Esterification of lignin to produce pharmaceutical intermediates using mSiO2@Al mesoporous molecular sieve spheres as a catalyst

Abstract

There is a critical need to produce 3,4-dimethoxyphenyl acetic acid esters to improve the use of lignin. However, the currently available catalysts either have insufficient activity for macromolecular biomass or they are too unstable for reuse. Here, a novel mesoporous silica sphere material doped with aluminum, designated as mSiO2@Al, was prepared under hydrothermal conditions by a top-down strategy. Application of various structural characterization methods revealed that Al was introduced into the skeleton to form Al-O-Si and it was distributed on the surface of the mesoporous spheres. Enhanced active component–lignin interactions led to exceptionally high yields of 3,4-dimethoxyphenyl acetic acid esters, and the catalyst exhibited outstanding stability under demanding conditions.