【摘要】：在化石燃料的燃燒、垃圾焚燒、金屬冶煉等過程中,排放煙氣中的單質(zhì)汞(Hg0)對(duì)人類及生態(tài)環(huán)境的危害越來越受到人們的關(guān)注和重視。論文利用分子篩獨(dú)特的孔道結(jié)構(gòu)和吸附性能,采用分子模擬與實(shí)驗(yàn)室試驗(yàn)研究相結(jié)合的方法,開展ZSM-5分子篩脫除Hg0的研究。應(yīng)用Materials Studio軟件并結(jié)合其他幾個(gè)條件,從145種不同骨架結(jié)構(gòu)的分子篩中篩選出脫汞最佳的分子篩是ZSM-5分子篩;為提高ZSM-5分子篩吸附劑脫汞效率,篩選出符合條件的兩種活性物質(zhì)高鐵酸鉀(K2Fe O4)和氯化銅(Cu Cl2),分別對(duì)ZSM-5分子篩進(jìn)行改性,形成復(fù)合型吸附劑。試驗(yàn)研究中,K2Fe O4改性ZSM-5分子篩采用固態(tài)離子交換法,Cu Cl2則用浸漬法。具體研究結(jié)果與結(jié)論如下:(1)以分子篩的單個(gè)晶胞為研究對(duì)象,應(yīng)用Materials Studio軟件模擬145種不同骨架結(jié)構(gòu)的分子篩吸附Hg0,得到在相同條件下吸附達(dá)到平衡時(shí)吸附Hg0分子的個(gè)數(shù),在僅有Si和O原子構(gòu)成的條件下,不同的骨架結(jié)構(gòu)中平均單位Si O2吸附Hg0分子個(gè)數(shù)的順序是MFIVNIPAI,并結(jié)合高效分子篩吸附劑篩選標(biāo)準(zhǔn)得到吸附Hg0最佳的是ZSM-5分子篩。(2)用蒙特卡洛法(GCMC)模擬ZSM-5分子篩吸附Hg0及負(fù)載活性物質(zhì),觀察硅鋁比、溫度等因素對(duì)ZSM-5分子篩吸附Hg0的影響。模擬結(jié)果顯示,ZSM-5分子篩組成成分中鋁含量越高,越有利于汞吸附。ZSM-5分子篩吸附汞能力隨著溫度升高而降低;其吸附等溫線服從Henry定律。此外,根據(jù)Clausius-Clapeyron方程,得到K2Fe O4負(fù)載在5-ZSM分子篩上的等量吸附熱在381~383kcal/mol,Cu Cl2則為13~14kcal/mol,由此說明K2Fe O4在ZSM-5分子篩上吸附位很強(qiáng),Cu Cl2卻較弱。由負(fù)載分布位置圖可觀察到K2Fe O4分子只是分布在分子篩表面,而Cu Cl2分子則進(jìn)入到了分子篩內(nèi)部孔道;能量分布曲線顯示,兩種活性物質(zhì)在ZSM-5分子篩中均存在多個(gè)吸附位點(diǎn)。(3)實(shí)驗(yàn)室ZSM-5分子篩吸附Hg0的試驗(yàn)研究結(jié)果表明,ZSM-5分子篩骨架中硅鋁比對(duì)Hg0的吸附量存在較大影響,在硅鋁比小于50范圍內(nèi),隨著硅鋁比值增大脫汞效率隨之降低;當(dāng)硅鋁比大于50時(shí),脫汞效率趨于穩(wěn)定,處于55%左右。對(duì)于復(fù)合型吸附劑,K2Fe O4與ZSM-5分子篩最佳質(zhì)量混合比為10:1.6,Cu Cl2與ZSM-5分子篩最佳浸漬質(zhì)量溶度則為2.5%;復(fù)合型K2Fe O4-ZSM-5分子篩吸附汞最佳反應(yīng)溫度為80℃,復(fù)合型Cu Cl2-ZSM-5分子篩為30℃;ZSM-5分子篩改性后吸附效率得到較大提高,其中,K2Fe O4-ZSM-5分子篩最高吸附脫汞效率達(dá)85%,Cu Cl2-ZSM-5分子篩最高吸附脫汞效率達(dá)80%。
[Abstract]:In the process of fossil fuel combustion, waste incineration and metal smelting, people pay more and more attention to the harm to human and ecological environment caused by the emission of elemental mercury (Hg0) from flue gas. Based on the unique pore structure and adsorption properties of molecular sieve, the removal of Hg0 from ZSM-5 molecular sieve was studied by means of molecular simulation and laboratory experiments. Using Materials Studio software and several other conditions, the best molecular sieve for mercury removal is ZSM-5 molecular sieve from 145 kinds of molecular sieves with different skeleton structure. In order to improve the mercury removal efficiency of ZSM-5 molecular sieve adsorbent, two active substances, potassium ferrate (K2Fe O 4) and copper chloride (Cu Cl2), were screened out and modified respectively to form complex adsorbent. In the experimental study, K2Fe O 4 modified ZSM-5 molecular sieve by solid state ion exchange method and Cu Cl2 by impregnation method. The specific results and conclusions are as follows: (1) with single unit cell of molecular sieve as the research object, the Materials Studio software is used to simulate the adsorption of Hg0, on 145 kinds of molecular sieve with different skeleton structure. The number of Hg0 molecules adsorbed at equilibrium under the same conditions is obtained. In the case of only Si and O atoms, the order of the average number of Si O2 adsorbed Hg0 molecules in different skeleton structures is MFIVNIPAI,. The best adsorbent for Hg0 was ZSM-5 molecular sieve. (2) Monte Carlo (GCMC) was used to simulate the adsorption of Hg0 and active substances on ZSM-5 molecular sieve, and the ratio of Si to Al was observed. The influence of temperature and other factors on the adsorption of Hg0 by ZSM-5 molecular sieve. The simulation results show that the higher the aluminum content in the composition of ZSM-5 molecular sieve, the more favorable the mercury adsorption. The adsorption capacity of ZSM-5 molecular sieve decreases with the increase of temperature, and the adsorption isotherm of ZSM-5 molecular sieve obeys the Henry law. In addition, according to the Clausius-Clapeyron equation, the isobaric adsorption heat of K2Fe O _ 4 supported on 5-ZSM molecular sieve was found to be at 381kcal / mol ~ 383kcal / mol ~ (-1) Cu Cl2, which indicated that the adsorption potential of K2Fe O _ 4 on ZSM-5 molecular sieve was very strong, but Cu Cl2 was weak. It was observed that K2Fe O 4 molecules were only distributed on the surface of molecular sieve, while Cu Cl2 molecules entered the internal pore channels of molecular sieve. The energy distribution curves show that there are many adsorption sites in ZSM-5 molecular sieves. (3) the experimental results of Hg0 adsorption by ZSM-5 zeolites in laboratory show that, The ratio of Si to Al in the framework of ZSM-5 molecular sieve has a great influence on the adsorption capacity of Hg0. When the ratio of Si to Al is less than 50, the efficiency of removing mercury decreases with the increase of the ratio of Si to Al; When the ratio of Si to Al is more than 50, the removal efficiency of mercury tends to be stable at about 55%. For composite adsorbent, the optimum mass mixing ratio of K2Fe O 4 and ZSM-5 molecular sieve is 10: 1. 6% Cu Cl2 and ZSM-5 molecular sieve. The optimum reaction temperature for mercury adsorption by composite K2Fe O4-ZSM-5 molecular sieve is 80 鈩，

本文編號(hào)：2348121