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A new MoO3/SO4^2- -TiO2 catalyst was prepared by a conventional impregnation of SO42-/TiO2 as carrier with an aqueous solution of ammonium molybdate and used for the synthesis of transesterification of dimethyl carbonate (DMC) with phenol.A series of MoO3/SO42--TiO2 catalysts with different MoO3 loadings were investigated and characterized using X-ray diffraction (XRD),Fourier transform infrared spectrometer (FTIR),NH3-temperature programmed desorption (NH3-TPD) and X-ray photoelectron spectroscopy (XPS).The results show that MoO3 loading is related to the activity of transesterification reaction.With the increase of MoO3 loading,the activity of transesterification reaction increases.The sulfur species in the catalyst have an influence on the molybdenum species,and lead to an increase in the electropositive of molybdenum,which promotes the catalytic activity of MoO3/SO42--TiO2.Among the series of catalysts prepared,MoO3/SO42--TiO2 with 10% MoO3 and 823 K calcinated is found to be the most active catalyst for transesterification reaction.Under the reaction conditions of 453 K and 12 h,the conversion of DMC is 30.5 %,and the yields of MPC and DPC reach 21.2 % and 8.7 %,respectively. 相似文献
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LPCVD水解法制备TiO2薄膜 总被引:5,自引:0,他引:5
本文利用LPCVD法水解四异丙醇钛(TTIP)制备TiO2薄膜,研究了制备过程中水解TTIP的反应动力学。通过对沉积温度和沉积率关系的研究,计算出TTIP水解反应表观活化能为59.85kJ/mo1。沉积温度不仅影响反应速率,还对TO2薄膜结构、表面形貌有决定性的作用。XRD和Raman分析表明:TTIP水解法制备TiO2薄膜,薄膜结构主要依赖于沉积温度。180℃—220℃沉积TiO2薄膜为非晶态,240℃—300℃沉积为锐钛矿和非晶态混杂结构。在水分压对TTIP水解反应影响的研究中发现,水分压为零时,TTIP发生热解反应,TiO2沉积率不为零,热解反应240℃无锐钛矿特征峰出现。这说明水解反应制备TiO2有利于降低锐钛矿的生长温度。氧分子的加入可以消除TiO2薄膜表面的“针孔”。 相似文献
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以四异丙醇钛为原料 ,氧气作反应气体 ,高纯氮气作载气 ,采用低压MOCVD法在单晶Si基片上制备出了TiO2 薄膜。研究了基片温度和氧气流量对TiO2 薄膜沉积速率的影响 ,以及基片温度和退火温度对TiO2 薄膜的结构的影响。采用X射线衍射和喇曼光谱对TiO2 薄膜的结构进行分析。实验表明 :基片温度在1 1 0℃~ 2 5 0℃时制备的TiO2 薄膜是非晶态的 ,在 35 0℃~ 5 0 0℃时制备的TiO2 薄膜为锐钛矿和非晶态混杂结构 ,当基片温度超过 6 0 0℃时开始生成金红石。 相似文献
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