 20 , wherein the cathodic chamber comprises no inlets for the entry of gases and at least one outlet for the exit of gases for nitrate reduction to green ammonia.