科研之友
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摘要
To improve the stability of traditional SO42-/ZrO2 solid superacid catalysts, a kind of solid superacid catalyst SO42-/ZrO2- WO3-Al2O3(SWZA) modified with α-Al2O3 and ammonium tungstate is prepared. To obtain the high catalytic performance of the catalysts, the flow indictor method is used to measure the acidity of the catalysts. The X-ray diffraction (XRD), the Fourier transform infrared ray spectroscopy (FTIR), the thermal gravimetric analysis-differential scanning calorimetry (TGA-DSC) and the scanning electron microscope (SEM) are used for studying the catalytic mechanism. The effects of the preparation conditions, such as the precipitation temperature, the calcination temperature and the addition of α-Al2O3 and ammonium tungstate, on the catalytic performance of the catalysts are studied. The experimental results show that a low precipitation temperature can help form crystal centers on the surfaces of the catalysts, reduce the rate of particle migration, inhibit the grain growth and produce small but regular crystal particles, resulting in an increase of specific surface area of the obtained catalysts. During the preparation, the suitable calcination temperature 500°C induces the crystal transformation from the monoclinic phase to the tetragonal phase and the specific surface area of the superacid is increased. The addition of α-Al2O3 can increase the Lewis acid sites on the catalyst surfaces, improving the catalytic activity of the catalysts. The addition of WO3 can orientally induce the crystal formation of the catalysts, delay the crystallization of ZrO2, stabilize the tetragonal phase and constrain the loss of SO42- at the high temperature.
- 出版日期2010
- 单位东南大学
