Synthesis, characterization and catalytic activity of acid–base bifunctional materials through protection of amino groups

Acid–base bifunctional mesoporous material SO3H-SBA-15-NH2 was successfully synthesized under low acidic medium through protection of amino groups. X-ray diffraction (XRD), N2 adsorption–desorption, transmission electron micrographs (TEM), back titration, 13C magic-angle spinning (MAS) NMR and 29Si magic-angle spinning (MAS) NMR were employed to characterize the synthesized materials. The obtained bifunctional material was tested for aldol condensation reaction between acetone and 4-nitrobenzaldehyde. Compared with monofunctional catalysts of SO3H-SBA-15 and SBA-15-NH2, the bifunctional sample of SO3H-SBA-15-NH2 containing amine and sulfonic acid groups exhibited excellent acid–basic properties, which make it possess high activity for the aldol condensation.