On-Line H2 PPB Impurity Analysis Using FTIR - MKS Instruments, Inc.

On-Line H PPB Impurity
2 Impurity
2
Analysis Using FTIR
Arik Ultsch
MKS Instruments Deutschland

Background
� Volatile fossil fuel prices have created interest in
Hydrogen as a new energy source for the
auto industry
� Impurities in H 2 fuel directly affect the longevity of the
combustion or fuel cell engine
� Regulatory agencies have initiated
an H 2 quality threshold at the
ppb level
� FTIR spectroscopy is the
most viable method of providing
ppb level H 2 impurity detection
on-site at the pump

H 2 Impurity Analysis: Content
� Fuel cell principle
� Determining the effect of impurities on fuel cells
– How much can be tolerated?
– Is the effect reversible?
– Effects of impurities
� Sulfur (H 2S, COS), ammonia, CO, CO 2, H 2O
– Impurities from H 2 Fuel as well as Air Feed
� Cell Analysis by Air Liquide R&D Center USA
� Robert Benesch, Tracey Jacksier, and Sumaeya Salman
� FTIR Validation for H 2 impurity detection
– Method detection limits for:
� Multiple components
� Different FTIR detector ranges tested

Fuel Cell Principle
� Fuel cells generate electricity from a simple
electrochemical reaction in which oxygen and
hydrogen combine to form water
� Anode
– Porous carbon coated with tiny particles of platinum (Pt)
– Pt acts as a catalyst to form ions
(2H 2 => 4H + + 4e - )
� Proton Exchange Membrane (PEM)
– Allows positively charged
ions to travel through
� Cathode
– Forms oxygen atoms
– Oxygen and hydrogen
combine to form water
(O 2 + 4H + + 4e - => 2H 2O)

Impurity Effects on Cell Voltage
� Decrease in performance
– Affect different physical and chemical processes
� Removal of impurity
– Cell Performance: recoverable or non-recoverable

The Fuel – Hydrogen and Air
� Hydrogen
– Introduced to anode side of fuel cell
� Reducing environment
– Dependant upon production method
� Typical methods
- Biological – fermentation, anaerobic digestion
- Electrochemical – electrolysis of H 2 O
- Thermal – reforming, gasification
� Steam Methane Reforming (SMR)
- 95% of US H 2 production
- He, N 2 , CO, H 2 S, NH 3 , CH 4 …
� Air
– Introduced to cathode side of fuel cell
� Oxidizing environment

Sources of Impurities
� Carbon Monoxide in H 2
– Reported Mechanism*
� Physical adsorption onto fuel cell catalyst
� CO absorbs onto Pt site blocking H 2 adsorption
CO + Pt ⇔Pt⋅CO
g
s
* J. Baschuyuk and X. Li, “Carbon Monoxide Poisoning of Proton Exchange Membrane
Fuel Cells”; Int. J. Energy Res. 2001, 25; 695-713
ads
Pt g
+ −
⋅COads+ H2O→Pts
+ CO2
+ 2H
+ 2e

CO Effect on Fuel Cell
1.0 and 4.5 ppm CO in H 2
9.2 ppm CO in H 2

Sources of Impurities
� Ammonia in H 2
– Reported Mechanism*
� Concentration and exposure dependant
� Short-term exposure of trace concentrations
(~40ppm)
- Non-Reversible
- Mainly effects the Membrane structure
* F. Uribe, S. Gottesfeld, T. Zawodzinski, “Effect of Ammonia as Potential Fuel Impurity On Proton
Exchange Membrane Fuel Cell Performance” J. Electrochemical Society, 2002, 149 (3) A293-296

NH 3 Effects on Fuel Cell
pure H 2
0.5, 1.0 ppm NH 3 in H 2
No Effect
9.0, 44.7 ppm NH 3 in H 2
9.0 Non - Reversible
44.7 Non - Reversible

Summary of Impurities Tested
Impurity Electrode
Lowest Test
Conc (ppm)
Highest Test
Conc (ppm)
% Decrease
at Lowest
Conc
Typical Air Sample: (maximum hourly concentration detected at
EPA testing sites in Houston and Chicago area in 2005):
CO [3 ppm], NO [0.65 ppm], SO 2 [0.137 ppm]
% Decrease
at Highest
Conc
CO anode 0.52 9.2 5 >58
H2S anode 0.10 2.0 not detected >58
NH3 anode 0.50 44.7 not detected 14.7
CO cathode 0.40 68.6 not detected not detected
SO2 cathode 0.07 4.8 3 40
NO2 cathode 0.025 2.86 not detected 20

Current H 2 Fuel Cell Specification
SAE J2719
Property Value Unit Limit
1 Ammonia 0.1 ppm v/v Maximum
2 Carbon Dioxide 2 ppm v/v Maximum
3 Carbon Monoxide 0.2 ppm v/v Maximum
4 Formaldehyde 0.01 ppm v/v Maximum
5 Formic Acid 0.2 ppm v/v Maximum
6 Helium 300 ppm v/v Maximum
7 Hydrogen Fuel Index 99.97 % (a) Maximum
8 Nitrogen and Argon 100 ppm v/v Maximum
9 Oxygen 5 ppm v/v Maximum
10 Particulate Concentration 1 µg/L@NTP (b) Maximum
11 Particulates Size 10 µm Maximum
12 Total Gases 300 ppm v/v (c) Maximum
13 Total Halogenated Compounds 0.05 ppm v/v Maximum
14 Total Hydrocarbons 2 ppm v/v (d) Maximum
15 Total Sulfur Compounds 0.004 ppm v/v Maximum
16 Water 5 ppm v/v Maximum

FTIR For H 2 Impurity Analysis
� Real-time analysis at ppb levels
� FTIR advantage
– Multiple components analysis with one unit
� Single analyzer for all the impurities except O 2, H 2, Ar, N 2
– High resolution enables speciation between similar molecules
� Butane, Propane, Ethane, Methane, fuel sources, etc.
– Permanent calibration
– Analysis performed at various sites
� H 2 production site
� H 2 storage site: gas or liquid cylinders
� At - Line analysis at fueling station

Infrared (IR) Spectroscopy
� Based on IR light absorption
– Energy (IR radiation) heats molecule - vibrations and rotations
– The pattern and intensity of the spectrum provides all the information
about gas (type and concentration)

Background and Sample
BACKGROUND (Io)
N 2 Purge 1cm -1
SAMPLE (I)
1000 ppm NH 3 1cm -1
Absorbance = - Log (I/Io)

Absorbance is Proportional to
Concentration
Absorbance = - Log (I/Io)
Absorbance = ε •C •path
FFT of Sample
1000 ppm NH 3 1.0 cm -1

What Can FTIR Do?
Hydrogen (H2), %
Oxygen (O2), %
Nitrogen (N2), %
Water (H2O), %
Component
Hydrogen Sulfide (H2S), ppm
Carbon Monoxide (CO), %
Carbon Dioxide (CO2), %
Methane (CH4), %
Non-methane Hydrocarbons, %
Nitric Oxide (NO), ppm
Nitric Dioxide (NO2), ppm
Sulfur Dioxide (SO2), ppm
Product
40-80
0-1
0-10
0-300
0-25
0-25
0-25
0-10
0-10
Low ppm
Low ppm
Low ppm
Exhaust
0-10
0-5
0-80
Low ppm
0-25
0-25
0-25
0-10
0-10
0-100
Low ppm
0-100
� Analyze all components that:
– Are IR active
– Have Dipole Moments
� Examples
– Ammonia, CO, CO 2 , H 2 O,
Hydrocarbons, etc
� Raw Reformed Hydrogen
– Percent level analysis
� Purified Hydrogen
– PPB level analysis

FTIR Components Used For Test
� Gas Cell
– Stainless steel – path length 5.11 meters
– Metal sealed cell:

16u Cutoff
Ammonia
9u Cutoff
Water
Methane
Ethane
Formic Acid
Formaldehyde
CO2
CO

Method Validation
� EPA Method 40 CFR 136 Appendix B
– Build calibrations on FTIR
– Estimate a minimum detection limit
– Determine how low a concentration can be
detected with this method

FTIR Validation Method for H 2
� Gases validated on FTIR
– CO, CO 2, CH 4, C 2H 6, NH 3, H 2O, Formaldehyde
and Formic Acid
– All in Balance of H 2
� Gas standards creation
– NIST traceable gas cylinders for gases
� 100 ppm of CO, CO 2 , CH 4 , C 2 H 6 in H 2
– NIST traceable permeation tubes for liquids
� NH 3 , H 2 O, Formaldehyde and Formic Acid
– Blended with H 2
� Purified H 2 (

Method Detection Limits
Contaminant
SAE J2719
Detection
Limits (ppmv)
16u Stirling* 9.2u TE 16u LN2
Ammonia (NH3) 0.10 0.36 0.81 0.02
Carbon Monoxide (CO) 0.20 0.01 0.05 0.01
Carbon Dioxide (CO2) 2.00 0.01 0.01 0.01
Formaldehyde (HCHO) 0.01 0.02 0.02 0.02
Formic Acid (HCOOH) 0.20 0.03 0.02 0.02
Total Hydrocarbons
2.00 0.71
(Reported as C1)
Methane 0.10 0.02 0.02 0.03
Ethane 0.10 0.02 0.05 0.05
Ethylene 0.10 0.03
Water (H2O) 5.00 0.40 0.74 0.12
* Signal to noise ratio (SNR) was 1/3 that of 16u LN2 for this test
* However improved SNR to same level as 16u LN2

Acknowledgments
� Fuel cell work
– Air Liquide Research and Technology Center
� Robert Benesch, Tracey Jacksier, Sumaeya Salman
� Method validation / calibration work
– Elutions Design Bureau, Inc – Houston, TX
� Scott Thompson
– MKS Instruments – On Line Product Group
� Barbara Marshik
– Monetary support for this work
� MKS Instruments
� Shell Global Solutions Inc. - Westhollow Technology
Center