改性VO_x/Al_2O_3催化剂催化氧化甲醇的固体核磁共振研究(英文)

Catalyzed Oxidation of Methanol on Acid/Base Modified VO_x/Al_2O_3 Studied by Solid-state NMR

采用固体核磁共振研究了NaOH和HNO3改性的VOx/Al2O3上甲醇选择性催化氧化反应.实验结果表明:在甲醇的氧化反应中,酸位对二甲氧基甲烷的生成起了重要作用.与VOx/Al2O3催化剂相比,酸改性的VOx/Al2O3上的强的Brφnsted酸位对二甲氧基甲烷的选择性较高,没有Brφnsted酸位的碱改性的VOx/Al2O3上生成的不是二甲氧基甲烷而是甲酸盐.

Oxidation of methanol catalyzed by NaOH or HNO3 modified VOx/Al2O3 was studied by solid-state nuclear magnetic resonance （NMR） spectroscopy. The acid-treated VOx/Al2O3 catalyst showed stronger Bronsted acid sites compared to the unmodified VOx/Al2O3 catalyst, while the base-treated VOx/Al2O3 catalyst had no Bronsted acid sites. As a result, the former exhibited higher selectivity in producing dimethoxymethane from oxidation of methanol whereas the oxidation reaction catalyzed by the later yielded mainly formate. These results indicate that the Bronsted acid sites in VOx/Al2O3 catalysts play a key role in the oxidation reaction converting methanol to dimethoxymethane.