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Production of Hydrogen by Splitting of Water
The Copper-Chlorine Cycle
Liliana Trevani
Faculty of Science
UOIT
Outline
• Introduction
• Experimental Results
• Data Treatment: Thermodynamic Model
• Conclusions
• Future Work
Solubility of CuCl and CuCl2 in concentrated HCl solutions Complexation of Cu(I) and Cu(II) with Cl- in the same media Thermochemical data for concentrated HCl solutions Thermochemical properties of several copper-chloride compounds
To develop a practical engineering model for chemical and phase equilibrium calculations
OLI-MSE Model
Objective
Introduction
Heat
Abundant elements (Mg, Cu, Fe) Non toxic reactants or products Small number of reactions (3 to 5) Simple separation steps
H2O + H2(g) + ½ O2(g) Thermochemical Cycle
Gen.IV AECL
SCW reactor
The Cu-Cl Cycle
The Cu-Cl Cycle
• 2 CuCl (aq) + 2 HCl (aq) H2 (g) + 2 CuCl2 (aq) (electrolysis)
• 2 CuCl2 (s) + H2O (g) Cu2OCl2 (s) + 2 HCl (g) (350-400 oC)
• Cu2OCl2 (s) 2 CuCl (l) + ½ O2 (g) (530 oC)
The Cu-Cl Cycle
CuCl2(s) Cu2+(aq) + 2 Cl-(aq) Cu2+(aq) + n Cl-(aq) CuCln
2-n(aq)
CuCl (s) Cu+(aq) + Cl-(aq) Cu+(aq) + n Cl-(aq) CuCln
1-n(aq)
I- Solubility and complexation reactions
Cu2OCl2 (s)
III- Formation of metal oxychlorides (hydroxychlorides)
HCl (aq) HCl (g) H+(aq) + Cl-(aq) HCl(aq)
CuCl (aq) CuCl.nH2O (g) CuCl2(aq) CuCl2.nH2O (g)
II- Solubility in steam
Temperature + HCl concentration range
Highly corrosive conditions
Materials
Modeling chemical and phase equilibria requires data
x Cu+(aq) + y Cu2+(aq) + n Cl-(aq) CuxCuyCln3-n(aq) ?
Speciation Calculations
Types of data used in the model parameters regression
Speciation (pH, dissociation constant, etc) Water activity or osmotic coefficients
Vapor pressure (VLE)- Solubility (SLE) - Solubility (LLE) Enthalpy (dilH and mixH) - Heat capacity
Standard State Properties
HKF equation of state
Excess Properties
Model for concentrated Solutions
i i
o
i iRT m ln
Modeling the Cu-Cl System Requires data!!!
ai
Copper Complexation with Chloride
1/ T (K-1)
0.0020 0.0025 0.0030 0.0035lo
g K
(C
uC
l x2-x
)-8
-6
-4
-2
0
2 150oC 25 oC100oC
Trevani L., Ehlerova J., Sedlbauer J., and Tremaine P.R.,
Int. J. Hydrogen Energy, 96, 117-124, 2009.
Brugger, J.: BeerOz, a set of Matlab routines for quantitative
interpretation of spectrophotometric measurements of metal
speciation in solution. Computers & Geosciences 33: 248–261
(2007)
UV-Visible Spectroscopy Copper (II) Chloride Solutions
HCl
HCl increases
UV-Visible Spectroscopy Copper (II) Chloride Solutions
50 oC
20 oC
LiCl LiCl
HCl
Polynuclear copper complexes:
x Cu2+ (aq) + y Cl- (aq) CuxCly2x-y (aq)
Mixed complexes:
Cu+(aq) + Cu2+(aq) + 3 Cl- (aq) Cu2Cl3 (aq)
Speciation in Solution
Cu2+ (aq) + y Cl- (aq) CuCly2-y (aq) with y =0 and 4
Hydrolysis and Thermolysis Steps
• 2 CuCl (aq) + 2 HCl (aq) H2 (g) + 2 CuCl2 (aq) (electrolysis)
• 2 CuCl2 (s) + H2O (g) Cu2OCl2 (s) + 2 HCl (g) (350-400 oC)
• Cu2OCl2 (s) 2 CuCl (l) + ½ O2 (g) (530 oC)
Copper Oxychloride Standard
Cu2OCl2
Cu(OH)Cl
Heat Capacity Data as a Function of Temperature Heat of Formation Gibbs Energy of Formation
Powder XRD pattern of sample Al11 and ANL reference at 300 oC
d spacing
2 3 4 5 6
%
0
20
40
60
80
100
AL11
ANL2
Krivovichev et al.
Copper Chloride Compounds Raman Spectroscopy
Raman Shift / cm-1
32003250330033503400345035003550
Arb
itra
ry U
nits
0
20x103
40x103
60x103
CuCl
CuCl2 x 5
Empty vial x 10
Wet Aug10
Cu2OCl2 x 100
CuCl2. 2H2O
Raman Shift / cm-1
100200300400500600700800
Arb
itra
ry U
nits
0
10000
20000
30000
40000
50000
60000
CuCl
CuCl2 x10
Empty vial x 10
Wet Aug10
Cu2OCl2 x 100
CuCl2.2H2O
Conclusions Electrochemical step Experiments in HCl at 20 oC and 50 oC are completed.
New set of copper(II)-chloride complex formation constants will be available
soon.
Thermophysical data used in MSE regression have been collected and analyzed.
Hydrolysis and Thermolysis steps Copper oxychloride standard have been synthesized and characterized.
Possible reactions by-products have been identified.
Future Work
Experiments in HCl will be extended to CuCl and mixtures of CuCl/CuCl2.
Thermochemical characterization of copper oxychloride is underway.
A customized chemistry model will be developed.
o OLI-MSE model parameters will be improved using new experimental data to accurately reproduce the experimental results.
Acknowledgements
• Lin Yu
• Allan Nixon
• Dr. Jana Ehlerova (Tech. Univ. Liberec)
• Dr. Peter Tremaine (Univ. of Guelph)
• Dr. Josef Sedlbauer (Technical Univ. Liberec)
• Dr. Matthew Kaye (UOIT)
• Dr. Greg Naterer (UOIT)
Ministry of Research and Innovation Ontario Research Fund
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