Modulated CH4 oxidation over PGM/Spinel oxide dual layer catalysts: Experiments and modeling

• Two-phase reactor model developed for sub-stoichiometric methane oxidation on Pt + Pd/spinel (Mn 0.5 Fe 2.5 O 4 ) coated monolith. • Systematic approach combines literature kinetics for methane oxidation, steam reforming (SMR), and water gas shift (WGS) • Model predicts main trends in new spatially-resolved data for wet methane oxidation and published reactor data. • Reactor model validates methane oxidation experiments collected under steady and modulated feeds for PGO and PGS catalysts. • Confirmation of methane conversion enhancement mechanism involving transient removal of inhibiting CO and H 2 . A 1 + 1 D monolith reactor model is developed for the sub-stoichiometric (rich) methane oxidation on a (Pt + Pd)/Mn 0.5 Fe 2.5 O 4 (PGM/MFO) mixed metal oxide spinel (PGS). The model is applied to understand and optimize lean-rich modulation for enhanced performance for methane emission control of stoichiometric natural gas engines. The reactor model is used in tandem with reactor experiments to develop and tune a global kinetic model for the wet methane oxidation reaction system on the PGS monolith. The model combines kinetics for methane oxidation, steam methane reforming (SMR), and water gas shift (WGS) on PGM sites with kinetics for CO and H 2 oxidation on the MFO spinel. The reactor model is validated with results for both the PGS and PGO (Platinum Group Only) catalysts under time-invariant and modulated feed conditions. The results confirm that methane conversion enhancement during cycling involves reactive removal of products CO and H 2 that inhibit the SMR and WGS.