發(fā)布時(shí)間：2018-06-30 21:17

  本文選題：膨潤土改性 + 催化劑　； 參考：《湘潭大學(xué)》2016年碩士論文

【摘要】：膨潤土(Bent)是一種以蒙脫石為主要成分的天然礦物材料,因其特殊的結(jié)構(gòu)和獨(dú)特的化學(xué)組成而具有較大的比表面積和較高的熱穩(wěn)定性,常用作各種環(huán)境友好型催化劑的載體。為了使載體具有更大的比表面積和更高的熱穩(wěn)定性,往往需要對(duì)天然膨潤土進(jìn)行純化以去掉雜質(zhì)得到高含量的蒙脫石,然后通過負(fù)載等手段制得不同類型的固體催化劑。這種以膨潤土作為載體的催化劑與傳統(tǒng)的液相催化相比,具有制備成本低、催化活性高、易分離和可多次循環(huán)使用的優(yōu)點(diǎn),是一種有廣泛應(yīng)用前景的綠色催化劑。本文以純化酸化后的膨潤土為載體,制備出負(fù)載磷鎢酸、鈦交聯(lián)、羥基鐵鋁柱撐三種催化劑,并通過FTIR、XRD、SEM、TG、BET等手段對(duì)其結(jié)構(gòu)與形貌加以表征,研究了三種催化劑對(duì)不同酯化反應(yīng)的催化性能。主要內(nèi)容如下:1.以純化酸化膨潤土為載體,Ti(n-C4H9O)4為鈦源,采用溶膠-凝膠法將二氧化鈦與蒙脫石交聯(lián),得到了比表面積為243.3094 m2.g-1,總孔體積為0.20296cm3.g-1,且熱穩(wěn)定高的(640℃結(jié)構(gòu)不改變)鈦交聯(lián)催化劑(Ti-PILC)。同時(shí),對(duì)催化劑催化谷氨酸卞酯的產(chǎn)率進(jìn)行研究。結(jié)果表明,鈦交聯(lián)蒙脫石具有優(yōu)良的催化性能,谷氨酸卞酯的產(chǎn)率最高可達(dá)77.9%[n(谷氨酸):n(苯甲醇)=1:6,溫度:60℃,反應(yīng)回流時(shí)間:2 h,催化劑用量占反應(yīng)物總質(zhì)量的8%]。這也為其在固體酸催化領(lǐng)域的應(yīng)用提供了借鑒。2.采用浸漬蒸發(fā)法制備酸化蒙脫石負(fù)載不同量的磷鎢酸催化劑(HPW/AAB)。通過XRD,IR,SEM等對(duì)催化劑進(jìn)行表征分析,結(jié)果顯示,負(fù)載后的催化劑具有Keggin結(jié)構(gòu)。對(duì)棕櫚酸甲酯的催化性能研究表明,在反應(yīng)溫度為65℃,醇酸比為25:1時(shí),磷鎢酸負(fù)載量為20%,反應(yīng)6 h時(shí),催化效率最佳產(chǎn)率達(dá)到了87.2%。同時(shí),反應(yīng)后的催化劑容易分離。六次重復(fù)使用后的催化效率依然保持95%。3.本章使用Fe-Al柱撐蒙脫石,考察了不同條件對(duì)柱撐蒙脫石性質(zhì)的影響及其在催化油酸酯化的反應(yīng)中,對(duì)其產(chǎn)率的影響。結(jié)果表明,在500℃時(shí)柱撐蒙脫石仍有良好的熱穩(wěn)定性。500℃以后,XRD圖譜中d001峰降低,說明熱穩(wěn)定性變差,紅外圖譜中也有一些峰消失。結(jié)果顯示,在溫度80℃,焙燒溫度500℃,催化劑為原料總質(zhì)量的1.5%,反應(yīng)時(shí)間8 h,反應(yīng)醇酸摩爾比為9:1時(shí)油酸乙酯的產(chǎn)率達(dá)到最大86.7%。該方法簡(jiǎn)單易得,原料成本也低。
[Abstract]:Bentonite (Bent) is a kind of natural mineral material with montmorillonite as its main component. Because of its special structure and unique chemical composition, bentonite has large specific surface area and high thermal stability. Bent is often used as the carrier of various environment-friendly catalysts. In order to make the carrier have larger specific surface area and higher thermal stability, it is often necessary to purify natural bentonite in order to get high content of montmorillonite by removing impurities. Compared with the traditional liquid phase catalyst, this kind of catalyst with bentonite as the carrier has the advantages of low preparation cost, high catalytic activity, easy separation and multiple recycling. It is a green catalyst with wide application prospect. In this paper, supported phosphotungstic acid, titanium cross-linking and hydroxy-iron-aluminum pillared catalysts were prepared by using purified acidified bentonite as carrier, and their structure and morphology were characterized by FTIR, XRDX, SEM, TGG-BET, etc. The catalytic properties of three catalysts for different esterification reactions were studied. The main content is as follows: 1. Using purified acidified bentonite as carrier Ti (n-C _ 4H _ 9O) _ 4 as titanium source, titanium dioxide and montmorillonite were crosslinked by sol-gel method. The specific surface area was 243.3094 m2.g-1, the total pore volume was 0.20296 cm 3.g-1, and the structure of Ti-PILC was high (640 鈩，

本文編號(hào)：2086884