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Hunter, Joseph E.
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The Effect of Emission Control Systems and Fuel Composition on the Composition of Exhaust Gas Condensate

General Motors Research Laboratories-Joseph E. Hunter
Published 1983-02-01 by SAE International in United States
Condensate composition was determined for 1981–82 General Motors vehicles with a) diesel engines and no converters, b) gasoline engines with oxidizing converters, c) gasoline engines with computer command control and dual bed bead or dual bed monolith converters, and d) gasoline engines with computer command control and single bed bead converters having three-way catalysts.The pH was found to range between 2.3 and 9.2 for the systems studied. Anions present in low pH condensates were sulfate, nitrate and chloride. Near neutral condensates and basic condensates also contained ammonia plus bicarbonate and carbonate anion, and had generally higher sulfate content than the acid condensates. Results are shown to be related primarily to differences resulting from the catalytic reduction of NOX and fuel sulfur content.
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Precious Metal Demand for Automotive Catalysts versus Availability from Scrapped Vehicles

General Motors Research Labs., Warren, MI-Joseph E. Hunter
Published 1982-02-01 by SAE International in United States
Estimates were made of the annual demand for precious metal in automotive catalysts and the return from scrapped vehicles from 1975-1995 for the United States plus Canada. Results show that expected scrap returns are currently small; however, by the late 1980’s nearly half the yearly precious metal demand in automotive catalysts could be obtained from scrapped vehicles. Estimates also show that continued use of rhodium at current levels for the three-way catalyst will require mining and refining substantial extra platinum group metals for the rhodium content. Precious metal costs for catalysts will therefore be influenced strongly by the overall effectiveness of a recycle system and the amount of rhodium required for NOx control.
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Castings - A Better Use of Lightweight Metals?

General Motors Research Laboratories-Joseph E. Hunter
Published 1977-02-01 by SAE International in United States
In comparing the use of cast and wrought aluminum to reduce vehicle weight and energy consumption, cast aluminum is generally regarded as less energy intensive based on the extensive use of secondary aluminum in castings. Cast aluminum also offers potentially larger direct weight savings than wrought aluminum. However, increased use of aluminum in either cast or wrought form will require that the added demand be matched by a corresponding increase in primary aluminum production. Further, virtually all potential casting applications are in chassis parts which will generally yield lesser indirect weight savings than upper body applications of wrought aluminum. Despite these limiting factors, the substitution of cast aluminum for cast iron appears to compare favorably with the replacement of steel by wrought aluminum on the basis of general estimates of energy savings. In particular, the selective use of cast aluminum to reduce the weight of optional engines may offer opportunities to maximize weight and energy saving per unit of substitute material used.
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Studies of Catalyst Degradation in Automotive Emission Control Systems

Research Laboratories, General Motors Corp.-Joseph E. Hunter
Published 1972-02-01 by SAE International in United States
Reactions of sulfur, present in small amounts in gasoline, with catalyst and catalyst support materials are discussed.GMR studies have shown that sulfur accumulates in catalysts and support materials at temperatures of 600-1300 F under both oxidizing and reducing conditions. Partial sulfur release has been observed at 1200-1600 F.Concurrent with sulfur accumulation, there is a marked reduction in the carbon monoxide (CO) reactivity of noble metal, promoted and base metal catalysts. Lesser highly variable effects on hydrocarbon (HC) reactivity were noted. Studies of nitrogen oxide (NOx) reducing, noble metal catalysts also showed an adverse effect of sulfur accumulation on the NOx reactivity.These results indicate that steps must be taken to reduce or eliminate sulfur poisoning of automotive emission control systems. Approaches for achieving this objective are discussed.
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