Effect of carbon nanosheets with different graphitization degrees as a support of noble metals on selective hydrogenation of cinnamaldehyde

Abstract

In this work, Pt and Pd catalysts supported on carbon nanosheets (CNS) with different graphitization degrees were prepared via a simple borohydride reduction method. The effect of graphitization degree on the catalytic activity of Pt/CNS and Pd/CNS was investigated to obtain the optimal activity. The prepared catalysts were well characterized by X-ray diffraction (XRD), Raman, transmission electron microscopy (TEM) and X-ray photoemission spectroscopy (XPS). The activity and selectivity of Pt/CNS and Pd/CNS catalysts increases with the rise of the graphitization degree of CNS. A high graphitization degree of the CNS support can enhance the transfer of electrons from the CNS support to Pt and Pd nanoparticles, leading to the increase in the surface Pt⁰ and Pd⁰ content. The more surface Pt⁰ and Pd⁰ content the catalyst has, the higher selectivity to COL and CALD it exhibits, respectively. The good graphitization degree of the CNS support is an advantage of the strong π–π interactions between CAL and the surface sp²-bonded of CNS support. Thus, the different catalytic activity and selectivity over the Pt/CNS and Pd/CNS catalysts are attributed to the surface Pt⁰ and Pd⁰ content and the adsorption capacity for CAL on the catalyst surface that are closely related to the graphitization degree of CNS.