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Wigg, E. E.
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Control of Automotive Sulfate Emissions

Exxon Research and Engineering Company-E. L. Holt, K. C. Bachman, W. R. Leppard, E. E. Wigg
U. S. Environmental Protection Agency-J. H. Somers
Published 1975-02-01 by SAE International in United States
A study has been made of potential methods for controlling SO4= emissions from oxidation catalyst-equipped vehicles. The methods considered included operating condition and catalyst changes, as well as the use of a vehicle trap for SO4=. Emissions of SO4= from non-catalyst cars were also measured.The only engine operating variable we found to significantly lower SO4= emission was exhaust gas O2 level. Limiting air pump use reduced SO4= emissions by factors of 5 to 7 over the FTP, and by factors of 2 to more than 10 at 96 km/h. Some increase in CO and HC emissions was observed when the greatest SO4= reductions were achieved, but it appears that properly modulated carburetion could overcome this problem. Limited excess air shows great promise as a means of minimizing SO4= emissions. Use of a three-way or oxidation catalyst system with closed-loop fuel metering control achieved very low levels of SO4=, while simultaneously controlling CO and HC, at the stoichiometric A/F ratio and slightly leaner than stoichiometric.Pelleted catalysts emitted lower amounts of SO4= during low speed operation than…
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Fuel Effects on Oxidation Catalysts and Catalyst-Equipped Vehicles

Products Research Div., Esso Research and Engineering Co.-A. H. Neal, E. E. Wigg, E. L. Holt
Published 1973-02-01 by SAE International in United States
The effects of lead and sulfur in gasoline on the activity of two platinum oxidation catalysts have been studied using engine dynamometer units. Under the steady-state conditions used, no poisoning due to sulfur was observed. Prolonged operations with lead up to 0.07 g/gal reduced the hydrocarbon (HC) conversion activity of the catalysts in proportion to time and lead concentration, but did not affect carbon monoxide (CO) conversions. The overall extent of lead poisoning was relatively minor, however. Catalysts exposed to the equivalent of 25,000 miles' operation with a fuel containing 0.07 g of lead/gal still met the original 1975 federal emissions standards of 3.4 g/mile of CO and 0.41 g/mile of HC when tested on an experimental vehicle. Exposure of platinum catalysts to exhaust from 20 gal of fuel containing 0.5 g of lead/gal caused an immediate drop in catalyst activity, but this loss was rapidly recovered when operations continued with a lead-free fuel. Thus, short-term contamination of catalyst-equipped cars with lead may not be the serious problem it was formerly thought to be.Several 1973…
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Application of Catalysts to Automotive NOx Emissions Control

Esso Research and Engineering Co., Standard Oil Co. (N. J.)-L. S. Bernstein, K. K. Kearby, A. K. S. Raman, J. Vardi, E. E. Wigg
Published 1971-02-01 by SAE International in United States
Nickel-copper alloys, marketed under the name Monel, have been found to be extremely active NOx reduction catalysts. At temperatures above 1300 F, and under net reducing conditions, Monel will catalyze the removal of 90% or more of the NO in automotive exhaust at space velocities of up to 100,000 v/v/hr. On unleaded fuel, Monel catalysts have shown good activity maintenance in mileage accumulation runs as long as 31,000 miles. Catalyst life is limited by physical deterioration of the catalyst which causes increases in exhaust back pressure. On unleaded fuel, Monel in its present form will last approximately 10,000 miles at 1700 F (∼60 mph) before back pressure begins to rise rapidly. The presence of lead in the fuel substantially increases the rate of Monel deterioration.When Monel is used as part of a dual-bed catalyst system two problems, which appear to be generic to dual-bed catalyst systems, arise. First, under normal operating conditions, roughly 10% of the NO in the untreated exhaust reacts with H2 to form NH3 in the Monel bed. NH3 thus formed can…
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