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Towards integration of hydrolysis, decomposition andelectrolysis processes of the CueCl thermochemicalwater splitting cycle

Z. Wang*, V.N. Daggupati, G. Marin, K. Pope, Y. Xiong, E. Secnik, G.F. Naterer, K.S. Gabriel

Clean Energy Research Laboratory, Faculty of Engineering and Applied Science, University of Ontario Institute of Technology,

2000 Simcoe Street North, Oshawa, Ontario, Canada L1H 7K4

a r t i c l e i n f o

Article history:

Received 11 October 2011

Received in revised form

22 February 2012

Accepted 28 February 2012

Available online 28 April 2012

Keywords:

Thermochemical hydrogen

production

CueCl cycle

Process integration

* Corresponding author. Tel.: þ1 9057218668.E-mail addresses: [email protected],

uoit.ca (G. Marin), [email protected] (K. Pop(G.F. Naterer), [email protected] (K.S. G0360-3199/$ e see front matter Copyright ªdoi:10.1016/j.ijhydene.2012.02.172

a b s t r a c t

The thermochemical copperechlorine (CueCl) cycle is a promising technology that can

utilize various energy sources such as nuclear and solar energy to produce hydrogen with

minimal or no emissions of greenhouse gases. Past investigations have primarily focused

on the design and testing of individual unit operations of the CueCl cycle. This paper

investigates the chemical streams flowing through each individual process from the aspect

of system integration. The interactions between each of the two immediate upstream and

downstream processes are examined. Considering the integration of electrolytic hydrogen

production and cupric chloride hydrolysis steps, it is evident that an intermediate step to

concentrate CuCl2 and reduce HCl composition is required. Spray drying and crystalliza-

tion, serving as the intermediate steps, are examined from the aspects of energy require-

ments and viability of engineering. Regarding the integration of the hydrolysis and oxygen

production steps, thermodynamic and XRD analysis results are presented to study the

mutual impacts of these two steps on each other. Within the hydrolysis reactor, high

conversion of CuCl2 to Cu2OCl2 is preferable for the integration because it reduces the

release of chlorine gas during the oxygen production. Considering the integration of the

oxygen production step and electrolysis of CuCl, pulverization is needed for the solidified

CuCl. The recovery of CuCl vapour entrained in oxygen gas requires further research.

Residual CuCl2 introduced from the hydrolysis step into the oxygen production step may be

further entrained by CuCl into the electrolytic hydrogen production cell. Additionally,

thermal energy integration patterns are briefly discussed while integrating the various

chemical streams of the CueCl cycle. Steam generated from the heat recovery of cuprous

chloride can be introduced into the hydrolysis reactor to serve as a reactant.

Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights

reserved.

[email protected] (Z. Wang), [email protected] (V.N. Daggupati), gabriel.marin@e), [email protected] (Y. Xiong), [email protected] (E. Secnik), [email protected]).2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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i n t e rn a t i o n a l j o u r n a l o f h y d r o g e n en e r g y 3 7 ( 2 0 1 2 ) 1 6 5 5 7e1 6 5 6 916558

1. Introduction

It is becoming increasingly urgent to reduce greenhouse gas

(GHG) emissions and at the same time meet the growing

demand for a sustainable future of energy supply. Engineers

and scientists have developed innovative solutions, such as

solar, nuclear, hydroelectric, wind, and geothermal energy, to

meet the targets. Currently, electrical power grids are the

primary methods to distribute these energy forms to various

end users. However, some energy generation methods, such

as solar and wind energy, are intermittent with unstable and

highly variable power output. Sunlight is unavailable at night

and the irradiance magnitude varies monthly and seasonally.

For other energy forms, such as nuclear and geothermal, the

electricity output needs to follow the power demand on the

future power grid in order to reduce the portion of fossil fuel

based electricity on the grid. The power demand on the grid

varies on an hourly basis during the day. Therefore, it is

important to find a medium that can store and distribute the

intermittent and off-peak energy, hence reducing the “peaks

and valleys” to help achieve the demand following profile.

Hydrogen production at the intermittent and off-peak hours is

a promising option [1] because hydrogen has a higher energy

density than fossil fuels and its oxidization does not emit

GHGs [2].

Engineers and scientists have developed many technol-

ogies to produce hydrogen from clean energy. For example,

electrolysis utilizes electricity as the major input energy

form to split water, and thermochemical cycles utilize

thermal energy as the primary input form. Due to the

energy losses with electrolysis in the conversion of thermal

energy to electricity, thermochemical cycles have attracted

growing interest. Approximately 200 thermochemical

cycles of thermal water splitting that utilize various heat

sources have been reported previously [3]. Among these

cycles, the sulfureiodine (SeI) cycle is a leading example of

exclusively thermal cycles that has been scaled up from

proof-of-principle tests to a larger engineering scale facility

by the Japan Atomic Energy Agency (JAEA [4]). General

Atomics (GA [5]) developed an SeI hydrogen production

cycle capable of producing 2 kg of hydrogen per day.

Commissariat a l’energie atomique (CEA [6]) and the Sandia

National Laboratory (SNL [7]) have also extensively exam-

ined sulfur-based cycles. However, the minimum temper-

ature requirement of the SeI cycle is 850 �C, which can be

achieved by a very limited number of heat sources. Even the

temperatures of some Generation IV nuclear reactors, e.g.,

Table 1 e Chemical reactions of the copperechlorine cycle.

Reaction Process and heat flow

A Electrolysis for hydrogen production

B Hydrolysis of cupric chloride, endothermic

C Oxygen production, endothermic

Summation of all reactions

Symbols: aq, aqueous; g, gas; l, liquid; Q, heat; s, solid; VE, electricity.

supercritical water-cooled nuclear reactors [8], cannot

provide high enough temperatures.

In recent years, the copperechlorine (CueCl) cycle has

gained more attention due to its lower temperature require-

ment of 530 �C, which is about 300 �C lower than the SeI cycle.

The chemical reactions of the CueCl cycle are listed in Table 1.

Proof-of-principle experiments for each internal process have

been performed [9e11]. The experimental results have been

reported for most of the processes of the CueCl cycle, and

large laboratory scale reactors for the processes have been

tested successfully at UOIT (University of Ontario Institute of

Technology, Canada) [27]. Although the summation of the

reactions shown in Table 1 can form a closed cycle, most of

the past studies focused on individual reactors rather than an

integrated CueCl cycle with a holistic approach. Few past

studies have examined the mutual impacts between

upstream and downstream reactions.

This paper will present thermodynamic and experimental

studies of the interactions within the integrated system. This

paper will mainly discuss the engineering challenges and

solutions from the perspectives of chemical stream flows,

heat requirements and required processes. Other aspects

such as capital cost, economics, system hierarchy, process

control systems, and equipment materials will not be

considered in this paper. In particular, the chemical streams

across the boundaries between two contiguous steps of the

CueCl cycle will be quantified. The limitations and obstacles

to integration of current technologies for the various reactions

are analyzed for the system integration. The primary equip-

ment needed to process the chemical streams and facilitate

effective system integration is examined as well. The thermal

energy management aspects will also be discussed in the

paper.

2. Process integration of various reactions

2.1. Matching the chemical streams of electrolytichydrogen production and hydrolysis steps

As presented in Table 1, it can be observed that the output

stream from the electrolytic cell (reaction A) is an aqueous

solution of CuCl2, i.e., dissolved CuCl2 in water, which in

principle can directly provide water as the reactant for the

downstream hydrolysis step (reaction B). Since the tempera-

ture of the hydrolysis reaction is above 350 �C, the CuCl2 and

water reactants in the hydrolysis reaction can only exist in the

Major reaction

2CuCl (aq)þ 2HCl (aq)þVE¼H2 (g)þ 2CuCl2 (aq) in aqueous

solution, at 30e80 �C2CuCl2 (s)þH2O (g)þQ¼Cu2OCl2 (s)þ 2HCl (g), at 350e400 �CCu2OCl2 (s)þQ¼ 2CuCl (molten)þ 0.5O2 (g), at 500e530 �CH2O (l)¼H2 (g)þ 1/2O2 (g) (net reaction)



i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n en e r g y 3 7 ( 2 0 1 2 ) 1 6 5 5 7e1 6 5 6 9 16559

form of solid and steam, respectively. To match the chemical

streams, the water in the aqueous solution must be evapo-

rated and then regulated to a favorable operating range

required by the hydrolysis reactor. Therefore, the following

three key questions must be answered for the process inte-

gration: (1) can the flow rate and chemical composition

leaving the electrolytic cell match the input requirements of

a hydrolysis reactor? (2) What magnitude of thermal energy

is required to evaporate the excess water? (3) should the

water be evaporated in the hydrolysis reactor? Since it is

water and cupric chloride streams that cross the boundary of

the two reactors, it is also convenient to reference their ratio,

i.e., the molar ratio of water-to-cupric chloride [9,13,14]. The

minimum water-to-cupric chloride ratio of the aqueous

solution leaving the electrolytic cell occurs at the saturation

state of solubility. The actual ratio is determined by the

operating concentrations of the electrolysis reaction. Consid-

ering the minimum ratio required by the hydrolysis reaction,

it is the stoichiometric ratio, i.e., 0.5. The actual ratio that can

be accommodated by the hydrolysis reactor is determined

from the expected conversion of CuCl2 to Cu2OCl2.

Fig. 1 illustrates amajor difference between the electrolytic

cell output stream and the required hydrolysis input. Table 2

presents the quantitative details of the differences. In Table 2,

the thermodynamic minimum ratio of water to CuCl2 in the

electrolytic cell occurs when all dissolved CuCl is fully

oxidized to CuCl2 at the anode side and all available protons

(Hþ) eventually move to the cathode side. The minimum

water-to-cupric chloride ratio for the downstream hydrolysis

process is 0.5, which is the same as the stoichiometric value.

Fig. 2 illustrates the equilibrium concentration of HCl for

the hydrolysis reaction in the temperature range below 700 �Cat the water-to-cupric chloride ratio of 0.5 and the total

system pressure of 1 bar (absolute). The equilibrium concen-

tration of HCl is calculated from the standard Gibbs energy of

the hydrolysis reaction, which is based on the standard Gibbs

formation energy of the products and reactants. Since the

specific heat used for the calculation of the standard Gibbs

formation energy of Cu2OCl2 has not been reported for above

400 �C [12], there are some discrepancies in the reported

values. Fig. 2 adopts extrapolation and sensitivity analysis for

the influence of the specific heat (�30%) on the Gibbs free

Fig. 1 e Gap between the output streams of the electrolytic cell

hydrolysis reactor.

energy of the hydrolysis reaction. Fig. 2 suggests that the

increase of the conversion of both CuCl2 and steam comes at

the cost of a temperature increase, which means that the

steam fraction in the products depends strongly on the

operating temperature of the hydrolysis reaction. To reach

a full conversion of CuCl2 to Cu2OCl2 at temperatures lower

than 400 �C, excess steam is needed, or the producedHClmust

be removed immediately to create a non-equilibrium condi-

tion. Another option for lowering the excess steam quantity is

to reduce the systemoperating pressure to below atmospheric

pressure, but thismay increase the challenge of reactor seal to

avoid the air entering the hydrolysis reactor.

In regards to the matching of the water-to-cupric chloride

ratio between hydrolysis and electrolysis, Table 2 shows that

the minimum output water-to-cupric chloride ratio of an

electrolytic cell is 7.5, which is 15 times the stoichiometric

requirement of hydrolysis. Also, in actual operation, it may be

very challenging for all of the protons to move to the cathode

side in the electrolytic cell, and HCl is also needed in order to

dissolve the reactant CuCl. Thus, there is still a concentration

of HCl at the anode side and the output stream is a ternary

system, assuming all CuCl is fully converted to CuCl2 on the

anode side. As a consequence, the water-to-cupric chloride

ratio in the hydrolysis reaction may exceed the thermody-

namic minimum value in practical operation, and HCl may

enter the hydrolysis reactor. Table 2 presents the water-to-

cupric chloride ratio considering the existence of HCl in the

output stream of the electrolytic cell versus the input

requirement of hydrolysis in proof-of-principle tests. It can be

found that the output water-to-copper chloride ratio of elec-

trolysis lies in the range of 17e34, which is 2e5 times the 7

required by hydrolysis. Practically, the output stream of the

electrolytic cell is more likely to be a quaternary system con-

sisting of water, CuCl2, HCl and CuCl due to the incomplete

conversion of CuCl. Table 2 also considers this situationwhere

the output water-to-copper ratio of the electrolysis increases

to the range of 55e270, which is 8e39 times the 7 required by

hydrolysis. Therefore, at least 2e5 times the stoichiometric

surpluswatermust be separated from the output stream of an

electrolytic cell to effectively integrate the electrolysis and

hydrolysis reactors if the electrolysis output stream directly

supplies the hydrolysis reactor. Otherwise, additional thermal

and the input streams that can be accommodated by the



0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500 600 700

Temperature of hydrolysis reaction, o

C

HC

l fra

ctio

n in

th

e H

Cl-

ste

am

mix

tu

re

, %

reported andextrapolated Cp+ 30% Cp

- 30% Cp

Fig. 2 e Equilibrium concentration of HCl in the hydrolysis

reaction with sensitivity analysis of specific heat of

Cu2OCl2 (steam/copper ratio[ 0.5, stoichiometric; total

system pressure[ 1 bar abs).

Table 2 e Output streams from an electrolytic cell and required input streams to hydrolysis reactor.

Operating parameters Output chemical streamsof electrolytic cell

Magnitude Input chemical streams that canbe accommodated by hydrolysis

Binary system Limit in thermodynamics (all Hþ

goes to cathode and CuCl is fully

converted to CuCl2)

Limit in thermodynamicsa

Water/CuCl2 molar ratio 7.5 (minimum) � 0.5

CuCl2, M 7.3 (maximum) N/A

T, �C 80 350e400

Ternary system Limit in ideal operation for CuCl

conversionc

(CuCl is fully converted to CuCl2)

Limit in proof-of-principle testsb



HCl, M 5.3 (maximum) <30% 7.4 (maximum)

T, �C 25 350e400



HCl, M 7.3 (maximum) z 7.4 (maximum)

T, �C 25 350e400

Water/CuCl2, molar ratio 33.5 (minimum) � 7.0


HCl, M 11.8 (maximum) � 7.4 (maximum)

T, �C 25 350e400

Quaternary system Values in small lab-scale operations

(CuCl is fully converted to CuCl2)

Limit in proof-of-principle testsd

Water/CuCl2 molar ratio 55e270 � 7.0

CuCl2, M 0.2e1.0 N/A

HCl, M 6.0e11.0 Close or > 7.4 (maximum)

CuCl, M 0.2e2.0 Not known

T, �C 25 350e400

a The input minimum water-to-copper ratio is the stoichiometric value.

b The input minimum water-to-copper ratio was based on the proof-of-principle results of a fixed/fluidized bed and spray reactor [9,13,14].

c The output water-to-copper ratio was based on the 72-hour runtime data of a proof-of-principle electrolytic cell [10,11].

d The concentration of HCl in the hydrolysis product in this table is converted to an aqueous solution assuming the gaseous products are

condensed to an aqueous solution in order to be comparable with the input stream from the electrolytic cell.


energy must be utilized to evaporate the water to steam. This

may reduce the thermal efficiency of the proposed CueCl

cycle.

Fig. 3 illustrates the heat transfer requirements of

a hydrolysis reactor if all required water is evaporated in the

reactor. When the water-to-cupric chloride ratio exceeds 1.5,

i.e., 3 times the stoichiometric requirement, the evaporation

heat requirement of water will exceed the reaction enthalpy.

As a consequence, the hydrolysis reactor will function more

like a steam generator. It is unclear whether the excess steam

requirement of hydrolysis is caused by thermodynamic or

kinetic limits. However, the water-to-cupric chloride ratio is

recommended to be below the transition point 1.5, so that the

heat transfer rate to the hydrolysis reactor is primarily

directed to the reaction enthalpy. Another option is to utilize

a separate steam generator. This can more readily control the

water-to-cupric chloride ratio to be close to the stoichiometric

value and provide more flexibility for the selection of reactor

types, because other intake forms of CuCl2, such as solid

powder and slurry, can be introduced into the hydrolysis



0

10

20

30

40

50

60

70

0.0 0.5 1.0 1.5 2.0water/CuCl2, molar ratio

Evaporation of water

Reaction Enthalpy

Assumptions: (1) All water is evaporated in the hydrolysis reactor.(2) Heat transfer efficiency is 100%.(3) Hydrogen production scale is 100 tonnes/day.

Fig. 3 e Comparative roles of reaction enthalpy and water

evaporation in the hydrolysis reactor.


reactor. In addition, external water such as make-up water of

the CueCl cycle, rather than the water from the electrolytic

cell, can also be utilized. This will be studied in a later section

of this paper about the thermal energy integration. In

summary, it is crucial to reduce the water requirement of the

hydrolysis input stream.

Further consideration of the existence of large amounts

of HCl in the output stream of the electrolytic cell renders

the process integration more complicated. Table 2 presents

the minimum concentration of HCl in the output stream of

the electrolytic cell. In actual operations it lies in the range

of 5.3e11.0 M, which is very close or beyond the maximum

HCl concentration (7.4 M shown in Table 2) that can be effec-

tively produced in current experimental hydrolysis reactors

[9,13,14].

The maximum value of 7.4 M for the HCl concentration

was calculated from the minimum steam-to-cupric chloride

ratio of 7 that has been approached in proof-of-principle

tests in hydrolysis reactors [9,13,14]. Assuming there are no

side reactions competing with hydrolysis, then the molar

concentration of HCl in the gaseous product mixture of HCl

and H2O satisfies the following equation due to the stoichio-

metric mass balance of the hydrolysis reaction:

CM ¼ 2=ð2RSCu þ 1Þ (1)

where CM is the molar concentration of HCl in the gaseous

product mixture and RSCu is the molar ratio of steam to cupric

chloride. After the gas mixture is condensed to an aqueous

solution of HCl, CM still represents the molar concentration.

From the reported densities of HCl aqueous solutions at

different molar concentrations of HCl [15e17], the molarity of

HCl then corresponds to the steam-to-cupric chloride ratio.

Table 3 shows the correspondence.When the steam-to-cupric

chloride ratio is 7, the maximum HCl concentration is

approximately 7.4 M. Table 3 also shows that when the

hydrolysis reaction approaches thermodynamic equilibrium

at 375 �C, and if the specific heat is 30% lower than the

measured value, as shown in Fig. 2, then themolar percentage

of HCl in the gas mixture is approximately 23% or about 12 M

in the aqueous solution. With these assumptions,

a thermodynamic lower bound of the steam-to-cupric chlo-

ride ratio of 3.8 can be calculated. Furthermore, it is unlikely

that the specific heat is in excess of 30% below measured

values, thus the hydrolysis reactor is limited to provide

a concentration below 12 M into the electrolytic cell.

A higher HCl concentration leaving the electrolytic cell than

the hydrolysis reactor suggests that the hydrolysis reaction

may not occur and integrating the chemical streams is infea-

sible if HCl in the input streamof the hydrolysis is not removed

or the HCl concentration is not significantly reduced before

entering the hydrolysis reactor. This means an intermediate

HCl separator may be required for the integration of an elec-

trolytic cell and hydrolysis reactor. In regards to the HCl

produced from the hydrolysis reactor, it serves as the reactant

for electrolysis. However, as shown in Table 2 and Fig. 1, the

output concentration of HCl from hydrolysis is close or even

smaller than the input requirement of electrolysis, which

suggests an intermediateHCl concentratormaybeneeded.The

maximumvalue of HCl concentration in the hydrolysis reactor

is determined by the equilibrium constant which indicates the

minimum water-to-cupric chloride ratio. As discussed previ-

ously, it is unclearwhether themaximumvalueof 7.4 M for the

inputstreamofhydrolysis in theproof-of-principle is causedby

challenges of reaction kinetics or thermodynamic limits.

Therefore, accurate data for the equilibrium constant of the

hydrolysis reaction has a vital role in determiningwhether the

quaternaryoutput streamof electrolysis canbedirectlyusedas

the input stream of a hydrolysis reactor, and whether the

gaseous product from the hydrolysis reactor can be directly

utilized as an input to the electrolytic cell.

The existence of CuCl in the output stream from an elec-

trolysis reactor is another challenge of integrating with

a hydrolysis reactor. The potential chemical poisoning effect

of CuCl on hydrolysis has not been reported. However, the

presence of CuCl mixed with CuCl2 particles may reduce the

contact between steam and CuCl2 and increase the heat

transfer resistance. Therefore, it is preferable that all CuCl is

converted to CuCl2 on the anode side of the electrolytic cell or

separated fromCuCl2 before it enters a hydrolysis reactor. The

most efficientway to reduce the concentration of CuCl and the

ratio of water to CuCl2 may be to produce oversaturated CuCl2on the anode side allowing CuCl2 to precipitate on the anode

side, forming a slurry to be fed into the hydrolysis reactor.

2.2. Concentrating CuCl2 for the linkage of electrolytichydrogen production and hydrolysis steps

As discussed previously, the water-to-cupric chloride ratio in

the output stream of electrolysis is larger than required by

hydrolysis. The CuCl2 must be concentrated before it enters

the hydrolysis reactor. Currently, spray drying and crystalli-

zation are under investigation at UOIT for concentrating the

CuCl2. In spray drying, all or a portion of water is evaporated

with a drying medium. The minimum energy quantity

required by the spray drying can also be estimated by Fig. 3.

The required heat input can be below 120 �C so that waste

heat from many sources can be utilized. However, in order to

utilize low grade waste heat, the thermal efficiency is sacri-

ficed. Table 4 summarizes the large lab-scale experimental

results from UOIT and the estimates for industrial hydrogen



Table 3 e Steam-to-cupric chloride ratio and concentrations of HCl in the mixture of HCl and H2O before and aftercondensation.

Steam-to-cupricchloride molarratio (RSCu), mol/mol

Molar percentageof HCl in the gasmixture (CM), %

Molar ratio of HClto steam, mol/mol

Concentration of HCl in its aqueoussolution after condensation (molarity), M

0 �C 20 �C 100 �C

201.3 0.5 0.0050 0.28 0.27 0.26

99.9 1.0 0.010 0.55 0.55 0.53

49.2 2.0 0.021 1.12 1.12 1.07

32.3 3.1 0.032 1.70 1.69 1.63

23.8 4.1 0.043 2.28 2.27 2.19

18.8 5.2 0.055 2.88 2.87 2.76

15.4 6.3 0.067 3.50 3.48 3.35

13.0 7.4 0.080 4.12 4.09 3.95

11.1 8.6 0.094 4.76 4.72 4.55

9.7 9.8 0.108 5.40 5.36 5.17

8.6 11.0 0.123 6.06 6.02 5.79

7.7 12.2 0.139 6.74 6.68 6.43

6.9a 13.5 0.156 7.42 7.36 7.08

6.3 14.8 0.173 8.12 8.04 7.73

5.7 16.1 0.192 8.83 8.74 8.39

5.2 17.4 0.211 9.54 9.45 9.07

4.8 18.8 0.232 10.31 10.16 9.75

4.4 20.3 0.254 11.06 10.89 10.45

4.1 21.7 0.277 11.82 11.63 11.15

3.8 23.2b 0.302 12.60 12.37 11.86

a The minimum molar ratio of steam to cupric chloride is 7 in reported reactors [9,13,14].

b If the actual specific heat is 30% lower than the measured value, as shown in Fig. 2, then the molar percentage of HCl in the gas mixture is

approximately 23% when the hydrolysis reaction approaches thermodynamic equilibrium at 375 �C.


production scales in terms of the processing scales of water

evaporation, heat load, and drying air. Due to the lower cost of

air, Table 4 only presents the results for air, although in

principle theworking gases such as nitrogen and heliumother

than air can also be utilized for drying to avoid the chemical

effects with oxygen.

It was found in the experiments that the heat requirement

of spray drying with air is 3e5 times the water evaporation

energy requirement shown in Fig. 3 for complete drying of the

aqueous solution of CuCl2. Although the heat input can be low

grade waste heat as experimentally examined in UOIT, the

heat transfer may require large dimensions or numbers of

heat exchangers. In addition, the drying air requirement is

also large. The experimental results at UOIT show that the

mass ratio of air to water is usually higher than 8 in order to

completely evaporate the water with air below 120 �C.Another challenge of utilizing spray drying is the recovery

of HCl from the drying air. As previously discussed, the

output stream of the electrolytic cell is a quaternary system

with HCl that must be recycled back into the CueCl cycle to

Table 4 e Requirements of heat, water and drying air for conce

H2 productionscale, tonnes/dayb

Molar ratio of waterto copper, mole/mole

Mass ratio of dryair to water,a kg

Large lab scale 0.001 17.7 8e20

Industrial scale 100 17.7 8e20

a The inlet drying air temperature is 80e120 �C and the outlet temperatu

b The runtime of the large lab-scale experiments lies in the range of 1e5

replenish the chemicals used in the cycle. Also, the water in

the drying air should also be recycled to limit water

consumption. This means the usage of spray drying will

require a number of additional processing units of equipment

for the recovery of water and HCl, in addition to heat

exchangers for the drying air to capture thermal energy from

various heat sources.

Another technology for concentrating the CuCl2 is crys-

tallization, which utilizes the solubility difference of CuCl2 at

different temperatures. The CuCl2 crystals precipitated out of

the saturated binary system of CuCl2 and water, as demon-

strated at UOIT. A significant advantage of using crystalliza-

tion is its extensivematurity for commercialmanufacturing of

hydrated CuCl2 [18], either from the chlorination of Cu by Cl2or the reaction between CuO and HCl. The recovery of CuCl2from spent etchant was also reported [19]. Therefore, tech-

nical solutions can be found from commercially available

technology. In an industrial process, a cooling bath environ-

ment created by ice and inorganic salts such as NaCl and CaCl2can expedite the crystallization kinetics and increase the

ntrating CuCl2 with spray drying.

ing/kg

Water evaporated,tonnes/day

Heat needed,MWth

Drying air flowrate, tonnes/day

0.319 0.018e0.030 3.19e6.38

31,900 1800e3000 319,000e638,000

re is 50e80 �C.h. The data were normalized to units per day for a comparable basis.



Fig. 4 e CuCl2 particles generated from spray drying (air-to-

water mass ratio is 8 and air temperature is 120 �C).


crystal quantity by cooling the solution below 0 �C. Also, theCuCl2 aqueous solution is at a saturation state before starting

the crystallization process.

However, the energy penalty may become significant if

adopting a cooling process below the ambient temperature. To

study the cooling with a coolant at both ambient and lower

temperatures, experiments were performed for two temper-

ature drops at 80 to 22 �C and 20 to 0 �C. Fig. 5a and b shows the

dendritic crystals of hydrated CuCl2 precipitated out of an

experimental aqueous solution in the clear solution and out of

the solution, respectively. The coolants in the experiments for

the crystallization were room temperature water and

a mixture of water and ice. Experimental results showed that

60e90% of the available quantities corresponding to the

solubility difference precipitated out in four hours when the

coolant was applied to the binary system. It was also found

that before the CuCl2 solution was cooled to 33 �C, no crystals

were observed. Subsequently, CuCl2 crystals appeared rapidly

in several minutes to 60e90%. Then another two days were

required to precipitate the residual 5e10% of the quantities

accounted for by the solubility difference.

It is encouraging that CuCl2 can be precipitated out of the

aqueous solution with a coolant of ambient temperature for

the temperature drop of 80e22 �C. However, in two hours of

runtime, the crystallized quantity is only about 60% of the

total mass with the temperature drop of 80e0 �C. In addition,

a complete crystallization to reach equilibriumneeds a total of

about two days. To overcome this lengthy time challenge, the

dimensions of the crystallizer must be large enough to match

the CuCl2 feed rate required by the downstream hydrolysis

reactor, or alternatively an intermediate storage unit may be

needed.

The usage of crystallization discussed above is only suit-

able for CuCl2 solutions at the saturation state of either the

exiting stream of the electrolytic cell or after it is cooled down.

In practical operation, the exiting stream of the electrolytic

cell of the CueCl cycle may not be at the saturation state. To

utilize crystallization, the aqueous CuCl2 solution must be

saturated by some means, for example, the saturation can be

created by introducing another reagent such as HCl to satu-

rate the CuCl2. For the quaternary system of CuCl2, CuCl, HCl

and water, the saturation curve of CuCl2 is complex. A future

study on the crystallization could investigate a quaternary

system that can utilize room temperature coolant or inert

additives.

The crystallization is promising for the separation of CuCl2from a saturated binary system because of the advantages

over spray drying, wherein heat extraction from a heat source,

drying air processing, and equipment for the recovery of

additional HCl and water in the drying air are not needed with

crystallization. A filtration process can be adopted for the

separation of crystallized CuCl2 and a clear solution, which

has been tested at UOIT. The clear solution exiting the crys-

tallizer can be directly pumped back to the upstream elec-

trolyzer for reuse or for dissolution of incoming CuCl

produced in an oxygen production reactor. The energy cost of

a filtration process is primarily based on water pumping and

mechanical discharge of the slurry of hydrated CuCl2. If one

assumes the same energy cost for the discharge and pro-

cessing of solid CuCl2 in spray drying, similar power to move

and pressurize drying gas, and pump and atomize the CuCl2aqueous solution, it is expected that the crystallization can

save a significant portion of the amount of thermal energy

otherwise used for the evaporation of water in spray drying.

Compared to crystallization, the advantages of spray

drying include its ability to generate anhydrous CuCl2, but the

CuCl2 crystallized may comprise several hydrated water

molecules, i.e., CuCl2$nH2O. Consequently, the value for the

water-to-cupric chloride ratio could be larger than 2 in crys-

tallization. As to the particle size of CuCl2, it is unclear

whether smaller or larger particle sizes are more advanta-

geous. Spray drying can generate fine particles in the range of

4e50 microns and the Sauter mean value is about 31 microns

when the drying air temperature is about 120 �C and the air-

to-water mass ratio is 8e20. Fig. 4 shows the dimensions of

the particles generated from spray drying. Fig. 5a and b shows

the dimensions and structure of the crystals of hydrated

CuCl2. The length of the crystal that stems and branches can

be several millimeters to centimeters. Considering integration

with the downstream hydrolysis reaction, smaller particle

sizes may improve the hydrolysis reaction rate. However,

smaller particles are more readily entrained in a gas stream,

imposing limits on the hydrolysis reactor selection. For

example, the smaller particle size may reduce the operating

range of the steam flow rate in a fluidized bed because the

steam may carry large amounts of CuCl2 particles outside of

the reactor.

2.3. Matching the chemical streams of hydrolysis andoxygen production reactions

Fig. 6 summarizes the chemical streams of hydrolysis and

oxygen production reactions from a system integration

approach. In the hydrolysis reaction, the CuCl2 reacts with

steam producing solid Cu2OCl2 and gaseous HCl. If CuCl2 is in



Fig. 5 e (a) Dendritic crystals (CuCl2$2H2O) generated from

crystallization in clear solution (temperature decreases

from 80 to 20 �C and the minimum scale of the ruler is

mm). (b) Dendritic crystals (CuCl2$2H2O) generated from

crystallization after clear solution is removed.


the form of solid particles, then the reaction is a reactant

shrinking core process wherein the size of CuCl2 reactant core

is decreasing while the thickness of the product crust

(Cu2OCl2) outside of the core is increasing. This suggests the

Fig. 6 e Chemical stream connection of the h

possibility of a simultaneous partial decomposition of the

product Cu2OCl2 when it is produced. As shown in reaction C

of Table 1, the decomposition of the Cu2OCl2 crust produces

oxygen. In addition, the core composed of CuCl2 may

decompose to CuCl and Cl2 because of the continuous heating

but insufficient contact with steam for the hydrolysis reaction.

Consequently, the undesirable gaseous products, i.e., O2 and

Cl2, will mix with the desirable product HCl to form the output

gas steam of the hydrolysis reactor. As discussed in the

previous section, HCl is utilized in the electrolytic cell for the

production of H2. Therefore, introducing O2 and Cl2 into the

electrolyzer must be avoided and any O2 and Cl2 produced in

the hydrolysis reaction should be removed before entering the

electrolytic cell, or they are not produced in the hydrolysis

reactor.

The Deacon reaction may also be another important

undesirable side reaction producing Cl2 in the hydrolysis

reaction [20]. The reaction takes place at above 400 �C if

catalyzed by CuCl2, which has been used to produce Cl2 in

industry: 4HCl (g)þO2 (g)/ 2Cl2 (g)þ 2H2O (g). To avoid the

production of O2 and Cl2, the operating conditions must lie in

a spontaneous range for the hydrolysis of CuCl2 and mean-

while in the non-spontaneous range for the Deacon reaction,

and the decomposition of Cu2OCl2 and CuCl2. The spontaneity

of the reactions can be estimated with the Gibbs energy

change. Fig. 7 shows the standard Gibbs energy change of the

reactions at various temperatures. The Gibbs energy of

Cu2OCl2 was calculated from the specific heat, standard

enthalpy and conventional entropy of Cu2OCl2 [12]. The data

for HCl, CuCl, CuCl2, H2O, Cl2 and O2 are taken from the

databank of NIST [21]. It can be found that the spontaneity

transitional temperatures of the CuCl2 hydrolysis and Cu2OCl2decomposition have a gap of 60 �C, which provides a large gap

for the adjustment of the operating temperature, so as to

avoid the decomposition of the product Cu2OCl2 in the

hydrolysis reactor.

However, the adjustment gap for the avoidance of CuCl2decomposition ismuch smaller, whichmeans othermeasures

must be adopted in order to minimize the Cl2 release. The

thermodynamic spontaneity of the decomposition of CuCl2

ydrolysis and oxygen production steps.



-40

-20

0

20

40

60

80

0 100 200 300 400 500 600 700

Temperature, o

C

Stan

dard

G

ib

bs en

erg

y o

f reactio

ns, kJ/m

ol

Fig. 7 e Thermodynamic spontaneity of hydrolysis and

side reactions.

Table 5 e Chlorine gas generated in an oxygen productionreactor from the unreacted CuCl2 in a hydrolysis reactor.

T (reactor),�C

P (reactor),kPa

Test time,minutes

Weight ofsample,a

grams

Cl2/O2,mole/mole

560 99.99 70 79.58 0.056

547 99.99 70 79.58 0.0595

516 99.99 75 79.68 0.0410

506 99.99 80 79.55 0.0389

491 99.99 70 79.42 0.0500

489 99.99 90 106.99 0.1545

a The sample is an equimolar mixture of CuO and CuCl2.


and Cu2OCl2 is also shown in Fig. 7. It was found that the

production of Cl2 is difficult to avoid. The experiments of UOIT

also verified the thermodynamic analysis. An option is to

significantly differentiate the reaction kinetics so that the

hydrolysis proceeds much faster than the side reaction. For

example, the mixing of steam and CuCl2 can be improved by

adjusting some operating parameters such as particle size and

void fraction (the ratio of voids to particles) in the reactor to

improve the contact between steam and CuCl2. The steam

must diffuse into the core of the solid phase to reactwithCuCl2in the particle. If the steam diffusion rate was lower than the

CuCl2 decomposition rate, the side reaction would occur.

If further considering the solid products in a hydrolysis

reactor, the Cu2OCl2 crust will exist and encapsulate the

unreacted CuCl2 in the hydrolysis reaction. The crust also

creates obstacles to achieving full conversion of CuCl2 to

Cu2OCl2 because contact between the reactants CuCl2 and

steam is reduced, regardless of the steam-to-cupric chloride

ratio and the yield of HCl. The steam must penetrate the

product crust to reach CuCl2 to continue the reaction. If the

residence time of the solid particles does not cover the diffu-

sion time, then the full conversion of CuCl2 will not be ach-

ieved. As a consequence, the unreacted CuCl2 will be carried

with Cu2OCl2 to the downstreamO2 production reactor. When

the decomposition of Cu2OCl2 proceeds to produce O2, the

entrained CuCl2 may also decompose to produce Cl2, which is

carried with O2 leaving the CueCl cycle. The production of Cl2will offset the mass balance of the CueCl cycle that should

only have two output gases: H2 and O2.

Another option is to introduce some amount of Cl2 into the

hydrolysis reaction to sequestrate Cl2 production in the

decomposition of CuCl2. Thismethod can also sequestrate the

Deacon reaction. Since the solubility of Cl2 in water is much

smaller than HCl, the introduced Cl2 can be collected from

gaseous products of the hydrolysis reactor when the products

are condensed to form aqueous solution of HCl for use in the

downstream electrolytic hydrogen production reactor.

As presented in Table 5, the molar ratio of produced Cl2 to

O2 is about 0.04e0.16 in the oxygen production reactor if 50%

of the CuCl2 is not consumed in the upstream hydrolysis

reactor. In Table 5, an equimolar mixture of CuCl2 and CuO

was utilized rather than Cu2OCl2, anticipating that the CuO

would react with the released Cl2 in order to quantify the

minimum chlorine release for the CueCl cycle. If the mixture

is CuCl2 and Cu2OCl2, more Cl2 will be released. Therefore,

improving the conversion of CuCl2 in the hydrolysis reactor is

the preferable method to reduce the Cl2 release in the down-

stream oxygen production reactor.

It is preferable that the Cl2 formation is controlled below

a minimal level. The target of the current research at UOIT is

to utilize Cl2 to oxidize the counterpart of CuCl produced by

the decomposition of CuCl2. This can restore themass balance

of desirable compounds consisting of Cu and Cl elements

within the CueCl cycle. Then the solubility of Cl2 in the

aqueous solution of CuCl and HCl determines the total level of

Cl2 produced from the Deacon reaction and decomposition of

CuCl2. It was reported that the Cl2 solubility in the aqueous

chloride solution at 90 �C is approximately equivalent

to 0.5 gCl2/kgH2O or 1.3� 10�4 mol Cl2/mol H2O [22e24].

Assuming the steam-to-cupric chloride ratio is operated at the

minimum thermodynamic limit at 375 �C, then according to

Table 3, the HCl-to-steam ratio in the gaseous productmixture

is approximately 0.3. Thus, each mole of HCl produced per

mole CuCl2 will have 3.3 moles residual water mixed with the

HCl. If utilizing the condensed water to dissolve Cl2, then the

Cl2 amount is 3.9� 10�4 moles. This implies the Cl2 produced

from the Deacon reaction and CuCl2 decomposition should be

controlled to be 3e4 orders smaller than the concentration of

HCl in the hydrolysis reaction.

2.4. Matching the chemical streams of oxygenproduction and electrolytic steps

One of the chemical input streams to the electrolytic cell is

CuCl, which is produced in the upstream oxygen production

reactor. However, the CuCl produced in the oxygen production

reactor is in the form of molten salt at about 500 �C. So

auxiliary equipment is needed to solidify the CuCl and then

dissolve it in an aqueous solution of HCl. The HCl needed by

the dissolution of CuCl is produced from the hydrolysis

reactor, so the integration between the oxygen production

reactor and electrolysis must also consider the connection

with hydrolysis as well. Fig. 8 shows the chemical streams

that connect the three steps. As discussed previously, the

undesirable Cl2 gas produced from the hydrolysis reactor

must be removed from HCl before entering the CuCl



Fig. 8 e Chemical streams connecting the oxygen production and electrolytic steps.


dissolution vessel. To improve the dissolution rate, it is pref-

erable that the solidified CuCl is in the form of particles or

pellets. Also, the unreacted CuCl2 in the hydrolysis reactor

may enter the oxygen production reactor and influence its

output stream that serves as the input stream of the electro-

lytic cell. It was experimentally determined that the unreacted

CuCl2 does not completely decompose in the oxygen reactor.

Fig. 9 shows the XRD results of the decomposition. It can be

found that some amounts of CuCl2 are still present in the CuCl

Fig. 9 e XRD results of the residual of CuCl2 in the s

produced from the decomposition of Cu2OCl2. Since CuCl is

utilized in the electrolytic cell, the entrained CuCl2 will enter

the electrolytic cell.

There exists an alternative reaction to produce oxygen

with the mixture of CuO and CuCl2 rather than the single

compound Cu2OCl2 [25,26]:

CuO (s)þCuCl2 (s)¼ 2CuCl (molten)þ 1/2O2 (g), at

500e530 �C (2)

olidified CuCl (reaction time of 1 h, T[ 500 �C).




Since the mixing of CuO and CuCl2 is not ideal for the full

reaction, the following decomposition reaction will consume

a portion of CuCl2 before it reacts with CuO:

CuCl2¼CuClþ 1/2Cl2, at 300 �C and higher temperatures (3)

Consequently, there will be some unreacted CuO in the

oxygen production reaction, which was observed in past

experiments [25]. Since the unreacted CuO is distributed

within the molten CuCl product, it will be carried by CuCl into

the electrolytic cell, wherein CuO will react with HCl:

CuO (s)þ 2HCl (aq)¼ 2CuCl2 (aq)þ 2H2O (l) (4)

The consumption of HCl in reaction (4) will reduce the HCl

amount for the hydrogen production, in addition to the

introduction of undesirable excess CuCl2. Therefore, consid-

ering the substance balance for the process integration,

reaction (2) is not recommended for the oxygen production

process in the CueCl cycle.

The influence of the entrained CuCl2 on the electrolysis is

unclear, but entrained CuCl2 will have insignificant influence

on the solidification, granulation and dissolution of CuCl

because these auxiliary steps are physical and not chemical

processes. Conversely, it may even assist the percolation of

the CuCl pellets due to the high solubility of the entrained

CuCl2.

When oxygen leaves the reactor, the vapour of molten

CuCl will be entrained. Table 6 presents the CuCl vapour

pressure [28] and the quantity of CuCl entrained with oxygen

gas at various hydrogen production scales and operating

temperatures. The loss of CuCl will accumulate significantly

to several tonnes per day if the entrained CuCl is not recov-

ered. Therefore, the CuCl vapour must be recycled within the

cycle. One option is to condense the CuCl vapour when

cooling the oxygen for storage and then collect the

condensed CuCl into a dissolution vessel for the integration

of the oxygen production reactor and electrolytic cell. The

disadvantage of this option is the potential clogging of

condensed CuCl in the oxygen cooling equipment. Currently,

UOIT is examining the absorption of CuCl vapour with solid

Cu2OCl2 or CuCl2 particles. In the absorption process, oxygen

and CuCl vapour passes through an absorption bed packed

with Cu2OCl2 particles produced from the hydrolysis reactor.

Since the particle temperature is around 375 �C and the

condensation point of CuCl is 425 �C, it is expected the CuCl

Table 6 e Loss of CuCl in vapour entrained with oxygengas if the vapour is not recovered.

T,�C

Vapourpressure,

kPa

Operating pressure ofoxygen reactor, kPa

Mass loss of CuCl,tonnes/day

100tonnesH2/day

200tonnesH2/day

500 0.066 101.325 1.6 3.2

530 0.122 101.325 3.0 6.0

546 0.166 101.325 4.1 8.2

vapour can be condensed onto the surface of Cu2OCl2 parti-

cles that will decompose to CuCl and O2 in the downstream

O2 production reactor. This process can also recover the

condensation heat of CuCl and a portion of sensible heat

carried by the high temperature O2. Though CuCl2 can also be

used as the absorption reagent, it may experience decom-

position due to high local temperatures in the absorption

bed.

3. Thermal energy requirements for thesystem integration

Since two of the three chemical reactions of the CueCl cycle

shown in Table 1 are purely thermal reactions, the patterns

to integrate the processes will be strongly influenced by the

heat flows. The integration patterns will influence the overall

thermal efficiency of the hydrogen production cycle. There-

fore, the thermal energy integration patterns must aim to

recover as much thermal energy as possible which is inter-

nally released from the exothermic processes of the CueCl

cycle, while simultaneously utilizing minimum external heat

input. Regarding the integration of external heat flows within

the CueCl cycle, the studies at UOIT suggest a single heating

route for the heating fluid, where it initially passes through

the maximum temperature step, i.e., oxygen production

reaction at 530 �C, and then flows to the hydrolysis step

which requires a heat input at 375 �C. After leaving the CueCl

cycle, the heating fluid flows back to the thermal energy

source to complete the circulation. Multiple routes, such as

separate heating lines for the oxygen production and

hydrolysis steps, are not suggested so as to avoid the layout

complexity of the heat transport lines and increase the heat

usage efficiency.

Regarding the recovery of the internally released heat,

Table 7 shows the quality and quantity of input and output

heat flows for each process on the basis of stoichiometric

coefficients, i.e., the steam-to-cupric chloride ratio is 0.5 for

hydrolysis. Table 7 also shows the heat requirement consid-

ering the possible excess steam requirement of the hydrolysis

reaction. It can be found that there are three sources of heat

released from the exothermic processes: cooling the HCl

produced from hydrolysis (process B4), cooling the O2 (process

C3) and solidifying the CuCl (process C4) produced from the

oxygen production reactor. In processes C3 and C4, the heat

released has a temperature of 530 �C, which is 155 �C higher

than the hydrolysis temperature requirement of 375 �C. Thereleased heat quantity (82.71 kJ/mol) can cover the generation

of the stoichiometric steam requirement (60.5 kJ). If utilizing

the heat released in process B4 (22.38 kJ/mol) for the water

preheating and the heat released from processes C3 and C4 for

the generation of steam, the heat recovery efficiency is about

60%. A study at UOIT suggested that released heat from the

exothermic processeswould not be used to heat solid particles

due to lower efficiency than a heating fluid. Table 7 shows that

if excess steam is required, then the heat recovery load will be

increased significantly to the same magnitude as shown in

Fig. 3, indicating the vital importance of reducing the excess

steam requirement of the hydrolysis reactor.



Table 7 e Input and output heat flows in each process on the basis of stoichiometric coefficients (water-to-cupric chlorideratio in hydrolysis is 0.5) and excess steam requirement.

Label Processes in the step T, �C Heat input,kJ/mol H2

Heat output,kJ/mol H2

B 2CuCl2 (s)þH2O (g)¼CuOCuCl2 (s)þ 2HCl (g), hydrolysis step

B1 Heating CuCl2 (s) 25/375 62.70

B2 Heat of reaction 375 80.80

B3 Steam production H2O (l)¼H2O (g) 25/375 60.50

B3Xa Steam production 34.4 (l)¼ 34.4 H2O (g) 25/375 2081

B4 2HCl (g, 450 �C)/ 2HCl (g, 25 �C) 375/25 22.38

B4Xa Steam production 33.4 (l)¼ 33.4 H2O (g) 375/25 2021

C Cu2OCl2 (s)/ 2CuCl (l)þ 1/2O2 (g), oxygen production step

C1 Heating Cu2OCl2 (s) 375/530 20.20

C2 Heat of reaction 530 138.39

C3 Cooling, solidification of molten CuCl 530/25 74.74 Sum: 82.71

C4 Cooling of O2 (g) product 530/25 7.97

Total For production of 1 mole H2 362.59 105.09

For production of 100 tonnes H2/day 210 MWth 61 MWth

For production of 200 tonnes H2/day 420 MWth 122 MWth

a The steam-to-copper ratio is 17.7, i.e., steam is in excess of the stoichiometric ratio of 0.5.


4. Conclusions

This paper studied the CueCl cycle from the perspective of

system integration. Thermodynamic analysis and experi-

mental results were reported in terms of effective process

integration. It is concluded that the production of a high

concentration of CuCl2 or even slurry will significantly reduce

the integration challenges with the downstream hydrolysis

reactor. The concentrating process for CuCl2 cannot be

avoided if the electrolytic cell operates under the conditions

reported in past literature. Spray drying has challenges of

high heat transfer loads, which are the same challenges that

necessitate the water requirement of a hydrolysis reactor to

be reduced. Regarding the linkage between the hydrolysis

and oxygen production reactors, it was found that the

unreacted CuCl2 in a hydrolysis reactor will result in the

release of Cl2 in the oxygen production reactor. Furthermore,

residual CuCl2 transferred from the hydrolysis reactor to the

oxygen production reactor may be further entrained to the

electrolytic hydrogen production cell. It is suggested that

a future focus of the hydrolysis reaction is to reduce the

water requirement and achieve a high conversion of CuCl2 to

Cu2OCl2. To minimize the side reactions such as the Deacon

reaction, the decomposition of CuCl2 accompanying the

hydrolysis step is crucial to an effective system integration of

the CueCl cycle. The study of thermal energy integration

shows that the heat released by the exothermic processes

can be used to generate steam as input to the hydrolysis

reactor.

Acknowledgements

Financial support from Atomic Energy of Canada Limited and

the Ontario Research Fund is greatly acknowledged.

r e f e r e n c e s

[1] Naterer G, Gabriel K, Wang ZL, Daggupati V, Gravelsins R.Thermochemical hydrogen production witha copperechlorine cycle. I: oxygen release from copperoxychloride decomposition. International Journal ofHydrogen Energy 2008;33:5439e50.

[2] EVWorld. Energy content of fuels; 2010. Available from:http://www.evworld.com/library/energy_numbers.pdf[accessed December 8, 2010].

[3] Sadhankar RR, Li J, Li H, Ryland D, Suppiah S. Hydrogengeneration using high-temperature nuclear reactors. 55thCanadian chemical engineering conference, Toronto;October 2005.

[4] Kubo S, Kasahara S, Okuda H, Terada A, Tanaka N, Inaba Y,et al. A pilot test plan of the thermochemical water-splittingiodineesulfur process. Nuclear Engineering and Design 2004;233:355e62.

[5] Schultz K. Thermochemical production of hydrogen fromsolar and nuclear energy, Technical Report for The StanfordGlobal Climate and Energy Project. San Diego, CA: GeneralAtomics; 2003.

[6] Anzieu P, Carles P, Le Duigou A, Vitart X, Lemort F. Thesulfureiodine and other thermochemical process studies atCEA. International Journal of Nuclear Hydrogen Productionand Applications 2006;1:144e53.

[7] Moore R, Parma E. A laboratory-scale sulfuric aciddecomposition apparatus for use in hydrogen productioncycles. American nuclear society annual meeting, Boston,Massachusetts; June 24e28, 2007.

[8] Buongiorno J, MacDonald PE. Supercritical water reactor(SCWR) progress report for the FY-03 generation-IV R&Dactivities for the development of the SCWR in the U.S. INEEL/EXT-03-01210; Sept 30, 2003.

[9] Lewis MA. Update on the CueCl cycle R&D effort, Workshopof the ORF Hydrogen Project at AECL Chalk RiverLaboratories. Ontario: Chalk River; October 17, 2008. p. 25e33.

[10] Sharna R, Fedkin M, Lvov S. CuCl electrolyzer for hydrogenproduction via CueCl thermochemical cycle, 219th ECS(Electrochemical Society) Meeting. Montreal, QC: Canada;May 1e6, 2011.

http://www.evworld.com/library/energy_numbers.pdf




[11] Suppiah S, Stolberg L, Boniface H, Tan G, McMahon S, York S,et al. Canadian nuclear hydrogen R&D programme:development of the medium-temperature CueCl cycle andcontributions to the high-temperature sulphureiodine cycle.Nuclear Production of Hydrogen, Fourth InformationExchange Meeting, Oakbrook, Illinois, USA; April 14e16,2010. p. 77e86.

[12] Parry T. Thermodynamics and magnetism of Cu2OCl2.Masters thesis. Department of Chemistry and Biochemistry,Brigham Young University; 2008.

[13] Lewis MA. CueCl cycle R&D e recent research results for thehydrolysis reaction sensitivity studies. CueCl cycle researchand development at the Argonne National Laboratory,Canadian HydrogenWorkshop on Hydrogen Production fromNon-fossil Sources. Oshawa, Ontario, Canada: University ofOntario Institute of Technology; December 20, 2007.

[14] Lewis MA, Ferrandon MS, Tatterson DF, Mathias P.Evaluation of alternative thermochemical cycles e part IIIfurther development of the CueCl cycle. InternationalJournal of Hydrogen Energy 2009;34:4136e45.

[15] United States Environmental Protection Agency Office ofInformation Analysis & Access Washington, DC 20460. EPA-745-B-99-014; December 1999. p. 29e31.

[16] Bayer Material Science Ltd. In: Industrial OperationsBasic Chemicals, editor. Product data sheet:hydrochloric acid. Germany: Bayer Material Science AG;April 2008. p. 1e4.

[17] Solvay Chemicals International (Brussels). Hydrochloricacid e density. Data sheet number: PCH-1300-0001-W-EN(WW). Issue 1; April 2005.

[18] Bertz SH, Fairchild EH. Reagents, auxiliaries and catalysts forCeC bond formation. In: Coates RM, Denmark SE, editors.Handbook of Reagents for Organic Synthesis, vol. 1. JohnWiley & Sons; 1999. p. 220e3.

[19] Basir SMA. Recovery of cupric chloride from spent copperetchant solutions: a mechanistic study. Hydrometallurgy2003;69:135e43.

[20] Pan HY, Minet RG, Benson SW, Tsotsis TT. Process forconverting hydrogen chloride to chlorine. Industrial &Engineering Chemistry Research 1994;33:2996e3003.

[21] NIST (National Institute of Standards and Technology).Chemistry WebBook; 2010. Available from: http://webbook.nist.gov/chemistry/ [accessed on February 1, 2011].

[22] Alkan M, Oktay M, Kocakerim MM, Copur M. Solubility ofchlorine in aqueous hydrochloric acid solutions. Journal ofHazardous Materials 2005;119:13e8.

[23] Sherrill MS, Izard EF. The solubility of chlorine inaqueous solutions of chlorides and the free energy oftrichloride ion. Journal of American Chemical Society1931;53:1667e74.

[24] Awakura Y, Yoshitake S, Majima H. Solubility of Cl2 gas inaqueous chloride solution. Journal of the Japan Institute ofMetals 1989;53:1134e9.

[25] Marin GD, Wang Z, Naterer GF, Gabriel K. Byproducts andreaction pathways for integration of the CueCl cycle ofhydrogen production. International Journal of HydrogenEnergy 2011;36:13414e24.

[26] Serban M, Lewis MA, Basco JK. Kinetic study of the hydrogenand oxygen production reactions in the copper-chloridethermochemical cycle. AIChE 2004 Spring National MeetingNew Orleans. LA, US; April 25e29, 2004.

[27] Naterer GF, Fowler M, Cotton J, Gabriel K. Synergistic roles ofoff-peak electrolysis and thermochemical production ofhydrogen from nuclear energy in Canada. InternationalJournal of Hydrogen Energy 2008;33:6849e57.

[28] Brewer L, Lofgren NL. The thermodynamics of gaseouscuprous chloride, monomer and trimer. Journal of theAmerican Chemical Society 1950;72:3038.

http://webbook.nist.gov/chemistry/

http://webbook.nist.gov/chemistry/



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