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Euro IV-V and US 2007-2010 emission control regulations, combined with changing engine-out emission characteristics of advanced diesel combustion systems result in different performance and durability requirements for diesel oxidation catalysts depending upon specific platforms and regulation levels. A rational catalyst design approach has been utilized to develop a series of catalysts with performance, durability, and PGM utilization characteristics to meet different system requirements. Promoted-Pt catalysts with 40 °C lower CO light-off temperatures and improved thermal durability compared to Pt-only formulations have been developed for use in applications with low exhaust temperatures. The promoted-Pt catalysts also provide tunable NO oxidation activity, which is important for NO/NO2 control (SCR) and areas where excessive NO2 emissions are of concern.

A breakthrough catalyst technology utilizing new mixed metal oxides in conjunction with Platinum Group Metals has been developed. Stable synergies are designed into the catalyst washcoat that enable high performance and durability to be achieved at low Platinum Group Metal usage. Extensive vehicle data is reported on catalysts aged using a variety of high-temperature accelerated aging cycles. Vehicle performance at the LEV, ULEV and LEV-II levels is discussed in the context of unique calibration-catalyst interactions. Conclusions concerning further areas of improvement and future applications are also reviewed.

The College of Engineering-Center for Environmental Research and Technology at the University of California, Riverside and Honda Motor Company are conducting a cooperative research program to study the emission characteristics and evaluate the environmental impact of advanced technology vehicles designed to have emission rates at, or below, the California ULEV standard. This program involves a number of technical challenges relating to instrumentation capable of measuring emissions at these low levels and utilizing this instrumentation to gather data under realistic conditions that will allow assessments of the environmental impact of these advanced vehicle technologies. This paper presents results on the performance and suitability of a Fourier Transform Infrared (FTIR) based on-board measurement system developed principally by Honda R&D for this task. This system has been designed to simultaneously measure vehicle exhaust and ambient roadway pollutant concentrations.

The requirement to meet more stringent emission standards has focused attention on the effects of gasoline sulfur on automotive emissions. Numerous studies have shown that three-way catalyst performance is severely inhibited by sulfur. A literature review of laboratory studies on the interaction of sulfur with automotive catalyst components provides the basis for understanding impacts on catalyst activity under the variety of conditions encountered in vehicle operation. Under stoichiometric and rich conditions, SO2 formed during combustion is dissociatively adsorbed on platinum group metal surfaces to form strongly bound Sad. Sulfur inhibition results from both physical blockage and electronic effects of Sad, such that low coverage of Sad results in disproportionately higher levels of reaction site blockage. This is responsible for the nonlinear effects observed with increasing fuel sulfur level.