Pd-Cu interaction in Pd/Cu-MCM-41 catalysts: Effect of silica source and metal content

During template removal by thermal treatment, palladium and copper are on the surface of MCM-41 particles, forming Pd1-xCuxO solid solutions whose composition is silica source-dependent. The amount of copper in Pd1-xCuO is greater for TEOS-derived samples.

Pd/Cu-MCM-41 catalysts for the hydrodechlorination of CF(3)OCFC1CF(2)C1 to CF3COCF=CF2 were prepared. Palladium- and copper-containing samples (Pd/Cu= 1 molar ratio) were synthesized by adding Pd2+ and Cu2+ during the formation of MCM-41, and then the slurries were aged by microwave-hydrothermal treatment. The effect of the silica source (silicates or TEOS) and total metal loading (2.4 and 4.0 wt.%) on the chemical-physical properties and catalytic performances was studied. Bimetallic silicate-derived samples show features similar to those of the pristine MCM-41, regardless of the total metal content. Conversely, the long-range order of the mesoporous structure decreases for TEOS-derived catalysts, and large metal contents seem to alter the structure for these materials.