Preparation Of TiMgAl-LDH With CVD Method And Its Photocatalytic Performance

Semiconductor photocatalysis has the potential to degrade the pollutants in environment, and the contaminants can be mineralized to CO2, H2 O and other small molecules. The cmoposites were prepared by Ti species loading on the surface of the hydrotalcite particles as carriers can overlay spectral response range of the host and the guest, to improve the photocatalytic efficiency. In the thesis, the Ti species were loaded on the the surface of MgAl hydrotalcite material as a carrier to form the TiMgAl-LDH composite. And then the metallic oxides catalysts(TiMgAlO) were obtained through calcining the TiMgAl-LDH muffle. The microstructure, morphologies and textural properties of TiMgAl-LDH and TiMgAlO were investigated by means of XRD, SEM and so on. Their photocatalytical performances were assessed for their ability to degrade methylene blue(MB).Firstly, MgAl LDH precursor was synthesized by using urea method. And then, the highly fragmented TiMgAl-LDH was obtained by CVD method with TiCl4 as the source of Ti. The degradation retention rate of MB by the TiMgAl-LDH under the Ultraviolet light was used to optimized the CVD process parameters of loading time, loading tempretureand N2 flowing by the response surface analysis. Above all, the CVD mechanism of the TiMgAl-LDH formation was discussed combine with the characterization of XRD、UV-vis、SEM and so on. The results show that the most optimal CVD process parameters are loading time 6.5 h, loading tempreture210 oC and N2 flowing 85 mL?min-1. The Ti4+ is combined with the –OH on the surface of the MgAl LDH layer in coordination bond, which leads to the formation of heterostructure.Next, combined with the UV-vis and Tauc model the optical band gap of TiMgAl-LDH at the most optimal CVD process parameters was calculated. The photocatalytic degradation performance of TiMgAl-LDH for MB was studied compared with MgAl-LDH. The results show that the optical band gap of TiMgAl-LDH is at ultraviolet region(3.342ev) and the rate constant of photocatalytic degradation of TiMgAl-LDH for MB was-0.0395, which suggests that TiMgAl-LDH has higher catalytic activity than MgAl-LDH. All of these are attributed to the formation of heterostructure.Finally, in order to expand the application of TiMgAl-LDH composite catalyst, theTiMgAl-LDH was calcinated at different temperature for the further application in the probe reaction of MB degradation under the Ultraviolet light. And the catalytic performance and stability of the TiMgAl-LDH type catalyst was studied.