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

(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.