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- 2017
四丙基氢氧化铵处理钛硅分子筛催化1-己烯环氧化
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Abstract:
用不同浓度的四丙基氢氧化铵(TPAOH)处理钛硅分子筛(TS-1), 处理后的钛硅分子筛作催化剂催化1-己烯发生环氧化反应．用X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)、紫外漫反射(UV-Vis)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N2吸附-脱附曲线(BET)、氨气程序升温脱附(NH3-TPD)和电感耦合等离子体发射光谱(ICP)对催化剂进行了表征．表征结果表明：样品的MFI结构没有被破坏; 当TPAOH碱处理钛硅分子筛时, 晶体内部部分硅溶解导致分子筛内部有介孔生成; 随着四丙基氢氧化铵浓度的增加, 分子筛中的骨架钛含量逐渐减少同时有非骨架钛生成．在催化1-己烯环氧化反应中, 介孔的生成使处理后的钛硅分子筛活性和选择性得到明显改善．但是当介孔体积大于0.219 cm3/g时, 由于骨架钛损失较多, 1-己烯转化率和1, 2-环氧己烷相对于1-己烯和过氧化氢的选择性都显著降低．
Titanium silicalite-1(TS-1)was treated by tetrapropyl ammonium hydroxide(TPAOH)with different concentrations and used as catalyst in 1-hexene epoxidation. All the samples were characterized by X-ray powder diffraction(XRD)，Fourier-transform infrared spectrum(FT-IR)，ultraviolet-visible diffuse reflectance spectrum (UV-Vis)，scanning electron microscopy(SEM)，transmission electron microscopy(TEM)，nitrogen physical adsorption and desorption(BET)，NH3-temperature programmed desorption(TPD)and inductively coupled plasma atomic emission spectrometry(ICP). The results show that the MFI structures of the samples are not destroyed and mesopores are formed in TS-1 crystals due to the dissolution of silica when TS-1 samples are treated by TPAOH. However，the framework Ti content decreases gradually，forming extraframework Ti. Due to the formation of mesopores，the catalytic activity and selectivity of the treated TS-1 are markedly improved in the reaction of 1-hexene epoxidation. However，when the volumes of the mesopores are larger than 0.219 cm3/g，the 1-hexene conversion and the selectivities of 1，2-epoxyhexane to 1-hexene and H2O2 sharply decrease as a result of the appreciable loss of the framework Ti in the TPAOH treatment
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