Three-way Catalyst Reactivity of Novel High-performance Fuels for SI/ACI Engine Emissions Control
Sreshtha Sinha Majumdar, Oak Ridge National Laboratory
In order to reduce petroleum consumption, novel high-performance fuels are being developed simultaneously with the design of highly efficient engines. Commercial three-way catalysts (TWC) are very effective at meeting the stringent emissions regulations on pollutants such as nitrogen oxides (NOx), non-methane organic gases (NMOG) and carbon monoxide (CO) from gasoline fueled spark-ignition (SI) engines operating under stoichiometric conditions, when they are hot. Light-duty multimode engines operating under stoichiometric conditions (SI) during cold-start (and high loads), and lean conditions (Advanced Compression Ignition ACI) at low loads will continue to rely on TWCs for emissions control. Additionally, for commercialization, the novel fuels operating on the advanced engines must meet the emissions regulations. The main challenge when transitioning from SI to ACI mode is that the TWC is exposed to lean conditions which causes the exhaust temperature to drop. As fuel chemistry has been shown to significantly impact the temperatures at which TWCs are effective in reducing the emissions of the regulated pollutants, the current effort involves measuring the impact of these novel fuels on TWC reactivity under lean conditions relevant to ACI mode of operation. In the current study, prior to performance evaluation, a commercial three-way catalyst has been hydrothermally aged as per industry guidelines. A LabVIEW controlled automated reactor fitted with a vapor delivery module, Fourier transform infra-red (FTIR), flame ionization detector (FID) and a mass spectrometer (MS) has been used to measure the light-off and light-down temperatures of a wide range of fuels as per protocol set by industry. The influence of functional groups of the fuels such as alkanes, alkenes, alcohols, ketones, esters, and non-oxygenated aromatic hydrocarbons, on the catalyst light-off temperature has been investigated.