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Applications Overview
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Samples
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Last update: 2010-02-01
XRF Analysis of Catalyst Overview
of Samples
At this moment we do not have results obtained with UniQuant
4.
The results shown below have been obtained with UniQuant 1 or
2.
Automotive
Exhaust Catalyst
Material base: Corderite (ceramic string)
Layer (Al Ce Zr) by slurry washing, then Pt Rh added
Ground sample as loose powder on supporting film and analysed
by XRF + UniQuant 1 in Sweden, June 1991.
No standards have been used. UniQuant1 Production Target
--------- -----------------
Pt 0.27 0.237 ± 0.004
Rh 0.059 0.047 ± 0.002
Pd <0.01 0.02 ± 0.02
Al2O3 45.7 42.8 ± 0.4
CeO2 7.5 7.6 ± 0.2
ZrO2 0.34 0.25 ± 0.01
SiO2 33.0 35.9 ± 0.4
MgO 10.5 10.0 ± 0.1
Fe2O3 0.54 0.45 ± 0.02
TiO2 0.46 0.51 ± 0.02
Cl 0.30 0.23 ± 0.01
Na2O 0.12 0.2 ± 0.1
CaO 0.075 0.088 ± 0.002
CdO 0.043
K2O 0.033 0.04 ± 0.01
Sb2O3 0.023
SO3 <0.01 0.00 ± 0.01
Cr2O3 <0.01 0.02 ± 0.02
MnO <0.01 0.02 ± 0.02
NiO <0.01 0.02 ± 0.02
ZnO <0.01 0.00 ± 0.01
BaO <0.01 0.05 ± 0.01
La2O3 <0.01 0.02 ± 0.01
Pb <0.01 0.000 ± 0.001
Elements in bold (Pt, Rh, Al2O3, CeO2 and ZrO2)
are on the outside of the corderite,
which is the reason why the UniQuant values are somewhat too
high. This can be
corrected only by adapting Kappa's to this type of sample.
Catalytic
Converter Samples
Analysis by XRF + UniQuant1 in Italy, May 1991.
Calibration did not include any special standards. DIFFERENCES
Specified UniQuant-Specified
Range %C Low High
--------------- ----------------
Pt 0.158 ... 0.237 -0.016 +0.015
Rh 0.033 ... 0.057 -0.007 +0.002
Ce 2.38 ... 6.23 -0.55 -0.08
La 0.043 ... 0.205 -0.021 +0.024
Matrix:
SiO2 about 30
Al2O3 about 47
MgO about 9
Note:
The error range of Ce, -0.55 to -0.08, may be due to a
systematic error that is
easily overcome by a refinement of the instrumental sensitivity,
Kappa, for
the XRF line with which Cerium is measured.
Organic
Samples with Catalyst Residues
Twelve samples, labelled D1..D4,
E1..E4 and F1..F4, were submitted by Welcome Research,
UK, for standardless XRF analysis by UniQuant 2.The samples
are loose powders of cellulose.
For each sample, the Pd concentration is specified in ppm (range
89 to 915 ppm). Sample
Presentation
A 'de KAT' cup with a 6 mm polypropylene bottom
is used for measuring loose powder.
The sample is put on the film and slightly presses to have
a top surface that is parallel to the film.
The net mass that 'sits' over the 24 mm ø viewed area
is determined as well as the height
(thickness) of the sample since both are required by UniQuant.
The spectrometer uses Helium
(instead of vacuum) to avoid powder spilling.
Measurements
Each sample has been measured by the full analytical
program as prescribed by the UniQuant
method. The total spectrometer time then is 15 minutes per
sample. The full (comprehensive)
program is to determine the concentrations of 72 elements
(UniQuant 2). For routine analysis,
one could make a sub set analytical program with fewer analytical
lines while spending more
time at lines (elements) of direct interest. In the case of
the submitted samples, the spectrometer
time may be reduced to say 5 minutes whilst spending much
more time at elements like Pd.
PdKa was here measured for 10 seconds, all other (102) lines
at 6 or 10 seconds.
Evaluation by UniQuant
Results are sensitive to the exact nature of
the 'unknown Rest'. We have assumed that
the 'Unknown Rest' is Cellulose in the form of C6H10O5, of
which UniQuant is to determine the
concentration. If the molecular formula is not quite correct,
this may cause errors in the results for
the lighter elements in the order of 10 to 20 % relative.
UniQuant has not used any special standards.
For example, for Pd the instrument has merely been calibrated
by a 100% Pd metal sample.
Not any adaptations have been made for fitting the data.
Results for Pd
All Concentrations are in [mg/kg]
Sample Pd Pd Estim. %Rel.
specified UniQuant1 Max.Err. diff.
D1 96 97 10 +3 Light grey
D2 216 180 20 -17 Light grey
D3 403 370 30 -8 Light grey
D4 739 680 60 -9 Light grey
E1 77 76 9 -13 Medium grey
E2 206 140 10 -32 Medium grey
E3 391 300 30 -23 Medium grey
E4 861 640 50 -25 Medium grey
F1 105 89 10 -10 Darker grey
F2 193 180 20 -7 Darker grey
F3 376 360 30 -4 Darker grey
F4 915 900 70 -3 Darker grey
Because the UniQuant results for samples
E1..E4 have a larger bias with respect to the specified
values, we suspect that the organic material for these samples
is different from those in
the D and F series. This would also explain the difference
in the grey colour shades between
the three groups of samples. The estimated maximum UniQuant
errors do not include errors
caused by inaccurate specification of the nature (composition)
of the 'Rest'. Accurate specification
would eliminate such source of error. It would have been easy
to adapt the calibration of UniQuant
to compensate for the average bias. We did not do that in
order to show UniQuant's performance
on the basis of a one-off calibration that is universally
used for any type of sample (steel, soil, ash,
plastic, oil, etc.).
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