The Role of Open Cell Foams Supports on the Kinetics of PdO/Co3 O4 for the Wet and Dry Lean Methane Combustion

In this study, a kinetic analysis under differential conditions was conducted on three different open cell foams (OCFs) materials—FCA(FeCrAl)- OCF, SiC(silicon carbide)- OCF, and Alu(alumina)-OCF—w ashcoated with a PdO/Co3O4 catalyst for lean methane combustion in both dry and wet environments (10 vol% H2O). A comprehensive set of physicochemical characterizations, including CO chemisorption, FESEM, XRD, Raman spectroscopy, XPS, XRF, TPR, TPO, and TPD, was performed on the supported catalysts. All structures demonstrated comparable catalytic activity and excellent water stability over time. The activation energy was consistent across all catalytic systems, with values of approximately 117 kJ mol−1 in dry conditions and 129 kJ mol−1 in wet conditions. While all catalysts exhibited first-order kinetics with respect to methane, variations in water order were observed: –0.9 for Alu-OCF, –0.7 for FCA-OCF and SiC-OCF. Additionally, the preexponential factors in wet conditions followed the order Alu- OCF > SiC- OCF > FCA- OCF, which corresponded with the order of turnover frequencies. Validation of the kinetic modeling results was performed against the experimental data. The hydrophobicity of the supports appeared to play a role in water inhibition, with SiC-OCF, the most hydrophobic of the materials tested, demonstrating superior catalytic activity.