Exhaust Sulfur Oxide Measurement Using Air Dilution

Sulfate in diesel exhaust

“…All experiments with the diesel vehicles, described below, were run under the conditions of run 4 of Table I. The results from runs 2-4 (Table I) show that the controlled condensation sampling system can.be used to distinguish between total soluble SO42-and H2SO4 in vehicle exhaust, and that SO42-emissions from oxidation-catalystequipped gasoline-powered vehicles are H2SO4 as is already known (4, [15][16][17][18][19]. The total SO42-found in the controlled condensation sampling system generally amounted to 80-90% of that found in the standard sampling system (Table I).…”

“…The approximate 2% S -*• SO42-conversion in diesels is higher than is observed in noncatalyst spark-ignition vehicles (14)(15)(16)(17)(18)(19) and less than in oxidation-catalyst-equipped sparkignition systems (3,4,6,9,13). Because of the amount of sulfur in diesel fuel, however, the SO42-emission rate from a diesel system is comparable to that from an oxidation-catalystequipped spark-ignition system.…”

“…The SO42"" generated by oxidation-catalyst-equipped spark-ignition systems is known to be sulfuric acid (H2SO4) (4, [15][16][17][18][19], and the mechanism of SO42-formation in these systems is now well understood (19). In contrast, the chemical speciation of diesel SO42-has not been previously determined, nor is much known about its formation mechanism.…”

Effects of Hydrocarbons, Carbon Monoxide, and Oxygen on Sulfuric Acid Emission from an Automotive Catalyst

“…Where vehicle data on the conversions of S02 to H2SC>4 for the appropriate type of catalyst are available, the agreement between flow reactor data and the vehicle data is generally good. Careful vehicle dynamometer studies at steady-state speeds with measurement of exhaust or catalyst temperatures and taking care to equilibrate sulfur storage and release have been reported by Griffing et al (1975) and Trayser et al (1976). Griffing and co-workers report that thermodynamic equilibrium conversions of S02 are closely approached at catalyst exhaust temperatures of >440 °C-actual catalyst bed temperatures would be slightly higher.…”

Sulfate Emissions from Catalyst-Equipped Automobiles on the Highway

“…The fraction of all gasoline sulfur that was consumed in catalyst-equipped cars was determined from the sales figures coupled with our own sulfur analyses of each fuel grade from each plaza at the time of the experiment. From these relative sulfur consumption rates and the experimentally determined SO 2 and SO 4~2 mg/km emission rates for gasoline-powered vehicles overall, with a minor correction for SO2 -* SC>4~2 conversion in noncatalyst vehicles as measured in dynamometer tests, 3 ' 4 the % SO2 -* SO4~2 conversion in catalyst cars was readily calculated. ]…”