本文選題：金屬-有機框架材料 + 貴金屬　； 參考：《南昌大學》2017年碩士論文

【摘要】：金屬-有機框架材料(MOFs)是金屬離子與有機配體通過配位連接形成的三維多孔網(wǎng)狀結構材料,它們具有高的比表面積、可調的孔徑大小、不飽和金屬位點、較高的熱穩(wěn)定性以及規(guī)整有序的納米尺寸孔道,這些優(yōu)點使得MOFs能作為獨特的微反應器及理想載體。貴金屬納米顆粒(如Au、Pd等)因其特有的量子尺寸效應,在催化反應中往往表現(xiàn)出高效的催化活性,但其價格十分昂貴,在多相反應中分散度差,而且反應后很難回收,容易造成實驗成本的浪費,通常都會考慮將其固載。因此在最近的研究中,MOFs材料因其獨特的優(yōu)點,通常作為首選載體對Au、Pd納米顆粒進行固載。從其物理性質看,通過固載既能限域Au、Pd納米顆粒的尺寸大小,又可以增大Au、Pd納米顆粒的分散度,進而提高金屬活性中心的分散度,催化活性也因此會有明顯的提高;高比表面積性質使其存在大量的不飽和鍵,也相應的增加其表面臺階、皺褶和缺陷,其催化活性和選擇性也隨之提高。從工業(yè)經(jīng)濟角度看,相對于純貴金屬,固載型貴金屬催化劑參與非均相反應,易于回收利用,更為經(jīng)濟。本論文在充分考慮到MOFs自身特點的情況下,設計合成了兩種固載型催化劑,Au@MIL-101和Pd/MOF-808a。第一個工作中,注意到MIL-101自身3 nm左右的介孔孔道,利用其孔道對Au顆粒進行限域,制備3 nm左右的Au納米顆粒。對Au@MIL-101進行了一系列表征,其結構表征可知,Au納米顆粒能高度分散在MIL-101中,當Au濃度在一定范圍內時,MIL-101的限域作用可以將Au納米顆�？刂圃�3 nm左右,非常均勻,證明MIL-101對Au納米顆粒起到了限域的效果。首次把Au@MIL-101運用于對硝基苯酚加氫反應中對它進行催化性能的測試,在溫和條件下,該催化劑在對硝基苯酚還原反應中展現(xiàn)出十分優(yōu)秀的催化活性,相對于傳統(tǒng)的加氫催化劑表現(xiàn)出更小的活化能。在第一個催化劑的設計理念上,注意到單斜相的ZrO_2不僅具有酸催化性能,而且具有堿催化性能,原位紅外研究證明其堿性來自氧化鋯上存在的OH簇�？紤]Zr-MOFs是由具有OH基的多原子無機Zr-O簇構成,其與氧化鋯結構類似,我們提出一些Zr-MOFs可能具有布朗斯特堿性位點的設想�；谏鲜龅乃伎�,進行研究,開發(fā)出第一個具有B堿中心的Zr-MOF材料MOF-808a。通過驗證,MOF-808在熱的新鮮溶液中反應,MOF-808上的甲酸根會被t-OH取代,成為一種酸堿中心能均勻分散的材料,記作MOF-808a。具體證明過程如下:首先進行CO2-TPD-MS表征,分析發(fā)現(xiàn)MOF-808a對CO_2有很強的化學吸附,證明其存在堿中心;進一步進行酸滴定表征,從最終的數(shù)據(jù)譜圖中,分析發(fā)現(xiàn)只有一個突變點,可判斷在MOF-808a上面應該只有一種OH(b-OH或t-OH),PKb在10左右;最后對其進行原位紅外的表征,觀察不同溫度下譜圖中相應官能團的變化,發(fā)現(xiàn)MOF-808a上的OH最終歸屬為t-OH。為進一步證明MOF-808a的堿性作用,我們設計合成了催化劑Pd/MOF-808a,選擇需引入堿參與的有機反應,包括Heck反應和苯甲醇氧化反應。該催化劑在Heck反應中,在不使用外加堿的情況下,轉化率可達到93.6%,循環(huán)使用10次后,催化劑結構未發(fā)生明顯變化,且催化效果依然保持在90%左右;在苯甲醇氧化反應中,該催化劑同樣表現(xiàn)出優(yōu)良的催化活性,與其他固載型催化劑相比,對產(chǎn)物表現(xiàn)出更高的選擇性。通過上述兩個探針反應,充分證明MOF-808a具有較強的堿性作用,相信這一發(fā)現(xiàn),可以給其他科研工作者提供一點參考。
[Abstract]:Metal organic frame material (MOFs) is a three-dimensional porous network structure material formed by metal ions and organic ligands. They have high specific surface area, adjustable aperture size, unsaturated metal loci, high thermal stability and orderly and orderly nanoscale channel. These advantages make MOFs as a unique micrometer. The noble metal nanoparticles (such as Au, Pd, etc.) often exhibit high catalytic activity in the catalytic reaction because of their unique quantum size effect. However, the price is very expensive, and the dispersion is poor in the multiphase reaction, and it is difficult to recover after the reaction. It is easy to cause the waste of the experimental cost. Therefore, in recent studies, because of its unique advantages, MOFs is usually used as the preferred carrier to immobilizing the Au, Pd nanoparticles. From its physical properties, the dispersion of Au and Pd nanoparticles can be increased by immobilizing the limited domain Au, the size of Pd nanoparticles and the dispersion of Au and Pd nanoparticles, thus improving the dispersion of the metal active center and catalytic activity as well. Therefore, the high surface area properties make it have a large number of unsaturated bonds, and also increase their surface steps, wrinkles and defects, and their catalytic activity and selectivity also increase. From the industrial economic point of view, relative to the pure precious metals, the solid supported noble metal catalysts are involved in heterogeneous reaction, easy to recycle, and more easy to recycle. In this paper, two kinds of immobilized catalysts are designed and synthesized in this paper. In the first work of Au@MIL-101 and Pd/MOF-808a., the first work of Au@MIL-101 and Pd/MOF-808a. is to pay attention to the mesoporous pore of the MIL-101 itself around nm, and use its channel to limit the Au particles to prepare the Au nanoparticles about 3 nm. A series of Au@MIL-101 is made to Au@MIL-101. Characterization shows that Au nanoparticles can be highly dispersed in MIL-101. When the concentration of Au is within a certain range, the limiting effect of MIL-101 can be controlled at about 3 nm, very homogeneous, which proves that MIL-101 has a limited effect on Au nanoparticles. The first time Au@MIL-101 is applied to the hydrogenation of p-nitrophenol. The catalyst exhibits excellent catalytic activity in the reduction reaction of p-nitrophenol under mild conditions and shows smaller activation energy relative to the traditional hydrogenation catalyst. In the design concept of the first catalyst, it is noted that the monoclinic ZrO_2 has not only acid catalytic performance but also an acid catalytic performance. In situ FTIR performance, the in situ infrared study shows that its alkalinity comes from the OH cluster on zirconia. Considering that Zr-MOFs is composed of polyatomic inorganic Zr-O clusters with OH based, it is similar to the zirconia structure. We propose some ideas that Zr-MOFs may have the base site of the Bronx. Based on the above thinking, the first tool is developed. The Zr-MOF material MOF-808a. with B base is verified by the reaction of MOF-808 in the hot fresh solution. The formic acid roots on MOF-808 will be replaced by t-OH and become a kind of material with homogeneous dispersion in the center of acid and alkali. The specific process of proving MOF-808a. is as follows: first, CO2-TPD-MS is characterized, and MOF-808a is found to have strong chemical adsorption to CO_2, It was proved that there was an alkali center; further acid titration was carried out. From the final data spectrum, it was found that there was only one point of mutation. It was found that there should be only one kind of OH (b-OH or t-OH) and PKb at about 10 on the MOF-808a. Finally, it was characterized by in situ IR, and observed the changes of corresponding functional groups in the spectrum at different temperatures, and found MOF-8 The OH on 08A eventually belonged to t-OH. to further prove the alkaline effect of MOF-808a. We designed and synthesized the catalyst Pd/MOF-808a, and selected the organic reactions involving the introduction of alkali, including the Heck reaction and the oxidation of benzyl alcohol. In the Heck reaction, the conversion rate can reach 93.6% without the use of the applied alkali, and the catalyst can be recycled by 10. After that, the structure of the catalyst did not change obviously, and the catalytic effect remained at about 90%. In the oxidation of benzyl alcohol, the catalyst also showed excellent catalytic activity. Compared with other immobilized catalysts, the catalyst showed higher selectivity to the product. Through the reaction of the two probes, the MOF-808a was fully proved to be strong. It is believed that this discovery can provide some reference for other researchers.
【學位授予單位】：南昌大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.36

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