Carbon-coated mesoporous silica functionalized with sulfonic acid groups and its application to acetalization

Abstract

The inner surface of mesoporous silica SBA–15 was coated by a homogeneous polycyclic carbon layer through controlled carbonization of furfuryl alcohol. The composite was subsequently functionalized with sulfonic acid (−SO3H) groups to form a strong solid acid material, with a tunable acid site density in the range of 0.38–0.84 mmol/g by varying the thickness of the carbon layer. Structural analysis and reaction data revealed that the solid acid catalyst exhibited high reactivity towards the acetalization of aldehydes or ketones with alcohols because of the uniform carbon coating of the mesopores, high acid site density, and its mechanical stability. 采用浸渍法将糠醇负载在铝改性的SBA-15介孔孔道中, 经550 °C不完全碳化制备了结构规整、含多苯环的中空管状硅碳复合介孔材料. 结果表明, 通过温和磺酸化作用可使磺酸基团成功取代在多苯环上, 其酸量随着多苯环涂层厚度变化在0.38∼0.84 mmol/g范围内可控调变. 相比于蔗糖作为糖源的复合固体酸, 所制碳多苯环-硅酸催化剂具有中空碳纳米管堆积的类似CMK-5介孔结构, 以及较大的反应空间、稳定的机械性能、较高的比表面和大量可以接触的质子酸中心, 因而在大分子缩醛(酮)反应中表现了良好的催化性能.