Safety of Ammonia As Hydrogen and Energy Carriers

Wednesday, November 13, 2019 10:20-10:38Hyatt Regency Orlando - Regency Ballroom P

Ammonia Energy Conference 2019 at 19 AIChE Annual Meeting in Orlando, FL, November 12-14, 2019

Yoshitsugu KojimaNatural Science Center for Basic Research and

Development, Hiroshima University, Japan

0

2

4

6

8

10

12

14

0 5 10 15 20 25

NH30.1MPa, 240K

CH3OH-H2O

Liquid H20.1MPa,20K

AlH3

N2H4-H2O

NH3BH3Ti1.1CrMn

1MPa, 298K

Activated carbon 77K

LiBH4

Li-Mg-B-HMg(BH4)2

LiBH4-2H2O

100

~~

Gravimetric H2 density /wt%NH3: burnable substance ® Energy carrier

Light weight

CompactVo

lum

etric

H2

dens

ity /

kgH

2/100

L（

Pack

ing

ratio

: 50％）

NaBH4-4H2O

MethylcyclohexaneMgH2 Hydrides(theoretical values)

H2 storage materials (experimental values)

1. Introduction

Above 1.5´H2 density of liquid H2

Y. Kojima，Hydrogen storage materials for hydrogen and energy carriers, International Journal of Hydrogen Energy, 44, 18179-18192 (2019)

H2 densities of hydrogen carriers

Material fornitrides, gunpowder

Refrigerant

Fertilizer

Material for polymers

NOx reducing agent

Hydrogen andenergy carriers

Ammonia: deleterious substancePurpose： To figure out regulations for safety of NH3, survey NH3accident and propose new concept of ammonia removal system

NH 3

NH3

NH3

NH3

NOx

NOx

H2O

H2O

N2

N2

-NH(CH2)5CO-[ ]n

Expansion valve

Condenser

Compressor

Evaporator

High pressure liquid NH3

Low pressure NH3 gas

Application of anhydrous ammonia

2. Regulations for safety of NH3

(1)USA: NFPA(National Fire Protection Association) 704

(2)Japan: GHS (The Globally Harmonized System of Classification and Labelling of Chemicals)(3)EU: CLP regulation (Regulation on Classification, Labelling and Packaging of substances mixtures

103 -

Ammonia

Fire diamond of ammonia

Fire hazard (flammability)

Health hazard Instability

Specific hazard

0

1

2

3

4

5

23 123 223 323 423

NFPA flammability and flash point

The flammability increases with decreasing of the flash point, approaching to constant value 4.

Flash point /℃

NFP

A fla

mm

abili

ty

Ammonia

Hexane, organic hydride (methylcyclohexane, toluene)

Hydrogen, methane, propane

Fire hazard: Ammonia<Organic hydrides <HydrogenJapanese GHSFire hazard: Organic hydrides <Hydrogen, Ammonia

0

1

2

3

4

1 100 10000 1000000

NFPA health hazard and solubility

Health hazard: large

NFP

A he

alth

haz

ard

Solubility in water(293-298K) /mg/kg

H2 gas

Ammonia

methylcyclohexane, methane, propane, toluene

Hexane

® Liquid H2 ?

The health hazard increases with the solubility in water.

Health hazard: Hydrogen gas <Organic hydrides <Ammonia

Liquid hydrogen

Health hazardFire hazard(flammability)

Instability

103

-4

03 -3

02-

Ammonia (NH3) Organic hydrides(Methylcyclohexane,Toluene)

Fire diamond of hydrogen and energy carriers

Ammonia and liquid H2 have same health hazard.

Safety: Liquid hydrogen(7) <Organic hydrides(5) < Ammonia(4)

0

2000

4000

6000

8000

AMMONIA TOLUENE

LC50

/ppm

LC50 (50% lethal concentration, 4h rat inhalation)of ammonia and toluene

7500 ppm/4h7679 ppm/4h

Ammonia and toluene have same health hazard.

3. Survey of NH3 accident

October 27, 2004

Leakage from the ammonia pipeline, Kansas, USA

AmmoniaFluorocarbonliquefied petroleum gasHydrogenNatural gasArNitrogenCarbon dioxideAirHeOxygenAcetylenethe others

The ratio of the number of ammonia accidents tothe number of high pressure gas relatedaccidents in Japan (2014)

10%

Caused by the leakage from valve, pipe and flange

Ammonia storage (absorption, adsorption)materials

Metal halides

Porous materials

NaB

H

Complex hydrides

Proton-based materials

Evaluation and characterization ammonia storage materials

Water

PO

Zr

4. New concept of ammonia removal system

Ammonia remover

0

10

20

30

40

0 20 40 60

Compact

Volu

met

ric N

H3

dens

ity /k

gNH

3/100

L(P

acki

ng ra

tio: 5

0%)

Gravimetric NH3 density /wt%Light weight

Ammonia water (32wt%) Ca(NH3)8Cl2

Mg(NH3)6Cl2

Sr(NH3)8Cl2

Mn(NH3)6Cl2

Mg(NH3)2Cl2

Mn(NH3)2Cl2Mn(NH3)2Br2

(NH4)2SO4

Zr(NH4PO4)2(H2O)

NH3: large diffusion coefficient in water

Mn(NH3)6Br2

NH3 vapor pressure£0.1MPa

NH3 densities of NH3 storage materials

NH3 concentration: 2500ppm®NH3 vapor concentration: 2300ppm(To decrease NH3 vapor concentration ®

Insoluble proton-based materials)

0

10000

20000

30000

40000

0 10000 20000 30000 40000

Am

mon

ia v

apor

co

ncen

trat

ion

P/p

pm

Ammonia concentration in ammonia water C /ppm

P=4×10-6C2+0.9043C

Ammonia vapor concentration and ammonia concentration in ammonia water

298K

Ammonia molecule(hydrogen bond)

Insoluble ammonium ion-based materials(coordinate bond) to remove nitrogen

Ammonia molecule

The NH3 removal system combined water and Insoluble proton-based materials will be candidate to reduce NH3 concentration in the atmosphere by suppression of water pollution.

Insoluble proton-based materialsWater

Conceptive picture of ammonia removal system

5. Summary(1) NH3 is safer than liquid hydrogen and organic

hydrides by addition of health hazard and fire hazard based on fire diamond.

(2) Water absorbs large amount of NH3, although the vapor concentration is high.

(3) The NH3 removal systems combined water and insoluble proton-based materials will be candidate to reduce leaked NH3 in the atmosphere.

AcknowledgementsThis work was supported by Council for Science, Technology and Innovation(CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier”(funding agency : JST).

Thank you for your attention.