氮掺杂二氧化钛复合催化膜降解甲苯气体研究

采用溶胶-凝胶法以聚丙烯(PP)中空纤维膜为载体制备了N-Ti O2/PP复合催化膜,并考察了其催化降解甲苯有机废气的性能.结果发现,紫外光催化的甲苯降解率可达84%,去除负荷为89.8 g·m-3·h~(-1),自然光催化的甲苯降解率可达63.9%,去除负荷为69.25 g·m-3·h~(-1).同时,采用紫外-可见光谱(UV-Vis)、X-射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)表征了N-Ti O2/PP复合催化膜,并采用GC-MS分析甲苯降解过程的中间产物并推测甲苯反应过程机理.采用GC-MS分析出口气样的研究结果表明,苯(C6H6)、苯甲醛(C7H6O)、苯乙酸(C8H8O2)、丙烯醛(C3H4O)、甲酸甲酯(C2H4O2)为甲苯光催化降解的中间产物.N-Ti O2/PP复合催化膜降解甲苯的机制为甲苯气体通过中空纤维膜传质到N-Ti O2/PP复合催化膜,光催化产生羟基自由基,甲苯气体被羟基自由基氧化成中间产物,并继续降解为最终产物二氧化碳和水.

Photocatalytic degradation of toluene by nitrogen-doped titanium dioxide composite film

The N-doped titanium dioxide was prepared by the sol-gel method, which was then loaded on Polypropylene (PP) hollow fiber membranes to prepare N-TiO₂/PP composite members. The photocatalytic degradation of toluene over N-TiO₂/PP was tested with the use of UV irradiation and visible light. Removal efficiency of toluene by UV irradiation was up to 84% and the maximum elimination capacity reached 89.8 g·m^-3·h^-1. The removal efficiency of toluene by visible light was up to 63.9% and the maximum elimination capacity reached 69.25 g·m^-3·h^-1. UV-Vis spectra, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrometer (FT-IR) were used to characterize the prepared N-TiO₂/PP. GC-MS was used to detect outlet gases. The gas-phase photodegradation intermediate organic products identified by gas chromatography/mass spectrometry (GC-MS) were benzene (C₆H₆), benzaldehyde (C₇H₆O), phenylacetic acid (C₈H₈O₂), acrolein (C₃H₄O), and methyl formate (C₂H₄O₂). Toluene diffused from the gas-phase to the surface of the N-TiO₂/PP membranes, and then was oxidized into CO₂ and H₂O by the strong oxidant hydroxyl radicals.