We present a comparison of Mo, V and Nb oxides as shell materials atop haematite cores used for selective methanol oxidation. While Mo and V both yield high selectivity to formaldehyde, Nb does not. Very different rea...We present a comparison of Mo, V and Nb oxides as shell materials atop haematite cores used for selective methanol oxidation. While Mo and V both yield high selectivity to formaldehyde, Nb does not. Very different reactivity patterns are seen for Nb, which mainly shows dehydrogenation (to CO) and dehydration (to DME), indicating the lack of a complete shell, while Raman spectroscopy shows that the Mo and V formation process is not followed by NbOx. We suggest this is due to the large differences in mobility within the solid materials during formation, NbOx requiring significantly higher (and deleterious) calcination temperatures to allow sufficient mobility for shell completion.展开更多
A mechanochemical method was employed to prepare modified iron molybdate catalysts with various metal salts as precursors.The physicochemical properties of the iron molybdate catalysts were characterized,and their per...A mechanochemical method was employed to prepare modified iron molybdate catalysts with various metal salts as precursors.The physicochemical properties of the iron molybdate catalysts were characterized,and their performances in catalyzing the reaction from methanol to formaldehyde(HCHO)were evaluated.Iron molybdate catalysts doped with Co(NO_(3))_(2)·6H_(2)Oand Al(NO_(3))_(3)·9H_(2)O resulted in high HCHO yields.Compared with a commercial catalyst,the HCHO yields in the reaction with the modified catalyst at an optimal Co/Mo molar ratio reached 97.37%.According to chemical state analysis,the formation of CoO and the efficient decrease in the MoO_(3)sublimation rate could be important factors enhancing the HCHO yield in reactions catalyzed with iron molybdate doped with different Co/Mo mole ratios.展开更多
基金EPSRC for support via the UK Catalysis Hub(EP/K014854/1,EP/K014714/1)EPSRC and Diamond Light Source for funding the studentship to PH
文摘We present a comparison of Mo, V and Nb oxides as shell materials atop haematite cores used for selective methanol oxidation. While Mo and V both yield high selectivity to formaldehyde, Nb does not. Very different reactivity patterns are seen for Nb, which mainly shows dehydrogenation (to CO) and dehydration (to DME), indicating the lack of a complete shell, while Raman spectroscopy shows that the Mo and V formation process is not followed by NbOx. We suggest this is due to the large differences in mobility within the solid materials during formation, NbOx requiring significantly higher (and deleterious) calcination temperatures to allow sufficient mobility for shell completion.
基金the Natural Science Foundation Project of Xinjiang Uygur Autonomous(Grant No.2019D01C084)for financial support.
文摘A mechanochemical method was employed to prepare modified iron molybdate catalysts with various metal salts as precursors.The physicochemical properties of the iron molybdate catalysts were characterized,and their performances in catalyzing the reaction from methanol to formaldehyde(HCHO)were evaluated.Iron molybdate catalysts doped with Co(NO_(3))_(2)·6H_(2)Oand Al(NO_(3))_(3)·9H_(2)O resulted in high HCHO yields.Compared with a commercial catalyst,the HCHO yields in the reaction with the modified catalyst at an optimal Co/Mo molar ratio reached 97.37%.According to chemical state analysis,the formation of CoO and the efficient decrease in the MoO_(3)sublimation rate could be important factors enhancing the HCHO yield in reactions catalyzed with iron molybdate doped with different Co/Mo mole ratios.
