本文選題：結(jié)構(gòu)可控 + 鎳物種　； 參考：《蘭州大學(xué)》2016年博士論文

【摘要】：本論文以結(jié)構(gòu)可控的表面鎳物種催化劑在二氧化碳甲烷化反應(yīng)和可見光催化分解水制氫體系中的應(yīng)用為研究切入點,基于金屬有機框架(MOFs)材料設(shè)計并構(gòu)建了高分散、高活性的非貴金屬鎳基催化劑。此外,本論文還系統(tǒng)地研究了在CO_2甲烷化反應(yīng)和光催化制氫反應(yīng)中,表面鎳物種的構(gòu)效關(guān)系,取得了以下創(chuàng)新性成果:1.Ni-Ru/γ-Al_2O_3催化劑表面活性物種的調(diào)控與CO_2甲烷化性能的研究系統(tǒng)的考察了不同浸漬方法制備的CO_2甲烷化催化劑的構(gòu)效關(guān)系。研究發(fā)現(xiàn)催化劑10Ni-1.0Ru在共浸漬制備過程中,Ru存在表面偏析現(xiàn)象,使得Ru更加容易還原成金屬態(tài),并提供更多的活性物種,使得10Ni-1.0Ru表現(xiàn)出更高的活性與更好的穩(wěn)定性。此外,基于催化劑的表征,本文提出CO_2在催化劑10Ni-1.0Ru表面產(chǎn)生甲烷的機理,CO_2在Ru表面活化形成COads和Oads,最終在Ni表面的氫物種與Ru表面碳物種形成甲烷。2.基于MOF-5構(gòu)建高分散的納米Ni基催化劑及其催化CO_2甲烷化性能的研究利用原位浸漬還原法合成了一系列低溫條件下對CO_2甲烷化具有高活性的Ni@MOF-5催化劑。此催化劑比傳統(tǒng)方法制備的10Ni/SiO_2催化劑展示了更高的催化活性�；贐ET,TEM和化學(xué)吸附表征等技術(shù)對催化劑10Ni@MOF-5的結(jié)構(gòu)和狀態(tài)表征,發(fā)現(xiàn)Ni在大比表面積的MOF-5(~2961 m2/g)上具有高分散(~41.8%)和小尺寸(~9nm)特性。催化劑10Ni@MOF-5在320°C時,CO_2轉(zhuǎn)化率達到75.09%,CH4選擇性為100%。此外,該催化劑也展示了高穩(wěn)定性與選擇性,在100h內(nèi)幾乎沒有失活。3.Ni助劑晶面對Ni@MOF-5表面電荷轉(zhuǎn)移行為及其可見光催化制氫性能影響的研究基于金屬有機框架MOF的高比表面積特性構(gòu)建了一系列高分散、小尺寸、高活性的光催化分解水產(chǎn)氫非貴金屬催化劑Ni@MOF-5。Ni@MOF-5與貴金屬催化劑Pt@MOF-5具有相同的產(chǎn)氫過電位(-0.37V),但Ni@MOF-5表現(xiàn)出更高的產(chǎn)氫活性、穩(wěn)定性、熒光壽命和光電流。在430nm波長下,催化劑Ni@MOF-5的最高AQE為16.7%。此外,對Ni@MOF-5催化劑中Ni NPs不同晶面電荷轉(zhuǎn)移行為與光催化產(chǎn)氫性能的研究發(fā)現(xiàn)Ni NPs暴露出的(111)晶面相比(200)晶面更利于產(chǎn)氫和電荷轉(zhuǎn)移。4.基于MIL-101構(gòu)建低氫吸附自由能的Ni-Mo合金簇助催化劑及其可見光催化制氫性能的研究采用DFT和FMO計算分析得到單金屬鎳簇的氫吸附自由能為537 kJ·mol-1,而合金簇MoNi4具有更低的氫吸附自由能(458kJ·mol-1)。我們通過雙溶劑法制備了高活性、高穩(wěn)定性的光催化分解水產(chǎn)氫非貴金屬助催化劑NiMo@MIL-101。在可見光條件下,在EY敏化體系中,通過對比單金屬助催化劑(Ni@MIL-101和Mo@MIL-101)產(chǎn)氫活性發(fā)現(xiàn),合金催化劑NiMo@MIL-101展示出最高的產(chǎn)氫活性(2h內(nèi)產(chǎn)氫總量達到1480.4μmol,pH 7)和高的表觀量子效率(75.7%,520nm)。催化劑NiMo@MIL-101也存在最大的光電流、低的產(chǎn)氫過電位(-0.51V)和長的熒光壽命(1.57ns)。正是因為MoNi4納米合金簇具有低的氫吸附自由能才導(dǎo)致高的光催化產(chǎn)氫活性。
[Abstract]:In this paper, the application of surface nickel species catalyst with controllable structure in methanation of carbon dioxide and visible light catalytic decomposition of water for hydrogen production was studied. Based on organometallic framework MOFs, high dispersion was designed and constructed.Highly active non-noble metal nickel-based catalysts.In addition, the structure-activity relationships of nickel species on the surface of CO_2 methanation and photocatalytic hydrogen production have also been systematically studied.The following innovative results were obtained: 1. The structure-activity relationship between the surface active species of Ni-Ru-Al _ 2O _ 3 catalyst and the methanation performance of CO_2 was investigated systematically. The structure-activity relationship of CO_2 methanation catalysts prepared by different impregnation methods was investigated.It is found that the surface segregation of Ru in the co-impregnation process of catalyst 10Ni-1.0Ru makes it easier to reduce Ru to metal state and provide more active species, which makes 10Ni-1.0Ru exhibit higher activity and better stability.In addition, based on the characterization of the catalyst, the mechanism of methane production from CO_2 on the surface of the catalyst 10Ni-1.0Ru is proposed. CO-2 is activated on the surface of Ru to form COads and Oads.The hydrogen species on the surface of Ni and the carbon species on the surface of Ru form methane. 2.Preparation of highly dispersed Nano-Ni-based Catalysts based on MOF-5 and their Catalytic Properties for CO_2 methanation A series of Ni@MOF-5 catalysts with high activity for CO_2 methanation at low temperature were synthesized by in-situ impregnation reduction method.The catalytic activity of this catalyst is higher than that of 10Ni/SiO_2 catalyst prepared by traditional method.Based on the characterization of the structure and state of the catalyst 10Ni@MOF-5 by BET-TEM and chemisorption, it is found that Ni has the characteristics of high dispersion 41.8% and small size (9nm) on the MOF-5(~2961 m2 / g with large specific surface area.At 320 擄C, the conversion of the catalyst 10Ni@MOF-5 was 75.09 and CH4 selectivity was 100.In addition, the catalyst also showed high stability and selectivity.Charge transfer behavior on the Surface of Ni@MOF-5 and its effect on visible Light Catalytic hydrogen production; A series of high dispersions and small sizes were constructed based on the high specific surface area characteristics of organometallic frame MOF.The non-noble metal catalyst Ni@MOF-5.Ni@MOF-5 has the same hydrogen production potential as the noble metal catalyst Pt@MOF-5, but Ni@MOF-5 exhibits higher hydrogen production activity, stability, fluorescence lifetime and photocurrent.The maximum AQE of the catalyst Ni@MOF-5 is 16.7g at 430nm wavelength.In addition, the charge-transfer behavior and photocatalytic hydrogen production properties of Ni NPs on different crystal planes in Ni@MOF-5 catalyst were studied. It was found that the exposed surface of Ni NPs was more favorable for hydrogen production and charge transfer than that of #number0#).Construction of Ni-Mo Alloy Cluster Cocatalyst with low hydrogen adsorption Free Energy based on MIL-101 and its performance in visible Light Catalytic hydrogen production; calculated and analyzed by DFT and FMO, the hydrogen adsorption free energy of single metal nickel cluster was 537 kJ mol -1, while that of alloy cluster MoNi4 was lower than that of single metal nickel cluster.The free energy of hydrogen adsorption is 458 kJ mol-1.A high activity and high stability photocatalytic catalyst NiMoR MIL-101 was prepared by double solvent method for the catalytic decomposition of aquatic hydrogen.The catalyst NiMo@MIL-101 also has the largest photocurrent, low hydrogen overpotential (-0.51V) and long fluorescence lifetime (1.57nsg).It is due to the low hydrogen adsorption free energy of MoNi4 nanoclusters that the photocatalytic activity of hydrogen production is high.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：O643.36;TQ116.2
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本文編號：1745008