Synthesis of Mesoporous Aluminum Silicates and Their Catalytic Activity in Friedel-Crafts Alkylation Reaction

Ordered mesoporous aluminum silicates with strong acid sites were synthesized by sol-gel method. The resulted materials' structures were characterized by XRD, TEM, Al-27 NMR, NH3-TPD and Py-FT-IR. The amount of surfactant and the Si/Al mole ratio would both affect the materials' meso-structure; while, the amount of HAc has little effect on the structure. TEM analysis confirmed that these aluminum silicates with different Si/Al mole ratios have an ordered 2D hexagonal regularity. Friedel-Crafts alkylation reaction of anisole and benzyl alcohol was used as the probe reaction to detect the acidic properties of these aluminum silicates. The Si/Al mole ratio played an important role in catalytic activity and the aluminum silicates with n(si)/n(Al)=10 showed the best acid catalytic activity. NH3-TPD and Py-FT-IR suggested that the aluminum silicates with n(si)/n(Al)=10 had much more Bronsted acidic sites than that of other Si/Al ratios.