Methods of preparing a catalyst and an electrolytic cell for use in synthesising ammonia, and methods of synthesising ammonia

Abstract

One aspect of the present invention is concerned with a method of preparing a catalyst for use in synthesizing ammonia from nitrate. The method has the steps of i) providing a nickel foam material, ii) removing an oxide layer on the nickel foam material, iii) subjecting the nickel foam material to cooper sulphate (Cu2SO4) solution for a predetermined period of time for forming a copper (Cu) dopped nickel foam electrode, and iv) subjecting the Cu dopped nickel foam electrode to an annealing treatment at a predetermined temperature for a predetermined period of annealing time in atmospheric air thus forming a catalyst of copper oxide-nickel oxide nickel foam (CuO/NiO@NF) with a heterostructure. Other aspects of the invention are concerned with a method of preparing an electrolytic cell for use in synthesizing of ammonia, and a method of synthesis of ammonia from nitrate.

What is claimed is: 
     
         1 . A method of preparing a catalyst for use in synthesizing ammonia from nitrate, comprising the steps of:
 providing a nickel foam material,   removing an oxide layer on the nickel foam material,   subjecting the nickel foam material to cooper sulphate (Cu2SO4) solution for a predetermined period of time for forming a copper (Cu) dopped nickel foam electrode, and   subjecting the Cu dopped nickel foam electrode to an annealing treatment at a predetermined temperature for a predetermined period of annealing time in atmospheric air thus forming a catalyst of copper oxide-nickel oxide nickel foam (CuO/NiO@NF) with a heterostructure.   
     
     
         2 . A method as claimed in  claim 1 , wherein the step of removing the nickel oxide (NiO X ) layer on the nickel foam material is achieved by sonicating the nickel foam material in an acid solution for a predetermined period of time. 
     
     
         3 . A method as claimed in  claim 2  wherein the acid solution is hydrochloric acid (HCl) solution, sulfuric acid (H2SO4) solution, or nitric acid (HNO3) solution, the concentration of the acid is 0.5-1 M, and the period of time of the sonicating is 5-10 minutes. 
     
     
         4 . A method as claimed in  claim 2 , comprising a step, after the step of removing the NiO X , of removal of residuals from the acid solution, wherein the residual removal is achieved by rinsing with acetone or water. 
     
     
         5 . A method as claimed in  claim 1 , wherein the Cu 2 SO 4  solution has a concentration of 40-60 mM but preferably 50 mM and the period of time is 30-40 minutes but preferably 30 minutes. 
     
     
         6 . A method as claimed in  claim 1 , wherein the predetermined temperature of the annealing temperature ranges from 300° C. to 600° C., or 300° C., 400° C., 500° C. or 600° C., and the predetermined annealing time is 30-60 mins. 
     
     
         7 . A method as claimed in  claim 6 , wherein the predetermined annealing temperature is 400° C. 
     
     
         8 . A method of preparing an electrolytic cell for use in synthesizing of ammonia, comprising a step of:
 providing the catalyst CuO/NiO@NF made according to a method as claimed in  claim 1 , a platinum foil, and a saturated Ag/AgCl electrode, wherein the catalyst CuO/NiO@NF, the platinum foil, and the saturated Ag/AgCl electrode act as a working electrode, a counter electrode, and a reference electrode, respectively in the electrolytic cell.   
     
     
         9 . A method as claimed in  claim 8 , wherein the catalyst CuO/NiO@NF is in the formation of a sheet and has a dimension of 1×1 cm. 
     
     
         10 . A method as claimed in  claim 8 , comprising a step of providing a sodium sulfate (Na 2 SO 4 ) solution as a catholyte and an anolyte of the electrolytic cell for use in a cathode chamber and an anode chamber of the electrolytic cell. 
     
     
         11 . A method as claimed in  claim 10 , wherein the concentration of the (Na 2 SO 4 ) solution is 0.5-1 M. 
     
     
         12 . A method as claimed in  claim 10 , comprising a step of providing a proton exchange membrane between the cathode chamber and an anode chamber of the electrolytic cell. 
     
     
         13 . A method as claimed in  claim 12 , wherein the proton exchange membrane is a Nafion® 117 membrane. 
     
     
         14 . A method of synthesis of ammonia from nitrate, comprising the steps of:
 providing an electrolytic cell made according to  claim 8 ,   prior to using the electrolytic cell, purging all solutions used in preparing the electrolytic cell preparation and the electrode preparation including the Na 2 SO 4  solution with pure nitrogen (N 2 ) gas for a predetermined period of purging time.   
     
     
         15 . A method as claimed  claim 14 , wherein the purging time is 10 mins. 
     
     
         16 . A method as claimed in  claim 15 , comprising a step of adding a source of nitrate (NO3) to the cathode chamber and allowing reaction to take place for generating ammonia (NH 3 ). 
     
     
         17 . A method as claimed in  claim 16 , comprising a step of collecting the generated ammonia (NH 3 ) from the cathode chamber.