本文選題：光催化 + 氮氧化物��； 參考：《上海師范大學》2015年博士論文

【摘要】：隨著中國經(jīng)濟、社會的不斷發(fā)展,工業(yè)化程度不斷的提高,中國的自然環(huán)境遭到了嚴重的破壞。近幾年霧霾天氣的長時間出現(xiàn)以及PM2.5的爆表,大氣污染已經(jīng)引起了中國政府的高度重視。作為大氣污染物之一的氮氧化物(NOx),能夠直接或間接地對環(huán)境和人類造成嚴重危害,因此如何有效控制和去除空氣中氮氧化物的引起了研究人員的興趣。盡管如今對于熱電行業(yè)廢氣中的NOx處理技術已有較為成熟的工藝技術,但是這些技術如選擇性催化還原、選擇性非催化還原等僅能對濃度高、排放源固定、溫度高的NOx進行處理降解,而對于機動車、垃圾焚燒等產(chǎn)生的這類污染源卻無能為力。通常情況下,這類污染源產(chǎn)生的NOx具有相對濃度低、持續(xù)時間長、治理困難等特征,因此急需開發(fā)一種更為有效、溫和的催化技術來解決這一難題。光催化氧化技術去除氮氧化物具有反應條件溫和、能耗低、二次污染少,且最終產(chǎn)物易于被植物、微生物等吸收的優(yōu)點,因此被認為是去除NOx的一種極具應用前景的環(huán)境友好型技術。但目前光催化氧化處理氮氧化物依然存在著光催化效率不高、催化劑易失活等缺點,嚴重影響了光催化劑在實際中的應用。針對上述光催化氧化NOx技術所存在的問題,我們以Ti系光催化劑作為研究對象,通過先進的微波合成技術,制備了新型的Ti基光催化劑,考察其光催化氧化NO的活性和穩(wěn)定性。結合系統(tǒng)表征,探究了組分和結構對光催化氧化NO性能的影響,期望為光催化技術應用于實際的大氣污染物凈化提供實驗和理論依據(jù)。本論文的主要內(nèi)容和創(chuàng)新點可分為以下四部分:一、采用微波輔助醇解法合成了一種具有層狀結構高穩(wěn)定的多孔結構Au/Ce O2-Ti O2光催化劑,應用于光催化催化氧化去除NO,在模擬太陽光和紫外光照射下顯示高活性和良好的穩(wěn)定性及使用壽命。通過TEM、XPS、XRD等表征手段以及考察調(diào)變Au和Ce O2的摻入量對活性的影響,揭示了摻雜的Au和Ce O2不僅能夠促進光的吸收和利用,也能有效分離光生電子和空穴,抑制其復合,此外Ce O2亦能提高吸附氧能力,產(chǎn)生更多的光催化活性位如超氧自由基,顯著提高了光催化性能,同時對各組分的協(xié)同效應以及光催化機理進行了探索,為設計高效光催化劑提出了新思路。二、采用表面活性劑結合溶劑揮發(fā)自組裝法和后浸漬氫氣還原法,合成了一種新型的Au/Ce O2-Ti O2光催化劑,各種表征手段表明,樣品具有有序介孔孔道結構,Au納米粒子完全進入孔道內(nèi)并保持了較小的粒徑,而且能夠與Ti O2產(chǎn)生強相互作用。該光催化劑不僅保持并進一步提高了Au/Ce O2對Ti O2光催化性能的協(xié)同促進作用,而且提高了光催化劑結晶度,有利于進一步加速電子傳輸,降低光生電子與空穴的復合,同時有序介孔孔道能夠減少傳質阻力,提高對光的捕獲以及對NO的吸附,有利于提高催化劑活性,同時,介孔結構產(chǎn)生的高比表面積有利于吸附更多的NO光催化氧化產(chǎn)物,從而減少了中毒失活。三、采用微波輔助合成法,原位合成了一種銀負載的類MOFs結構的新型有機金屬鈦聚合物。通過對聚合物材料的各類表征可以發(fā)現(xiàn),該復合材料具有比表面積大、銀納米粒子分散均勻等特征。在光催化反應中,有機配體因小的禁帶寬度而被可見光激發(fā),產(chǎn)生的光生電子能夠通過分子內(nèi)內(nèi)通道轉移至活性位Ti或銀納米粒子上,一方面啟動光催化反應,另一方面有效抑制光生電子與空穴的復合。該催化劑在可見光光催化氧化去除NO中,不僅具有較高活性,同時具有優(yōu)良的穩(wěn)定性。結合動力學考察和光催化劑結構表征,提出了光催化劑的活化機理,并對構效關系進行了探索。在此基礎上,通過改進微波合成技術和配方,最終合成了MOFs結構的高結晶度的NH2-MIL-125(Ti),在可見光催化氧化NO中顯示高活性,結合表征和反應動力學考察,初步探索了結晶度以及其他因素對光催化活性的促進作用。四、采用微波技術,以四氯化硅和金屬鈉為原材料,液相低溫合了高純度塊狀結構單晶硅,初步考察了其電化學性能和穩(wěn)定性,并分析了微波條件下單晶硅的生長機理,在此基礎上,通過改變反應體系和條件,制備了單晶硅和Si C復合材料。
[Abstract]:With the continuous development of China's economy, society and the continuous improvement of the degree of industrialization, the natural environment of China has been seriously damaged. In recent years, the appearance of fog and haze, as well as the explosion of the PM2.5, has caused the Chinese government to attach great importance to the air pollution. As one of the atmospheric pollutants, the nitrogen oxide (NOx) can be directly or between them. Grounding has caused serious harm to the environment and human beings, so how to effectively control and remove the nitrogen oxides in the air has aroused the interest of the researchers. Although more mature technology has been made for the NOx treatment technology in the exhaust gas of the thermoelectric industry, these technologies, such as selective catalytic reduction and selective non catalytic reduction, can only be used. The NOx, which has high concentration, fixed emission source and high temperature, can be treated and degraded, but it can not be used for the pollution sources such as motor vehicle and waste incineration. Generally, the NOx produced by this kind of pollution source has the characteristics of low relative concentration, long lasting time and difficult treatment. Therefore, it is urgent to develop a more effective and mild catalytic technology. In order to solve this problem, the photocatalytic oxidation technology has the advantages of mild reaction conditions, low energy consumption, low two pollution, and the advantages of the final product easy to be absorbed by plants and microbes. Therefore, it is considered to be a very promising environment friendly technology for the removal of NOx. However, the photocatalytic oxidation of nitrogen oxides is still still available at present. There are disadvantages of low photocatalytic efficiency and easy to lose catalyst, which seriously affect the application of photocatalyst in practice. Aiming at the problems existing in NOx technology, we take Ti photocatalyst as the research object. Through the advanced microwave synthesis technology, a new Ti based photocatalyst is prepared and its photocatalytic oxygen is investigated. The activity and stability of NO were changed. Combined with the system characterization, the effects of composition and structure on the photocatalytic oxidation of NO were investigated. It was expected to provide experimental and theoretical basis for the application of photocatalytic technology to the purification of the actual air pollutants. The main contents and innovation points of this paper can be divided into four parts: first, the microwave assisted alcoholysis method is used. A porous structure Au/Ce O2-Ti O2 photocatalyst with highly stable layered structure was used to remove NO by photocatalytic catalytic oxidation and showed high activity and good stability and service life in simulated solar and ultraviolet light. The effects of TEM, XPS, XRD and other characterization methods on the activity of Au and Ce O2 were observed. It is shown that doped Au and Ce O2 can not only promote the absorption and utilization of light, but also effectively separate the photoelectron and hole and inhibit its recombination. In addition, Ce O2 can also improve the adsorption oxygen ability, and produce more photocatalytic active sites such as superoxide radical, which significantly improves the photocatalytic performance and the synergistic effect and the photocatalytic mechanism of each component. A new idea for the design of high efficiency photocatalyst was put forward. Two, a new type of Au/Ce O2-Ti O2 photocatalyst was synthesized by using surface active agent combined with solvent evaporation and after impregnating hydrogen reduction. Various characterization means showed that the sample had an ordered mesoporous pore structure, and the Au nanoparticles were completely entered into the channel and guaranteed. The photocatalyst not only maintains and further improves the synergistic effect of Au/Ce O2 on the photocatalytic activity of Ti O2, but also improves the crystallinity of the photocatalyst, which is beneficial to the further acceleration of the electron transport and the reduction of the recombination of the photoelectrons and holes, and the ordered mesoporous pores at the same time. The channel can reduce the mass transfer resistance, improve the capture of light and the adsorption of NO, and improve the activity of the catalyst. At the same time, the high specific surface area produced by the mesoporous structure is beneficial to the adsorption of more NO photocatalytic oxidation products, thus reducing the inactivation. Three, a kind of silver like MOFs structure was synthesized by microwave assisted synthesis. A new type of organometallic titanium polymer. Through various characterization of the polymer material, it is found that the composite has the characteristics of large specific surface area and uniform dispersion of silver nanoparticles. In the photocatalytic reaction, the organic ligands are visible light due to the small band gap, and the produced photoelectrons can be transferred through the inner inner channel of the molecule. On the one hand, the photocatalytic reaction is initiated on the active site Ti or silver nanoparticles. On the other hand, the combination of photoinduced electrons and holes is effectively suppressed. The catalyst not only has high activity but also has excellent stability in the removal of NO by visible light photocatalytic oxidation. The photocatalyst is proposed by the combination of kinetic investigation and the structure characterization of photocatalyst. On the basis of this, the high crystallinity NH2-MIL-125 (Ti) of MOFs structure was synthesized by improving the microwave synthesis technology and formula. The high activity in the visible photocatalytic oxidation NO, the combination characterization and the reaction kinetics examination, and the preliminary exploration of the crystallinity and other factors on the photocatalytic activity. Four, using microwave technology, using four silicon chloride and sodium metal as raw materials, liquid phase low temperature combined high purity bulk single crystal silicon, preliminary investigation of its electrochemical properties and stability, and analyzed the growth mechanism of monocrystalline silicon under microwave conditions. On this basis, single crystal was prepared by changing the reaction system and conditions. Silicon and Si C composites.

【學位授予單位】：上海師范大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB383.1;X701

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