Functionalization of HMS mesoporous molecular sieves and their base-catalytic performance

摘要

Organic NH_2 group was grafted onto the surface of mesoporous molecular sieves by reacting 3-aminopropyltriethoxysilane or 3-ethyldiaminopropyltrimethoxysilane with calcined pure siliceous HMS with different pore sizes. Characterization of functionalized samples was made by means of XRD, FT-IR and N_2 adsorption-desorption isotherms. These NH_2-grafted HMS materials are highly active catalysts for Knoevenagel reaction of benzaldehyde with ethyl cyanoacetate. The initial activity of catalyst depends not only on the density of NH_2 groups, but also on the pore size and the size of organosilane molecule. In addition, the effect of reaction temperature and solvent on the activity, and the recycling of the catalyst are also investigated.