Facile fabrication of magnesium-enriched porous carbon for highly active and stable isomerization of glucose in water

Abstract

The endogenous MgO in-situ self-doped porous carbon (MgO@C) was fabricated from reliable magnesium citrate by a facile one-step pyrolysis process. Up to ∼60 wt% active magnesium oxide could be successfully embedded into the carbon skeleton with uniformly distributed MgO nanoparticles. The characterization analyses suggested that MgO@C had a “sand rose” structure with a large surface area, uniform pore-size distribution and small MgO crystal size. The MgO@C showed a high catalytic ability with a maximum fructose yield of 31.2% and selectivity of 86.2% from glucose isomerization in water at 85 °C within 60 min, which was better than that of the pure MgO and MgO supported on porous carbon (MgO/C). Moreover, the activation energy of glucose-fructose over MgO@C was calculated to be 54.20 kJ⋅mol−1, the value was less than that of MgO and MgO/C. The excellent catalytic activity was closely related to the moderate catalyst basicity, which was mainly caused by the smaller crystal size of magnesium oxide due to the confinement effect of porous carbon. More significantly, the as-prepared MgO@C exhibited good tolerability under high substrate concentrations (20 wt%), and could maintain good reusability without a serious decrease in activity during five cycles.