触媒活性サイトの空間組織が反応に及ぼす影響研究

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Metal copper was certified as the best promoter in carbonylation of dimethyl ether (DME) to methyl acetate (MA) over mordenite (MOR) zeolite. To date, the major reaction mechanism suggested that the activation of either CO or DME needed assistance from both metal functional sites and Bronsted acid sites (BAS) in zeolites. Therefore, almost all reported Cu modified MOR catalysts employed the preparation method of impregnation or ion exchange for a closer connection. However, the impact of intimacy between copper and BAS at different scales is still not well described.In the past year, we designed and prepared catalysts with different spatial assembly styles. Cu/MOR and Cu-MOR with the distance between Cu and BAS of zeolite in nanoscale were prepared by impregnation and ion exchange respectively. The Cu/SiO2&H-MOR was prepared via mixing, grinding, and pelleting of Cu/SiO2 with MOR. For Cu/SiO2+H-MOR style, Cu/SiO2 particles and pelleted H-MOR granules were mixed without further grinding. The Cu/SiO2//H-MOR and H-MOR//Cu/SiO2 represent the completely separated assembly style (centimeter-scale). The STY of MA over Cu/SiO2&H-MOR was found to increase from 1725 to 2946 mmol/(kg h) along with raising the reduced temperature.However, here we adopted the mixture catalyst of Cu/SiO2 and H-MOR, in which the distance between the metal and BAS was much farther than the conventional Cu/MOR and Cu-MOR catalysts by former researchers. Therefore, the intrinsic mechanism of DME carbonylation in our catalytic system should be fundamentally different from all of the previous reports.