ZSM-5-TiO_2协同吸附-光催化去除空气中甲苯污染物的研究

Adsorption-Photocatalytic Synergistic Removal of Toluene Vapor in Air on ZSM-5-TiO_2 Composites

通过溶剂热制备纳米晶TiO2,再通过浸渍法将其负载于ZSM-5,获得ZSM-5-TiO2复合材料.考察了多种因素对吸附和光催化性能的影响,发现控制TiO2负载量及改变ZSM-5样品的硅铝比可显著改善HI疏水因子,提高对有机污染物的吸附能力和光催化降解效率,实现吸附和光催化协同净化空气.结合表征,对吸附及光催化的构效关系和协同效应进行了初步探索.

As we all know,titanium dioxide(TiO2) is one of the most promising photocatalysts for degradation of toxic volatile organic compounds(VOC) ideally under environmentally friendly conditions.While H-ZSM-5 zeolites are commonly used in industrial catalysis as an important adsorbent or host material.This paper mainly focused on designing TiO2-sorbent hybrid photocatalytic materials,especially those supported on ZSM-5 zeolites,with the objective of fabricating efficient photodegradation systems toward organic compounds diluted in air.ZSM-5-TiO2 composites were fabricated by an impregnation method.First,the TiO2 nanocrystals with diameter about 5 nm were prepared by solvothermal process.Next,these TiO2 nanocrystals were loaded on the ZSM-5 zeolites through impregnating at a relatively low temperature about 150 ℃.The obtained samples were characterized by scanning electron microscopy(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) techniques.The fundamental adsorptionphotocatalytic behaviors were investigated in the removal of toluene vapor diluted in air.In the case of hybrid photocatalysts,the initial toluene concentration in gas phase was significantly reduced because of adsorption into the ZSM-5.After photo-irradiation started,toluene was continuously decomposed.The results found that TiO2nanocrystals were uniformly distributed on the surface of ZSM-5 zeolites by using of impregnation method.Simultaneously the synergistic effects between adsorption properties and photocatalysis were discussed in this paper,as well as the structure-activity relationship.The weight ratio of TiO2and SiO2/Al2O3 ratio of the ZSM-5-TiO2 composites will significantly affect hydrophobicity index(HI),adsorption and photocatalytic efficiency.The effect of the amount of the adsorbent on the photocatalytic activity was investigated and provided a novel physicochemical insight into adsorption-photocatalytic synergistic removal of organic pollutants.The present study affords a fundamental understanding of hybrid materials of TiO2 and ZSM-5 zeolite,highlighting an enhancement of photocatalytic activity of supported TiO2on such adsorbed materials.