本文關(guān)鍵詞： 介孔氧化鋁 無機(jī)鋁鹽 環(huán)氧丙烷 合成 表征　出處：《太原理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本工作以無機(jī)鋁鹽作前驅(qū)體,分別采用陽離子季銨鹽類表面活性劑(C_nTAB,n=12,14,16,18)和非離子嵌段共聚物(F127,F68,P123和Brij56)作模板劑,在未加酸或堿作pH調(diào)節(jié)劑的水及非水(乙醇EtOH)體系中,首次通過引入環(huán)氧丙烷(PO)作凝膠促進(jìn)劑,在溫和的條件下控制合成了具有不同結(jié)構(gòu)特征的介孔氧化鋁材料,并對(duì)材料的控制制備規(guī)律利用各種表征技術(shù)如XRD、N_2吸附、TG、SEM和TEM等進(jìn)行了系統(tǒng)的研究。具體的研究結(jié)果如下:1、在Al(NO_3)3·9H_2O-EtOH-C_nTAB-PO組成的非水體系中,控制合成了比表面積高達(dá)456m2/g的具有類γ-Al2O_3相的介孔氧化鋁材料。研究發(fā)現(xiàn)PO的用量在介孔氧化鋁的形成中起著至關(guān)重要的作用,過低的PO量將使體系難以凝膠化,而過高的PO量又會(huì)使反應(yīng)自組裝的過程無法控制而難以形成有序的介孔氧化鋁物相。通過對(duì)PO/Al摩爾比的調(diào)節(jié)可實(shí)現(xiàn)材料孔徑在3.4~4.8nm范圍內(nèi)的調(diào)節(jié)。與無模板的空白樣相比,模板劑的引入將使材料的比表面積和孔容顯著增加。將該方法擴(kuò)展至F127模板體系,采用40℃敞口凝膠化的方式獲得了熱穩(wěn)定性可達(dá)800℃的介孔γ-Al2O_3,通過對(duì)模板劑種類的調(diào)節(jié)可實(shí)現(xiàn)對(duì)材料孔徑在4.6~7.8nm范圍內(nèi)的控制。2、在AlCl_3·6H_2O-C_nTAB-H_2O-PO構(gòu)成的純水體系中,控制合成了熱穩(wěn)定性高達(dá)800℃的孔壁晶化的介孔γ-Al2O_3,研究發(fā)現(xiàn)PO/Al的摩爾比在3~7,模板劑濃度在8.08~19.47%范圍更有利于有序介孔氧化鋁的合成,隨著體系中EtOH/H_2O體積比的增加,樣品有序性變差。而烷基鏈長度的改變對(duì)材料孔徑的影響較小。3、在AlCl_3·6H_2O-H_2O-F127-PO體系中,采用40℃敞口凝膠化程序控制合成了高熱穩(wěn)定且高度有序的介孔γ-Al2O_3材料,實(shí)驗(yàn)發(fā)現(xiàn)隨著PO量或EtOH量的增加,樣品的有序性均變差;模板劑濃度可在1.6~9.77%范圍內(nèi)進(jìn)行有效調(diào)節(jié)。然而,對(duì)孔結(jié)構(gòu)的分析表征卻顯示該材料的比表面積極低,僅為65m2/g,具有雙介孔(3.8nm、6.2nm)分布特征,其原因目前尚不清楚,可能暗示樣品在焙燒脫模板過程中介孔孔道發(fā)生了部分的閉合,進(jìn)一步的研究仍在進(jìn)行中。本工作提出的利用環(huán)氧丙烷的開環(huán)作用控制合成介孔氧化鋁的思想,與已有工作相比,不僅合成過程更加簡潔、高效、環(huán)保,而且易于實(shí)現(xiàn)對(duì)材料結(jié)構(gòu)和性能的有效調(diào)控,預(yù)期這種合成思想可進(jìn)一步拓展至其它非硅基介孔金屬氧化物的合成中去,更為廣泛的擴(kuò)展研究工作已經(jīng)展開。
[Abstract]:In this work, inorganic aluminum salts were used as precursors, using CnTABN surfactants CnTABN 1214 (16 / 18) and Nonionic block copolymers (F127, F68P123 and Brij56) as templates, respectively, in aqueous and non-aqueous (EtOH) systems without acid or alkali as pH regulators. For the first time, mesoporous alumina materials with different structural characteristics were synthesized under mild conditions by introducing propylene oxide (PO) as gel accelerator. The controlled preparation rules of materials were systematically studied by using various characterization techniques such as TEM and TEM. The specific results are as follows: 1. In the non-aqueous system composed of Al(NO_3)3 路9H _ 2O -EtOH-CnTAB-PO, the main results are as follows: (1) in the non-aqueous system composed of Al(NO_3)3 路9H _ 2O -EtOH-CnTAB-PO, A mesoporous alumina material with 緯 -Al _ 2O _ 3-like phase with a specific surface area of 456m2 / g was synthesized. It was found that the amount of PO played an important role in the formation of mesoporous alumina, and that too low PO content would make it difficult to gel the system. However, the excessive amount of PO can make the reaction self-assembly process uncontrollable and difficult to form an ordered mesoporous alumina phase. The pore size of the material can be adjusted in the range of 3.4 ~ 4.8nm by adjusting the molar ratio of PO/Al. Compared with the blank sample without template, With the introduction of template agent, the specific surface area and pore volume of the material will be significantly increased, and the method will be extended to F127 template system. Mesoporous 緯 -Al _ 2O _ 3 with thermal stability up to 800 鈩，

本文編號(hào)：1544325