Sulfate Emissions from Catalyst Cars -A Review

A review of the available data on sulfate emissions methods and emissions rates from both catalyst-equipped and noncatalyst cars has been made. Air-dilution methods of various sorts appear to give similar sulfates emissions results, comparable with those obtained by controlled condensation procedures. Mobile source SO₂ measurements technology requires much more attention. At present, only the hydrogen peroxide oxidation to sulfate has been demonstrated to give reliable results. Summaries of several hundred catalyst and non-catalyst emission rates are treated to estimate California and 49-state emissions. A cruise-mode emission rate of about 0.03 g/mile appears appropriate for both monolithic and pelleted catalysts in 49-state cars.