Co/SiO2 catalysts for selective hydrogenation of crotonaldehyde II: influence of the Co surface structure on selectivity
Co/SiO2 catalysts for selective hydrogenation of crotonaldehyde II: influence of the Co surface structure on selectivity
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DOI：
10.1016/s0926-860x(02)00090-x
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发表时间：
2002-06
影响因子：
5.5
通讯作者：
E. Rodrigues;J. M. Bueno
中科院分区：
文献类型：
--
作者：
E. Rodrigues;J. M. Bueno
考察了SiO_2负载CoOx型催化剂相互作用对Co/SiO_2催化剂催化性能的影响。采用硝酸钴浸渍法制备了二氧化硅负载的CoOx前驱体。通过改变浸渍溶剂、干燥时间和温度以及焙烧温度，得到了与载体相互作用不同的钴前驱体。用CO吸附的漫反射红外光谱(DRIFT)和程序升温脱氢(TPD-H2)表征了催化剂的表面结构。TPD-H_2和CO光谱的漂移表明至少存在四个不同的Co表面位置，标记为α，β，γ和σ。这些物种的相对数量取决于CoOxin与SiO2In前体相互作用的程度。对于巴豆醛的气相加氢，巴豆醇和丁醇的选择性与β/(γ+σ的比例有很大关系。有趣的是，丁醛的选择性并不依赖于β，γ或σ位点的存在。
The effect of interaction of silica-supported CoOxon catalytic properties of Co/SiO2catalysts was investigated. The CoOxprecursors supported on silica were obtained by impregnation of the support with cobalt nitrate solution. Cobalt precursors, with different interactions with support, were obtained by changes of impregnation solvent, drying time and temperature; and calcination temperature. The Co surface structure of the catalysts was characterized by diffuse reflectance FTIR spectroscopy (DRIFTS) of adsorbed CO and temperature-programmed desorption of hydrogen (TPD-H2). The TPD-H2and DRIFT of CO spectra indicate the presence of at least four different Co surface sites, labeled α, β, γ, and σ. The relative amount of these species varied depending on the degree of CoOxinteraction with SiO2in precursors. For crotonaldehyde (CROALD) hydrogenation in gas phase, selectivity to crotyl alcohol and butanol depended strongly on the β/(γ+σ) ratio. Interestingly, selectivity to butyraldehyde does not depend on β, γ, or σ sites present.