Technical Paper
Sulfuric Acid and Nitrate Emissions from Oxidation Catalysts
1975-02-01
750091
The authors have investigated the emission of sulfuric acid and nitrates from a 1973 Ford 351C V-8 engine equipped with prototype 1975 emission controls and mounted on a dynamometer test stand. Tests were performed on unleaded fuel at 60 mph road-load conditions, using monolithic noble-metal catalysts and no catalyst, and at 60 and 30 mph road-load conditions using a pellet-bed noble-metal catalyst. Sampling for SO2 and H2SO4/SO3 measurement was effected at several points within the exhaust system as well as from a dilution tunnel where the exhaust was diluted ten-fold with filtered air. Samples collected in the dilution tunnel were analyzed for total particulate mass, sulfate, condensed water, and pH. Ammonia injection into the dilution tunnel on selected runs permitted collection of nitrate and HNO3 on the filters as NH4NO3. Nearly all of the fuel sulfur was emitted as SO2, and less than 1% as sulfate, in the absence of a catalyst.