Synthesis of dimethyl carbonate by urea alcoholysis over Zn/Al bi-functional catalysts

• The Zn/Al mixed oxides were prepared via the decomposition of hydrotalcite-type precursors.
• Bi-functional catalysts presented noticeable activity and stability for the DMC synthesis by urea alcoholysis.
• Surface weak acidic/basic sites of ZAO catalysts synergistically promoted the DMC synthesis.
• Urea and methanol were respectively activated on the weak acidic and basic sites, advancing the DMC synthesis.

Zn/Al mixed oxides (ZAO) were prepared via thermal decomposition of hydrotalcite-type precursors derived from urea precipitation. Specially, ZAO catalysts with a Zn/Al molar ratio of 4:1 exhibited high dimethyl carbonate (DMC) yield (∼36.5%) when utilized for the DMC synthesis from urea and methanol. The XRD, IR, TPD and computational analysis revealed that the formation of ZnAl2O4 spinel significantly modified the surface acidity and basicity of ZAO catalysts, which were beneficial for the DMC synthesis. We thus opened up a bi-functional mechanism that urea and methanol were respectively activated on the weak acidic and basic sites, advancing the DMC synthesis synergistically.

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