本文選題：密度泛函理論 + α-Fe_2O_3　； 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：目前,煤燃燒釋放的汞污染物是全球大氣汞污染物的主要來源之一。為了清潔有效利用煤資源,各個國家和地區(qū)先后推出了一系列相應(yīng)的法律法規(guī)對各類燃煤污染物進行了嚴(yán)格的限排。但基于我國的基本國情,尚未開發(fā)及設(shè)計出適合于我國燃煤電站現(xiàn)有污染物排放控制設(shè)備的燃煤煙氣中汞的脫除技術(shù)及吸附劑。本文從計算和實驗兩方面出發(fā)進行鐵基氧化物的設(shè)計和研究,旨在設(shè)計出高效廉價的可應(yīng)用于脫除燃煤煙氣中單質(zhì)汞的鐵錳氧化物類吸附劑。本文首先對氧化鐵在汞脫除方面的應(yīng)用進行理論計算和設(shè)計。利用量子化學(xué)密度泛函理論計算了不同形態(tài)汞在a-Fe2O3(001)表面上的吸附情況。計算結(jié)果顯示,單質(zhì)汞在a-Fe2O3(001)表面的吸附較弱,為物理吸附,Hg0垂直吸附在與Fetop成鍵的Otop位時,吸附能最大；而HgO在其表面的吸附卻是化學(xué)吸附,垂直于吸附劑表面吸附在Fetop位上能夠得到兩種穩(wěn)定平衡結(jié)構(gòu),即Hg先吸附在Fe原子上和O先吸附在Fe原子上的兩種吸附模型。基于理論計算結(jié)果分析,設(shè)計制備了鐵錳氧化物吸附劑,并將其用于燃煤煙氣中的汞的脫除實驗。為制備出高效脫汞吸附劑,探討了制備條件的影響。結(jié)果表明：鐵錳摩爾比為1：1,焙燒溫度為400℃條件下制備的樣品具有高穩(wěn)定性和高效脫除單質(zhì)汞的性能。進一步考察了反應(yīng)溫度和模擬煙氣組分對單質(zhì)汞的脫除影響,發(fā)現(xiàn)100,200,300,400℃條件下反應(yīng)的脫汞性能相差不大,單質(zhì)汞脫除效率都能達到98%以上,但相對而言低溫條件更有利于單質(zhì)汞的脫除；煙氣組分中O2和C02都能夠促進單質(zhì)汞的脫除,且02濃度的變化不能改變氧化物的脫除汞能力,推斷脫汞反應(yīng)機理是晶格氧機理。另外,當(dāng)吸附劑混合石英砂時,可大大提高氧化物利用率�？疾煳絼┑脑偕詴r發(fā)現(xiàn),吸附產(chǎn)物經(jīng)高溫脫附,再次應(yīng)用于模擬煙氣中單質(zhì)汞脫除試驗,雖然較新鮮樣品脫汞能力有所下降,單質(zhì)汞脫除率仍能達到94%的。
[Abstract]:At present, mercury released from coal combustion is one of the main sources of atmospheric mercury pollutants in the world. In order to make clean and effective use of coal resources, various countries and regions have introduced a series of corresponding laws and regulations to strictly limit the emission of all kinds of coal pollutants. However, based on the basic conditions of our country, the removal technology and adsorbent of mercury from coal-fired flue gas suitable for the existing pollutant emission control equipment of coal-fired power stations in China have not been developed and designed. In this paper, the iron based oxides were designed and studied from two aspects of calculation and experiment. The purpose of this paper is to design an efficient and cheap iron manganese oxide adsorbent which can be used to remove elemental mercury from coal-fired flue gas. In this paper, the application of ferric oxide in mercury removal is theoretically calculated and designed. The adsorption of different forms of mercury on a-Fe _ 2O _ 3 (001) surface has been calculated by using the density functional theory of quantum chemistry. The results show that the adsorption of elemental mercury on the surface of a-Fe _ 2O _ 3 (001) is weak, and the adsorption energy of Hg _ 0 is the largest when it is perpendicular to the site of Otop bonded with feed, while the adsorption of HgO on the surface is chemisorption. Two stable equilibrium structures can be obtained when adsorbed perpendicular to the surface of the adsorbent at the Fetop site, that is, two adsorption models of Hg adsorbing on Fe atom and O adsorbing on Fe atom first. Based on the analysis of theoretical calculation results, the iron and manganese oxide adsorbents were designed and prepared and used in the removal of mercury from coal-fired flue gas. In order to prepare high-efficiency mercury removal adsorbent, the influence of preparation conditions was discussed. The results show that the samples prepared under the conditions of iron-manganese molar ratio of 1: 1 and calcination temperature of 400 鈩，

本文編號：2108606