Fe-Cr-AI Alloy Monolithic Catalysts for Total Oxidation of Alkane Fuels

摘要

The texture and structure of oxidised, wash-coated and catalyst-coated Fecralloy combustion catalysts have been characterised using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), microprobe analysis and atomic force microscopy (AFM). Elemental distributions and roughness varied with surface location. The oxidised surfaces contained Fe-Cr finely dispersed in alumina which had preferentially found its way to the surface during oxidation; this dispersed phase may have contributed to the high-temperature activity of Fecralloy itself in methane oxidation. The surface of wash-coated Fecralloy contained alumina islands about 2 μm thick. With Pd impregnation of this wash-coating, the catalytic combustion of gaseous methane occurred at low temperature. However, diffusion into the wash-coatings appeared to limit the overall rate of CH{sub}4 oxidation at intermediate temperatures and the activation energy dropped as a result to a mere 42kJ/mol (compared to 203kJ/mol for the homogeneous reaction). The catalytic combustion of liquid decane also occurred at low temperature on Pd-impregnated wash-coated Fecralloy. It therefore seems that Fecralloy surfaces can be useful for the clean combustion of gaseous and liquid hydrocarbon fuels, although care needs to be taken over levels of CO production.