(512a) Net-Zero Carbon Fuel Reactivity on Commercial Oxidation Catalysts for Emissions Control

Rail, marine and off-road transportation sectors are hard to electrify due to longer uptime needs, large travel distances, and lack of charging facilities in remote locations. The “U.S. Blueprint for Transportation Decarbonization” has identified the use of sustainable liquid fuels or net-zero carbon fuels as a promising alternative to achieve decarbonization of these sectors. However, engines running on net-zero carbon fuels must still meet the stringent U.S. EPA emissions regulations. To ensure emissions compliance and to identify unique emissions control challenges and opportunities with net-zero carbon fuels, a systematic study evaluating the reactivity of different net-zero carbon fuels on commercial diesel oxidation catalysts was conducted.

In this communication, an automated synthetic exhaust flow reactor was used to measure the light-off temperatures of alcohols and a C10 diesel surrogate fuel (baseline) over hydrothermally aged, commercial Pd+Pt diesel oxidation catalyst (DOC) as per industry guidelines. Ethanol (EtOH) and methanol (MeOH) oxidation were studied in the presence of water vapor and carbon monoxide (CO) by using state-of-the-art in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique to investigate the formation of surface intermediates and effects of adsorbed CO on alcohol reactivity. The investigation showed formation of strongly adsorbing acetate and formate species which were stable on the catalyst surface up to 275⁰C and 225⁰C during EtOH and MeOH oxidation, respectively. The DRIFTS results were consistent with the flow reactor experiments where a significant level of aldehyde formation was observed during alcohol oxidation. The competitive adsorption of CO and EtOH/MeOH oxidation were also studied. The results showed CO was preferentially adsorbed on the surface-active sites and inhibited total/partial oxidation of EtOH/MeOH at temperatures < 150⁰C.