LAUSR

Abstract A full size ceramic substrate was successfully prepared using a robocasting 3D printer and tested as a methane oxidation catalyst in the after treatment system (ATS) of a heavy-duty diesel engine, converted to co-combust (dual fuel) with natural gas (NG). The 3D printed substrate performance exceeded that of a commercially sourced straight-channelled DOC over most working conditions, despite the 3D printed structure having a lower precious group metal (PGM) loading and channels per square inch (CPSI) density. At moderate and high inlet temperatures, where the reaction rate is limited by internal and external mass transfer, the enhanced catalytic activity of the 3D printed substrate is attributed to the generation of internal turbulence, which increases oxidation rates of methane (CH4) and non-methane hydrocarbons (NMHC). In contrast, there is relatively little difference between the catalytic activity of the 3D and straight-channelled substrates at low temperatures (e.g. cold start up), where the reaction is kinetically controlled and the additional turbulence/mass transfer of the 3D printed complex structure did not measurably alter the catalytic converter performance. Computational fluid dynamics (CFD) confirmed the increased turbulence within the channels of the 3D printed structure. We also report the effects of NG substitution on the fuel combustion efficiency under different engine load settings. The findings provide proof of concept evidence that 3D printing is a suitable means of designing a catalytic converter prototype with higher reaction activity than a conventionally extruded structure. This has significant implications for the design and potential mass production of new catalytic converters with enhanced efficiencies.