K-doped CuO/ZnO with Dual Active Centers of Synergism for Highly
Efficient Dimethyl Carbonate Synthesis
Abstract
The application of heterogeneous catalysts in dimethyl carbonate (DMC)
synthesis from methanol is hindered by low activation efficiency of
methanol to methoxy intermediates (CH3O*), which is the key intermediate
for DMC generation. Herein, a catalyst of alkali metal K anchored on the
CuO/ZnO oxide is rationally designed for offering Lewis acid-base pairs
as dual active centers to improve the activation efficiency of methanol.
Characterizations of CO2-TPD, NH3-TPD, XPS, and DRIFTS revealed that the
addition of Lewis base K observably boosted the dissociation of methanol
and combined with Lewis acid CuO/ZnO oxide to adsorb the formed CH3O*
stably, thus synergistically promoted the transesterification. Finally,
the CuO/ZnO-9%K2O catalyst exhibited the optimal catalytic activity,
achieving a high yield of 74.4% with an excellent selectivity of 98.9%
for DMC at a low temperature of 90 °C. The strategy of constructing
Lewis acid-base pairs provides a reference for the design of
heterogeneous catalysts.
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