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Accelerated aging of automotive catalysts has become a routine process for the development of new catalytic formulations and for homologation of vehicle emissions. In the standard approach, catalyst samples are subjected to temperatures in excess of 800°C on a predefined test cycle and aged for precise timescales representative of certain vehicle mileage. The high temperature feed gas is traditionally provided by a large gasoline engine but, increasingly, alternative bench-aging techniques are being applied as these offer more precise control and considerable cost savings, as well as offering more development possibilities. In the past few years, emissions control of light duty vehicles has become increasingly prominent as more stringent emissions legislations require more complex after-treatment systems. Aging of the catalysts are not fully understood as they are subjected to many varying environments, including temperature and gas concentrations.

Previously, an initial investigation examined the effect of the catalytic substrate on the gas dynamics of the blowdown pulse on the QUB single shot rig. This initial investigation measured the resulting waves from the catalytic converter in the exhaust pipe. In this early study the substrate was at ambient temperature but it is recognised that after light-off higher reaction temperatures will result from the exothermic nature of exhaust gas oxidation and reduction. Therefore substantially different results will occur. This paper details a series of experiments which investigate the influence of an operating catalyst on the unsteady gas dynamics in an exhaust system using the QUB single shot rig. In addition to measuring the effect of temperature on the gas dynamics previous work is reviewed with emphasis now on specifically measuring the features present rather than having to decipher superimposed pressure traces.

This study describes an innovative monolith structure designed for applications in automotive catalysis using an advanced manufacturing approach developed at Imperial College London. The production process combines extrusion with phase inversion of a ceramic-polymer-solvent mixture in order to design highly ordered substrate micro-structures that offer improvements in performance, including reduced PGM loading, reduced catalyst ageing and reduced backpressure. This study compares the performance of the novel substrate for CO oxidation against commercially available 400 cpsi and 900 cpsi catalysts using gas concentrations and a flow rate equivalent to those experienced by a full catalyst brick when attached to a vehicle. Due to the novel micro-structure, no washcoat was required for the initial testing and 13 g/ft3 of Pd was deposited directly throughout the substrate structure in the absence of a washcoat.

One of the most critical aspects in the development of a kinetic model for automotive applications is the method used to control the switch between limiting factors over the period of the chemical reaction, namely mass transfer and reaction kinetics. This balance becomes increasingly more critical with the automotive application with the gas composition and gas flow varying throughout the automotive cycles resulting in a large number of competing reactions, with a constantly changing space velocity. A methodology is presented that successfully switches the limitation between mass transfer and reaction kinetics. This method originally developed for the global kinetics model using the Langmuir Hinshelwood approach for kinetics is presented. The methodology presented is further expanded to the much more complex micro-kinetics approach taking into account various kinetic steps such as adsorption/desorption and surface reactions.