Production of Hydrogen by Splitting of Water The Copper-Chlorine Cycle

Transcription

1 Production of Hydrogen by Splitting of Water The Copper-Chlorine Cycle Liliana Trevani Faculty of Science

2 UOIT

3 Outline Introduction Experimental Results Data Treatment: Thermodynamic Model Conclusions Future Work

4 Objective To develop a practical engineering model for chemical and phase equilibrium calculations OLI-MSE Model Solubility of CuCl and CuCl 2 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

5 Introduction H 2 O + Heat Thermochemical Cycle H 2 (g) + ½ O 2 (g) Gen.IV AECL SCW reactor Abundant elements (Mg, Cu, Fe) Non toxic reactants or products Small number of reactions (3 to 5) Simple separation steps

6 The Cu-Cl Cycle

7 The Cu-Cl Cycle 2 CuCl (aq) + 2 HCl (aq) H 2 (g) + 2 CuCl 2 (aq) (electrolysis) 2 CuCl 2 (s) + H 2 O (g) Cu 2 OCl 2 (s) + 2 HCl (g) ( o C) Cu 2 OCl 2 (s) 2 CuCl (l) + ½ O 2 (g) (530 o C)

8 I- Solubility and complexation reactions The Cu-Cl Cycle CuCl 2 (s) Cu 2+ (aq) + 2 Cl - (aq) Cu 2+ (aq) + n Cl - (aq) CuCl n 2-n (aq) CuCl (s) Cu + (aq) + Cl - (aq) Cu + (aq) + n Cl - (aq) CuCl n 1-n (aq) x Cu + (aq) + y Cu 2+ (aq) + n Cl - (aq) Cu x Cu y Cl n 3-n (aq)? Modeling chemical and phase equilibria requires data Highly corrosive conditions II- Solubility in steam CuCl (aq) CuCl.nH 2 O (g) CuCl 2 (aq) CuCl 2.nH 2 O (g) HCl (aq) HCl (g) H + (aq) + Cl - (aq) HCl(aq) Materials Temperature + HCl concentration range III- Formation of metal oxychlorides (hydroxychlorides) Cu 2 OCl 2 (s)

9 Speciation Calculations o i i RT ln m i i Standard State Properties HKF equation of state a i Modeling the Cu-Cl System Requires data!!! Excess Properties Model for concentrated Solutions 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 ( dil H and mix H) - Heat capacity

10 Copper Complexation with Chloride o C 100 o C 25 o C log K (CuClx 2-x ) Brugger, J.: BeerOz, a set of Matlab routines for quantitative interpretation of spectrophotometric measurements of metal speciation in solution. Computers & Geosciences 33: (2007) / T (K -1 ) Trevani L., Ehlerova J., Sedlbauer J., and Tremaine P.R., Int. J. Hydrogen Energy, 96, , 2009.

11 UV-Visible Spectroscopy Copper (II) Chloride Solutions HCl HCl increases

12 UV-Visible Spectroscopy Copper (II) Chloride Solutions HCl 50 o C 20 o C LiCl LiCl

13 Speciation in Solution Polynuclear copper complexes: x Cu 2+ (aq) + y Cl - (aq) Cu x Cl 2x-y y (aq) Mixed complexes: Cu + (aq) + Cu 2+ (aq) + 3 Cl - (aq) Cu 2 Cl 3 (aq) Cu 2+ (aq) + y Cl - (aq) CuCl y 2-y (aq) with y =0 and 4

14 Hydrolysis and Thermolysis Steps 2 CuCl (aq) + 2 HCl (aq) H 2 (g) + 2 CuCl 2 (aq) (electrolysis) 2 CuCl 2 (s) + H 2 O (g) Cu 2 OCl 2 (s) + 2 HCl (g) ( o C) Cu 2 OCl 2 (s) 2 CuCl (l) + ½ O 2 (g) (530 o C)

15 Copper Oxychloride Standard Cu 2 OCl 2 Powder XRD pattern of sample Al11 and ANL reference at 300 o C Cu(OH)Cl AL11 ANL2 Krivovichev et al. Heat Capacity Data as a Function of Temperature Heat of Formation Gibbs Energy of Formation % d spacing

16 Copper Chloride Compounds Raman Spectroscopy Arbitrary Units CuCl CuCl2 x10 Empty vial x 10 Wet Aug10 Cu2OCl2 x 100 CuCl2.2H2O Arbitrary Units 60x x x10 3 CuCl CuCl2 x 5 Empty vial x 10 Wet Aug10 Cu2OCl2 x 100 CuCl2. 2H2O Raman Shift / cm -1 Raman Shift / cm -1

17 Conclusions Electrochemical step Experiments in HCl at 20 o C and 50 o C 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.

18 Future Work Experiments in HCl will be extended to CuCl and mixtures of CuCl/CuCl 2. 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.

19 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