Transition metal pairs on ceria-promoted, ordered mesoporous alumina as catalysts for the CO sub(2) reforming reaction of methane

CoFe, CoW, NiFe and NiW bimetallic pairs deposited over CeO sub(2)-ZrO sub(2) promoted ordered mesoporous gamma -Al sub(2)O sub(3) were tested in the methane dry reforming reaction. The catalysts were characterized by N sub(2) adsorption, wide and small angle XRD, TEM, UV-vis DRS and H sub(2)-TPR techniques. Upon thermal treatment, diffusion of Ni and Co into the alumina matrix occurred, resulting in the formation of corresponding aluminate spinels. Based on UV-vis characterization, the formation of bulk Fe sub(2)O sub(3) could be only tentatively assigned to the NiFe/AlCZ catalyst. Bulk Co sub(3)O sub(4) is likely present in both CoW and CoFe catalysts. CoFe/AlCZ and NiFe/AlCZ catalysts achieved high and stable methane conversion rates of 8.8 and 6.0 mmol of CH sub(4) per g sub(cat) per min, respectively. The activity of tungsten-containing catalysts (CoW/AlCZ and NiW/AlCZ) was substantially lower compared to iron-containing catalysts (2.8 and 0.8 mmol of CH sub(4) per g sub(cat) per min, respectively) and their deactivation was likely related to sintering and oxidation of active metal clusters. A low carbon content was accumulated on the surface of spent NiFe/AlCZ, CoFe/AlCZ and NiW/AlCZ catalysts after 20 h tests (0.6-1.2 wt%), indicating the high efficiency of the redox promoter under dry reforming conditions.