Transition metal-modified mesoporous Mg-Al mixed oxides: Stable base catalysts for the synthesis of diethyl carbonate from ethyl carbamate and ethanol
Transition metal-modified mesoporous Mg-Al mixed oxides: Stable base catalysts for the synthesis of diethyl carbonate from ethyl carbamate and ethanol
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DOI：
10.1016/j.apcata.2015.04.034
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发表时间：
2015-09-25
影响因子：
5.5
通讯作者：
Sun, Yuhan
中科院分区：
文献类型：
--
作者：
Wang, Dengfeng;Zhang, Xuelan;Sun, Yuhan
利用镁铝水滑石的“记忆效应”制备了一系列过渡金属修饰的水滑石前驱体（HT-M、M = Cr3+、Mn2+、Fe3+、Co2+、Ni2+、Cu2+和Zn2+）。然后，对制备的水滑石前驱体在773 K下进行热分解，得到了不同组成的混合氧化物，并通过热重法和差热重法（TG-DTG）、x射线衍射（XRD）、N-2吸附-解吸、x射线光电子能谱（XPS）、扫描电镜（SEM）和CO2程序升温解吸（CO2- tpd）技术对其理化性质进行了表征。煅烧过程中形成了介孔结构。更重要的是，煅烧的水滑石（HTC-M）样品的碱度取决于过渡金属的类型。同时，用它们作为固体碱催化剂，对氨基甲酸乙酯和乙醇合成碳酸二乙酯（DEC）进行了评价。其中，在最佳反应条件下，HTC-Mn活性最高，DEC产率为56.7%。然后，详细研究了HTC-M催化剂的基本性质与催化性能之间的关系。此外，HTC-Mn催化剂可以很容易地回收，同时保持对该反应的高催化活性。(C) 2015 Elsevier B.V.版权所有
A series of transition metal-modified hydrotalcite precursors (HT-M, M = Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) were prepared by using the "memory effect" of Mg-Al hydrotalcite. Then, the mixed oxides with different composition were obtained by thermal decomposition of as-prepared hydrotalcite precursors at 773 K, and their physicochemical properies were characterized by thermogravimetry and differential thermogravimetry (TG-DTG), X-ray diffraction (XRD), N-2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), scanning electron micrograph (SEM) and CO2 temperature-programmed desorption (CO2-TPD) technique. It was found that the mesoporous structure was formed during calcination. More important, the basicity of the calcined hytrotalcites (HTC-M) samples was depended on the type of transition metal. Simultaneously, they were used as solid base catalysts and evaluated for the synthesis of diethyl carbonate (DEC) from ethyl carbamate and ethanol. Among them, HTC-Mn exhibited maximum activity with the DEC yield of 56.7% under optimum reaction conditions. Then, the correlation between their basic properties and catalytic performance was studied in detail for the HTC-M catalysts. Furthermore, HTC-Mn catalyst could be readily recycled while maintaining high catalytic activity toward this reaction. (C) 2015 Elsevier B.V. All rights reserved.