Abstract
Silica-Alumina mixed oxides with Si-O-Al bonds show a high brønsted acidity since protons (H+) are introduced as Si-OH-Al due to the charge compensation of Si4+ and Al3+. In order to obtain high proton conductivity, it is important that Si and Al atoms are alternately arranged. In this study, we focused an acid-base reaction to obtain highly dispersed Si-OH-Al bonds. AlCl3 and Si(OC2H5)4 or Si(OCH3)4 were used as acidic and basic raw materials, respectively. Gas chromatography-mass spectrometry (GC-MS) measurements revealed that C2H5Cl gas was formed after mixing AlCl3 and Si(OC2H5)4, suggesting the formation of alternate Si-O-Al bonds. On the other hand, a by-product of C2H5OC2H5 was also obtained at room temperature. Molecular simulation (gaussian09) results suggested both Si-O-Al and Si-O-Si bonds were formed at room temperature. The obtained mixed oxides were characterized by XRD, 27Al-MAS-NMR and FT-IR.
