【摘要】：自二十世紀(jì)90年代初期以來,介孔材料因其獨特的結(jié)構(gòu)被廣泛用于吸附、催化、傳感器、電化學(xué)等方面。繼介孔二氧化硅之后,ZrO2、WO3、TiO2、Al2O3、HfO2、 Nb2O5、Ta2O5、SnO2等多種介孔材料被開發(fā)制備,其中介孔氧化鋁因具有高比表面積,孔道均一,孔徑在大范圍內(nèi)可調(diào)節(jié),表面存在路易斯酸性位等結(jié)構(gòu)優(yōu)勢,而受到廣泛關(guān)注。本論文主要利用溶劑揮發(fā)誘導(dǎo)自組裝(EISA)法可控地制備有序介孔氧化鋁基復(fù)合氧化物材料,在不同氣氛下調(diào)控Cu-Mg-Al復(fù)合氧化物的微結(jié)構(gòu),運用一系列的表征手段證明不同氣氛下銅物種的存在狀態(tài)不同,同時針對性地研究含有不同狀態(tài)銅物種的Cu-Mg-Al復(fù)合氧化物在CO氧化反應(yīng)中的催化性能。研究內(nèi)容如下：首先,用溶劑揮發(fā)誘導(dǎo)自組裝法制備Mg-Al、Cu-Mg-Al復(fù)合氧化物介孔材料。SXRD圖中均顯示一強一弱衍射峰,TEM圖中可以直觀地看到長程有序的介孔結(jié)構(gòu)。結(jié)合SXRD和TEM結(jié)果分析,證明EISA法制備的Mg-Al、Cu-Mg-Al復(fù)合氧化物具有二維-六方有序的介孔結(jié)構(gòu)。Cu-Mg-Al復(fù)合氧化物在空氣氣氛下800℃處理4h后,比表面積仍高達(dá)137 m2/g,孔體積0.30 cm3/g,平均孔徑分布在7.1 nm,這一系列數(shù)據(jù)說明Cu-Mg-Al介孔材料具有較好的熱穩(wěn)定性。其次,將Cu-Mg-Al復(fù)合氧化物在不同氣氛下處理：空氣氣氛下,結(jié)合XRD和TEM分析表明得到尖晶石結(jié)構(gòu)的Cu-Mg-Al復(fù)合氧化物,TPR中CuO還原峰在305℃,均說明銅均勻插入到有序介孔尖晶石的骨架中；還原氣氛下,結(jié)合XRD和TEM分析表明6-10 nm的金屬銅顆粒均勻分散在孔道表面,TPR顯示CuO還原峰在220℃,再次表明骨架中銅遷移到介孔材料表面,并長大聚集為金屬銅顆粒；上述樣品進(jìn)一步在氧化氣氛中處理,XRD中只有尖晶石的衍射峰,TPR顯示CuO還原峰在290℃,說明表面金屬銅再次進(jìn)入到尖晶石的骨架中。在CO催化性能測試實驗中發(fā)現(xiàn)：尖晶石結(jié)構(gòu)的Cu-Mg-Al催化氧化CO的完全轉(zhuǎn)化溫度為270℃,而含表面Cu顆粒的Cu-Mg-Al的CO完全轉(zhuǎn)化溫度為165℃,表明與骨架中的Cu相比,分布在表面的Cu物種表現(xiàn)出更高的催化活性。在本論文中,我們利用EISA法合成有序介孔Cu-Mg-Al復(fù)合氧化物。調(diào)控銅物種的存在狀態(tài),研究發(fā)現(xiàn)Cu物種在骨架與表面間轉(zhuǎn)換。CO催化性能實驗表明Cu物種的分布微結(jié)構(gòu)與催化性能存在一定的構(gòu)效關(guān)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，

本文編號：2499540