The adsorption and reaction of alcohols on TiO2 and Pd/TiO2 catalysts

The decomposition of alcohols (methanol, ethanol, n-propanol, i-propanol) on TiO2 and Pd/TiO2 catalysts has been studied using temperature programmed desorption. The alcohols mainly decompose via a dehydration pathway on TiO2 catalysts, with no evidence for reactions involving α CC scission or dehydrogenation. However, the reaction pathway was fundamentally altered by the presence of Pd nanoparticles, and products of α CC scission became dominant due to decarbonylation pathways. For the reaction with ethanol, there was no evidence of the dehydration product ethylene even though the surface is mainly composed of titania, indicating that diffusion of alkoxy species from the support to the Pd occurs efficiently during TPD. However, competing dehydration reactions did occur on Pd/TiO2 in the cases of n-propanol and i-propanol decomposition which is postulated to be due to more limited diffusivity of the bulkier alkoxides.

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► We report decomposition pathways for alcohol decomposition on titania and Pd–TiO2.
► These catalysts are active for photocatalytic reforming and hydrogen production.
► Two dehydration pathways are identified on titania, monomolecular and bimolecular.
► With Pd addition pathways are changed to mainly dehydrogenation/decarbonylation.
► We suggest that reverse spillover of ethoxy occurs from the support to the metal nanoparticles.