有序介孔氧化铝基复合金属氧化物的合成、结构分析及性能研究
发布时间：2019-06-14 17:03
【摘要】：自二十世纪90年代初期以来,介孔材料因其独特的结构被广泛用于吸附、催化、传感器、电化学等方面。继介孔二氧化硅之后,ZrO2、WO3、TiO2、Al2O3、HfO2、 Nb2O5、Ta2O5、SnO2等多种介孔材料被开发制备,其中介孔氧化铝因具有高比表面积,孔道均一,孔径在大范围内可调节,表面存在路易斯酸性位等结构优势,而受到广泛关注。本论文主要利用溶剂挥发诱导自组装(EISA)法可控地制备有序介孔氧化铝基复合氧化物材料,在不同气氛下调控Cu-Mg-Al复合氧化物的微结构,运用一系列的表征手段证明不同气氛下铜物种的存在状态不同,同时针对性地研究含有不同状态铜物种的Cu-Mg-Al复合氧化物在CO氧化反应中的催化性能。研究内容如下：首先,用溶剂挥发诱导自组装法制备Mg-Al、Cu-Mg-Al复合氧化物介孔材料。SXRD图中均显示一强一弱衍射峰,TEM图中可以直观地看到长程有序的介孔结构。结合SXRD和TEM结果分析,证明EISA法制备的Mg-Al、Cu-Mg-Al复合氧化物具有二维-六方有序的介孔结构。Cu-Mg-Al复合氧化物在空气气氛下800℃处理4h后,比表面积仍高达137 m2/g,孔体积0.30 cm3/g,平均孔径分布在7.1 nm,这一系列数据说明Cu-Mg-Al介孔材料具有较好的热稳定性。其次,将Cu-Mg-Al复合氧化物在不同气氛下处理：空气气氛下,结合XRD和TEM分析表明得到尖晶石结构的Cu-Mg-Al复合氧化物,TPR中CuO还原峰在305℃,均说明铜均匀插入到有序介孔尖晶石的骨架中；还原气氛下,结合XRD和TEM分析表明6-10 nm的金属铜颗粒均匀分散在孔道表面,TPR显示CuO还原峰在220℃,再次表明骨架中铜迁移到介孔材料表面,并长大聚集为金属铜颗粒；上述样品进一步在氧化气氛中处理,XRD中只有尖晶石的衍射峰,TPR显示CuO还原峰在290℃,说明表面金属铜再次进入到尖晶石的骨架中。在CO催化性能测试实验中发现：尖晶石结构的Cu-Mg-Al催化氧化CO的完全转化温度为270℃,而含表面Cu颗粒的Cu-Mg-Al的CO完全转化温度为165℃,表明与骨架中的Cu相比,分布在表面的Cu物种表现出更高的催化活性。在本论文中,我们利用EISA法合成有序介孔Cu-Mg-Al复合氧化物。调控铜物种的存在状态,研究发现Cu物种在骨架与表面间转换。CO催化性能实验表明Cu物种的分布微结构与催化性能存在一定的构效关系。
[Abstract]:Since the early 1990s, mesoporous materials have been widely used in adsorption, catalysis, sensor, electrochemistry and so on because of their unique structure. After mesoporous silica, ZrO2,WO3,TiO2,Al2O3,HfO2, Nb2O5,Ta2O5,SnO2 and other mesoporous materials have been developed and prepared. Mesoporous alumina has been widely concerned because of its high specific surface area, uniform pore size, adjustable pore size in a large range and Lewis acid site on the surface. In this paper, ordered mesoporous alumina based composite oxides were prepared by solvent volatilization induced self-assembly (EISA) method, and the microstructure of Cu-Mg-Al composite oxides was regulated in different atmosphere. A series of characterization methods were used to prove that the existence of copper species in different atmosphere was different. At the same time, the catalytic performance of Cu-Mg-Al composite oxides containing different copper species in CO oxidation was studied. The research contents are as follows: firstly, Mg-Al,Cu-Mg-Al composite oxide mesoporous materials were prepared by solvent volatilization induced self-assembly method. XRD diagram showed a strong and weak diffraction peak, and long-range ordered mesoporous structure can be seen intuitively in TEM diagram. Combined with the results of SXRD and TEM, it is proved that the Mg-Al,Cu-Mg-Al composite oxides prepared by EISA method have two-dimensional-hexagonal mesoporous structure. After treatment at 800 鈩，
本文编号：2499540
[Abstract]:Since the early 1990s, mesoporous materials have been widely used in adsorption, catalysis, sensor, electrochemistry and so on because of their unique structure. After mesoporous silica, ZrO2,WO3,TiO2,Al2O3,HfO2, Nb2O5,Ta2O5,SnO2 and other mesoporous materials have been developed and prepared. Mesoporous alumina has been widely concerned because of its high specific surface area, uniform pore size, adjustable pore size in a large range and Lewis acid site on the surface. In this paper, ordered mesoporous alumina based composite oxides were prepared by solvent volatilization induced self-assembly (EISA) method, and the microstructure of Cu-Mg-Al composite oxides was regulated in different atmosphere. A series of characterization methods were used to prove that the existence of copper species in different atmosphere was different. At the same time, the catalytic performance of Cu-Mg-Al composite oxides containing different copper species in CO oxidation was studied. The research contents are as follows: firstly, Mg-Al,Cu-Mg-Al composite oxide mesoporous materials were prepared by solvent volatilization induced self-assembly method. XRD diagram showed a strong and weak diffraction peak, and long-range ordered mesoporous structure can be seen intuitively in TEM diagram. Combined with the results of SXRD and TEM, it is proved that the Mg-Al,Cu-Mg-Al composite oxides prepared by EISA method have two-dimensional-hexagonal mesoporous structure. After treatment at 800 鈩，
本文编号：2499540
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