Sol-gel Synthesis of Nano-sized TiO2Supported on HZSM-5

Background: Photocatalytic degradation of organic pollutants on TiO2-based materials has become a research focus in environmental cleaning. It is worthy of studying the effects of pre-treating of zeolite on the properties of the supported TiO2 photocatalyst. However, hydrothermal treatment is still a new approach to prepare HZSM-5. Hydrochloric acid concentration is a key factor in the Na+- H+ exchanging process using NaZSM-5 as the raw material. Methods: HZSM-5 was treated in hydrochloric acid aqueous solution by hydrothermal method and was used to synthesize supported nanosized TiO2. Characterizations of the materials were conducted by means of XRD, SEM, XPS, BET and BJH analyses. Results: The distribution of TiO2 on the surface of HZSM-5 leads to shrinking crystallite size of anatase TiO2. 50%TiO2/ 0.3HZSM-5 has the maximum surface area of 243.1 m2/g among the supported 50%TiO2/HZSM-5. Rising hydrochloric acid concentration during treating of NaZSM-5 zeolite can lead to enlarging pore size of the supported materials. The Ti2p and O1s electron binding energies in 50%TiO2/0.3HZSM-5 shift to higher energy due to the existence of HZSM-5. 92.8% of methyl orange is degraded in 100 min under irradiation on 50%TiO2/0.3HZSM-5. Conclusion: The composite TiO2/HZSM-5 materials were prepared for the purpose of photocatalytic decoloration of methyl orange. TiO2 is in the anatase phase in the supported 50%TiO2/HZSM-5. Photocatalytic activity of 50%TiO2/HZSM-5 varies with hydrochloric acid concentration. Keywords: HZSM-5, methyl orange, photocatalysis, TiO2.