Effect of reduction in liquid phase on the properties and the catalytic activity of Pd/Al2O3 catalysts

The change in structural and surface properties of Pd/Al2O3 catalysts as the effect of reduction in liquid phase during preparation is investigated by a multi-technical approach. It has been found that, although the treatment leaves an external shell of oxidized Pd because of the exposure to air of final wet catalyst, it affects both the catalyst reducibility and the properties of the supported Pd nanoparticles, in terms of dispersion, particle size, morphology, interaction with the support, structural order, and surface properties. Consequently, unreduced and pre-reduced catalysts show different performances in the debenzylation of 4-benzyloxyphenol reaction.

Relationships between the reduction state of a supported palladium catalyst, its surface structural properties, and its catalytic performance are investigated in a multi-technique approach.Figure optionsDownload high-quality image (98 K)Download as PowerPoint slideHighlights
► Reduction state–catalytic performances relationship for Pd/Al2O3 catalysts.
► After pre-reduction, about 50% of the Pd in the catalyst is still oxidized.
► Pre-reduction causes a decrease in Pd dispersion.
► Pd particles in the pre-reduced catalyst are more structurally ordered.
► A great structural order of Pd particles favours all the surface-sensitive reactions.