Impact of a Commercially Available Low Carbon Renewable Diesel Fuel on the Light-Off and Light-Down Characteristics of a Diesel Oxidation Catalyst.

Abstract

Meeting future greenhouse gas emissions targets in transportation may require transition in part to renewable low carbon fuels to power the medium- and heavy-duty sectors. At this moment, market renewable low carbon diesel fuels are available and integrated with the fueling infrastructure in select areas. Though this is encouraging, little is known about the impact these renewable diesel fuels may have on modern aftertreatment systems and their ability to convert toxic emissions. This work explores the impact of a renewable hydrotreated vegetable oil (HVO) diesel fuel on catalyst light-off and light-down of a diesel oxidation catalyst (DOC) with a production diesel engine over ramp rates reflective of real-world operation. Hydrocarbon (HC) and carbon monoxide (CO) emissions were investigated using various exhaust analyzing instruments placed before and after the model γ-Al2O3 DOC: Flame ionization detector (FID), nondispersive infrared (NDIR), and Fourier transform infrared spectroscopy (FTIR). The results of this work conclude that HC and CO conversion during catalyst light-off and light-down is significantly impacted by the fuel properties unique to the mostly paraffinic renewable HVO diesel, with light-off and light-down of the catalyst being improved for the renewable diesel fuel with respect to a certification diesel fuel for all ramp rates explored. Compared to certification diesel, HVO diesel reduced steady-state DOC-out HC and CO at idle by >50% and reduced the 50% conversion temperature (T50) during light-off by 45 °C for both HC and CO at a 20 °C/min ramp rate.