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

Chemical Looping Combustion

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

Method of Analysis Thermogravimetric Analysis ThermoFisher HP-TGA TA Q500 ThermoFisher HP-TGA

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)

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

Looping

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

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

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΄ = k[B]1/2 A= amount of copper B= partial pressure of oxygen

Method of fit Fitted Parameters Fixed Parameter 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

Shifting k values (TA-Q500)

Shifting k values (HP-TGA)

Cu2O/CuO/Cu2O system

Temperature effects Sintering Tamman Temperature Change the pics here

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

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΄ = k[B]1/2 A= amount of copper B= partial pressure of oxygen

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

Observations Stoichiometric conversion Rate at which sample is being oxidized

Oxidation at different pressures Cu →CuO

Observations Stoichiometric conversion

Oxidation at different pressures Cu →CuO

Observations Stoichiometric conversion Rate at which sample is being oxidized

Oxidation at different pressures Cu →CuO

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

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

Oxygen analyzer Gas cylinders HP-TGA

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

Oxygen analysis of Cu →CuO

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

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