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18 AIChE Annual Meeting in Pittsburgh, PA, October 28-November 2, 2018, Wednesday, October, 31, 2018 from 9:45 - 10:00 David L. Lawrence
Convention Center, 317 Yoshitsugu Kojima1 and Takayoshi Adachi2
1Natural Science Center for Basic Research and Development, Hiroshima University, Japan
2Taiyo Nippon Sanso Corporation, Japan
Ammonia As a Hydrogen Carrier for PEM Fuel Cells
0
2
4
6
8
10
12
14
0 5 10 15 20 25
NH3 0.1MPa, 240K
CH3OH-H2O
Liquid H2
AlH3
N2H4-H2O
NH3BH3 Ti1.1CrMn
1MPa, 298K
Activated carbon 77K
LiBH4
Li-Mg-B-H
Mg(BH4)2
LiBH4-2H2O
100
∼ ∼
Gravimetric H2 density /wt%
90% of heat of combustion for H2 Light weight
Compact
Volu
met
ric H
2 den
sity
/kg
H2/1
00L (
Pack
ing
ratio
: 50%)
H2 densities of hydrogen carriers
Above 1.5×H2 density of liquid H2
NaBH4-4H2O
Methylcyclohexane MgH2 Hydride(theoreticalvalue)
H2storagematerials(experimentalvalue)
1. Research on hydrogen carriers (1999~2018)
Species Concentration Purity of H2 99.97%
N2, Ar 100ppm Ammonia 0.1ppm
Specification of hydrogen fuel for FCV (ISO 14687-2:2012)
Excellent storage capacity and high heat of combustion Hydrogen station utilizing ammonia: Key issue
2. Basic technology for hydrogen station utilizing ammonia
History of this research (press release, July, 19 2016) Component technologies to produce high-purity hydrogen from ammonia (NH3 <0.1ppm, N2 <1ppm, H2 >99.98%)
(1)NH3 decomposition catalyst (Ru/MgO, Ru: 3wt%) and 1Nm3/h-scale simulated shell and tube cracker: Low heat transfer performance (2)NH3 storage material (zeolite) and 1Nm3/h-scale remover: NH3 <0.1ppm
(3) 1Nm3/h-scale H2 purifier (two-tower-type): Purification efficiency of 70%
Purpose of this research 1. Component technologies to detect ammonia concentration smaller than
0.1 ppm 2. Component technologies to improve purification efficiency and H2
conversion efficiency without emission of CO2 (1) NH3 storage materials and remover
Zeolite: High adsorption power, flow channel, recyclable by heating
Mirror
Gas inlet
Gas outlet
H275% N225% NH3 1000ppm
Flow meter
WS-CRDS
Zeolite (500mg)
Laser
Light Detector
Mirror Mirror
Sample cavity
500cm3/min
Exit NH3 concentration: Cavity ring-down spectroscopy is a reliable technique to measure trace ammonia in gases even at ppb level.
Simulated NH3 Decomposed gas
Conceptive picture of specially designed breakthrough testing apparatus
Residual ammonia concentration passed through zeolite packed column R
esid
ual a
mm
onia
co
ncen
trat
ion
/ppm
Accumulation amount of ammonia supply /gNH3/L
Residual ammonia concentration: 0.01-0.02ppm (10-20ppb)
NH3 concentration: Sufficient satisfaction of hydrogen fuel specification
40 30 10 0 50
0.10
0.08
0.06
0.04
0.02
0
20°C
Dynamic adsorption capacity:5.7wt%
Maximum value of hydrogen fuel specification
20
Ammonia remover (1Nm3/h-scale)
H2, N2
H2
0
1.0
2.0
3.0
Pressure /MPa 0 0.2 0.4 0.6 0.8 1.0 N
2 ads
orbe
d /m
mol
g-1
Nitrogen
Nitrogen adsorption isotherm on zeolite Pressure swing adsorption (PSA)
(2) H2 purifier with off-gas supply unit
Hydrogen
Nitrogen is adsorbed on the surface of the zeolite and hydrogen passes through the zeolite. Residual nitrogen concentration: Below 1ppm
Purification efficiency (two-tower-type) : 70%← gas pulsation
Overview of 1Nm3/h-scale H2 purifier (four-tower-type)
H2 1.5Nm3/h N2 0.5Nm3/h
Purity >99.98% H2 1.35Nm3/h N2<1ppm
Off-gas H2 0.15 Nm3/h N2 0.5Nm3/h
Off-gas supply unit
Mixture of hydrogen and nitrogen
Purification efficiency: 70%(two-tower-type)→ 90%(four-tower-type) Hydrogen production rate: 1.3times (four-tower-type) Off-gas(10%): Heat source for ammonia decomposition Scale-up from 1Nm3/h to 10Nm3/h
High purity hydrogen
Off-gas H2 1.5 Nm3/h N2 5Nm3/h
Heat source for ammonia decomposition
Off-gas supply unit
H2 15Nm3/h N2 5Nm3/h
Purity of H2 >99.98%
Overview of 10Nm3/h-scale H2 purifier (four-tower-type)
H2 13.5Nm3/h N2<1ppm
We have a prospect for production of 300-1000Nm3/h H2 purifier.
NH3
H2
Off-gas
ENH3: Heat of combustion for ammonia, 17.1MJ/(1Nm3/hNH3)
G: Hydrogen purification efficiency EH2: Heat of combustion for hydrogen 19.2MJ/(1.5Nm3/hH2)
Input
Off-gas
GEH2 ENH3
Hydrogen conversion efficiency ec
GEH2 ec=
Calculated hydrogen conversion efficiency: 82%(G=0.9) >78%(G=0.7)
ENH3 + (G-0.7)1.12ENH3
Output
(G-0.7)1.12ENH3: Additional heat of decomposition
(1-G)EH2
High purity H2 supply system
(G-0.7)1.12ENH3
Energy balance of ammonia decomposition and high purity H2 supply system
NH3
N2,H2排気
燃焼ガス
NH3
NH3燃焼ガス
燃焼ガス
Micro-channel cracker(1Nm3/h-scale) with heat supply unit Micro-channel: High heat transfer performance compared with shell and tube
Ammonia entrance N2, H2, small amount of NH3
Simulated off gas H2 and NH3 for heat supply
NH3
Catalytic combustion gas
Catalytic combustion gas
Residual ammonia concentration is 1500-2000ppm at 550°C and 10000h-1. Hydrogen conversion efficiency is 80 %.
Exhaust
(3) NH3 cracker with heat supply unit
Hydrogen conversion efficiency(ec): 80%
Energy efficiency(ec×eg): About 50%
Power generation efficiency(eg): 60%
Energy efficiency
3. Summary (1) We have developed component technologies to detect ammonia
concentration below 0.1ppm. (2) We have developed 10Nm3/h-scale high efficiency H2 purifier. (3) Hydrogen purification efficiency (hydrogen recovery rate) was
90% and production amount was 1.3times of the conventional purifier.
(4) Hydrogen conversion efficiency using micro-channel cracker was 80% and similar to the calculated value (82%).
This work was supported by Council for Science, Technology and Innovation(CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier”(funding agency : JST). We are greatly indebted to Dr. T. Fujitani of AIST, Mr. H. Kubo of Toyota Industries Corporation, Mr. T. Kuriyama of Showa Denko K.K., Professor T. Ichikawa and Associate Professor H. Miyaoka of Hiroshima University for collaboration of this work.
Acknowledgements
Thank you for your attention.
H2O
N2
High-pressure H2
Storage/Transportation
70MPa
Ammonia decomposition and high purity H2 supply system
Ammonia synthesis
Compressor, gas storage unit and dispenser
Fuel Cell Bus
Hydrogen station