Fundamental mechanistic insights into in-situ reduction of Pd2+ coupling with benzyl alcohol oxidation at oil–water interface

The supported noble metal-based catalysts, which are promising and deliver a high activity for the industrial synthesis of fine chemicals, still face the various issues such as complex preparation steps and migrating or leaching of the metal. Herein, we demonstrate an integrated Pickering emulsion system stabilized by carbon nanotubes (CNTs) after acid treatment to achieve in-situ reduction of Pd 2+ coupling with benzyl alcohol (BA) oxidation. Kinetic analysis confirms the reduction of Pd 2+ to Pd 0 with BA as reductant and the selective oxidation of BA catalyzed by Pd 0 occur simultaneously at the oil–water interface in more details. The homogeneous immobilization of Pd particles on the defects of CNTs and efficient reduction of Pd 2+ in the Pickering interfacial catalysis (PIC) system are also decoupled. Moreover, the in-situ diffuse reflectance infrared-fourier transform spectra (DRIFTS) reveal that the interaction between BA and Pd/CNTs-PIC with water can be enhanced. Benefiting from the enlarged biphasic interface, the Pickering emulsion system achieves a higher efficiency, with a turnover frequency (TOF) of 424 h −1 , representing a 9.5-fold increase compared to the conventional single-toluene system (TOF, 44 h −1 ). The general applicability of the integrated system is also demonstrated over different precursors and supports.