The study for the adsorption of benzene over the acidic oxide

• Main Authors: C.H.Woang, 翁佳宏
• Other Authors: S.D.Lin
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/39823474200371192135

碩士 === 元智大學 === 化學工程研究所 === 86 === The benzene adsorption (desorption) over oxides support were investigated in order to find correlation with the acidity of oxide. The oxides examined included SiO2, TiO2, TiO2/SiO2, SO42-/SiO2 and SO42-/TiO2. The benzene adsorption experiments were conducted at 50℃ and atmospheric pressure; thereafter, the surface residue on the oxides were analyzed by the temperature- programmed desorption. The adsorption isotherm, the possible dehydrogenation occurred during the adsorption process and the temperature-programmed desorption were examined using a home-made flow-type adsorption system. Besides, the physical properties of the modified oxides were studied using ASAP 2000 and TGA. The results indicated that the benzene uptake and the degree of dehydrogenation during the adsorption were related to the oxide acidity. Furthermone, irreversible adsorption of benzene takes place on the more acidic oxides. The irreversible benzene adsorption isotherms on TiO2 and SO42-/TiO2 correspond to the Type I (Langmuir)isotherm, and that of sulfated silica increases with the pressure of benzene. The TPD results showed that the residue due to the irreversibly adsorped benzene could be detected with MS=27, 39 and 52 in mass spectrum. Silica itself had no desorption singnal detected, but all other oxides examined showed various type of TPD spectrum. The desorption spectrum depends on the type of oxides. This suggests that the benzene-TPD may be a useful tool for characterizing the surface acidity of oxides.