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用红外光谱法表征了Ir/Al_2O_3催化剂的表面性质。发现该催化剂在200—400℃通H_2还原后表面有Ir—H键存在。并用D_2交换法归属了～2030cm~(-1)的强吸收峰属Ir—H键伸缩振动。经适当条件下抽空后,在2080、2020、1980和1980cm~(-1)附近可观察到四个分辨很好的吸收峰,表明H_2吸附时有四种不同的吸附物种。NH_3吸附时,在2300—1900cm~(-1)间也出现四个吸附峰,分别在2230、2170、2080和1980cm~(-1)附近。此外还用吡啶作为分子探针考察了该催化剂的表面酸性。
The surface properties of Ir / Al 2 O 3 catalyst were characterized by infrared spectroscopy. The catalyst was found to have an Ir-H bond on the surface after H_2 reduction at 200-400 ° C. The strong absorption peak assigned to ~ 2030cm -1 by D_2 exchange belongs to Ir-H stretching vibration. Four well-resolved absorption peaks were observed near 2080, 2020, 1980 and 1980 cm -1 after evacuation under appropriate conditions, indicating that there are four different adsorption species for H 2 adsorption. When NH_3 was adsorbed, four adsorption peaks appeared between 2300-1900cm ~ (-1), near 2230, 2170, 2080 and 1980cm ~ (-1), respectively. Pyridine was also used as a molecular probe to investigate the surface acidity of the catalyst.