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The regulated and non-regulated emissions of a current diesel passenger car and two light-duty diesel trucks with catalysts and particulate traps were measured to better understand the effects of aftertreatment devises on the environment. The passenger car, a 1.8 L IDI TC Sierra, was tested both with and without three different diesel oxidation catalysts (DOC) and with two fuel sulfur levels, 0 and 0.05 wt%. One light-duty truck, a 2.5 L DI NA Transit, was tested on one fuel, 0.05 wt% sulfur, with and without three different particulate trap/regeneration systems and with and without a urea lean NOx catalyst (LNC) system. A second similar Transit was tested on the 0.05 wt% sulfur fuel with an electrically regenerated trap system. The results are compared to each other, regulated emission standards, and to emissions from gasoline vehicles.

Future European air quality standards for light duty diesel vehicles will include stringent NOx emission regulations. In order to meet these regulations, a lean NOx catalyst system may be necessary. Since the catalytic removal of NOx is very difficult with the large concentration of oxygen present in diesel exhaust, a reductant is usually added to the exhaust to increase the NOx conversion. This paper describes a lean NOx catalyst system for a Transit light-duty truck which uses a reductant solution of urea in water. In this work, a microprocessor was used to vary the amount of the reductant injected depending on the operating conditions of a 2,5 L naturally aspirated HSDI engine. The NOx conversions were 60% and 80% on the current European driving cycle and the U.S. FTP cycles, respectively. Data on the emissions of HC, CO, NOx, particulate mass and composition, individual HC species, aldehydes, PAH and most HC species were evaluated.

Regulated and non-regulated emissions from five current European diesel passenger cars and one light-duty diesel truck were measured to assess the environmental impact of diesel vehicles and to help determine the emission characteristics of the two types of combustion systems: indirect injection (IDI) and high speed direct injection (HSDI). The vehicle emissions were measured using the European Motor Vehicle Emissions Group (MVEG) cycle and the U.S. Federal (FTP 75) test procedures. Measured emissions included HC, CO, NOx and particulate mass (PM), C1 to C12 hydrocarbon species (here called light hydrocarbon or LHC), aldehydes, particulate composition and particle size distribution. The particulate composition measurements included soluble organic fraction (SOF), its oil and fuel sub-fractions, and the sulfate fraction. All passenger cars and the light-duty commercial vehicle tested complied with the current European Emissions Directive 91/441/EEC.

Passenger cars with diesel engines have better fuel economy than cars with gasoline engines. Also diesel engines typically have lower HC and CO emissions than all but the very best, state-of-the-art gasoline engines. On the other hand, diesel NOx and particulate emissions are higher, but recent developments have significantly reduced diesel particulate emissions. While the regulated emissions from both engines are well known, there are relatively few data on the non-regulated emissions for modern diesel engines.

Particulate and manganese mass emissions have been measured as a function of mileage for four Escort and four Explorer vehicles using 1) MMT (Methylcyclopentadienyl Manganese Tricarbonyl) added to the gasoline at 1/32 g Mn/gal and 2) gasoline without MMT. The MMT was used in half of the fleet starting at 5,000 miles. The vehicles were driven on public roads at an average speed of 54 mph to accumulate mileage. This report describes the particulate and manganese emissions, plus emissions of four air toxics at 5,000, 20,000, 55,000, 85,000 and 105,000 miles. Four non-regulated emissions were measured and their average values for vehicles without MMT were 0.6 mg/mi for formaldehyde, 0.7 mg/mi for 1,3-butadiene, 9 mg/mi for benzene and 12 mg/mi for toluene. Corresponding values for MMT-fueled vehicles were between 1.5 and 2.4 times higher.

Vehicle emissions have been measured and the results statistically evaluated for a vehicle test fleet consisting of four Escorts and four Explorers using both a fully formulated durability fuel doped with methylcyclopentadienyl manganese tricarbonyl (MMT) at 1/32 gram Mn/gallon and the same fully formulated durability fuel without the MMT. The fleet was divided in half -- half with MMT and half without MMT doped fuel. This report covers emission measurement results at 5,000; 15,000; 50,000 and 100,000 miles of exposure to MMT doped fuel. A modified paired t-test is used to analyze the emission data obtained from all the fleet vehicles. The statistical evaluation of both feedgas and tailpipe emissions indicate that the use of MMT is detrimental to emissions of HC at the 15,000 mile; 50,000 mile and 100,000 mile levels of MMT exposure. As mileage is accumulated, the pronounced the effect on HC by the fuel additive MMT.

A modeling procedure for selecting exhaust gas oxidation catalysts was applied to a lean air/fuel, high compression engine. The procedure was used to select the lowest cost catalyst that could meet given CVS C/H emission targets. The procedure consisted of 1) aging a variety of oxidation catalysts using an engine dynamometer, 2) measuring the conversion efficiencies of the aged catalysts during increasing and steady temperature conditions, 3) determining relevant properties of the exhaust gas at the catalyst inlet, 4) determining the activity parameters for oxidizing hydrocarbons. HC, and carbon monoxide, CO, on the aged catalysts, 5) predicting vehicle CVS HC and CO emissions as a function of catalyst volume, and 6) determining the most cost effective catalyst to meet a given CVS emission level as a function of the precious metal used, its concentration, the catalyst volume, and their incremental costs.

An on-board, computer-controlled recorder has been developed to help determine the causes of vehicle malfunctions, especially those which are ordinarily difficult to diagnose, such as those causing catalyst melting. The computer is programmed to log the output of eight, engine-monitoring sensors every 0.1 second and temporarily store each record for 15 seconds. When a malfunction occurs, the data in the computer, as well as that collected during the malfunction, are recorded on magnetic tape. This report describes the use of the diagnostic recorder to help identify problems that caused catalyst melting on two prototype vehicles. When this work began, the cause of the catalyst melts was unknown, but the new ignition system on these vehicles was suspected. On the first vehicle, work with the recorder showed that two malfunctions of the electronic engine control unit caused, and a design fault of the ignition module aggravated, the catalyst melts.

An on-board, computer-controlled recorder has been developed to help determine the causes of vehicle malfunctions, especially those which are ordinarily difficult to diagnose because they are infrequent, fast and/or intermittent. The computer is programmed to log the output of eight, engine-monitoring sensors every 0.1 second and temporarily store each record for 15 seconds. When a malfunction occurs, the data in the computer, as well as that collected during the malfunction, are recorded on magnetic tape. An earlier report showed the effectiveness of this recorder in diagnosing catalyst melting problems. This report describes a second application of the recorder, namely diagnosing an engine preignition problem on prototype vehicles. Preignition suddenly and unexplainably caused engine damage on these vehicles after a history of trouble-free operation.

The thermal deactivation of current automotive three-way catalysts (TWCs) was studied under various high temperature conditions to determine which were most damaging. The catalysts were aged on an engine dynamometer simulating the U.S. emission durability cycle with additional periodic exposure to high temperatures. The deactivation was measured as a function of the duration, temperature and air-fuel ratio during the high temperature exposure. With lean air-fuel ratios during the high temperature exposure, TWC performance as measured at 600 F was most susceptible to deactivation showing appreciable loss of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) conversions after 20 minutes of aging at 1600 F. The TWC performance as measured at 800 F had comparable loss only after 60 minutes of aging at 2200 F. With rich air-fuel ratios the TWC performance remained nearly unaffected by aging up to 2000 F, but it dropped substantially after aging at 2200 F.

Engine dynamometer and laboratory flow reactor studies of automotive catalyst deactivation caused by the use of leaded fuel indicate that there are two different deactivation mechanisms: one, which dominates between 700 and 800 C, is the poisoning of the active platinum sites by lead oxide, or perhaps lead, and the other, which occurs below 550 C, is a build up of a gas diffusion barrier of lead sulfate. Both deactivation mechanisms can be temporarily reversed. Poisoning is reversed when the platinum is freed of lead oxide by lead sulfate formation below 650 C; and the barrier formed below 550 C can be made more permeable by thermal sintering of the lead sulfate at 600 to 700 C or its decomposition to lead oxide at 700 to 800 C. However, further exposure of the catalyst will again render it inactive via the mechanism predominating in that temperature region.

The sulfur dioxide to sulfur trioxide conversion has been measured for three different automotive exhaust catalysts. Two of the catalysts were 1975 production catalysts (Engelhard IIB and Matthey-Bishop 3C) and the third is a palladium catalyst on a monolith support. The carbon monoxide and propylene conversions were also measured so that the activity of the three catalysts for these gases could be compared to their sulfur dioxide activity. The measurements were made using a flow reactor with simulated exhaust gas and show that, while the carbon monoxide and propylene conversions were very similar for all three catalysts, there was a wide range of sulfur dioxide conversions. At 525°C and 73,000 hr-1 space velocity the sulfur dioxide conversion was 70% for the Engelhard IIB, 40% for the Matthey-Bishop 3C and from 25 to 70% for the palladium catalyst. The palladium catalyst has a range of conversions under these conditions which are associated with different states of the catalyst.