In the present study, a comprehensive characterization of natural gas engine exhaust both upstream and downstream of two different catalyst systems was conducted in order to determine the effects of the catalysts on different emission components, e.g. hydrocarbons, NOx and particles.
Both catalysts were observed to have a clear influence on gaseous and particulate emissions. Measurements were conducted in co-operation with Tampere University of Technology and VTT Technical Research Centre of Finland Ltd.
Natural gas (NG) engines are used worldwide in energy production and various vehicle applications. In order to meet stringent emission limits, after-treatment systems are utilized also in NG engine applications. In this study a passenger car engine modified to run with natural gas was used in a VTT research facility. A comprehensive emission study was conducted both upstream and downstream of two different catalyst systems (1. Methane oxidation catalyst + selective catalytic reduction (SCR) catalyst and 2. SCR combined with oxidation catalyst) in order to determine the effects of the catalysts on gaseous and particulate emission components,
Both the studied catalyst systems were found to have a significant effect on exhaust emissions. High NOx reductions were observed when using SCR. The relatively fresh methane oxidation catalyst was found to reach methane reductions greater than 50% when the exhaust temperature and the catalyst size were sufficient. However, further studies are needed to solve the long-term performance and the deactivation by sulphur. The observed particle mass reduction due to the catalysts was found to be caused by a decrease in the amount of organics passing over the catalyst. However, downstream of the catalyst particle formation was detected and it depended greatly on the exhaust temperature. At higher exhaust temperatures, a higher number of volatile nanoparticles was observed likely indicating that Sulphur compounds were involved in the particle formation.". This study contributes to understanding emissions from future NG engine applications with catalysts in use.
This research was done in Tekes funded project "Controlling Emissions of Natural Gas Engines (CENGE)" . In addition to VTT, Tampere University of Technology and FMI collaboration partners in project were Wärtsilä Finland, Dinex Ecocat, Dekati, Neste, Suomi Analytics and AGCO Power.
Researcher Hilkka Timonen, Hilkka.firstname.lastname@example.org
Lehtoranta, K., Murtonen, T., Vesala, H., Koponen, P., Alanen, J., Simonen, P., Rönkkö, T., Timonen, H., Saarikoski, S., Maunula, T., Kallinen, K., and Korhonen, S.: Natural Gas Engine Emission Reduction by Catalysts, Emission Control Science and Technology, 10.1007/s40825-016-0057-8, 2016.
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