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