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Commercial three way catalysts (TWC) are designed to eliminate HC, CO and NOx pollutants emitted from gasoline powered internal combustion engines. TWC have been optimized over many years to meet ever more stringent emission regulations. It has long been speculated that surface electrical conductivity may be a key parameter in controlling catalytic activity, however until now it has not been possible to reliably measure this physical parameter on a catalytic surface. In this study, the surface electrical conductivity of catalyst powders, such as Rh/ CeO1-x-ZrxO2, Rh/ZrO2 and Rh/Al2O3, were measured by EUPS (Extreme Ultraviolet excited Photoelectron Spectroscopy). Then the measured electrical conductivity was compared with catalyst performance from CO-NO and water gas shift reactions which are important for controlling automobile exhaust emissions from gasoline vehicles.

Battery models are being developed as a component of the powertrain systems of hybrid electric vehicles (HEVs) to predict the state of charge (SOC) accurately. Electrically heated catalysts (EHCs) can be employed in the powertrains of HEVs to reach the catalyst light off temperature in advance. However, EHCs draw power from the battery pack and hence sufficient energy needs to be stored to power auxiliary components. In series HEVs, the engine is primarily used to charge the battery pack. Therefore, it is important to develop a control strategy that triggers engine start/stop conditions and reduces the frequency of engine operation to minimize the equivalent fuel consumption. In this study, a battery pack model was constructed in MATLAB-Simulink to investigate the SOC variation of a high-power lithium ion battery during extreme engine cold start conditions (-7°C) with/without application of an EHC.

This paper describes the development of an integrated simulation model for evaluating the effects of electrically heating the three-way catalyst (TWC) in a series hybrid electric vehicle (s-HEV) on fuel economy and exhaust gas purification performance. Engine and TWC models were developed in GT-Power to predict exhaust emissions during transient operation. These models were validated against data from vehicle tests using a chassis dynamometer and integrated into an s-HEV model built in MATLAB/Simulink. The s-HEV model accurately reproduced the performance characteristics of the vehicle’s engine, motor, generator, and battery during WLTC mode operation. It can thus be used to predict the fuel consumption, emissions, and performance of individual powertrain components. The engine combustion characteristics were reproduced with reasonable accuracy for the first 50 combustion cycles, representing the cold-start condition of the driving mode.

Three way catalysts (TWC) contain Oxygen Storage Component (OSC) materials to enhance HC, CO oxidation and NOx reduction performance under standard operating conditions where there is rapid perturbation of the air-to-fuel ratio (A/F). The OSC function is required to storage and to release oxygen, however the optimum storage capacity and release rate to maximize HC, CO and NOx conversion varies as a function of engine operating conditions, such as A/F perturbation frequency, amplitude and temperature. At the same time, it is necessary for the vehicle on board diagnostics (OBD) systems to monitor that the catalyst OSC is functioning correctly. Detailed understanding of how OSC characteristics can simultaneously match gas performance and OBD functionality are not well known. In this study, modeling of the OSC function was attempted by considering chemical functions to be analogous to that in an equivalent electrical circuit, having components of resistance and capacitance.

Three Way Catalysts (TWC) contain oxygen storage components (OSC) to enhance HC, CO oxidation and NOx reduction performance under standard operating conditions where there is rapid perturbation of the air-to-fuel ratio (A/F). The OSC function is required to storage and to release oxygen, however the optimum storage capacity and release rate to maximize HC, CO and NOx conversion varies as a function of engine operating conditions, such as A/F perturbation frequency, amplitude and temperature. At the same time it is necessary for the vehicle on board diagnostics (OBD) systems to monitor that the catalyst OSC is functioning correctly. Detailed understanding of how OSC characteristics can simultaneously match gas performance and OBD functionality are not well known. In this study, several TWC catalysts were prepared with different types of OSC materials such that oxygen storage capacity and activation energy for oxygen release could be varied over a wide range.

A new Pd-Rh three-way catalyst (TWC) for close-coupled (CC) applications was developed to improve low temperature gas activity. In this study the TWC has a layered structure with Pd in the top layer and Rh in the bottom layer. The specific objectives of this study was to compare Ba and La additives to Pd in the top layer. Alumina was used for the Pd support and La or Ba were co-impregnated with Pd. The catalysts were engine aged at 950°C for 200 h and evaluated on a vehicle using the European NEDC test, for CO, HC and NOx performance. After this aging, the Pd-La catalyst showed higher gas performance than the Pd-Ba catalyst, especially in the cold start region. This improvement was correlated to the Pd particle size and the sintering suppression observed upon addition of La. Sintering suppression was also observed upon addition of Ba; however, the mechanism appears to be different from that of La addition.

Three-way catalyst (TWC) converters are used to remove harmful substances (e.g., carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC)) emitted from gasoline engines. However, a large amount of emissions could be emitted before the TWC reaches its light-off temperature during a cold start. For hybrid electric vehicles (HEVs) powered by gasoline engines, the emission purification performance by TWC converters unfortunately deteriorates because of mode switching from engine to battery and vice versa, which can repeatedly generate cold start conditions for the TWCs. In this study, aiming to reduce emissions from series HEVs by early activation of TWCs, numerical simulations and experiments are carried out. An HEV is tested on a chassis dynamometer in the Worldwide Light-duty Test Cycle (WLTC) mode. The upstream and downstream gas conditions of the close-coupled catalyst converter are measured.

Three-way catalysts (TWCs) for gasoline-powered vehicles commonly contain Pt group metals (Pt, Pd, and Rh) as active components and Al2O3 or OSC as supports, with Pd and Rh being most frequently employed in view of their high thermal durability. Hybrid electric vehicles (HEVs) have been recently developed to meet strict fuel efficiency regulations, by using feature engines that are much more energy-efficient than those of conventional gasoline vehicles and lend themselves to fixed-point operation control. Therefore, the engine exhaust-induced stress experienced by TWCs in HEVs and the corresponding aging conditions are expected to differ from those in conventional vehicles, which, in turn, should be reflected by a change in the optimal catalyst design. Herein, to facilitate the design of optimum next-generation TWCs, we investigate the deterioration of these catalysts (Pt, Pd, Rh supported on Al2O3 or OSC) under various conditions reflecting different engine operation modes.

Reduction of the amount of platinum group metals (PGM: Pt, Pd, Rh) utilized in three-way catalysts (TWC) has been required from a point of resource shortage and cost effectiveness. A conventional TWC system is composed of a close-coupled (CC) catalyst and an underfloor (UF) catalyst, both PGM-based. The CC-TWC promotes HC/CO oxidation and NOx reduction by CO. The UF-TWC mainly facilitates further NOx reduction by CO. In this study, a TWC system comprising a CC catalyst with PGM and an UF catalyst without PGM has been described. The newly developed system, performing reasonably well with a conventional stoichiometric gasoline combustion engine, offers an opportunity to reduce PGM usage. In this system, the UF-non-PGM catalyst is composed of a Ni/CeO2 bottom layer which functions as a deNOx catalyst with CO-NO reaction and a zeolite based top layer which works as a deNOx catalyst with passive NH3-SCR reaction.