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

(Pd-CuCl2)/gamma-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 gamma-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)/gamma-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.