(Pd–CuCl2)/γ-Al2O3: a high-performance catalyst for carbonylation of methyl nitrite to dimethyl carbonate

Abstract

(Pd–CuCl₂)/γ-Al₂O₃ catalyst with excellent activity and selectivity has been successfully developed for vapor-phase carbonylation of methyl nitrite to dimethyl carbonate (DMC). It has been demonstrated that Cl⁻ is necessary for the superior selectivity (99.8%) to DMC, and that Cl⁻ and Cu²⁺ have a synergetic effect. The Lewis acid sites of the γ-Al₂O₃ support may be suitable for vapor-phase carbonylation of methyl nitrite to DMC. Moreover, the catalytic mechanism of DMC formation on the (Pd–CuCl₂)/γ-Al₂O₃ catalyst has been reasonably proposed based on the results of XPS and in situ diffuse reflectance infrared spectroscopy. The intermediate Cl–Pd(II)–COOCH₃ is the key factor for the synthesis of DMC.