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本文应用XPS研究了Nb_2O_5/SiO_2(氧化态)、Nb_2O_5/SiO_2(还原态)、Rh/SiO_2(还原态)、Rh-Nb_2O_5/SiO_2(氧化态)、Rh-Nb_2O_5/SiO_2(还原态)、Rh-Nb_2O_5/SiO_2(反应后,氧化态)等一系列样品,比较它们的光电子结合能,证明了Rh-Nb_2O_5-SiO_2有较强的相互作用;Nb_2O_5与SiO_2可能生成表面化合物;Rh通过氢溢出促进了较难还原的表面Nb(Ⅴ)的加氢还原;Rh与SiO_2相互作用并高度分散在载体表面;Nb_2O_5的添加改变了负载Rh的价带结构,抑制了CO在Rh吸附位上的解离,提高了制醇的选择性;由于与Nb_2O_5接触的程度不同,表面存在两类不同化学微环境的Rh。Rh与Nb_2O_5对表面吸附的CO加H的协合化学作用是本体系金属-载体或金属-助催剂强相互作用的实质。
In this paper, the effects of Nb 2 O 5 / SiO 2 (oxidation state), Nb 2 O 5 / SiO 2 (reduced state), Rh / SiO 2 (reduced state), Rh-Nb 2 O 5 / SiO 2 (oxidation state), Rh-Nb 2 O 5 / SiO 2 N 2 O 5 / SiO 2 (after the reaction, the oxidation state) and a series of samples. Comparing their photoelectron binding energies, Rh-Nb 2 O 5 -SiO 2 is proved to have a strong interaction; Nb 2 O 5 and SiO 2 may generate surface compounds; Rh promotes hydrogen spill Hydrogen reduction of the surface Nb (Ⅴ) which is more difficult to be reduced; Rh interacts with SiO 2 and is highly dispersed on the surface of the support; addition of Nb 2 O 5 changes the structure of the valence band supporting Rh and inhibits the dissociation of CO on the adsorption sites of Rh , Which increased the selectivity of alcohol. Due to the different degree of contact with Nb 2 O 5, there were two types of Rh on the surface with different chemical microenvironment. The synergistic chemical interaction between Rh and Nb 2 O 5 on the surface of the adsorbed CO plus H is essential for the strong interaction of the metal-support or metal-promoter.