ZSM-5分子筛吸附烟气中Hg~0的分子模拟与试验研究
发布时间：2018-11-21 19:58
【摘要】：在化石燃料的燃烧、垃圾焚烧、金属冶炼等过程中,排放烟气中的单质汞(Hg0)对人类及生态环境的危害越来越受到人们的关注和重视。论文利用分子筛独特的孔道结构和吸附性能,采用分子模拟与实验室试验研究相结合的方法,开展ZSM-5分子筛脱除Hg0的研究。应用Materials Studio软件并结合其他几个条件,从145种不同骨架结构的分子筛中筛选出脱汞最佳的分子筛是ZSM-5分子筛;为提高ZSM-5分子筛吸附剂脱汞效率,筛选出符合条件的两种活性物质高铁酸钾(K2Fe O4)和氯化铜(Cu Cl2),分别对ZSM-5分子筛进行改性,形成复合型吸附剂。试验研究中,K2Fe O4改性ZSM-5分子筛采用固态离子交换法,Cu Cl2则用浸渍法。具体研究结果与结论如下:(1)以分子筛的单个晶胞为研究对象,应用Materials Studio软件模拟145种不同骨架结构的分子筛吸附Hg0,得到在相同条件下吸附达到平衡时吸附Hg0分子的个数,在仅有Si和O原子构成的条件下,不同的骨架结构中平均单位Si O2吸附Hg0分子个数的顺序是MFIVNIPAI,并结合高效分子筛吸附剂筛选标准得到吸附Hg0最佳的是ZSM-5分子筛。(2)用蒙特卡洛法(GCMC)模拟ZSM-5分子筛吸附Hg0及负载活性物质,观察硅铝比、温度等因素对ZSM-5分子筛吸附Hg0的影响。模拟结果显示,ZSM-5分子筛组成成分中铝含量越高,越有利于汞吸附。ZSM-5分子筛吸附汞能力随着温度升高而降低;其吸附等温线服从Henry定律。此外,根据Clausius-Clapeyron方程,得到K2Fe O4负载在5-ZSM分子筛上的等量吸附热在381~383kcal/mol,Cu Cl2则为13~14kcal/mol,由此说明K2Fe O4在ZSM-5分子筛上吸附位很强,Cu Cl2却较弱。由负载分布位置图可观察到K2Fe O4分子只是分布在分子筛表面,而Cu Cl2分子则进入到了分子筛内部孔道;能量分布曲线显示,两种活性物质在ZSM-5分子筛中均存在多个吸附位点。(3)实验室ZSM-5分子筛吸附Hg0的试验研究结果表明,ZSM-5分子筛骨架中硅铝比对Hg0的吸附量存在较大影响,在硅铝比小于50范围内,随着硅铝比值增大脱汞效率随之降低;当硅铝比大于50时,脱汞效率趋于稳定,处于55%左右。对于复合型吸附剂,K2Fe O4与ZSM-5分子筛最佳质量混合比为10:1.6,Cu Cl2与ZSM-5分子筛最佳浸渍质量溶度则为2.5%;复合型K2Fe O4-ZSM-5分子筛吸附汞最佳反应温度为80℃,复合型Cu Cl2-ZSM-5分子筛为30℃;ZSM-5分子筛改性后吸附效率得到较大提高,其中,K2Fe O4-ZSM-5分子筛最高吸附脱汞效率达85%,Cu Cl2-ZSM-5分子筛最高吸附脱汞效率达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，
本文编号：2348121
[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，
本文编号：2348121
本文链接：https://www.wllwen.com/kejilunwen/huanjinggongchenglunwen/2348121.html
最近更新
教材专著
