Synthesis of MgO-doped ordered mesoporous carbons by Mg2+-tannin coordination for efficient isomerization of glucose to fructose

In-situ MgO-doped ordered mesoporous carbon (OMC@MgO) was fabricated by formaldehyde-free self-assembly method, in which biomass-derived tannin was used as carbon precursor replacing fossil-based phenolics, Mg2+ as both cross-linker and precursor of catalytic sites. Up to similar to 20 wt% MgO could be doped in the carbon skeleton with good dispersion retaining well-ordered mesoporous structures, while more MgO content (35 wt%) led to the failing in the formation of ordered mesoporous structure. The OMC@MgO possessed a high specific surface area (298.8 m(2) g(-1)), uniform pore size distribution (4.8 nm) and small crystallite size of MgO (1.73 nm) due to the confinement effect of ordered mesoporous structure. Using OMC@MgO as the heterogeneous catalyst, a maximum fructose yield of 32.4% with a selectivity up to 81.1% was achieved from glucose in water (90 degrees C, 60 min), which is much higher than that obtained using the MgO doped active carbon via conventional post-impregnation method (26.5% yield with 58.3% selectivity). Higher reaction temperature (>90 degrees C) resulted in decrease of selectivity due to the formation of humins. The designed OMC@MgO displayed tolerant to high initial glucose concentrations (10 wt%) and could remain good recyclability without significant loss of activity for three cycles. (c) 2021 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communi-cations Co., Ltd.

Automated summary

In-situ MgO-doped ordered mesoporous carbon (OMC@MgO) was fabricated using a formaldehyde-free self-assembly method, with biomass-derived tannin as the carbon precursor and Mg2+ as the cross-linker and catalyst precursor. The OMC@MgO exhibited well-controlled mesoporous structures, high surface area, and good catalytic activity, achieving a high fructose yield with good selectivity from glucose. It also showed tolerance to high glucose concentrations and maintained recyclability.