水相重构法制备Ce改性Mg-Al复合氧化物及其在丙酮气相缩合反应中的应用  

Preparation of Ce Modified Mg-Al Mixed Metal Oxides by Aqueous Reconstruction for Vapor Self-condensation of Acetone

作　　者：吴斌泉 王圣[1] 黄亮[1] 秦枫[1] 黄镇[1] 徐华龙[1] 沈伟[1] 

机构地区：[1]复旦大学化学系,上海市分子催化与功能材料重点实验室,先进材料实验室,能源材料化学协同创新中心,上海200433

出　　处：《高等学校化学学报》2016年第4期745-751,共7页Chemical Journal of Chinese Universities

基　　金：上海市科委项目(批准号:14DZ2273900)资助

摘　　要：通过水相重构法合成了Ce改性的Mg-Al复合金属氧化物HTc-Ce,采用X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)和氮气吸附-脱附表征了复合金属氧化物的组成和表面结构.水相重构过程使复合金属氧化物产生更多缺陷位,从而具有更多碱性位.Ce通过液相重构过程有效进入到水滑石的骨架,撑大了水滑石的层间距,进一步增加了催化剂的可接触碱性位,同时氧化铈丰富的氧空位显著提高了表面碱性位,特别是强碱性位的数量.XPS实验结果表明,三价Ce在氧化铈中的含量约为30%,氧空位提高有助于改善表面氧的迁移.原位红外漫反射(in situ DRIFTS)证实增加了表面低配氧的数量,CO2-程序升温脱附(CO2-TPD)实验证实了Ce的引入提高了表面强碱性位浓度.水相重构法合成Ce修饰的Mg-Al复合金属氧化物对于丙酮自缩合反应具有高效活性,HTc-Ce-3.2催化的丙酮转化率达到56.8%,是HTc催化剂的2.5倍,该催化剂因其层间距增加和结构疏松更有利于五聚产物的生成.Ce modified Mg-Al mixed metal oxides（ HTc-Ce） were prepared by aqueous reconstruction method. The construct and surface properties of catalysts were characterized by X-ray diffraction（ XRD）,X-ray photoelectron spectrometry（ XPS）,transmission electron microscopy（ TEM） and N2 adsorption and desorption isotherms. Aqueous reconstruction process promotes forming more defects on the Mg-Al mixed oxides,Ce is successfully embedded into the interlayer of hydrotalcite framework and enlarges its spaces,which improves the accessibility of active sites. The oxygen mobility of ceria increases the amount of basic sites on the surface. XPS results indicate that there is about 30% of Ce（ Ⅲ） in cerium oxides. Oxygen vacancies are beneficial to enhancing the ability of oxygen mobility. In situ diffuse reflectance infrared Fourier transform spectroscopy（ DRIFTS） verifies the augment of low-coordinated oxygen, CO2-temperature programmed desorption（ CO2-TPD） experiment reveals that modification of Ce increases the density of basic sites on surface. Aqueous reconstructed HTc-Ce-3. 2 catalyst exhibits high activity for acetone self-condensation. The conversion of acetone is 56. 8%. It is 2. 5 times higher than that of HTc catalyst,the selectivity of pentamers enhance significantly.

关 键 词：水相重构 氧空位 复合金属氧化物 丙酮气相自缩合 铈改性 

分 类 号：O643.3[理学—物理化学]