关键词: Mo/γ-Al2O3, 水热温度, 金属-载体相互作用, 平衡吸附量, 作用位点

Abstract: Metal-support interaction imposes a great influence on the structure and catalytic activity of the hydrogenation catalysts, and meanwhile it directly depends on the surface properties of the support. In this article, for deeply understanding the influencing mechanism of the support properties on the interaction, the support used for industrial RS-2100 catalyst was first hydrothermally treated under different temperatures (from 20 ℃ to 180 ℃) and the relative concentration of sites on support surface (including basic hydroxyl groups, neutral hydroxyl groups, acidic hydroxyl groups and coordinatively unsaturated sites) were modified. The obtained samples were then characterized by IR-OH and Py-IR, and the strength of metal-support interaction was evaluated according to the equilibrium adsorption contents of MoO3 on the support surface. IR-OH and Py-IR analysis results indicate that, with the increase of the hydrothermal temperature, the relative concentration of either basic hydroxyl groups or acidic hydroxyl groups first increases and then decreases, and reaches the maximum at 100 ℃. While the relative concentration of acidic hydroxyl groups decreases slightly after 100 ℃, and whereas that of either the neutral hydroxyl groups or Al-CUS gradually decreases. Meanwhile, according to the results of equilibrium adsorption contents of MoO3, it can be seen that, with the increase of temperature, the metal-support interaction first increases and then decreases. Based on the above analysis results, the suggestion that the metal-support interaction is mainly originated from the basic hydroxyl groups on the alumina surface can be given.

Key words: Mo/γ-Al2O3, hydrothermal temperature, metal-support interaction, equilibrium adsorption site, interaction site