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On-vehicle proof-of-concept testing was conducted to evaluate the ability of the dual oxygen sensor catalyst evaluation method to identify serious losses in catalyst efficiency under actual vehicle operating conditions. The dual oxygen sensor method, which utilizes a comparison between an upstream oxygen sensor and an oxygen sensor placed downstream of the catalyst, was initially studied by the Environmental Protection Agency (EPA) under steady-state operating conditions on an engine dynamometer and reported in Clemmens, et al. (1).* At the time that study was released, questions were raised as to whether the technological concepts developed on a test fixture could be transferred to a vehicle operating under normal transient conditions.

The United States Environmental Protection Agency (U.S. EPA) National Enforcement Investigations Center (NEIC) has developed a test method for the analysis of washcoat material in small engine catalytic converters. Each small engine catalytic converter contains a metallic monolith. Each metallic monolith is removed from its outer casing, manually disassembled, and then separated into washcoat and substrate. The washcoat material is analyzed for platinum group metals (PGMs) using X-ray fluorescence (XRF) spectrometry. Results from the XRF analysis are used to calculate PGM ratios in the washcoat. During monolith disassembly, care is taken to minimize loss of washcoat or substrate, but some material is inevitably lost. The recovered washcoat mass does not necessarily equal the quantity of washcoat that was present in the intact catalytic converter.

In 2005, the United States Environmental Protection Agency (EPA) and Southwest Research Institute (SwRI) embarked on a mission to help the city of Beijing, China, clean its air. Working with the Beijing Environmental Protection Bureau (BEPB), the effort was a pilot diesel retrofit demonstration program involving three basic retrofit technologies to reduce particulate matter (PM). The three basic technologies were the diesel oxidation catalyst (DOC), the flowthrough diesel particulate filter (FT-DPF), and the wallflow diesel particulate filter (WF-DPF). The specific retrofit systems selected for the project were verified through the California Air Resources Board (CARB) or the EPA verification protocol [1]. These technologies are generally verified for PM reductions of 20-40 percent for DOCs, 40-50 percent for the FT-DPF, and 85 percent or more for the high efficiency WF-DPF.

The use of a partial flow sampling system (PFSS) to measure nonroad steady-state diesel engine particulate matter (PM) emissions is a technique for certification approved by a number of regulatory agencies around the world including the US EPA. Recently, there have been proposals to change future nonroad tests to include testing over a nonroad transient cycle. PFSS units that can quantify PM over the transient cycle have also been discussed. The full flow constant volume sampling (CVS) technique has been the standard method for collecting PM under transient engine operation. It is expensive and requires large facilities as compared to a typical PFSS. Despite the need for a cheaper alternative to the CVS, there has been a concern regarding how well the PM measured using a PFSS compared to that measured by the CVS. In this study, three PFSS units, including AVL SPC, Horiba MDLT, and Sierra BG-2 were investigated in parallel with a full flow CVS.

Twenty in-use vehicles that had failed the I/M test in the State of Michigan were inspected for engine mechanical condition as well as the state of the emission control system. Mass emission tests were conducted before and after repairs to the emission control system. The internal engine condition (i.e., high or low levels of cylinder leakage, or compression difference) showed little effect on the ability of the repaired vehicles to achieve moderate mass emission levels. Nine of the twenty vehicles were recruited after three years, and with the exception of tampering, the original emission control system repairs proved to be durable.

Simple tests were performed to investigate the operating characteristics of zirconia galvanic cells (lambda sensors) in automotive closed loop “three-way” emission control systems. Commercially available cells were exposed to typical gaseous components of exhaust gas mixtures. The voltages generated by the cells were at their maximum values when hydrogen, and, in some instances, carbon monoxide, was available for reaction with atmospheric oxygen that migrated through the cells' ceramic thimbles in ionic form. This dependence of galvanic activity on the availability of these particular reducing agents indicated that the cells were voltaic devices which operated as oxidation/reduction reaction cells, rather than simple oxygen concentration cells.

Regulated emissions (THC, CO, NOx, and PM) and particulate SOF and sulfate fractions were determined for a 1995 Detroit Diesel Series 50 urban bus engine at varying fuel sulfur levels, with and without catalytic converters. When tested on EPA certification fuel without an oxidation catalyst this engine does not appear to meet the 1994 emissions standards for heavy duty trucks, when operating at high altitude. An ultra-low (5 ppm) sulfur diesel base stock with 23% aromatics and 42.4 cetane number was used to examine the effect of fuel sulfur. Sulfur was adjusted above the 5 ppm level to 50, 100, 200, 315 and 500 ppm using tert-butyl disulfide. Current EPA regulations limit the sulfur content to 500 ppm for on highway fuel. A low Pt diesel oxidation catalyst (DOC) was tested with all fuels and a high Pt diesel oxidation catalyst was tested with the 5 and 50 ppm sulfur fuels.

This paper summarizes a laboratory effort toward reducing nine-mode cycle composite emissions and fuel consumption in a heavy-duty gasoline engine, while retaining current durability performance. Evaluations involved standard carburetors, a Dresserator inductor, a Bendix electronic fuel injection system, exhaust manifold thermal reactors, and exhaust gas recirculation, along with other components and engine operating parameters. A system consisting of electronic fuel injection, thermal reactors with air injection and exhaust gas recirculation, was assembled which met specified project goals. An oxidation catalyst was included as an add-on during the service accumulation demonstration. In addition, the driveability of this engine configuration was demonstrated.

High mileage vehicles (in excess of 50,000 miles) contribute more than half of all vehicular emissions. With the new catalytic converter equipped cars, the proportional contribution of these vehicles may be even higher than for pre-catalyst vehicles. Thus a substantial portion of motor vehicle related air pollution may be caused by vehicles not subject to the manufacturer directed provisions of the Clean Air Act. This paper presents a modeling effort based on hypotheses and some preliminary data, and suggests some alternatives to combat this potential problem.

The increased interest in use of methanol makes it important to determine what levels of methanol and formaldehyde emissions may be acceptable. This paper reviews the available health data for methanol and formaldehyde to define what approximate ranges of concentrations, termed ranges of concern, could be acceptable from a toxicological viewpoint. Air quality models are then used to predict the in-use fleet average exhaust emission levels in localized situations (heavily impacted by mobile sources) corresponding to these ranges of concern. Using predicted fleet compositions, approximate target emission levels are given for the light-duty portion of the fleet which could yield these fleet averages. Finally, there is a brief summary of available methanol and formaldehyde emissions data from neat methanol-fueled vehicles which are compared to the target levels.

The application of resistive materials as part of an exhaust emission control system is presented and discussed. The importance of cold start emissions is emphasized, and results are presented from experiments conducted with two different conductive materials. Most of the testing was conducted using methanol as the fuel, although some tests were run using gasoline-fueled vehicles.

A Methanol catalyst test program has been conducted in two phases. The purpose of Phase I was to determine whether a base metal or lightly-loaded noble metal catalyst could reduce Methanol engine exhaust emissions with an efficiency comparable to conventional gasoline engine catalytic converters. The goal of Phase II was the reduction of aldehyde and unburned fuel emissions to very low levels by the use of noble metal catalysts with catalyst loadings higher than those in Phase I. Catalysts tested in Phase I were evaluated as three-way converters as well as under simulated oxidation catalyst conditions. Phase II catalysts were tested as three-way converters only. For Phase I, the most consistently efficient catalysts over the range of pollutants measured were platinum/rhodium configurations. None of the catalysts tested in Phase I were able to meet a NOx level of 1 gram per mile when operated in the oxidation mode.

A 2001 General Motors 4.3 liter V-6 marine engine was baseline emissions tested and then equipped with catalysts. Emission reduction effects of exhaust gas recirculation (EGR) were also explored. Because of a U.S. Coast Guard requirement that inboard engine surface temperatures be kept below 200°F, the engine's exhaust system, including the catalysts, was water-cooled. Engine emissions were measured using the ISO-8178-E4 5-mode steady-state test for recreational marine engines. In baseline configuration, the engine produced 16.6 g HC+NOx/kW-hr, and 111 g CO/kW-hr. In closed-loop control with catalysts, HC+NOx emissions were reduced by 75 percent to 4.1 g/kW-hr, and CO emissions were reduced by 36 percent to 70 g/kW-hr of CO. The catalyzed engine was then installed in a Sea Ray 190 boat, and tested for water reversion on both fresh and salt water using National Marine Manufacturers Association procedures.