Pd nanoparticles supported on amino-functionalized magnetic mesoporous silica nanotubes: a highly selective catalyst for the catalytic hydrodechlorination reaction

Abstract

Highly dispersed Pd nanoparticles supported on amine-functionalized magnetic mesoporous silica nanotubes (NH₂-MSNTs) have been successfully prepared and tested in the aqueous phase catalytic hydrodechlorination (HDC) of chlorophenols (CPs). The as-synthesized Pd@NH₂-MSNTs catalyst is investigated by transmission electron micrograph (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier-transfer infrared spectroscopy (FT-IR) and N₂ adsorption–desorption. The synthesized MSNTs material exhibits a large surface area of 966 m² g⁻¹, high pore volume of 0.81 cm³ g⁻¹, highly open mesoporous size of 3.4 nm and high saturation magnetizations of 19.65 emu g⁻¹. For the HDC of CPs, the catalyst shows 100% conversion with 99% selectivity for cyclohexanone in aqueous solution at mild conditions of temperature (60 °C) under ambient pressure. It is astonishing that the Pd@NH₂-MSNTs catalyst shows better catalytic performance, and it can synthesize cyclohexanone in one pot, in comparison with other heterogeneous catalysts for which phenol is the only reaction product. The novel heterogeneous magnetic catalyst exhibits excellent catalytic stability and can be used seven times without an obvious decrease of product selectivity. In addition, our study further reveals that the synergetic effect between Pd nanoparticles and NH₂-MSNTs support plays a key role in the HDC of CPs.