solar powered high temperature photochemical water splitting · splitting or other techniques fsec...
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Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 1
Solar Powered High Temperature Photochemical Water Splitting
Cunping Huang, Olawale AdebiyiNazim Muradov, Ali T-Raissi
Florida Solar Energy CenterUniversity of Central Florida
Project Start Date: October 1, 2004
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 2
Research Goals and Objectives
Produce hydrogen using resources available in Florida without GHG emissionsUtilize both solar heat & photonic energy to increase hydrogen production efficiencyDevelop a new thermochemical water splitting cycle that is optimum for solar interfaceSynthesize highly efficient & selective photocatalysts
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 3
Relevance to Current State-of-the-ArtSolar thermochemical splitting of water for hydrogen production is a carbon free process that is presently of great interest to the scientific communityThermochemical water splitting cycles have been shown to be more efficient method for hydrogen production from water than those that utilize water electrolysis, high temperature direct splitting or other techniquesFSEC is developing an innovative cycle that is one of only few true solar-based thermochemical water-splitting cycle in the world
Relevance to NASALocal hydrogen production for NASA-KSC using a renewable carbon-free energy sourceTechnology developed can be used on the Moon & in space
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 4
Budget, Schedule and DeliverablesBudget: $185,000
Schedule:1st quarter: Experimental setup & feasibility tests 2nd quarter: UV light photolytic H2 production3rd quarter: Solar H2 production 4th quarter: Photocatalyst screening
Deliverables:1 - A solar thermochemical process for production of H2 from H2O2 – Preparation of nanosized photocatalyst particles & photoelectrodes3 – development of a method for the photocatalyst preparation4 - Process design & optimization
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 5
Anticipated Technology End Use
Local hydrogen production for the NASA Kennedy Space CenterInexhaustible H2 production for hydrogen economySpace exploration - H2 production in space and on the Moon & MarsTechnology developed can be employed for O2productionTechnology developed can potentially be used for O2 production from lunar soil
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 6
A New S-A Thermochemical Water Splitting Cycle
photocatalytic reactor
absorber
gas-liquid separator
NH3 recovery unit
NH3
mixer
dish
sulfuric acid decomp. reactor
SO2(g) + 2NH3(g) + H2O(l) → (NH4)2SO3(aq)(NH4)2SO3(aq)+H2O→ (NH4)2SO4(aq)+H2(g)(NH4)2SO4(aq)→2NH3(g) + H2SO4(l)H2SO4(l) → SO2(g) + H2O(g) + 1/2O2(g)
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 7
UV Photolytic H2 Production Advantages:
No catalyst is neededHigher efficiency Low cost & less
complicated Potentially applicable in
space & on the MoonResults:
Optimized reaction conditions (temperature, pH, concentration)
Investigated reaction mechanisms
Calculated material balanceDetermined H2 production rate
& efficiency (>30% UV to H2)
Reaction:(NH4)2SO3 + H2O + UV light → (NH4)2SO4+H2
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 8
Results: UV Photolytic H2 Production - Reaction Mechanism & Material Balance
SO32- + hv SO4
2- + H2
S2O62- +
H2O + hv
k1
k 2k3k4
H2O +
(I) H2O + SO32- + hν = SO4
2- + H2
(II) 2SO32- = S2O6
2-
S2O62- + H2O + hν = SO4
2- + H2
Average Component In (mol) Out (mol) Prod/Cons.(mol) %Difference
Liquid Phase SO32- 0.040606 0.000000 0.040606 0.920415
SO42- 0.014432 0.054665 0.040232
Gas Phase H2 Expected H2 (mL) Actual H2 (mL) Difference (mL) % Diff986.9 909.0 77.9 7.9
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 9
Solar Photocatalytic H2 ProductionReaction:
(NH4)2SO3 + H2O + sunlight +catalyst→ (NH4)2SO4+H2
Experimental Setup & PhotoreactorResults: Concentration, Temperature, Platinum
Loading, Catalyst Lifespan, Catalyst Screening, Kinetics, Process Efficiency
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 10
Results - Solar H2 Production (1)
Temperature has a significant affect on H2 production rate. The optimal temperature is in the range of 50 to 70oC. Solar heat can increase reaction rate
Concentration of Sulfite solutionaffects H2 evolution rate. Optimal concentration is in the range of 0.8 to 1.0 M
0
200
400
600
800
1000
1200
1400
0 50 100 150 200 250 300 350 400 450
Reaction Time (min)
Hydr
ogen
(mL)
50C
70C
0
100
200
300
400
500
600
700
800
0 50 100 150 200 250 300 350 400
0.432M
0.866M1.731M
Hy d
ro
ge
n (
mL
)
Reaction Time (min)
Temp = 50oCVolume = 250mLInitial pH = 8.00
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 11
Results - Solar H2 Production (2)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
CdS Platinum Loading (wt%)
H2 R
ate
(mL/
min
)
0
500
1000
1500
2000
2500
3000
0 500 1000 1500 2000 2500 3000 3500 4000
Time(min)
H2 (m
L)
0.00
22.32
44.64
66.96
89.28
111.6
133.9
Day 1
2.6hrs
Day 2
7.98 hrs
Day 3
7.48 hrs
Day 4
7.16 hrs
Day 5
8.21 hrs
Day 6
8.16 hrs
Day 7
8.15 hrs
Day 8
8.00 hrs
Day 9
7.18 hrs
Optimal Pt loading is 0.5 to 1.0% wt of CdS catalyst weight which is 0.01 % wt of reaction solution
Lifespan of Catalyst is expected to exceed 100 hours with SO3
2- totally converted to SO4
2-
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 12
Results - Solar H2 Production (3)
Photocatalyst ScreeningPlatinum doped CdS photocatalyst is highly efficient in
converting SO32- to SO42-
CdS activity depends strongly upon the Pt dopant sizeFour techniques were used to prepare the catalysts including
synthesizing nanosized Pt particles from chloroplatinic acid solutionSuperior techniques involved: 1) sodium borohydride reduction &
2) polymer protected process for Pt nanoparticle preparation
Process efficiencyFor the H2 production, the light (λ < 450 nm) to hydrogen chemical
energy conversion efficiency was about 12%. Efficiency of 25-30% is achievable
Solar thermal energy can be utilized to elevate temperatures &increase the reaction rates
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 13
Future Plans
Identify more effective photocatalysts capable of absorbing light with λ in the visible regionDevelop novel photoreactors to increase the photoefficiency of solar light harvestingPerform closed loop S-NH3 testsFind new techniques for preparing nanosize photocatalystsExplore the application of the S-NH3 cycle for O2productionSeek additional U.S. DOE & other Agency support – DOE has already committed $500k as FY’06 funding
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 14
Patents and Publications Patents:
One provisional patent has been filed and one is under preparation
Publications:Cunping Huang, Olawale Adebiyi, Nazim Muradov, Ali T-Raissi, “UV Photolysis of Ammonium Sulfite Aqueous Solution for the Production of Hydrogen,” 16th World Hydrogen Energy Conference, Lyon, France, June 13-16, 2006
Ali T-Raissi, Cunping Huang, Nazim Muradov, Olawale Adebiyi, “Production of Hydrogen via a Sulfur-Ammonia Solar Thermochemical Water Splitting Cycle,” 16th World Hydrogen Energy Conference, Lyon, France, June 13-16, 2006
Ali T-Raissi, Cunping Huang, Nazim Muradov, Olawale Adebiyi, “Production of Hydrogen by Solar Water Splitting via Hybrid Sulfur-Ammonia Cycle,” NHA Annual Meeting 2006, Long Beach, CA, March 12-16, 2006
Muradov, N., T-Raissi, A., Huang, C., Adebiyi, O., Taylor, R. and Davenport, R., “Solar hybrid water-splitting cycles with photon component,” 2nd European Hydrogen Energy Conference, Zaragoza, Spain, November 22-25, 2005
Ali T-Raissi, Nazim Muradov, Cunping Huang, “Solar Hydrogen via High-Temperature Water-Splitting Cycle with Quantum Boost,” International Solar Energy Conference &Journal of Solar Engineering, Orlando, USA, August 6-12, 2005
Florida Universities Hydrogen Review 2005Florida Solar Energy Center November 1-4, 2005
Task Title – PI – Organization 15
Thank YouThank You
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