Preparation And Catalytic Performance Of Pd/g-C₃N₄ Catalyst

Graphitic carbon nitride?g-C₃N₄?,as a new two-dimensional material,has attracted increasing interest in the field of material and catalytic science due to it's large specific surface area and abundant nitrogen-containing functional groups.g-C₃N₄ is not only an excellent substrate for supporting catalysts,but also a superior photocatalyst.Using g-C₃N₄ as a substrate to support noble-metal catalysts for styrene and p-nitroaniline hydrogenation reactions offers a number of inherent advantages,including maintaining the noble-metal atoms in their neutral state,directly providing the hydrogen source,and possessing excellent solar light absorption.In this work,a novel realized catalyst that Pd nanoparticles supported on g-C₃N₄?Pd/g-C₃N₄?was investigated for the hydrogenation of styrene and photocatalytic reduction of p-nitroaniline,respectively.The structure,chemical morphology and photoelectric properties of the Pd/g-C₃N₄ catalyst were characterized by X-ray powder diffraction?XRD?,transmission electron microscopy?TEM?,X-ray electron spectroscopy?XPS?,UV-visible diffuse reflectance spectroscopy?UV-vis?,fluorescence spectroscopy?PL?and Inductively coupled ion emission spectroscopy?ICP-AES?.In the catalytic hydrogenation of styrene,the structure-activity relationship between Pd/g-C₃N₄ and catalytic activity was studied from the Pd loading,the amount of catalyst and the different stripping conditions of g-C₃N₄.In addition to the physicochemical properties of g-C₃N₄,process conditions such as hole trapping agents and solvents also seriously affect the photocatalytic reduction efficiency of p-nitroaniline catalytic activity.The main contents are summarized as follows:?1?A method for the preparation of Pd/g-C₃N₄ was proposed.The Pd/g-C₃N₄exhibits high catalytic activity in the hydrogenation of styrene due to the introduction of g-C₃N₄.Optimization of Pd loading and amount of the Pd/g-C₃N₄ catalyst manifested that the Pd loading of 0.58 wt%and the amount of the catalyst of 35 mg were optimum.Under optimal conditions,the unit activity reaches the maximum and the styrene conversion of 100%was achieved.?2?The study on the peeling conditions of the carrier g-C₃N₄ shows that the specific surface area of g-C₃N₄ increases with the increase of thermal oxidative stripping temperature,and the peak intensity of PL spectrum decreases continuously,indicating that the separation of electron holes is continuously enhanced and the heat is prolonged.The oxidation time is also beneficial to improve the photoelectric performance of g-C₃N₄.When the thermal oxidation stripping temperature is 550?for 4 h,the supported Pd/g-C₃N₄ has the highest catalytic hydrogenation activity.?3?Seletive using ethanol as the solvent and the presence of N₂ and the hole trapping agent triethanolamine can greatly increase the conversion rate of the reaction in the photocatalytic reduction of p-nitroaniline.When the amount of triethanolamine is 0.1 mol,the conversion of the reaction reaches a maximum.