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. 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. After reduction, both Pd- and Cu-enriched alloys were found by XRD in silicate-derived samples, while XPS measurements indicated that the surface of the catalyst is enriched with copper. XRD and XPS analyses on TEOS samples indicated that the surface Cu/Pd ratio is closer to 1, and fcc PdCu alloys with a high copper content were identified. The composition of metallic particles modifies the selectivity, TEOS-derived catalysts being more selective to the target CF3'OCF=CF2.

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

BENITO MARTIN, PATRICIA;GREGORI, MANUEL;ANDREOLI, SARA;FORNASARI, GIUSEPPE;OSPITALI, FRANCESCA;ALBONETTI, STEFANIA
2015

Abstract

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. 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. After reduction, both Pd- and Cu-enriched alloys were found by XRD in silicate-derived samples, while XPS measurements indicated that the surface of the catalyst is enriched with copper. XRD and XPS analyses on TEOS samples indicated that the surface Cu/Pd ratio is closer to 1, and fcc PdCu alloys with a high copper content were identified. The composition of metallic particles modifies the selectivity, TEOS-derived catalysts being more selective to the target CF3'OCF=CF2.
Patricia Benito; Manuel Gregori; Sara Andreoli; Giuseppe Fornasari; Francesca Ospitali; Stefano Millefanti; Maria Sol Avil; Teresita F. Garetto; Stefania Albonetti
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/462578
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