A vapor phase synthesis of dimethyl carbonate (DMC) from carbon monoxide and methyl nitrite (MN) has been carried out over Pd/NaY catalysts at 383 K, DMC was produced in a good yield. The selectivity to DMC was [85% on the basis of consumed CO or MN. The by-products were dimethyl oxalate, methyl formate and dimethoxymethane. The catalytic properties CO 2, N 2 O, of Pd/NaY were investigated as a function of Pd content and calcination temperature. It was found that 1 wt.% Pd/NaY calcined at 473 K in air was the optimum catalyst for the present DMC synthesis. The oxidation state and dispersion of Pd in the Pd/NaY catalysts were characterized by EXAFS and XPS. It was revealed that in 1 wt.% Pd/NaY changed into Pd metal Pd(NH 3 ) 4 2c lusters during the catalytic reaction. Pd metal clusters/NaY showed a stable activity for the DMC synthesis even after 700 h. These results suggest that the cage structure of NaY and anchoring e †ects of protons suppress Pd metal sintering and stabilize very small Pd metal clusters in the zeolite cages during the reaction.
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