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Urea Electrolysis

Urea is the main component of human and livestock urine, as well as a key ingredient of fertilizers. There is, as a result, an abundance of urea-rich wastewater. If this wastewater is left untreated and then discharged into rivers, creeks, and lakes, the urea will naturally hydrolyze into pollutants such as ammonia and nitrates. 

In the Center for Electrochemical Engineering Research (CEER), a novel technology has been developed to directly convert urea to hydrogen using electricity (please see below): 

 

urea

Schematic representation of the direct urea to hydrogen process

Anode reaction:

CO(NH2)2 + 6OH- ----> N2 + 5H2O + CO2 + 6e-

Cathode reaction:

6H2O + 6e- -----> 3H2 + 6OH-

Overall reaction:

CO(NH2)2 + H2O -----> N2 + 3H2 + CO2

These reactions take place at room temperature and under normal pressure conditions. Theoretically, the cell voltage for the electrochemical conversion of urea to hydrogen is only 0.37 V, whereas water electrolysis, a popular electrochemical method to produce hydrogen, requires 1.23 V to split water into hydrogen and oxygen. Hydrogen gas produced from urea electrolysis does not require any further purification.

Advantages

  1. Raw material for urea electrolysis is urea-rich wastewater, which is readily available and abundant.

  2. This process consumes less energy than conventional steam methane reforming (SMR) and water electrolysis.

  3. Hydrogen gas produced from this process is pure and, as such, does not require further purification.

  4. In addition to producing hydrogen, urea electrolysis remediates wastewater.

  5. Urea electrolysis uses an inexpensive Nickel catalyst.

  6. This technology is operated at low temperatures (less than 60°C).

  7. Urea electrolysis is compatible with any renewable form of energy, such as solar and wind energy.

  8. This technology can be implemented in residential areas, farms, and industry.

Sponsors

  • Department of Defense through the U.S. Army Construction Engineering Research Laboratory

Publications

  1. Botte, G. G. Electrolytic Cells and Methods for the Production of Ammonia and Hydrogen. U.S. Pending Patent 12/250 864, 2007.
  2. B.K. Boggs, R.L. King and G.G. Botte, "Urea electrolysis: direct hydrogen production from urine," Chem. Commun., p4859 (2009)
  3. D.A. Daramola, D. Singh and G.G. Botte, "Dissociation Rates of Urea in the Presence of NiOOH Catalyst: A DFT Analysis," J. Phys. Chem. A, 114, p11513 (2010)
  4. R.L. King and G.G. Botte, "Hydrogen Production via Urea Electrolysis using a Gel Electrolyte," J. Power Sources 196, p2773 (2011)
  5. D. Wang, W. Yan and G.G. Botte, "Exfoliated nickel hydroxide nanosheets for urea electrolysis," Electrochem. Commun. 13, p1135 (2011)
  6. R.L. King and G.G. Botte, "Investigation of multi-metal catalysts for stable hydrogen production via urea electrolysis," J. Power Sources 196, p9579 (2011)
  7. W. Yan, D. Wang and G.G. Botte, "Nickel and cobalt bimetallic hydroxide catalysts for urea electro-oxidation," Electrochim. Acta 61, p25 (2012)