beads or pellets or of any suitable form if substrate is a metal honeycomb the metal may be a heat resistant base metal alloy particularly an alloy in which iron and chromium is a substantial or major component the surface of the metal substrate may be oxidized at temperatures higher than 1000 u00b0 c to improve the corrosion resistance of the alloy by forming an oxide layer on the surface of the alloy metallic substrate may be a monolithic carrier having a plurality of fine parallel flow passages extending through the monolith the passages may be of any suitable cross sectional shape and or size the passages may be trapezoidal rectangular square sinusoidal hexagonal oval or circular although other shapes may be suitable the monolith may contain from about 9 to about 1 200 or more gas inlet openings or passages per square inch of cross section although fewer passages may be used the wc material composition may free of zpgm transition metal catalyst a wc may include support oxides material referred to as carrier material oxides cmo which may include aluminum oxide doped aluminum oxide spinel delafossite lyonsite garnet perovksite pyrochlore doped ceria fluorite zirconium oxide doped zirconia titanium oxide tin oxide silicon dioxide zeolite and mixtures thereof the material composition of wc may also include other components such as acid or base solutions or various salts or organic compounds that may be added to adjust rheology.