Investigation into Testing and Controlling Emissions of Hydrogen Sulfide from Gasoline Vehicles 2001-01-3530
The prevention of automotive releases of the unpleasant smelling hydrogen sulfide (H2S) is highly desirable. However, the ability to routinely test catalysts for dynamic H2S releases corresponding to the real world has traditionally proved difficult. The work herein identifies the key steps taken to produce a highly repeatable (overall relative standard deviation of typically less than 10%) procedure capable of replicating H2S releases from wide-open throttle (WOT) events.
The testing utilized a chassis dynamometer to test a gasoline vehicle (fitted with one TWC system) over a specific transient drive cycle with H2S emissions detected using a chemical ionization mass spectrometer and an infra-red detection based system. The importance of the warm-up and catalyst preparation parts of the test are discussed, including statistical analysis. A repeatable and short test suited to rapid developmental screening of potential catalyst systems is also presented.
Following test protocol optimization, the following factors are reported as to the importance to H2S releases: sulfur adsorption period, WOT dynamics (temperature and acceleration / deceleration rates), evaporative canister purging and fuel sulfur levels.
Key control parameters to the H2S formation (outside of catalyst formulation and fuelling strategies) were found to be the sulfur loading (defined by a combination of fuel sulfur levels and adsorption periods) and drive characteristics.