1. Development of Pt/Zirconia Catalyst for
liquid phase HI Decomposition Reaction
in S-I Cycle
Deepak Tyagi, Alisha Gogia, Salil Varma, A. K. Tripathi, S. R.
Bharadwaj
Chemistry Division
Bhabha Atomic Research Centre, Mumbai

2. Hydrogen as future fuel
• Hydrogen as a future source of energy is a scenario of
high probability and necessity, considering the illeffects of fossil fuel based systems on the environment
and also the depleting natural resources.
• The fast development of hydrogen based power
sources like fuel cells will lead to more efficient and
cleaner energy supply.
• For this to be economically feasible, large scale
production of hydrogen has to be attained by
environment friendly route.
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3. ICAER-2013, IITB

4. Production of Hydrogen:
Today hydrogen is mainly produced from fossil resources.
Origin
Percent
Natural gas
48
Oil
30
Coal
18
Electrolysis
4
Total
100
In the long term, because of
increasing energy demand,
lack of fossil resources
limitations on the release of green house gases
Water suitable raw materials for hydrogen production.
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5. Production of Hydrogen from Water:
The two processes that have the greatest
likelihood of successful massive hydrogen
production from water are (i) steam electrolysis
(ii) thermochemical cycles.
This way hydrogen can be produced from water
at temperatures much lower than the direct
water decomposition at 3000 °C.
As heat can be directly used in thermochemical
cycles, they have the potential of better
efficiency than alkaline electrolysis.
The required thermal energy can be provided by
nuclear reactor (CHTR).
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6. Sulfur - Iodine Cycle
Exothermic; T = 120 °C
Endothermic; T = 870 °C
9I2 + SO2 + 16 H2O
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→
Endothermic; T = 450 °C
(2HI + 10H2O + 8I2) + (H2SO4+ 4H2O)

7. Hydriodic Acid Decomposition
Decomposition of hydriodic acid an integral part of Sulfur - Iodine
and Magnesium – Iodine thermochemical cycle.
Homogeneous azeotrope in HI-H2O binary system and
thermodynamically limited slow gaseous HI decomposition - highly
energy consuming step.
1.The General Atomic Co. proposed use of phosphoric acid
(Extractive Distillation) for concentration of the HI solution to obtain
99.7% molar HI vapour. But, concentration of recycled phosphoric
acid consumes large amount of heat and electricity.
2.Employment of electro-electrodialysis concentration method and
hydrogen permselective membrane reactor also reported by JAERI.
3.Reactive distillation - combining reaction and separation in a single
step leading to overall shift of equilibrium towards production of I 2
and H2. First reported by Roth et al in 1989.
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8. Catalyst reported for HI decomposition
Ceria
IJHE 34(2009) 1688-1695
Ni/Ceria
IJHE 34(2009) 5637-5644
IJHE 34(2009)8792-8798
Ni/Alumina
IJHE 34(2009) 4059-4056
Activated Carbon
IJHE 34(2009) 4057-4064
Pt/Ceria
IJHE 33(2008) 602 – 607
IJHE 33(2008) 2211-2217
Pt/Alumina
Chinese chemical letters 20 (2009) 102-105
Pt/Ceria-Zirconia
IJHE 35(2010) 445-451
“ D. R. O’keefe et al, Catalysis Reviews 22(3), 325-369 (1980)”
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9. Objective of the present
Work
• Develop Pt catalysts over Zirconia support (with
different Pt loading)
• Demonstrate stability of the catalysts under the
reaction conditions
• Evaluate activity of these catalysts for HI
decomposition reaction
• Derive
structure
activity
correlation
for
development of future catalysts
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10. Preparation of Catalyst
Zirconyl Nitrate solution
NH4OH solution added dropwise
with constant stirring
Zirconium Hydroxide Gel
Dried at 100°C for 6h
Calcined at 350°C for 3h
Zirconia
(i) Add Chloroplatinic acid Dropwise
With constant stirring
(ii) Reduction by Hydrazine at RT
(iii) Reduction by H2 flow at 300 °C
Platinum Zirconia Catalyst

11. Characterization:
•
XRD
•
SEM
•
FEG-SEM
•
N2 Adsorption
•
ICP OES
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12. Intensity
X-Ray Diffraction:
120
100
80
60
40
20
0
120
10
100
80
60
40
20
0
120
10
100
80
60
40
20
0
10
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2 % Pt/ZrO2
20
30
40
50
60
70
1 % Pt/ZrO2
20
30
40
50
60
70
0.5 % Pt/ZrO2
20
30
40
2θ
50
60
70

13. SEM & EDAX:
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14. FEG-SEM:
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15. Adsorption and Desorption isotherms
1% Pt/ZrO2
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2% Pt/ZrO2

16. Pore Size Distribution:
1% Pt/ZrO2
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2% Pt/ZrO2

17. Surface Area:
S.
No
1.
Sample
Surafce Area Pore Size
Pore Volume
ZrO2
108.64
3.62
0.1125
2.
1%Pt ZrO2
139.71
3.72
0.1573
3.
2%Pt ZrO2
133.47
3.72
0.1492
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18. Activity & Stability of Catalysts
50 ml of 27% HI + 250 mg of Catalyst
Heated for 2h at ~ 120oC
Filtered
Filtrate analyzed for presence of Pt by ICP-OES
&
Used catalyst evaluated by XRD and SEM.
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19. Activity & Stability of Catalysts
HI ←
→ 1 I 2 + 1 H 2
2
2
For liquid phase decomposition reaction, dissolution of the I2 formed at
catalyst surface into the iodide solution as Ix- and continued intimate
contact between HI and catalyst maintains high reactivity levels even in
presence of I2.
Upto 50% conversion is reported by O’Keefe et al for 48h study at room
temperature.
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20. Activity Measurement
H+ Titration
I- Titration
Using Glass electrode
Using Ag/AgCl electrode
Titration against NaOH
Titration against AgNO3
NaOH was standardized
using KHP
AgNO3 was standardized
using NaCl
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21. Activity and stability of the catalysts
S. No.
% Conversion
1.
0.5% Pt/ZrO2
13.9 %
2.
1% Pt/ZrO2
16.7 %
3.
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Catalyst
2% Pt/ZrO2
18.5 %

22. XRD Used Catalysts:
100
80
Used 2% Pt/ZrO2
60
40
20
Intensity
0
120
20
100
80
60
40
20
0
120
20
100
80
60
40
20
0
20
30
40
50
70
Used 1% Pt/ZrO2
30
40
50
60
70
Used 0.5% Pt/ZrO2
30
40
50
2θ
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60
60
70

23. Comparison with Pt/Carbon catalysts
S.
No.
% Conversion
(H+ Titration)
1
Pt/Gr
17.5 %
2
Pt/SBA
15.0 %
3
Pt/MCM-C
17.0 %
4
Pt/Zirconia
16.7 %
5
Pt/AC
12.1 %
6
Pt/FS-C
7.2 %
7
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Catalyst
Blank
2.8 %

24. Conclusions
Pt/Zirconia catalyst prepared was active for HI
decomposition.
The percentage conversion is dependent on noble
metal loading.
Catalyst prepared was found to be stable under liquid
phase HI decomposition conditions.
Catalytic activity of Pt/Titania catalyst was better as
compared to some of the Pt/C catalysts.
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25. ICAER-2013, IITB