9797 - a0 poster - m downey v8 lr
TRANSCRIPT
8/2/2019 9797 - A0 Poster - M Downey v8 LR
http://slidepdf.com/reader/full/9797-a0-poster-m-downey-v8-lr 1/1
© Q u e e n ’ s P r i n t e r a n d C o n t r o l l e r o f
H M S O , 2 0 1 1 .
9 7 9 7 / 1 0 1 1
www.npl.co.uk
Hydrogen Purity Analysis forFuel Cell Vehicles
M. Downey, A. Brown and G. Vargha
National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK
a Hydrogen uel - Product Specifcation - Part 2: Proton exchange membrane (PEM) uel cell applications or road vehicles
Conclusions• The target LoDs have been achieved for all species of key industrial impor tance
(see chart).
• The new suite of methods has been tested on hydrogen samples produced by ITM
Power’s novel electrolytic hydrogen production facility. The results greatly pleased our
collaborators and we look forward to working with them again in the near future.
Future Work The next challenges are:
• Measurement of the remaining few species below the limits specied in ISO/DIS 14687-2.
• Development of a single method to analyse as many of the potential impurities as
possible. GC-MS is the most promising technique to be able to do this.
• Development of a selective membrane system that can enrich the impurities within
the hydrogen.• Investigation into the eects of sampling hydrogen from 7 00bar sources on the levels of impuri ties.
The Driver There is a pressing need to move away from the conventional fossil fuels used as vehicle fuels today due to their damaging environmental eects and dwindling resources.
One solution is the use of hydrogen as a fuel as this would signicantly reduce harmful emissions from vehicles as well as being po tentially produced by renewable energy
sources.
The Measurement NeedImpurities in hydrogen have a severe aect on the per formance of fuel cells. For example at several
hundred ppb carbon monoxide will po ison the expensive platinum catalyst. It is therefore crucial to
be able to detect any impurities before the fuel is used. An international standard ISO/DIS 14687-2a is
being developed to highlight all of the impurities that need to be identied and at what level, these are
illustrated on the left.
SpeciesMaximum Concentration
(µmol/mol) (ppm)
Water 5
Total hydrocarbons 2
Oxygen 5
Helium 300
Nitrogen/Argon 100
Carbon Dioxide 2
Carbon Monoxide 0.2
Total sulphur compounds 0.004
Formaldehyde 0.01
Formic acid 0.2
Ammonia 0.1
Total halogenated compounds 0.05
Maximum particulates concentration 1mg/kg
Analytical ChallengesMost of the impuri ties in the table are challenging in several dierent ways: some will be aected by air
contamination (e.g. oxygen at 5ppm), others are at an extremely low level (e.g. 4ppb total sulphur species)
and some species are not stable (e.g. formaldehyde). Preparation of stable gaseous reference materials for
a number of these species is highly challenging.
Method Developments at NPLA suite of methods have been developed to analyse impurities in hydrogen at or below the specication
in ISO/DIS 14687-2. Two highlights are:
1) Total Sulphur Compounds at 4ppb by GC-SCD
Usually only achievable by pre-concentration. The challenge here is two-fold, rstly to be able to
measure all sulphur species together, and secondly to achieve an extremely low LoD. NPL designed
passivated cylinders and a bespoke sampling system to prevent any adsorption to su rfaces were used.
For the analysis, a column with very low retention was u sed to ensure that ve dierent sulphur species
would all elute as a single peak. The result was a calculated LoD of 1ppb.
2) O2, N
2, CH
4, and CO by GC-PDHID
A novel pulsed discharge helium ionisation detection gas chromatography (GC-PDHID) method has
been developed at NPL to measure very low levels of permanent gases including oxygen, ni trogen,
methane and carbon monoxide. The method shows outstanding separation of the target impurities,
LoD’s for these species were calculated to be below 100ppb.
www.itm-power.com