Vehicle and Engine Dynamometer Studies of H ₂ S Emissions Using a Semi-Continuous analytical Method

The emphasis on H₂S emissions has increased in recent years due to significant levels being emitted by some single-bed three-way catalyst equipped vehicles. Studies to identify the mechanisms of H₂S formation have suffered due to the sample time dependent wet chemical methods used for H₂S analyses. A simple but effective dilution and sample system has been developed for use with a commercially available gold film H₂S analyzer. This provides semi-continuous H₂S analyses directly from the engine exhaust and has proven to be an excellent tool for defining the effects of vehicle operating conditions on H₂S formation. Engine dynamometer studies have been used to investigate the effects of air/fuel, catalyst inlet temperature, and transient duration on sulfur storage and release over single-bed three-way catalyst systems.