含Bi中孔分子筛(Ⅰ) 合成和表征与催化性能

Bi-Si MESOPOROUS ZEOLITES(Ⅰ)SYNTHESIS,CHARACTERIZATION AND CATALYTIC ACTIVITY

以十六烷基三甲基溴化铵为模板剂 ,正硅酸乙酯为硅源 ,硝酸铋为铋源 ,在弱碱性条件下用水热法合成了具有MobileCrystallineMaterial 4 1结构的Bi Si中孔分子筛 ,通过XRD、N2 吸附等温线、TG、SEM、FT IR、UV Vis等多种表征手段对其进行结构、性质分析 ,结果表明 :所合成的分子筛具有良好的长程有序结构和孔结构 ,并且铋高度分散于分子筛骨架中 .在苯乙烯催化氧化制苯甲醛中有很好的催化活性 ,当Si/Bi=2 2 5 (摩尔比 ) ,反应时间为 1h ,反应温度为 80℃时苯甲醛的产率达到 14 1% .考察了分子筛有序度与铋含量及改性金属对催化活性的影响 .

Bi-Si mesoporous zeolites(Bi-Si)with different Si/Bi ratios were synthesized with the hydrothermal method which used TEOS as silica source, Bi(NO 3) 3·5H 2O as metal source, cetyltrimethylammonium bromide as template, and the oxidation of styrene by hydrogen peroxide to benzaldehyde catalyzed by the zeolite prepared was investigated.The nature of the catalysts was discussed based on the characterization results with nitrogen adsorption-desorption (BET), X-ray diffraction(XRD), scanning electron microscopy(SEM),Fourier transform infrared spectroscopy (FT-IR),ultraviolet-visible spectroscopy(UV-Vis),and thermogravimetric method(TG).Bi-Si had high ordering structures of Mobile Crystalline Material-41 and bismuth was highly dispersed in the mesostructure framework.With increasing bismuth content, the crystallite of Bi-Si became disorderly,and at the same time the value of d 100 decreased.Bi-Si was found to be catalytically active in the oxidation of styrene to benzaldehyde with H 2O 2 as oxidant and methanol as solvent.The conversion of styrene increased with increasing Bi content,while the selectivity of benzaldehyde decreased.The catalyst with Si/Bi=22.5(mole ratio) showed higher catalytic activity,and the yield of benzaldehyde reached 14.1%.The influence of the ordering of mesostructure and the Bi content on the oxidation activity of Bi-Si was also discussed.