Process for the Electrochemical Synthesis of Green Urea, an Electrochemical Cell for the Electrochemical Synthesis of Green Urea and the Green Urea Produced Thereby

Abstract

This invention relates to a process for the electrochemical synthesis of green urea, and the urea produced thereby. The electrochemical synthesis of urea involves the reduction of dual purging gases N2 and CO2 via six electron transfer process (N2+CO2+6H++6e−→CO (NH2)2+H2O) & reduction of the NO3− ions and CO2 via sixteen electron transfer process (2NO3−+CO2+18H++16e−→CO(NH2)2+7H2O) under ambient condition using copper phthalocyanine (CuPc) catalyst. The binding of two intermediate products during dual reduction simultaneously, leads to the production of urea in water medium under ambient conditions.

1 . A process for the electrochemical synthesis of green urea in an electrochemical cell, comprising an electrolyte and a three-electrode system, said three-electrode system comprising:
 a working electrode comprising carbon paper loaded with copper phthalocyanine (CuPc) catalyst ink,   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 subjecting a nitrogen source and carbon dioxide gas to produce green urea by electrocatalytic reduction.   
     
     
         2 . The process as claimed in  claim 1 , wherein the reference electrode is saturated with KCl. 
     
     
         3 . The process as claimed in  claim 1 , wherein said nitrogen source is selected from N 2  gas and ionic forms of nitrogen oxides (NO 2   −  and NO 3   − ). 
     
     
         4 . The process as claimed in  claim 3 , wherein when the nitrogen source is N 2 , N 2  gas is diffused into the electrolyte for electrocatalytic reduction. 
     
     
         5 . The process as claimed in  claim 2 , wherein when the nitrogen source is ionic forms of nitrogen oxides, the ionic forms of nitrogen oxides (NO 2   −  and NO −3 ) are present as the electrolyte. 
     
     
         6 . The process as claimed in  claim 1 , wherein the urea is green urea which is obtained from the electrolyte in liquid form. 
     
     
         7 . The process as claimed in  claim 1 , wherein during the reduction process, the rate of entry of nitrogen gas is 2-5 ml/min and carbon dioxide gas is 1-3 ml/min. 
     
     
         8 . The process as claimed in  claim 1 , wherein the electro-reduction is effected for a period ranging from about 1-3.5 hours. 
     
     
         9 . A process for the electrochemical synthesis of green urea in an electrochemical cell, comprising an electrolyte and a three-electrode system said three-electrode system comprising:
 a working electrode comprising carbon paper loaded with copper phthalocyanine (CuPc) catalyst ink,   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 purging nitrogen (N 2 ) and carbon dioxide (CO 2 ) gases into the electrolyte, followed by electro-reduction of the gases and combination of the electrocatalytic reduced products to produce green urea. 
     
     
         10 . A process for the electrochemical synthesis of urea in an electrochemical cell, comprising an electrolyte and a three-electrode system said three-electrode system comprising:
 a working electrode comprising carbon paper loaded with copper phthalocyanine (CuPc) catalyst ink,   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 providing the NO 2  and NO 3  ion containing nitrogen source as the electrolyte, purging carbon dioxide (CO 2 ) gas into the electrolyte solution, followed by electrocatalytic reduction of the ions and CO 2  gas, and combination of the electrocatalytic reduced products to produce green urea. 
     
     
         11 . An electrochemical cell for the electrochemical synthesis of green urea, 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 copper phthalocyanine (CuPc) catalyst ink 
 a reference electrode of silver/silver chloride (Ag/AgCl) saturated with potassium chloride (KCl); and 
 an auxiliary or counter electrode being a platinum wire; 
   said cathodic chamber comprising at least two inlets for the entry of gases and at least one outlet for the exit of gases therefrom.