Effects of calcination temperature on characterization and photocatalytic activity of La2Ti2O7 supported on HZSM-5 zeolite
Effects of calcination temperature on characterization and photocatalytic activity of La2Ti2O7 supported on HZSM-5 zeolite
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DOI：
10.1016/j.jallcom.2016.11.416
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发表时间：
2017-02
影响因子：
6.2
通讯作者：
Wenjie Zhang;Zheng Ma;Ling Du;Li-Lan Yang;Xijuan Chen;Hongbo He
中科院分区：
文献类型：
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作者：
Wenjie Zhang;Zheng Ma;Ling Du;Li-Lan Yang;Xijuan Chen;Hongbo He
研究了焙烧温度对溶胶-凝胶法制备的70%La2Ti2O7/HZSM-5催化剂性能的影响。研究了该材料对活性艳红X3 B的光催化降解性能。在70%La2Ti2O7/HZSM-5复合材料中，负载La 2 Ti 2 O 7倾向于分散在HZSM-5颗粒表面。在800 °C时，材料中主要形成单斜晶系的La 2 Ti 2 O 7相，而在900 °C时出现少量正交晶系的La 4 Ti 9 O24相。在800、900和1000 °C煅烧的样品中，La 2 Ti 2 O 7的晶粒尺寸分别为24.5、29.9和42.0 nm。在900 °C以下，随着焙烧温度的升高，70%La2Ti2O7/HZSM-5的禁带宽度逐渐减小，这是由于高温下晶体生长过程中的量子尺寸效应沿着的影响。随着煅烧温度的升高，复合材料的BET比表面积逐渐减小。在800 °C焙烧的70%La_2Ti_2O_7/HZSM-5催化剂上，光催化活性最高，这与光照射产生的羟基自由基有关。当材料重复使用5次时，仍保持73.7%的初始光催化活性。
The effects of calcination temperature on properties of 70%La2Ti2O7/HZSM-5 prepared by sol-gel method were studied. Photocatalytic degradation of Reactive Brilliant Red X3B on the materials was measured. The supported La2Ti2O7tends to disperse on the surface of HZSM-5 particles in 70%La2Ti2O7/HZSM-5 composites. The majority phase of lanthanum titanate, monoclinic La2Ti2O7, forms in the material at 800 °C, while a small amount of orthorhombic La4Ti9O24appears at 900 °C. The crystallite sizes of La2Ti2O7are 24.5, 29.9 and 42.0 nm in the samples calcinated at 800, 900 and 1000 °C, respectively. The band gaps of 70%La2Ti2O7/HZSM-5 is gradually reduced with the increase of calcination temperature up to 900 °C, due to the quantum size effect along with crystal growth at high temperature. BET surface area of the composite gradually decreases with rising calcination temperature. The maximum photocatalytic acitvity is found on 70%La2Ti2O7/HZSM-5 calcinated at 800 °C, which is in accordance to production of hydroxyl radical under irradiation. 73.7% of the initial photocatalytic activity is still retained when the material is reused for the fifth time.