Study the liquid-phase Beckmann rearrangement on the surface of SBA-15-SO3H catalyst

Hybrid inorganic–organic solid acid material SBA-15-Ph–SO3H was synthesized by the co-condensation of tetraethoxysilane and 2-(4-chlorosulfonylphenyl) ethyltrimethoxysilane in the presence of a Poly (alkylene oxide) block copolymer under acid conditions. The catalytic activity of the obtained materials was studied in liquid-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. The results show that there exists an obvious “Solvent effect” in this reaction system and the strong Bronsted acid is proofed again to be at the origin of the formation of ε-caprolactam. Moreover, we tentatively proposed a reaction mechanism involving a five-member ring intermediate product when toluene was used as solvent.