官能化介孔二氧化矽材料作為雙環戊二烯衍生物合成之觸媒的開發與研究

Functionalized Mesoporous Silica as Catalysts for the Preparation of DCPD Derivatives

林禹丞(Yu-Cheng Lin)

指導教授 ： 鄭淑芬

國立臺灣大學/理學院/化學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801601

摘要

基於有限的石油蘊藏量及人類大量的取用下，原油供應日益短缺，油價隨政治與社會環境變化而波動，整個石化產業的成本增加。因此，石化產品的高值化是目前石油化學工業非常重要的發展方向。而在石油精煉的過程，會產生大量低沸點的五碳化合物之衍生物，例如：環戊二烯。環戊二烯在常溫會經由 Diels-Alder reaction 自行聚合生成二聚體-雙環戊二烯。
本研究開發官能化二氧化矽材料做為雙環戊二烯衍生物之觸媒，生成具有較高經濟價值的雙環戊二烯醇以及雙環戊二烯環氧化物。第一部分著重在使用具有磺酸官能基之短隧道大孔徑之介孔二氧化矽材料當作固態酸觸媒，催化雙環戊二烯水解反應，生成具有較高經濟價值的雙環戊二烯醇。與傳統的勻相催化相比，發現使用固體酸觸媒催化反應時可獲得較高的雙環戊二烯醇選擇率，並可有效的減少雙環戊二烯在強酸催化條件下自身聚合成無法利用的寡聚物。之後更進一步對反應的幾個變因做最佳化調控，包括：雙環戊二烯/水的比例、反應溫度與觸媒用量，並評估觸媒重複使用性，發現在過量水的條件下，不加入共溶劑可以得到較高的雙環戊二烯轉化率及雙環戊二烯一醇產率，成功開發出有效的觸媒催化雙環戊二烯的水解反應以生成雙環戊二烯一醇。
第二部分則是著重在開發能將雙環戊二烯轉化為雙環戊二烯之環氧基衍生物的固體觸媒，而嵌入二氧化矽骨架結構，呈四配位的鈦離子被發現是催化選擇性氧化反應的活性位置，故含鈦之介孔二氧化矽材料為主要的開發目標。所製備的含鈦介孔材料利用X光繞射圖譜鑑定其結構，利用氮氣吸脫附圖檢測其孔洞性質，利用紫外-可見光光譜鑑定鈦離子的配位數，利用元素分析確認Ti(IV)離子含量。在所有合成之含鈦介孔材料中，發現利用一步合成法合成的Ti-MCM-41能最有效的將雙環戊二烯轉化為雙環戊二烯雙環氧化物，之後探討了不同的反應條件與觸媒用量及試劑比例，發現以第三丁基過氧化氫(TBHP)做為氧化劑在反應溫度95oC下反應5小時之後，產率可高達85%以上，後續並測試了觸媒的重複使用性，並且評估觸媒材料及催化製程之工業化可行性。
含鈦介孔材料中，由於SBA-15介孔二氧化矽必須在酸性的環境下進行合成，使用一步法合成Ti-SBA-15會因為鈦離子在酸性下溶解而只能將少量的鈦離子嵌入在二氧化矽結構內，導致催化反應性不佳。改採用後修飾法，發現利用正丁醇作為嫁接溶劑可將鈦離子分散嫁接在材料SBA-15的表面上，得到高活性的Ti-SBA-15，由紫外-可見光光譜確認鈦離子主要的配位環境為四配位，而使用常見的甲苯作為嫁接溶劑時則會得到六配位為主的配位環境。在發現這一現象之後，我們合成了不同鈦/矽莫耳比例的Ti-SBA-15，以環己烯以及雙環戊二烯的環氧化反應作為觸媒的活性測試比較，探討不同的鈦離子前驅物對觸媒活性的影響，最後發現7%Ti-SBA-15的活性最高，可得到最好的轉化率以及產率，並可有效的回收重覆使用。催化結果與紫外-可見光光譜的鑑定結果一致，確定四配位的Ti(IV)為催化活性位置。

關鍵字

雙環戊二烯 ； 固態酸觸媒 ； 環氧化 ； 含鈦介孔觸媒

並列摘要

Cyclopentadiene (CPD) and dicyclopentadiene (DCPD) are commercially obtained from coal tar and by steam cracking of Naphtha. DCPD is formed by dimerization of CPD via a Diels–Alder reaction, and can be used as a monomer in polymerization reactions, either in olefin polymerization or in ring-opening metathesis polymerization. As the global oil supply and crude oil price are markedly affected by geo-political events and natural disasters, value-added products of raw petrochemical materials are urgently developed worldwide. Among them, the oxygen containing derivatives, like alcohols, epoxides, and ketones of DCPD have attracted the researchers.
The purpose of this research is to incorporate functional groups on mesoporous silica materials in order to use as the recyclable catalysts in preparing oxygen-containing derivatives of DCPD. Mesoporous silica materials of ordered pores were chosen because their relatively large pores facilitate the diffusion of bulky molecules. The first part of this research focused on using sulfonic acid-functionalized SBA-15 materials (SA-SBA-15) to catalyze the hydration of DCPD. The target product, cydecanol (DCPD-OH) has been used as a modifier for polyester or alkyd resin. Propylsulfonic acid functionalized SBA-15 with medium acidic strength was found to be more efficient than the silica gel counterpart or arylsulfonic acid functionalized material in catalyzing DCPD hydration to yield DCPD-OH.
The second part focused on using titanium incorporated mesoporous silica to catalyze the epoxidation of DCPD. The target product is DCPD diepoxide. Among all the catalysts prepared, Ti-incorporated MCM-41 prepared by one-pot co-condensation show the highest activity in DCPD epoxidation using tert-butyl hydroperoxide (TBHP) as oxidant.
In the effort of preparing Ti-incorporated SBA-15 (Ti-SBA-15), one-pot co-condensation can only incorporate very small amount of Ti(IV) due to the dissolution of TiO2 under acidic synthesis environment of SBA-15. The third part of this research focused on the preparation of Ti-SBA-15 by grafting with titanium alkoxides. Using 1-butanol as the solvent was found to give better dispersion of Ti(IV) than using toluene. The DR UV-vis spectra revealed that Ti(IV) species grafted on SBA-15 were mainly in tetrahedral coordination. Epoxidation of cyclohexene using tert-butyl hydroperoxide as oxidant was chosen to test the catalytic activity. Among Ti-SBA-15 catalysts prepared, 7%Ti-SBA-15 gave the highest cyclohexene conversion and epoxide yield, and the catalyst was fully recyclable. The catalytic activity was in consistence with the results of DR UV-vis spectra, inferring that Ti(IV) species in tetrahedral coordination are the active centers for catalytic epoxidation of olefins.

並列關鍵字

DCPD ； solid acid catalyst ； functionalized SBA-15 ； Ti-SBA-15 ； Ti-MCM-41

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