本文關(guān)鍵詞： 光催化 溶膠—凝膠法 共摻雜 HZSM-5 甲基橙　出處：《沈陽(yáng)理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：納米TiO_2光催化劑因其具有化學(xué)穩(wěn)定性好、無(wú)污染、較高的比表面積以及較高的光催化活性等優(yōu)點(diǎn),受到廣泛關(guān)注。但是TiO_2存在禁帶較寬(3.2 e V),光響應(yīng)范圍窄,光量子效率低,懸浮態(tài)的TiO_2易凝聚、分離回收困難等問(wèn)題,極大的限制了其在實(shí)際中的應(yīng)用。針對(duì)以上存在的問(wèn)題,本文擬通過(guò)單一金屬離子摻雜和兩種金屬離子共摻雜以及負(fù)載的方法對(duì)TiO_2進(jìn)行優(yōu)化改性,以提高TiO_2的光催化效率及回收重復(fù)利用率。并利用XRD、SEM、FT-IR、XPS、UV-Vis DRS以及N2吸附-脫附等手段對(duì)復(fù)合光催化劑進(jìn)行表征,同時(shí)以甲基橙為目標(biāo)降解物考察不同制備條件對(duì)光催化活性的影響。本實(shí)驗(yàn)主要分為以下三個(gè)部分:1采用溶膠-凝膠法制備x%In-0.1%Gd-TiO_2復(fù)合光催化劑。結(jié)果表明,所制備的催化劑在不同In摻雜濃度和煅燒溫度下均為銳鈦礦相,Gd~(3+)、In~(3+)以取代Ti~(4+)的方式進(jìn)入TiO_2晶格中,使晶格發(fā)生畸變,膨脹,導(dǎo)致晶格參數(shù)變大。適量的摻雜抑制了TiO_2晶粒的生長(zhǎng),使催化劑平均孔徑減小,比表面積增大,3%In-0.1%Gd-TiO_2催化劑的比表面積最大,為122.7 m2/g。同時(shí),摻雜使TiO_2吸收邊帶發(fā)生紅移,帶隙減小。隨著煅燒溫度的升高,TiO_2晶粒不斷增大,比表面積逐漸減小。當(dāng)煅燒溫度為400 ℃時(shí)3%In-0.1%Gd-TiO_2的光催化活性最好,達(dá)63%。光照60 min后,3%In-0.1%Gd-TiO_2對(duì)甲基橙的降解率達(dá)到90%,而0.1%Gd-TiO_2對(duì)甲基橙的降解率只有70%。本實(shí)驗(yàn)催化劑的最佳投入量為200 mg/L。2采用溶膠-凝膠法合成x%In-0.05%Sm-TiO_2復(fù)合材料。結(jié)果表明,在不同In摻雜量和煅燒溫度下所制備的樣品均為銳鈦礦相,適量共摻雜抑制了二氧化鈦晶粒的生長(zhǎng),使晶粒尺寸減小,TiO_2吸收邊界紅移,表面羥基數(shù)量增加。摻雜增加了催化劑的比表面積,5%In-0.05%Sm-TiO_2催化劑的比表面積最大,為113.1 m~2/g。隨著煅燒溫度的升高,樣品晶粒逐漸增大,比表面積逐漸減小。煅燒溫度為400 ℃時(shí),5%In-0.05%Sm-TiO_2具有最強(qiáng)的光催化能力,降解率高達(dá)69.8%。光照60 min后,5%In-0.05%Sm-TiO_2對(duì)甲基橙的降解率高達(dá)97.7%,幾乎使甲基橙完全脫色。3以鈦酸四丁酯為鈦源,HZSM-5分子篩為載體,采用溶膠-凝膠法制備不同負(fù)載量的In-TiO_2(x%)/HZSM-5復(fù)合光催化劑。結(jié)果表明,負(fù)載后TiO_2仍保持了銳鈦礦晶體結(jié)構(gòu),負(fù)載抑制了TiO_2顆粒的生長(zhǎng),使其晶粒尺寸減小。隨著TiO_2負(fù)載量的增加,比表面積逐漸減小,In-TiO_2(20%)/HZSM-5的比表面積最大,可達(dá)253.3m2/g。由甲基橙光降解實(shí)驗(yàn)知,In-TiO_2(50%)/HZSM-5的光催化活性最高,為60%。采用同樣的方法制備3%In-0.1%Gd-TiO_2(x%)/HZSM-5,3%In-0.05%Sm-TiO_2(x%)/HZSM-5復(fù)合光催化劑。結(jié)果表明,與3%In-0.1%Gd-TiO_2,5%In-0.05%Sm-TiO_2相比,負(fù)載后光催化活性降低。
[Abstract]:Nanocrystalline TiO_2 photocatalysts have the advantages of good chemical stability, no pollution, high specific surface area and high photocatalytic activity. However, there are some problems in TiO_2, such as wide band gap, narrow optical response range, low optical quantum efficiency, easy aggregation of suspended TiO_2 and difficulty in separation and recovery. In view of the above problems, this paper intends to optimize the modification of TiO_2 by single metal ion doping, two metal ions co-doping and loading methods. In order to improve the photocatalytic efficiency and recycle efficiency of TiO_2. The composite photocatalysts were characterized by UV-Vis DRS and N2 adsorption-desorption. At the same time, the effects of different preparation conditions on photocatalytic activity of methyl orange were investigated. 1Sol gel method was used to prepare x In-0.1 Gd-TiOs _ 2 photocatalyst. The prepared catalyst is anatase phase at different concentration of in doping and calcination temperature. The catalyst enters the TiO_2 lattice in the way of replacing Ti~(4). The crystal lattice is distorted and expanded, and the lattice parameters become larger. Proper doping inhibits the growth of TiO_2 grains, decreases the average pore size and increases the specific surface area of the catalyst. 3In-0.1 and Gd-TiO-2 catalysts have the largest specific surface area of 122.7 m2 / g. At the same time, doping results in red-shift of the absorption sideband of TiO_2. With the increase of calcination temperature, the grain size of TiO2 increases. The photocatalytic activity of 3In-0.1Gd-TiO-2 was the best at the calcination temperature of 400 鈩，

本文編號(hào)：1455947