Aging and regeneration of Pt/TiO2 oxidation catalysts for methanol fueled marine engines

The reduction of greenhouse gases is an important and global topic. The maritime sector significantly contributes to global greenhouse gas emissions. To mitigate these emissions, renewable and environmentally friendly fuels such as green methanol (MeOH) can be utilized. However, to reduce toxic and environmentally harmful emissions, MeOH fueled engines require an oxidation catalyst which is able to maintain sufficient high activity under hydrothermal stress and exposure to sulfur. We investigate for the first time the degradation behavior of a Pt/TiO 2 oxidation catalyst under four distinct aging conditions (thermal, hydrothermal, sulfur and field aging) by using the exhaust gas composition of a MeOH engine. A comparison of these aging effects, including their dependence on Pt loading, is presented. Unexpectedly, sulfur and field aged Pt/TiO 2 oxidation catalysts exhibited enhanced NO oxidation activity, revealing a previously unreported aging-induced catalytic behavior. In addition, the sulfur and field aged oxidation catalysts were regenerated using the exhaust gas composition of a MeOH engine. Moreover, the impact of different gas compositions in the exhaust gas of a MeOH engine on the regeneration effect was evaluated. Finally, characterization analyses were conducted to correlate catalytic performance with physicochemical changes induced by aging and regeneration. Our findings provide new insights into degradation and regeneration behavior of Pt/TiO 2 catalysts under realistic MeOH marine engine conditions and contribute to the development of the exhaust aftertreatment system of a MeOH fueled engine. The development is particularly supported by the unexpected aging-induced enhancement of NO oxidation activity.