Copper Functioning as an Oxygen Carrier in Chemical Looping Combustion

1. Copper Functioning as an Oxygen Carrier in Chemical Looping Combustion Authors: Richard Baraki, Dr. Gabor Konya, Dr. Edward M. Eyring. Departments of: Chemistry and Chemical Engineering

2. Chemical Looping Combustion

3. Observed Oxygen Carrier • Copper • 2 Cu(s) + O2(g)↔ 2 CuO(s) http://gwydir.demon.co.uk/jo/minerals/pix/copper1.jpg

4. Method of Analysis • Thermogravimetric Analysis TA Q500 • ThermoFisher HP-TGA

5. Copper • Overall oxidation 2 Cu(s) + O2(g)↔ 2 CuO(s) • Cu → Cu(I) 4Cu(s) + O2(g)↔ 2Cu2O(s) • Cu(I) → Cu(II) 2Cu2O(s) + O2(g)↔ 4 CuO(s)

6. 2 days of looping (200+ loops) @ 850 °C

7. Looping

8. Cu(I) →Cu(II) Cu(I) →Cu(II) @ 850 °C Fitted Cu(I) →Cu(II) @ 850 °C

9. Residual plot Residual of Y, (mg) Independent Variable, (sec)

10. Pseudo first order equation • First-order reaction • r = -d[A]/dt = k[A] • k = rate constant • A = amount of copper • Pseudo first order reaction for • r = k[A][B]1/2 = k΄[A] • k = rate constant • k΄ = k[B]1/2 • A= amount of copper • B= partial pressure of oxygen

11. Method of fit y = Wf + (Wi - Wf) * e(-k * (t-t0)) • Fitted Parameters • Wf - final weight of oxide • Wi - initial weight of oxide • k- rate constant • Fixed Parameter • t0- indicates start of reaction

12. Shifting k values (TA-Q500)

13. Shifting k values (HP-TGA)

14. Cu2O/CuO/Cu2O system

15. Temperature effects • Sintering • Tamman Temperature

16. Pressure using HP-TGA • Pressure plots • 1 atm • 9 atm • 16atm • 25atm • Oxygen analyzer

17. Pseudo first order equation • First-order reaction • r = -d[A]/dt = k[A] • k = rate constant • A = amount of copper • Pseudo first order reaction for • r = k[A][B]1/2 = k΄[A] • k = rate constant • k΄ = k[B]1/2 • A= amount of copper • B= partial pressure of oxygen

18. Experimental Procedure • Sample loaded into quartz bucket • 200mg copper powder • Chamber closed and purged with pure nitrogen 15+ min • Temperature ramp from 21°C to 950°C in pure nitrogen gas at 25°C/min • Given experiment, pressure build up • At desired temperature and pressure, air is introduced

19. Observations • Stoichiometric conversion • Rate at which sample is being oxidized

20. Oxidation at different pressures Cu →CuO

21. Observations • Stoichiometric conversion

22. Oxidation at different pressures Cu →CuO

23. Observations • Stoichiometric conversion • Rate at which sample is being oxidized

24. Oxidation at different pressures Cu →CuO

25. Reaction Rates for Range of Mass Increases of 101 to 105%: Decrease in rate with increasing pressure indicative of diffusional limitations

26. Theoretical rates versus experimental rates based on the pseudo-first order model, to be revisited after experimental constraints eliminated Cu →CuO

27. Oxygen analyzer Gas cylinders HP-TGA

28. Oxygen concentrations at exit of reactor corresponding to HP-TGA plots previously shown. Failure to reach 21% to be explored Oxygen analysis of Cu →CuO Cu →CuO

29. Oxygen analysis of Cu →CuO

30. Conclusion • Pseudo first order model does not fit Cu/Cu2O/CuO system • Data indicate diffusional limitations

31. Acknowledgements • Department of Energy • under Award Number DE-NT0005015. • Dana Overacker • Kevin Tucker • Blake R. Wilde