The substitution of pure metal particles by metal phosphides in catalysis represents a promising opportunity to lower the required metal quantity in the context of a sustainable use of metal resources. Herein we show the synthesis of palladium phosphide, Pd3 P, supported on silica, which is tested as catalyst for the Wacker-Tsuji-oxidation of styrene to acetophenone. The synthesized catalyst is characterized by PXRD, SEM-EDX, FTIR, ICP-AES and XPS measurements. Four different reaction systems are investigated in this study including different co-catalysts and reaction media. Conversions of styrene up to 95 % with a selectivity of 73 % towards acetophenone are observed using Pd3 P/SiO2 as catalyst, CuCl2 as co-catalyst and O2 as oxidant. An enhanced selectivity up to 100 % towards acetophenone is obtained in other reaction systems. The use of Pd3 P/SiO2 leads to an optimized selectivity and conversion in the oxidation reaction in comparison with the purely Pd-based system Pd/SiO2 . These results give an insight on how the incorporation of phosphorus has a great effect on the performance of heterogeneous catalysts.
Keywords: alkenes; heterogeneous catalysis; oxidation; palladium phosphide; supported catalysts.
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