Probing into Surface Sites of Fresh Mo2N/Al2O3, Mo2C/Al2O3 and MoP/Al2O3 Catalysts by CO Adsorption and In Situ FT-IR Spectroscopy

摘要

The surface nature of fresh Mo_2N/Al_2O_3,Mo_2C/Al_2O_3 and M0P/Al_2O_3 catalysts,which were synthesized directly in the IR cell to avoid passivation,were characterized by in situ IR spectroscopy with CO as a probe molecule. CO adsorbed on fresh catalysts showed characteristic IR bands at 2045 cm^(-1) for Mo_2N/Al_2O_3 catalyst,2054 cm^(-1) for Mo_2C/Al_2O_3 catalyst and 2037 cm^(-1) for MoP/Al_2O_3 catalyst,respectively.A strong band at 2200 cm^(-1) for Mo_2N/Al_2O_3 catalyst,which could be ascribed to NCO species formed when CO reacted upon surface active nitrogen atoms,and a weak band at 2196 cm^(-1) for Mo_2C/Al_2O_3 catalyst,which could be attributed to CCO species,were also detected.CO adsorbed on fresh Mo_2N/Al_2O_3 catalyst,Mo_2C/Al_2O_3 catalyst and MoP/Al_2O_3 catalyst,showed strong molecular adsorption,just like noble metals.Our experimental results are bolstered by direct IR evidence demonstrating the similarity in surface electronic property between the fresh Mo_2N/Al_2O_3,Mo_2C/Al_2O_3 and MoP/Al_2O_3 catalysts and noble metals.