树枝状介孔二氧化硅纳米球负载氧化钴催化剂催化氧化甲苯

以树枝状介孔二氧化硅纳米球(DMSNs)为载体，采用等体积浸渍法制备了一系列不同钴负载量的催化剂，利用XRD、SEM、TEM、BET、H₂-TPR、O₂-TPD、XPS、EPR、Raman等技术对催化剂的物理化学性质进行了表征分析，同时考察了催化剂对甲苯的催化氧化活性及其稳定性。结果表明：所制备的钴基DMSNs催化剂具有高比表面积和有序介孔结构，有利于活性组分的分散及活性位与反应物的接触；随着Co负载量的增加，催化剂活性呈现先增加后下降的趋势；其中，10%Co/DMSNs催化剂活性最佳，甲苯转化率为90%时的温度(T90)达到268 ℃(质量空速为15000 mL/(g·h)、甲苯初始体积分数为50μL/L)，并且表现了优异的抗水性能和稳定性。该催化剂活性组分主要以Co²⁺形式存在，拥有更多的氧空位和高活性氧物种，有利于甲苯催化氧化反应的进行。而载体特殊的形貌结构和钴氧物种与载体较强的相互作用提高了催化剂的稳定性。

Cobaltous Oxide-loaded Dendritic Mesoporous Silica Nanospheres for Catalytic Oxidation of Toluene

A series of catalysts with different cobalt loadings were prepared using dendritic mesoporous silica nanospheres (DMSNs) as carriers by the isovolume impregnation method. The physicochemical properties of the catalysts were characterized with XRD, SEM, TEM, BET, H₂-TPR, O₂-TPD, XPS, EPR and Raman, and the catalytic oxidation activity of the catalysts towards toluene and their stability were investigated. The results show that the prepared cobalt-based DMSNs catalysts have a high specific surface area and ordered mesoporous structure, which are beneficial to the dispersion of active components and the contact between active sites and reactants. With the increase of Co loading, the activity of catalyst shows a trend of increasing first and then decreasing. Among them, 10%Co/DMSNs catalyst shows the best catalytic activity when the temperature (T90) is up to 268 ℃ at the toluene conversion rate of 90% (under the mass space velocity of 15000 mL/(g·h) and the initial toluene concentration of 50 μL/L), and also exhibits excellent water resistance and stability. The active component of the catalyst is mainly in the form of Co²⁺, which possesses more oxygen vacancies and highly reactive oxygen species, and thus can facilitate the catalytic oxidation of toluene. The special morphological structure of the carrier and the strong interaction between the cobalt oxygen species and the carrier have improved the catalyst stability.