本文關(guān)鍵詞： 甲醇部分氧化 催化活性 密度泛函理論（DFT） 反應(yīng)機(jī)理 鉑釕合金 直接甲醇燃料電池（DMFC）　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：直接甲醇燃料電池（DMFC）是一種以液態(tài)的甲醇為燃料的特殊的質(zhì)子交換膜燃料電池，是一種可以將甲醇的化學(xué)能直接有效地轉(zhuǎn)化成電能的裝置，因?yàn)榻Y(jié)構(gòu)簡單、操作溫度低、無污染、高效安全可靠等優(yōu)點(diǎn)而受到人們的廣泛關(guān)注，直接甲醇燃料電池的開發(fā)和應(yīng)用可以有效地緩解能源危機(jī)，并減少環(huán)境污染。眾所周知，金屬Pt是用于DMFC中最有效的一元陽極催化劑，但是，，陽極催化劑存在的一些問題限制了DMFC的商業(yè)化應(yīng)用。首先，Pt是貴金屬，在地球上的存儲量有限，而且價(jià)格昂貴、成本高；其次，甲醇在氧化過程中產(chǎn)生的一氧化碳容易使鉑催化劑中毒，降低催化劑的催化活性，減少催化劑的利用率。因此，尋找催化活性好、抗一氧化碳中毒能力強(qiáng)的催化劑已經(jīng)成為DMFC目前發(fā)展中急需解決的問題。研究甲醇在陽極催化劑上電化學(xué)氧化的反應(yīng)機(jī)理，將有助于研發(fā)出更好的直接甲醇燃料電池催化劑。本文采用高水平的量子化學(xué)計(jì)算方法，研究了甲醇在陽極催化劑上的吸附和脫氫機(jī)理，比較了不同催化劑對甲醇部分氧化的催化活性，可以為進(jìn)一步對高效的陽極催化劑的研究提供可靠的理論依據(jù)。主要研究內(nèi)容如下： 我們用Pt6M（M=Pt，Sn，Ru）二元合金模型來模擬DMFC陽極的催化劑，采用密度泛函理論（DFT）中的B3PW91方法，研究了甲醇在Pt6M（M=Pt，Sn，Ru）二元合金催化劑上吸附和脫氫反應(yīng)的反應(yīng)機(jī)理，并且比較了Pt6M（M=Pt，Sn，Ru）三種催化劑對于甲醇部分氧化的催化活性。甲醇的吸附和脫氫機(jī)理主要有兩種：（1）用羥基H原子和甲基H原子分別進(jìn)攻Pt6M團(tuán)簇的Pt原子和M原子，形成甲基吸附復(fù)合物，進(jìn)而發(fā)生C-H鍵斷裂；（2）用羥基O原子和羥基H原子分別進(jìn)攻Pt6M團(tuán)簇的M原子和Pt原子，形成了羥基吸附復(fù)合物，進(jìn)而發(fā)生O-H鍵的斷裂。在B3PW91/LANL2DZ理論水平討論了反應(yīng)的吸附能、活化能壘、分解能、自然鍵軌道分析和前線分子軌道分析。通過計(jì)算得到的反應(yīng)勢能面（PES）表明，在純鉑催化劑Pt7上更有利的脫氫反應(yīng)通道是甲基吸附復(fù)合物的分解；在Pt6Sn二元合金催化劑上更有利的反應(yīng)通道是羥基吸附復(fù)合物的分解；在Pt6Ru二元合金催化劑上甲基吸附復(fù)合物的分解和羥基吸附復(fù)合物的分解都是主要的反應(yīng)通道。我們可以得出結(jié)論，在純Pt催化劑中引入的第二種金屬Ru和Sn提高了對甲醇部分氧化反應(yīng)的催化活性，對于DMFC中甲醇的吸附和脫氫反應(yīng)，Pt6Ru二元合金是Pt6M（M=Pt，Sn，Ru）三種催化劑當(dāng)中最有效的。
[Abstract]:Direct methanol fuel cell (DMFC) is a kind of liquid methanol as fuel special proton exchange membrane fuel cell is a methanol chemical energy directly and efficiently into electrical energy device, because of simple structure, low operation temperature, no pollution, the advantages of high efficiency, safety and attention the development and application of direct methanol fuel cell can effectively alleviate the energy crisis, and reduce environmental pollution. As everyone knows, Pt is a metal element for an anode catalyst, the most effective in DMFC but some problems of anode catalyst have limited commercial application of DMFC. First, Pt is a precious metal, storage in the face of the earth is limited, and the price is expensive, the cost is high; secondly, methanol produced during oxidation of carbon monoxide to platinum catalyst poisoning, reduce the catalytic activity of the catalyst, reduce the catalyst utilization Rate. Therefore, looking for good catalytic activity, resistance to carbon monoxide poisoning catalyst ability has become the urgent problems in the development of DMFC. The reaction mechanism of methanol oxidation on the anode catalyst in the electrochemical, will contribute to the development of direct methanol fuel cell is a better catalyst. By using high level quantum chemical calculation method, to study the adsorption and dehydrogenation mechanism of methanol in the anode catalyst, the catalytic activity of different catalysts for partial oxidation of methanol, can provide a reliable theoretical basis for further research on the anode catalyst efficiency. The main research contents are as follows:
We use Pt6M (M=Pt, Sn, Ru) catalyst two element alloy model to simulate the DMFC anode, using density functional theory (DFT) in the B3PW91 method, the study of methanol on Pt6M (M=Pt, Sn, Ru) reaction mechanism of adsorption and dehydrogenation of two alloy catalyst, and more than Pt6M (M=Pt, Sn, Ru) three catalysts for catalytic partial oxidation of methanol. There are two main types of adsorption and dehydrogenation mechanism of methanol: (1) Pt6M clusters were used to attack the H atom and hydroxyl methyl H atoms Pt and M atoms, forming methyl adsorption complexes, and cleavage of C-H (; 2) attack Pt6M clusters respectively with O atoms and hydroxyl hydroxyl H atoms M and Pt atoms, the formation of hydroxyl adsorption complexes, and then breaking O-H bonds. At the B3PW91/LANL2DZ level of theory was discussed and the adsorption energy, activation energy, dissociation energy, natural bond orbital analysis and frontier molecular orbital Division Through the analysis. The calculated potential energy surface (PES) show that in pure platinum catalyst Pt7 on the dehydrogenation reaction channel more favorable is the decomposition of methyl adsorption complexes; Pt6Sn two element alloy catalyst reaction channel more favorable is the decomposition of hydroxyl adsorption complexes; decomposition in Pt6Ru two alloy catalyst on the adsorption of methyl complex decomposition and hydroxyl adsorption complexes are the major reaction channel. We can conclude that the introduction of pure Pt catalyst in second kinds of metal Ru and Sn enhanced the catalytic activity of the methanol oxidation reaction, the adsorption and dehydrogenation of DMFC in methanol, Pt6Ru alloy Pt6M (M=Pt is two yuan Sn, Ru, three) the most effective catalyst.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O621.254;TM911.4

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