VO@g?C3N4-T可见光催化苯羟基化制苯酚

Photocatalytic Hydroxylation of Benzene for Synthesis of Phenol over VO@g-C3N4-T under Visible Light

摘要:

以尿素和乙酰丙酮氧钒为原料制备了钒氧化合物络合在纳米薄片石墨化氮化碳上的光催化剂(VO@g?C3N4-T),并与石墨化氮化碳（g?C3N4）、钒氧化合物负载在石墨化氮化碳上催化剂（VO/g?C3N4）进行了对比。采用N2吸附、X射线衍射光谱(XRD)、扫描电镜(SEM)、能谱（EDS）、电感耦合等离子体-原子发射光谱(ICP-AES)分析手段对制备的催化剂进行了表征。考察了所得催化剂可见光催化苯羟基化制 苯酚的性能。结果表明，高比表面积、纳米薄片状的VO@g?C3N4-T催化剂具有合适的带差，导致可见光催化苯的C-H键活化及羟基化具有较好的催化性能，转化率和选择性可以达到98.4%、91.1%。由于石墨化氮化碳和钒具有较强的相互作用，这减少了钒的溶脱，所以该催化剂具有很好的可重复使用性，连续使用五次后，苯的转化率和苯酚的选择性没有明显降低。

Abstract:

Oxovanadium-graphitic carbon nitride thin nanosheet (VO@g?C3N4-T) had been prepared using urea and vanadium(IV)oxy acetylacetonate as precursors, compared with graphite nitride carbon (g?C3N4), oxovanadium-supported graphite nitride carbon (VO/g?C3N4).The structure and textural properties of the materials were thoroughly characterized by X-ray diffraction (XRD), N2 adsorption, scanning electron microscopeenergy(SEM), dispersive spectroscopy (EDS),inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The photocatalytic performances of the samples were tested in the hydroxylation of benzene to produce phenol under visible light. The results showed that VO@g?C3N4-T possesses high specific surface area, the shape of nanosheets and favorable bandgap, lead to a very good photocatalytic activity for the hydroxylation of benzene via C?H activation under visible light. 98.4% conversion of phenol was obtained with the selectivity to phenol as high as 91.1%. There was the strong interaction between the graphitic carbon nitride surface and vanadium metal, which minimizes vanadium leaching. The catalyst also exhibited good reusability and was reused five times without a significant decrease in conversion and selectivity.