Desulfation Strategies for Catalytic Devices
The Sulfur compounds SO2, COS and H2S are formed in combustion engines when fuel contaminants or engine oil are burned in the cylinder. They are a strong catalyst poison and in addition the nuclei of particle formation. The standard desulfation mechanism is a rich hydrocarbon load and hydrogen feed to the catalyst. This applies to nitrogen traps, particulate filters and in general to all catalytic devices in exhaust gas treatment. The development and fine tuning of such strategies require instrumentation that cannot only measure the sulfur compounds of interest but can properly distinguish also between SO2, COS and H2S while providing sensitivity down to the low ppm levels as well as rapid response times.
The V&F IMR technology (Ion Molecule Reaction) inside the AirSense mass spectrometer is capable of measuring all sulfur compounds of interest with the required sensitivity and selectivity. Inlet pressure regulation (0 to 5 bar), filters for particulates and a heated transfer capillary are additional features prerequisite for measuring exhaust gas emissions. A variety of interface options such as AK protocol ensure easy implementation into the test bench environment.
Figure: Sulfur compounds in lean and rich engine operation
Common technologies such as FTIR cannot measure certain sulfur compounds e.g. SO2. In addition, they may struggle with interferences when determining H2S. The IMR-Technology with its fast response times of < 200 ms enable the user to create detailed time profiles of the desulfation process in order to closely monitor its efficiency. The robust and compact design of the AirSense combined with low maintenance effort makes it an excellent tool for advanced applications within the field of exhaust gas measurements.
- Selectively measures SO2, COS and H2S
- Fast response times
- AK protocol