THE FORMATION AND CONTROL OF SULFURIC ACID EMISSIONS OVER AUTOMOTIVE CATALYSTS

In order to find a way to minimize sulfuric acid formation while maintaining high HC and CO conversion, the effect of temperature, air-fuel ratio, space velocity and catalyst metal composition on SO₂ conversion was studied. Both pelleted and monolithic catalysts were investigated using an engine dynamometer and a small diameter dilution tunnel. The effect of engine operating conditions on SO₂ conversion was clarified and an advantageous shape for the catalytic converter was found. Thirteen pelleted and four monolithic catalysts were tested with rhodium showing a remarkable effect on HC conversion selectivity.