ZSM-5分子筛光催化活性的初步研究

开发具有广泛用途包括光催化合成和选择性氧化有机物的新型光催化剂是光催化研究领域所面临的重要挑战之一[1] . Kato等[2 ] 报道了HZSM- 5和丝光沸石对甲烷无氧偶联反应具有光催化活性,我们也发现HZSM- 5原粉对乙烯、溴代甲烷和染料都表现出明显的光催化活性.由于分子筛不是半导体,所以其光催化性能难于用传统的半导体光催化理论加以解释.Kato[2 ] 认为分子筛中Al—O单元是HZSM- 5和丝光沸石产生光催化活性的活性位,Anpo等[3]认为,过渡金属原子在Y沸石和MCM- 41介孔分子筛的骨架内形成了孤立的金属-氧物种电荷转移激发态:[Me(n- 1…

A Primary Study on Photocatalytic Properties of ZSM-5 Zeolite

The photocatalytic degradation of several organic compounds in airstreams was studied at room temperature by using a bed reactor packed with the commercial HZSM-5 and operated in a circulating mode. It was found that the raw HZSM-5 shows an unanticipated photocatalytic activity for oxidating ethylene, bromomethane and methyl orange. XRF and AAS analyses reveal that the photocatalytic activity of the ZSM-5 results from the trace amount of iron impurity in the sample, and the photoactivity is positively related with the content of iron. The primary results of characterization by XRD, DRS, XPS and SPVS suggest that the most of Fe existed in the framework of zeolite and in a tetrahedral coordination. The iron species might be excited by UV irradiation to form a charge transfer excited complex along with the ligands and an electron excited state of Fe 3+, which are responsible for the photocatalytic behavior of zeolites.