Highly selective isomerization of biomass β-pinene over hierarchically acidic MCM-22 catalyst

Abstract Hierarchical MCM-22 material with microporous-mesoporous structure is found to be a highly efficient solid acid catalyst for the liquid phase isomerization of β-pinene, which can achieve 100% conversion of β-pinene and 93.7% yield for main products inclusive of 76.2% limonene and 17.5% camphene under mild reaction conditions. The excellent catalytic activity of the catalyst is ascribed to hierarchical pore structure and suitable Bronsted/Lewis ratio of surface acidity on the material, widely characterized by XRD, SEM, TEM, N 2 adsorption, ICP, NH 3 -TPD, and pyridine-IR analyses. More importantly, this catalyst can be regenerated by simple MeOH-washing without calcination, different from traditional recovery by calcination at high temperature, and reused 7 times without an appreciable decrease of both the conversion of β-pinene and the selectivity of camphene and limonene, implying its excellent recyclable stability.