本文選題：鈰鈦催化劑　切入點：脫硝　出處：《華中科技大學》2015年碩士論文

【摘要】：能源與環(huán)境是目前人類發(fā)展所面臨的最重大的兩個問題。眾所周知,煤是中國最主要的能源。煤炭的燃燒利用不僅向環(huán)境中排放了粉塵、SO2以及NOx等污染物,還會造成汞污染。汞是一種有毒重金屬,對人體有極大的危害,因此燃煤煙氣中汞的排放及控制近年來受到了極大的關注。隨著燃煤電廠逐步配備脫硫及脫硝設備,利用常規(guī)污染物控制設備限制汞的排放成為了一種有前景的汞排放控制方法。大量研究表明SCR(Selective Catalytic Reduction)催化劑可以有效地捕獲并促進汞的氧化。本文首先采用溶膠凝膠法制備了不同配比的鈰鈦催化劑(CeO2-TiO2),并通過X射線衍射儀(XRD),掃描電鏡(SEM)等手段對其進行了表征;在固定床反應器上對催化劑的脫硝性能進行了測試,考察了溫度、配比以及煙氣組分的影響。在高效脫硝的前提下,又進行了單質汞脫除實驗,考察了煙氣組分的影響。實驗結果表明,在200-500℃范圍內,溶膠凝膠法制備的CeTi催化劑的脫硝性能要優(yōu)于超聲波浸漬法制備的CeTi(u)催化劑,且其效率隨著溫度的升高出現(xiàn)先升高后下降的趨勢;在400℃溫度下,質量配比為CeO2/Ti O2=0.5的鈰鈦催化劑取得了最高的脫硝效率(91.58%);在0-4%范圍內,O2濃度的提高對脫硝效率有著明顯的促進作用;氨氮比(NH3/NO)的升高會在一定程度上促進NO的轉化;SO2和H2O均對鈰鈦催化劑的脫硝反應有著明顯的抑制作用;脫汞實驗中,CeO2含量的增加有助于脫汞效率的提高;而O2作為氧化劑會吸附在CeTi催化劑表面,進而與氣相單質汞發(fā)生反應;HCl對脫汞效果的促進十分明顯,但前提是有O2存在;由于NH3會與Hg0競爭消耗催化劑上的活性氧,SCR反應的存在會明顯抑制脫汞反應;為提升CeTi催化劑的性能,向催化劑中添加了Cu,結果發(fā)現(xiàn)在低溫區(qū)間脫硝性能和脫汞性能均有明顯提升;但在高溫區(qū)間脫硝性能會急劇下降,而H2O有助于緩解這一現(xiàn)象;與CeTi催化劑不同,SO2的存在會促進單質汞的脫除;最后,通過CeTi催化表面Hg0和O2的吸附實驗確定了在400℃時,CeTi催化劑表面的單質汞催化氧化反應遵循Eley-Rideal機制,并建立了反應動力學模型。
[Abstract]:Energy and environment are two of the most important current human development faced. As everyone knows, coal is the main energy Chinese. The combustion of coal dust emissions using not only to the environment, SO2, NOx and other pollutants, will cause pollution of mercury. Mercury is a toxic heavy metal, there is great harm to the human body, so the control of mercury in coal-fired flue gas emissions in recent years has attracted great attention. Gradually equipped with the coal-fired power plant desulfurization and denitrification equipment, the use of conventional pollutant control equipment to limit mercury emissions has become a promising method for mercury emission control. A large number of studies show that SCR (Selective Catalytic Reduction) can effectively capture the oxidation catalyst and to promote mercury. Firstly by sol-gel method of cerium titanium catalyst prepared by different ratio (CeO2-TiO2), and by X ray diffraction (XRD), scanning electron microscopy (SEM) and other means It was characterized in a fixed bed reactor; denitrification performance of catalyst was tested, the effects of temperature, ratio and the influence of flue gas components. In the premise of efficient denitrification, and the mercury removal experiments, the effects of flue gas components. The experimental results show that in the 200-500 the temperature range of CeTi, the catalyst prepared by sol gel denitration performance is better than ultrasonic impregnation of CeTi (U) catalyst, and the efficiency with the increase of temperature increased first and then decreased slowly; in 400 degrees temperature, mass ratio of cerium and titanium catalyst CeO2/ O2=0.5 Ti achieved denitration efficiency the highest (91.58%); in the range of 0-4%, the increase of the concentration of O2 has a significant role in promoting the efficiency of denitrification; ammonia nitrogen ratio (NH3/NO) increased conversion will promote NO to a certain extent; the SO2 and H2O of cerium titanium catalyst denitration reaction with Ming Significant inhibition; mercury removal experiment, the increase of the content of CeO2 is helpful to improve the efficiency of mercury removal; and O2 as oxidant can be adsorbed on the surface of CeTi catalyst, then react with gas phase mercury; HCl for mercury removal effect is very obvious, but the premise is the existence of O2 by NH3; can compete with Hg0 consumption of reactive oxygen species on the catalyst, SCR reaction can significantly inhibit the mercury removal reaction; to improve the performance of CeTi catalyst, adding Cu to the catalyst, the denitrification performance and mercury removal performance have improved significantly in the low temperature range; but in the high temperature region between the denitrification performance will drop drastically. H2O helps alleviate this phenomenon; unlike the CeTi catalyst, the presence of SO2 could promote the removal of elemental mercury; finally, through adsorption experiments catalyzed by CeTi and Hg0 on the surface of O2 was determined at 400 DEG C, the mercury oxidation reaction of CeTi on the surface of the catalyst based on Eley-R The ideal mechanism and the kinetic model of the reaction have been established.

【學位授予單位】：華中科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X773;O643.36

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