本文選題：鈀 + 團(tuán)簇��； 參考：《安徽大學(xué)》2015年碩士論文

【摘要】：貴金屬作為珠寶和流通貨幣,是因?yàn)樗麄儾环频膬r(jià)值和穩(wěn)定的物理化學(xué)性質(zhì),所以受到了人們的廣泛親睞�？茖W(xué)家們發(fā)現(xiàn)貴金屬鈀與其它貴金屬相比,穩(wěn)定性高,催化效果好,可以用于催化很多的有機(jī)反應(yīng)。更為重要的是,隨著合成方法的改進(jìn)和單晶衍射技術(shù)的發(fā)展,科學(xué)家們合成了各種各樣的原子精確鈀團(tuán)簇,這給鈀團(tuán)簇在催化領(lǐng)域提供了有力的保障。原子精確的金屬團(tuán)簇與普通的金屬納米粒子相比,由于他們的結(jié)構(gòu)確定,可以幫助人們探索催化劑結(jié)構(gòu)與性質(zhì)之間的關(guān)系。本文就在前人的研究基礎(chǔ)上,合成單一分散的精確原子鈀團(tuán)簇與合金,應(yīng)用于催化有機(jī)反應(yīng),研究催化活性以及在分子原子級水平上探討催化反應(yīng)機(jī)理。主要內(nèi)容如下：1.本文通過共還原的方法有效合成一系列組分可控的金鈀納米合金,在這個(gè)合成過程中,硼烷叔丁胺化合物作為還原劑,油胺作為溶劑和還原劑對于合成這樣一系列的單分散納米合金有著重要的作用。我們研究這些合金對于苯胺脫氫偶聯(lián)反應(yīng)的催化活性,表明合金比等量的單純Au或Pd的催化效果好。并且Au1Pd3@C在所有合金中表現(xiàn)最好,這表明隨著Pd含量的升高轉(zhuǎn)化率和選擇性明顯升高。但是,如果AuPd合金中Pd的含量太高,比如Au1Pd7@C催化劑,催化效果反而不好(在這個(gè)反應(yīng)中只有81%的轉(zhuǎn)化率)。2.Pd催化Suzuki-Miyaura偶聯(lián)反應(yīng)是構(gòu)建碳骨架最通用且最有利的方法之一然而,由于Pd納米粒子表面的活性物質(zhì)和活性位點(diǎn)未知,很難準(zhǔn)確的說明為什么Pd納米粒子可以在有氧的條件下催化Suzuki-Miyaura偶聯(lián)反應(yīng)。因此,設(shè)計(jì)一種原子精確的團(tuán)簇催化劑在原子水平上研究催化反應(yīng)的本質(zhì)十分重要。本文中,我們設(shè)計(jì)和合成了一個(gè)單一活性位點(diǎn)的[Pd3Cl(PPh2)2(PPh3)3]+團(tuán)簇,然后利用它研究有氧條件下Suzuki-Miyaura偶聯(lián)反應(yīng)的反應(yīng)機(jī)理。我們的研究系統(tǒng)的揭示了催化循環(huán)過程中的中間體是[Pd3Ar(PPh2)2(PPh3)3]+,這一結(jié)果通過質(zhì)譜、快速X-射線吸收精細(xì)結(jié)構(gòu)和密度泛函理論計(jì)算分析得到了驗(yàn)證。我們提出來的團(tuán)簇催化Suzuki-Miyaura偶聯(lián)反應(yīng)的反應(yīng)機(jī)理與傳統(tǒng)的Suzuki-Miyaura偶聯(lián)反應(yīng)的反應(yīng)機(jī)理完全不同。更重要的是,我們的研究將會對更多的金屬團(tuán)簇或者納米粒子催化C-C偶聯(lián)反應(yīng)在反應(yīng)機(jī)理的研究中提供更多的幫助。
[Abstract]:Precious metals as jewelry and currency are popular because of their high value and stable physical and chemical properties. The scientists found that palladium, a precious metal, is more stable and more efficient than other precious metals and can be used to catalyze many organic reactions. More importantly, with the improvement of synthesis method and the development of single crystal diffraction technology, scientists have synthesized a variety of atomic precise palladium clusters, which provides a strong guarantee for palladium clusters in the field of catalysis. Compared with ordinary metal nanoparticles, metal clusters with precise atoms can help to explore the relationship between the structure and properties of catalysts because of their structure determination. On the basis of previous studies, a single dispersed and precise atomic palladium cluster and alloy were synthesized, which were used to catalyze organic reactions, to study catalytic activity and to explore the mechanism of catalytic reactions at the molecular atomic level. The main content is as follows: 1. In this paper, a series of controllable gold and palladium nanocrystalline alloys were synthesized by co-reduction. In this process, borane tert-butylamine compounds were used as reductants. As a solvent and reducing agent, oleamine plays an important role in the synthesis of such a series of monodisperse nanocrystalline alloys. The catalytic activity of these alloys for the dehydrogenation of aniline was studied. Moreover, Au1Pd3 @ C exhibited the best performance in all alloys, which indicated that the conversion and selectivity increased obviously with the increase of PD content. However, if the content of PD in AuPD alloy is too high, such as Au1Pd7@ C catalyst, the catalytic effect is not good (only 81% conversion in this reaction) .2.Pd catalytic Suzuki-Miyaura coupling reaction is one of the most common and advantageous methods to construct carbon skeleton. It is difficult to explain exactly why PD nanoparticles can catalyze Suzuki-Miyaura coupling reaction under aerobic conditions because the active substances and active sites on the surface of PD nanoparticles are unknown. Therefore, it is very important to design a kind of atom precise cluster catalyst to study the nature of catalytic reaction at atomic level. In this paper, we designed and synthesized a single active site [Pd3Cl (PPh2) 2 (PPh3) 3] cluster, and then used it to study the reaction mechanism of Suzuki-Miyaura coupling under aerobic conditions. Our study systematically revealed that the intermediate in the catalytic cycle was [PD _ 3Ar (PPh2) _ 2 (PPh3) _ 3], which was verified by mass spectrometry, fast X-ray absorption fine structure and density functional theory calculation. The reaction mechanism of the cluster catalyzed Suzuki-Miyaura coupling reaction is completely different from that of the traditional Suzuki-Miyaura coupling reaction. More importantly, our research will provide more help in the study of the reaction mechanism of C-C coupling reaction catalyzed by more metal clusters or nanoparticles.
【學(xué)位授予單位】：安徽大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1;O614.823

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