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TXRF analysis of aged three way catalysts
R Fernández-Ruiz1, F Cabello Galisteo, C Larese
1Servicio Interdepartamental de Investigación. Facultad de Ciencias. Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain. ramon.fernandez@uam.es
The Analyst
|March 29, 2006
Summary
This study quantifies elements in car exhaust catalysts using TXRF, revealing differences between catalytic blocks and proving lead and zinc loss to the environment after vehicle aging.
Area of Science:
- Materials Science
- Analytical Chemistry
- Environmental Science
Background:
- Automotive exhaust catalysts are critical for emissions control.
- Understanding elemental distribution and aging is vital for catalyst performance and environmental impact assessment.
- Three Way Catalysts (TWCs) contain precious metals and are susceptible to contaminants.
Purpose of the Study:
- To develop and apply a quantitative analysis methodology for elements in car exhaust catalysts.
- To investigate the axial elemental profile and distribution within a TWC after vehicle aging (59,000 km).
- To compare elemental concentrations in aged catalysts with fresh ones and assess contaminant absorption and loss.
Main Methods:
- Total reflection X-ray fluorescence (TXRF) spectrometry was employed for elemental quantification.
- Analysis was performed along the main axis of a Ford Focus 1.6i catalytic cartridge.
- Elemental concentrations of catalytic components (Zr, Rh, Pd) and contaminants (P, Pb, Zn, Pt, Ca, Ni) were measured.
Main Results:
- Significant differences in elemental concentration were quantitatively measured for the first time at the interphase between the two catalytic blocks.
- The contaminant absorption capacity of both catalytic blocks was determined.
- The loss of lead (Pb) and zinc (Zn) to the environment was demonstrated.
Conclusions:
- TXRF provides a robust method for analyzing elemental profiles in aged automotive catalysts.
- Distinct elemental distributions exist between catalytic blocks, impacting performance and aging.
- Environmental release of contaminants like lead and zinc from catalysts is confirmed.
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