Multifunctional Wall-Flow Monoliths: Advanced Coating Technologies and Efficient Computations

Souzana  Lorentzou, APT Lab. CPERI/CERTH

Following the successful market introduction of diesel particulate filters (DPFs), this class of emission control devices is expanding to include additional functionalities such as gas species oxidation (such as CO, HC and NO), storage phenomena (such as NOx and NH3 storage) to the extent that we should today refer not to DPFs but to Multifunctional Reactor-Separators.
The optimization of these devices relies on the interplay of chemistry and geometry in order to enhance soot-catalyst proximity and achieve direct catalytic soot oxidation as well as exploit synergies among the gas species participating in the complex heterogeneous and interfacial kinetic phenomena, occuring at the filter wall scale. This trend poses many challenges for the modeling of such systems since the complexity of the coupled reaction and transport phenomena makes any direct general numerical approach to require unacceptably high computing times. In the present paper we discuss a new framework and its application for the implementation of such phenomena into system level emission control simulation tools in a robust and computationally efficient manner. Among other results it is demonstrated that this approach guides the development of advanced catalyst coating technologies which are shown to provide sustained or even accelerated soot oxidation over the entire conversion range, overcoming the shortcomings of conventional catalytic coatings which loose fast their reactivity as conversion proceeds.