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Calcined at different temperatures AMT / SiO2 catalyst XRD spectrum were shown. When the firing temperature ≤623K, the XRD spectra of the sample is only a large dispersion peak for amorphous silicon dioxide carrier diffraction peaks, indicating on the catalyst surface small particles of tungsten species or amorphous form dispersed in the surface of the carrier. when the calcination temperature of 773K, the spectrum of the sample appears in the corresponding diffraction peak at WO3 crystal phase, indicating a higher calcination temperature on the catalyst can be treated the AMT decomposition of WO3.

Calcined at different temperatures AMT / SiO2(silicon dioxide) catalyst CO2- TPD spectrum shown in Figure, a CO2 desorption peak on the spectra of all samples occur in the vicinity of 410K, with the peak firing temperature increased slightly to move towards low temperature, and the peak intensity decreased. this indicates that all the samples have a certain amount of a weak base centers exist, and with calcination temperature, intensity and number of weak base centers on the catalyst surface are gradually reduced. in addition, the baking temperature is 623 and the sample at around 542K, 773K has a small desorption peaks, indicating the presence of a base is also the center of a small amount of moderate intensity in the sample.

  FIG. 1 showed NH3-TPD spectra of the sample. The figure shows that all the samples were about 416K have NH3 desorption peaks appear. With calcination temperature, peak intensity decreased slightly, but the desorption peak temperature essentially unchanged. this indicates the presence of weak acid sites are calcined at different temperatures on the surface of the catalyst prepared, and with calcination temperature has decreased the amount of weak acid.


 

 

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