Modelling NOX Storage and Thermal Desorption: Is It Possible to Model the Effect of Changing the Catalyst Composition?
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In this work, a series of model NOX storage catalysts with different Pt and Ba loadings (in the range 0–2 wt% and 0–20 wt%, respectively) have been studied for NOX storage and desorption. The samples have been characterised by in-situ DRIFTS to identify the nature of the stored species and by EXAFS to gather information about the Pt particle size. A correlation between the average Pt particle size and the Pt/Ba ratio has been found. A simple kinetic model for NOX storage and thermal desorption has been developed, which can reasonably capture the experimental results over a wide range of conditions. The fitting parameters have been optimised independently for each of the samples and have been found to be dependent on the catalyst’s structural properties (average Pt particle size, total Pt perimeter and Ba loading). The so found correlations have been introduced in the model, which can now be used to simulate the behaviour of catalysts with different Pt and Ba loadings as well as to optimise the catalyst composition for different applications.
KeywordsLean NOX trap NOX storage catalyst Kinetic modelling Emissions control Platinum Barium
The authors thank the Advanced Characterisation Department at Johnson Matthey Technology Centre for ICP and TG–MS analysis and Johnson Matthey PLC for permission to publish.
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