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Holt, E. L.
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Hydrogen Cyanide Emissions from Three-Way Catalyst Prototypes under Malfunctioning Conditions

Exxon Research & Engineering Company-M. H. Keirns, E. L. Holt
Published 1978-02-01 by SAE International in United States
Measurements have been made of the emissions from a prototype three-way catalyst automobile, during normal and simulated malfunction driving conditions. Four ceramic-supported catalyst compositions were investigated, ranging from Rh through two mixtures of Rh-Pt to Pt. Driving conditions included cyclic and cruise modes. Under normal operating conditions no HCN was detected. Under rich malfunction conditions, HCN was generally observed, even in the absence of a catalyst. In some cases, catalysts appeared to remove HCN from the exhaust gas; in others they increased its level. The highest emission rate for HCN was observed for the Rh catalyst, about 40 mg/km at 64 kph cruise.
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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 a Monel-Platinum Dual-Catalyst System to Automotive Emission Control

Esso Res. & Engrg. Co.-R. S. Lunt, L. S. Bernstein, J. G. Hansel, E. L. Holt
Published 1972-02-01 by SAE International in United States
A dual-catalyst-equipped test vehicle, containing Monel catalysts for the reduction of oxides of nitrogen followed by platinum oxidation catalysts, has controlled emissions of carbon monoxide, hydrocarbons, and oxides of nitrogen to levels of 8.0, 0.4, and 0.8 g/mile, respectively, using the single-bag 1972 federal test procedure. The Monel catalyst was fabricated in a low-mass, high-surface-area, open-mesh structure. The low mass contributed to rapid warmup of both the reduction and oxidation catalysts. The high geometric surface area permitted efficient conversion of all three pollutants simultaneously when the vehicle was operated only slightly richer than stoichiometric. As a result the amount of oxidation required of the platinum catalyst was greatly reduced.The durability of Monel is a major problem. The mechanism of Monel strength loss, currently the limiting factor in catalyst life, was shown to be grain-boundary widening due to alternate oxidation-reduction reactions undergone by the metal. Reinforcement of Monel by an oxidation-resistant metal, particularly when accompanied by fabrication into a unitary structure, significantly improves strength and maintenance of low pressure drop. However, durability equivalent to 50,000 miles…
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