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