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Question
Category: Emissions Control
Subject: Platinum oxidation state for catalytic converters
What is the oxidation state of platinum used as catalyst in catalytic converters? Is the platinum zerovalent or used as an oxide or any other type of compound?
Answer
The preparative route is designed to ensure that the platinum precursor is converted to highly dispersed metallic particles. Analytical techniques, such as X-ray photoelectron spectroscopy (XPS) or temperature-programmed reduction, often show some residual oxidised platinum in freshly prepared catalysts. However, the oxide is confined to the surface of the metal particles, and can be readily removed (e.g. just by exposure to operating conditions).
Answer posted 08 August 2007
Submitted by: Mr Jaime Werner
Affiliation:
Answered by: Dr Stan Golunski
Affiliation: Technology Manager of Gas Phase Catalysis, Johnson Matthey Technology Centre