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The goal of this project was to demonstrate a low emissions, high efficiency heavy-duty on-highway natural gas engine. The emissions targets for this project are to demonstrate US 2010 emissions standards on the 13-mode steady state test. To meet this goal, a chemically correct combustion (stoichiometric) natural gas engine with exhaust gas recirculation (EGR) and a three way catalyst (TWC) was developed. In addition, a Sturman Industries, Inc. camless Hydraulic Valve Actuation (HVA) system was used to improve efficiency. A Volvo 11 liter diesel engine was converted to operate as a stoichiometric natural gas engine. Operating a natural gas engine with stoichiometric combustion allows for the effective use of a TWC, which can simultaneously oxidize hydrocarbons and carbon monoxide and reduce NOx. High conversion efficiencies are possible through proper control of air-fuel ratio.

Due to its high efficiency and superior durability the diesel engine is again becoming a prime candidate for future light-duty vehicle applications within the United States. While in Europe the overall diesel share exceeds 40%, the current diesel share in the U.S. is 1%. Despite the current situation and the very stringent Tier 2 emission standards, efforts are being made to introduce the diesel engine back into the U.S. market. In order to succeed, these vehicles have to comply with emissions standards over a 120,000 miles distance while maintaining their excellent fuel economy. The availability of technologies such as high-pressure common-rail fuel systems, low sulfur diesel fuel, NOx adsorber catalysts (NAC), and diesel particle filters (DPFs) allow the development of powertrain systems that have the potential to comply with the light-duty Tier 2 emission requirements. In support of this, the U.S.

The increasing severity in emission standards around the world has been accompanied by the development of more active, durable catalysts. With a view to investigating the effects of high thermal aging on the catalyst performance and structure, the relationships of washcoat composition, washcoat structure, and PGM location with respect to catalyst activity were clarified using a model gas test, as well as physical and chemical characterization methods. The influence of newly developed washcoat components and PGM location on catalyst performance are also demonstrated by engine bench tests. The results obtained in this study indicate the newly developed Pt/Rh catalyst techologies are appropriate for future applications in which the catalyst will be exposed to extremely high temperature and flowrates.

New advanced Pd only, Pd:Rh and Pt:Pd:Rh catalysts are compared with a current platinum rhodium catalyst after poisoning and thermal ageing. The results indicate that at equivalent precious metal cost (at 1994 prices) the advanced palladium based catalysts achieve significantly improved performance compared with current Pt, Rh and Pd technology. The new Pd:Rh formulation is recommended for close coupled locations and the Pt:Pd:Rh formulation recommended for underfloor locations where residual fuel lead may be present. The formation of H2S is shown to be low with the palladium based catalysts. Finally, it is shown that the new catalysts with balanced oxidation and reduction capability perform better in multi-brick systems than addition of a highly loaded palladium only front brick.

In this work, the influences of ethanol and iso-butanol blended with gasoline on engine-out and post three-way catalyst (TWC) particle size distribution and number concentration were studied using a General Motors (GM) 2.0L turbocharged spark ignition direct injection (SIDI) engine. The engine was operated using the production engine control unit (ECU) with a dynamometer controlling the engine speed and the accelerator pedal position controlling the engine load. A TSI Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle size distribution in the range from 5.6 to 560 nm with a sampling rate of 1 Hz. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuel (BU12) were tested. Measurements were conducted at 10 selected steady-state engine operation conditions. Bi-modal particle size distributions were observed for all operating conditions with peak values at particle sizes of 10 nm and 70 nm.

With the advent of stricter vehicle emission standards, the improvement of three way catalyst performance and durability remains a pressing issue. A critical consideration in catalyst design is the potential for variations in fuel sulfur levels to have a significant impact on the ability to reach TLEV, LEV, and ULEV emission levels. As a result, a better understanding of the role of PGM composition in the interplay between thermal durability and sulfur tolerance is required. Three way catalysts representative of standard Pd-only, Pd/Rh and Pt/Rh formulations were studied over a variety of aging and evaluation conditions. The parameters investigated included aging temperature, air fuel ratio and sulfur level. Evaluations were performed on a 1994 TLEV vehicle using different sulfur level fuels. The effect of PGM loading was also included within the study.

A 1.3-L direct injection diesel engine was used in steady-state testing to determine the emissions performance of a matrix of ultra-low sulfur diesel fuels encompassing two types of sulfur removal and the use of fuel oxygenates. As expected, exhaust gas recirculation was the most effective technique for NOx reduction. With regard to fuel effects, an oxygenated diesel fuel produced with a conventional sulfur removal process reduced particulate emissions substantially, and these particulate reductions could be converted into NOx reductions by using higher levels of exhaust gas recirculation. On a simulated FTP, this oxygenated fuel simultaneously decreased NOx emissions by 30% and total particulate emissions by 50% compared to a baseline fuel.

The performance characteristics of a commercial lean-NOX trap catalyst were evaluated between 200 and 500°C, using H2, CO, and a mixture of both H2 and CO as reductants before and after different high-temperature aging steps, from 600 to 750°C. Tests included NOX reduction efficiency during cycling, NOX storage capacity (NSC), oxygen storage capacity (OSC), and water-gas-shift (WGS) and NO oxidation reaction extents. The WGS reaction extent at 200 and 300°C was negatively affected by thermal degradation, but at 400 and 500°C no significant change was observed. Changes in the extent of NO oxidation did not show a consistent trend as a function of thermal degradation. The total NSC was tested at 200, 350 and 500°C. Little change was observed at 500°C with thermal degradation but a steady decrease was observed at 350°C as the thermal degradation temperature was increased.

In a collaborative programme, the effects of gasoline sulphur content on regulated emissions from three-way catalyst equipped vehicles have been studied. The programme evaluated the sulphur tolerance of three different catalyst formulations on the same range of vehicles. The catalyst chemistries were chosen to be representative of typical current formulations in different markets, as follows: 1. Platinum/Rhodium (Pt/Rh) 2. Platinum/Rhodium/Nickel (Pt/Rh/Ni) 3. Palladium/Rhodium (Pd/Rh) Each vehicle/catalyst combination was tested with fuels containing sulphur at nominal levels of 50, 250 and 450 ppm weight. All fuels were produced using the low sulphur fuel as a base and doping to 250 and 450 ppm S with a mixture of nine sulphur compounds, typical of those actually occurring in European gasolines. The results show clear differences between the magnitudes of the sulphur effect with different catalyst formulations.

Following concern about the association between adverse health effects and ambient particulate concentrations, there are now an increasing number of heavy-duty Diesel engines fitted with catalysed particulate filters. These filters virtually eliminate carbon particle emissions but there is some evidence suggesting a potential to form a cloud of secondary nucleation particles post trap. This event occurs at high temperature operating conditions and is produced mainly from the increased sulphate production over the catalyst. This paper investigates the measurement of particle emissions from a heavy-duty engine operating over the European legislated cycle, both with and without a filter fitted and investigates how emissions are affected by the use of a sulphur-free Diesel fuel. The work also demonstrates a contribution to the measured nucleation particles from material desorbed not only from the trap, but also from the exhaust system.

Progress made in reducing engine-out particulate emissions has prompted a revival in the design of flow-through oxidation catalysts for diesel engine applications. Effort in this area has focused primarily in the area of SOF control for the further reduction of particulate emissions. The work reported here covers some of the catalyst design parameters important for SOF and gas phase pollutant control. This is illustrated with both laboratory reactor and engine evaluation data for several formulary and operating parameters. Platinum-based catalysts are shown to be generally the most active, but they require treatments or additives to reduce the inherently high activity of platinum for the oxidation of SO2 present in the exhaust. The effect of additives and their loading on the oxidation activity of Pt/alumina for HC, CO, SOF and SO2 oxidation is discussed in detail and additives are identified which reduce SO2 oxidation with minimal effect on HC, CO or SOF oxidation activity.

The Advanced Petroleum-Based Fuels - Diesel Emissions Control (APBF-DEC) project is a joint U.S. government/industry research effort to identify optimal combinations of fuels, lubricants, engines, and emission control systems to meet projected emissions regulations during the period 2000 to 2010. APBF-DEC is conducting five separate projects involving light- and heavy-duty engine platforms. Four projects are focusing on the performance of emission control technologies for reducing criteria emissions using different fuels. This project is investigating the effects of lubricant formulation on engine-out emissions (Phase I) and the resulting impact on emission control systems (Phase II). This paper describes the statistical design and analysis methods used during Phase I of the lubricants project.

It is widely understood that cold ambient temperatures increase vehicle fuel consumption due to heat transfer losses, increased friction (increased viscosity lubricants), and enrichment strategies (accelerated catalyst heating). However, relatively little effort has been dedicated to thoroughly quantifying these impacts across a large set of real world drive cycle data and ambient conditions. This work leverages experimental dynamometer vehicle data collected under various drive cycles and ambient conditions to develop a simplified modeling framework for quantifying thermal effects on vehicle energy consumption. These models are applied over a wide array of real-world usage profiles and typical meteorological data to develop estimates of in-use fuel economy. The paper concludes with a discussion of how this integrated testing/modeling approach may be applied to quantify real-world, off-cycle fuel economy benefits of various technologies.

In a consortium of European industrial partners and research institutes, a combination of industrial development and scientific research was organised. The objective was to improve the catalytic NOx conversion for lean burn cars and heavy-duty trucks, taking into account boundary conditions for the fuel consumption. The project lasted for three years. During this period parallel research was conducted in research areas ranging from basic research based on a theoretical approach to full scale emission system development. NOx storage catalysts became a central part of the project. Catalysts were evaluated with respect to resistance towards sulphur poisoning. It was concluded that very low sulphur fuel is a necessity for efficient use of NOx trap technology. Additionally, attempts were made to develop methods for reactivating poisoned catalysts. Methods for short distance mixing were developed for the addition of reducing agent.

Selective NOx recirculation (SNR), involving adsorption, selective external recirculation and decomposition of the NOx by the combustion process, is itself a promising technique to abate NOx emissions. Three types of materials containing Ba: barium aluminate, barium tin perovskite and barium Y-zeolites have been developed to adsorb NOx under lean-burn or Diesel conditions, with or without the presence of S02. All these materials adsorb NO2 selectively (lean-burn conditions), and store it as nitrate/nitrite species. The desorption takes place by decomposition of these species at higher temperatures. Nitrate formation implies also sulfate formation in the presence of SO2 and SO3, while the NO2/SO2 competition governs the poisoning of such catalysts.

To help guide heavy vehicle engine, fuel, and exhaust after-treatment technology development, the U.S. Department of Energy and the Lovelace Respiratory Research Institute are conducting research not addressed elsewhere on aspects of the toxicity of particulate engine emissions. Advances in these technologies that reduce diesel particulate mass emissions may result in changes in particle composition, and there is concern that the number of ultrafine (<0.1 micron) particles may increase. All present epidemiological and laboratory data on the toxicity of diesel emissions were derived from emissions of older-technology engines. New, short-term toxicity data are needed to make health-based choices among diesel technologies and to compare the toxicity of diesel emissions to those of other engine technologies.

In this study, a 15-L heavy-duty diesel engine and an emission control system consisting of diesel oxidation catalysts, NOx adsorber catalysts, and diesel particle filters were evaluated over the course of a 2000 hour aging study. The work is a follow-on to a previously documented development effort to establish system regeneration and sulfur management strategies. The study is one of five projects being conducted as part of the U.S. Department of Energy's Advanced Petroleum Based Fuels - Diesel Emission Control (APBF-DEC) activity. The primary objective of the study was to determine if the significant NOx and PM reduction efficiency (>90%) demonstrated in the development work could be maintained over time with a 15-ppm sulfur diesel fuel. The study showed that high NOx reduction efficiency can be restored after 2000 hours of operation and 23 desulfation cycles.

The objective of this effort was to develop an understanding of how different converter substrate cell structures impact tailpipe emissions and pressure drop from a total systems perspective. The cell structures studied were the following: The catalyst technologies utilized were a new technology palladium only catalyst in combination with a palladium/rhodium catalyst. A 4.0-liter, 1997 Jeep Cherokee with a modified calibration was chosen as the test platform for performing the FTP test. The experimental design focused on quantifying emissions performance as a function of converter volume for the different cell structures. The results from this study demonstrate that the 93 square cell/cm2 structure has superior performance versus the 62 square cell/cm2 structure and the 46 triangle cell/cm2 structure when the converter volumes were relatively small. However, as converter volume increases the emissions differences diminish.

A Robust Engineering experiment was performed to determine the effects PGM loading and placement on the FTP emissions of a 4 cylinder 2.4L and two 8 cylinder 4.7L vehicles. 1.3L catalytic converters were used containing a front and rear catalyst of equal volume. The experiment is defined by a Taguchi L-8 array. Eight different combinations of catalyst PGM loadings were aged and evaluated. Results show that nmHC and NOx emissions are predominately affected by the PGM loading of the front catalyst. The rear catalyst is insensitive to either Pt or Pd which can be used at low concentrations. Results also compare the benefits of Pd and Rh to reduce emissions. Confirmation runs suggest that significant reductions in PGM cost can be achieved over baseline designs.

This paper describes the results of Phase 1 of the Diesel Emission Control - Sulfur Effects (DECSE) Program. The objective of the program is to determine the impact of fuel sulfur levels on emissions control systems that could be used to lower emissions of nitrogen oxides (NOx) and particulate matter (PM) from vehicles with diesel engines. The DECSE program has now issued four interim reports for its first phase, with conclusions about the effect of diesel sulfur level on PM and total hydrocarbon (THC) emissions from the high-temperature lean-NOx catalyst, the increase of engine-out sulfate emissions with higher sulfur fuel levels, the effect of sulfur content on NOx adsorber conversion efficiencies, and the effect of fuel sulfur content on diesel oxidation catalysts, causing increased PM emissions above engine-out emissions under certain operating conditions.