The tremendous effect of trace amounts of Rh on redox and catalytic properties of CeO2–TiO2 and Al2O3 in CH4 partial oxidation

Trace amounts of Rh (0.005 wt.%) were found to strongly improve both overall and surface reducibility of Al2O3 and CeO2–TiO2 prepared via hardcast- and cellulose-templating methods. The latter approach is more suitable for tuning surface reducibility as proven by H2-TPR tests due to favored stabilization of surface Rh species. High surface reducibility of support is an important activity- and selectivity-governing factor in the partial oxidation of methane to syngas, because it promotes reaction-induced transformation of RhOx species to metallic Rh. Close-to-equilibrium and stable syngas production was achieved over cellulose templated Rh(0.005 wt.%)–CeO2–TiO2.

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► Rh traces (0.005wt%) effect surface and/or bulk reducibility of Al2O3 and CeO2–TiO2.
► Preparation method determines concentration of active Rh surface species.
► Lowest surface reduction temperature via cellulose templating.
► Improved bulk reduction via exo templating.
► High surface reducibility is required for partial oxidation of CH4 to CO and H2.