Method for synthesizing ammonia through electro-catalysis of nitrate or nitrite

A technology of nitrite and nitrate, applied in the field of electrocatalysis, can solve the problems of poor structural stability, poor selectivity, and overpotential, etc., and achieves the effects of stable structure, simple preparation process, and high-efficiency electrocatalysis.

Active Publication Date: 2021-11-12
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the electrocatalytic process of these metals or metal-doped materials in the prior art, the required applied overpotential is still high, the stability of the material structure is poor, and the selectivity (Ferrari efficiency) needs to be improved.

Method used

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  • Method for synthesizing ammonia through electro-catalysis of nitrate or nitrite
  • Method for synthesizing ammonia through electro-catalysis of nitrate or nitrite
  • Method for synthesizing ammonia through electro-catalysis of nitrate or nitrite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] Commercially purchased copper foam with a thickness of 0.5 cm, a width of 10 cm, and a length of 10 cm was ultrasonically cleaned in water, acetone, and ethanol for 30 min, respectively, and then dried. Then heat for a certain period of time in an air atmosphere at 80° C. to obtain a foamed copper-copper oxide catalytic electrode, and the content of copper oxide is controlled by the heating time. In this embodiment, the heating time is 40 minutes, and copper oxide accounts for 10%.

[0045] figure 1 It is a scanning electron micrograph of foamy copper-copper oxide. figure 2 The XPS ray energy spectrum confirmed that copper oxide was produced after heating.

[0046] The catalytic electrode cut according to the size of 2cm in length and width is used as the working electrode (cathode). In the three-electrode (counter electrode: nickel foam; reference electrode: Ag / AgCl electrode) system, the electrolyte is: 0.5mmol / L Aqueous solution of potassium nitrate. In the atmosp...

Embodiment 2

[0049] Replace the aqueous solution of 0.5mmol / L potassium nitrate with 0.1mol / L potassium nitrate and 0.1mol / L sodium nitrite aqueous solution of higher concentration, all the other are with embodiment 1. In the atmospheric environment, apply -0.15V (vs RHE) and test for 1800s.

[0050] Figure 5 It is the obtained i-t diagram, which shows that during the test, the catalytic electrode can obtain a relatively stable and high ammonia production current. The ammonia concentration in the electrolyte was tested by spectrophotometry, and the ammonia production rate was analyzed to be 1.24mmol h -1 cm -2 , the selectivity of electrochemical ammonia production is 98.9%.

Embodiment 3

[0052] Replace copper foam with metal copper sheet, all the other are the same as embodiment 1. In the atmospheric environment, apply -0.15V (vs RHE) to test for 1800s, Figure 6 In order to obtain current-time (i-t) and Figure 7 The graph (c-t) of corresponding ammonia and nitrite concentration and time shows that the current decreases with the decrease of nitrate concentration during the test, and the rate of ammonia production after analysis is 1.12mmolh -1 cm -2 , the selectivity of electrochemical ammonia production is 93.9%.

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Abstract

The invention discloses a method for synthesizing ammonia through electro-catalysis of nitrate or nitrite, an electro-catalyst adopted in the method is a metal-metal oxide, and the metal-metal oxide is used as a cathode or is loaded on the surface of a conductive material to serve as the cathode. The metal-metal oxide is selected from one or a combination of more of ruthenium-ruthenium oxide, copper-copper oxide, copper-cuprous oxide, nickel-nickel oxide, iron-ferric oxide, iron-ferrous oxide, iron-ferroferric oxide, cobalt-cobalt oxide, cobalt-cobaltosic oxide and zinc-zinc oxide. The catalytic electrode material provided by the invention is stable in structure and simple in preparation process, and can be effectively prepared in an amplified manner, so that the application of the catalytic electrode material in changing nitrate or nitrite-containing wastewater into valuable ammonia is realized. The catalytic electrode material provided by the invention can realize efficient electro-catalysis of reduction of nitrate or nitrite into ammonia, and has high selectivity.

Description

technical field [0001] The invention belongs to the technical field of electrocatalysis, and in particular relates to a method for electrocatalyzing nitrate or nitrite to synthesize ammonia. Background technique [0002] The use of nitrogen fertilizers such as ammonium nitrate and urea has contributed significantly to agricultural production over the past century. However, nitrogen use efficiency is usually less than 40%, so most of the nitrogen in fertilization is not absorbed into plants, but is easily leached from the soil into groundwater. Therefore, the concentration of nitrate or nitrite (NO 3- / NO 2- ). Causes serious environmental problems such as eutrophication in groundwater, rivers, lakes and coastal areas. [0003] In order to remove nitrate or nitrite in wastewater for denitrification and restoration of water environment, many efforts have been made, such as: biological method, ion exchange method and membrane separation, etc., but these methods often have h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25B1/27C25B1/50C25B11/091
CPCC25B1/27C25B1/50C25B11/091
Inventor 刘承斌唐艳红袁继理
Owner HUNAN UNIV
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