负载型分子筛对挥发性有机气体的吸附特性研究

发布时间：2018-01-11 06:25

本文关键词：负载型分子筛对挥发性有机气体的吸附特性研究　出处：《西安建筑科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：挥发性有机物(Volatile Organic Compounds,VOCs)在常温下以蒸汽的形式存在于空气中,大多具有刺激性、毒性和致癌性,长期接触会损害人体健康并诱发癌症;作为PM2.5的前驱物,VOCs是造成雾霾的元凶之一,公众健康和生存环境已经严重受到威胁。无所不在的VOCs以其危害性和对大气污染的严重性,早已受到了国内外的广泛关注,对其的处理更是迫在眉睫。对于无回收利用价值的低浓度VOCs废气而言,吸附法因其操作方便等优点,在石化、油漆涂料、化学制造等行业的工业废气处理中被广泛应用。实际生产生活中,排放的VOCs废气成分较多,有必要探讨双组分以及多组分VOCs废气的吸附污染治理。由于研究VOCs在分子筛上的吸附动力学及竞争吸附鲜有报道,因此有必要开展研究工作,从而为工业放大及生产应用奠定基础。本研究采用以浸渍法制备的Cu-Mn-Ce负载型分子筛为固定床填充材料,以甲苯、乙酸乙酯和丙酮作为VOCs的典型代表,考察了单组分和多组分VOCs在固定床上的吸附特性,同时对Cu-Mn-Ce负载型分子筛吸附VOCs的动力学进行了分析研究。试验研究基础上,得到如下研究成果:(1)单因子实验中,得到甲苯吸附的最佳参数条件为:空气流量Q=0.5m3/h、气体浓度C=400mg/m3和吸附剂量A=800g。(2)本研究中决定Cu-Mn-Ce/5A吸附床层吸附性能的主要因素是VOCs的极性,随着有机分子极性的增大,甲苯、乙酸乙酯和丙酮在负载型分子筛上的吸附性能不断提高。(3)Cu-Mn-Ce/5A吸附剂的吸附等温线属于I型等温线,为Langmuir单层可逆吸附过程。根据甲苯、乙酸乙酯和丙酮的吸附等温线以及Langmuir方程的拟合结果可得到:同等条件下,三种有机物的饱和吸附量由大到小的顺序是:丙酮乙酸乙酯甲苯。根据其吸附不同组分VOCs之后的比表面积等指标比较,三种不同吸附质中丙酮的吸附性能最好,甲苯最差。(4)负载型分子筛对于单组分和多组分VOCs的吸附穿透过程大体上相似,但后者的穿透时间显著缩短,单位质量吸附剂吸附量明显下降,穿透曲线上出现了明显的“驼峰”,认为其吸附穿透过程存在共吸附和竞争吸附现象。(5)选择Thomas模型和Yoon-Nelson模型模拟吸附过程,发现))/(ln(0CCC?与时间t之间存在线性关系。实验表明,这两个模型能够直观的反映吸附过程中两个重要的变量之间的关系,可以较好的应用于模拟气体的吸附特性研究。(6)Yoon-Nelson模型能够较好模拟Cu-Mn-Ce/5A吸附床吸附不同组分VOCs的吸附过程,说明Cu-Mn-Ce/5A吸附床对不同组分VOCs出口浓度与吸附时间存在固定的关联,这对工业放大及生产应用具有实际的指导意义。
[Abstract]:Volatile organic compounds (VOCs) exist in the air in the form of steam at room temperature, and most of them are irritating. Toxicity and carcinogenicity, long-term exposure will damage human health and induce cancer; As the precursor of PM2.5, PM2.5 is one of the main causes of smog. The public health and living environment have been seriously threatened. The ubiquitous VOCs is harmful and serious to the air pollution. It has been widely concerned at home and abroad, and its treatment is even more urgent. For the low concentration VOCs waste gas without recycling value, adsorption method in petrochemical, paint paint because of its advantages such as ease of operation. Industrial waste gas treatment in chemical manufacturing and other industries is widely used. In actual production and life, there are more components of VOCs emissions. It is necessary to study the adsorption pollution control of two-component and multi-component VOCs waste gas. Because there are few reports on the adsorption kinetics and competitive adsorption of VOCs on molecular sieve, it is necessary to carry out research work. In this study, the Cu-Mn-Ce supported molecular sieve prepared by impregnation method was used as the fixed bed filling material and toluene was used as the filling material. Ethyl acetate and acetone were used as typical representatives of VOCs. The adsorption characteristics of single and multicomponent VOCs on fixed bed were investigated. At the same time, the kinetics of adsorption of VOCs by Cu-Mn-Ce supported molecular sieve was studied. On the basis of the experimental study, the following results were obtained: 1) in the single factor experiment. The optimum parameters for toluene adsorption were obtained as follows: air flow rate: Q ~ (2 +) = 0.5 m ~ (3 / h). In this study, the polarity of VOCs is the main factor that determines the adsorption performance of Cu-Mn-Ce/5A adsorption bed. With the increase of the polarity of organic molecules, toluene. The adsorption isotherms of ethyl acetate and acetone on the supported molecular sieve have been improved. The adsorption isotherms of Cu-Mn-Ce5A adsorbent belong to the I-type isotherms. According to the adsorption isotherms of toluene, ethyl acetate and acetone and the fitting results of Langmuir equation, we can get the following results: under the same conditions. The order of saturated adsorption capacity of the three organic compounds from large to small is acetone ethyl acetate toluene. The specific surface area of the three organic compounds is compared according to the specific surface area after the adsorption of different components VOCs. The adsorption performance of acetone was the best among the three adsorbents, and the adsorption penetration process of the supported molecular sieve was similar to that of the single-component and multi-component VOCs. However, the penetration time of the latter was significantly shortened, and the adsorption capacity per unit mass of adsorbent was obviously decreased, and the "hump" appeared obviously on the penetration curve. Thomas model and Yoon-Nelson model were selected to simulate the adsorption process. The experimental results show that the two models can directly reflect the relationship between two important variables in the adsorption process. It can be used to study the adsorption characteristics of simulated gas. Yoon-Nelson model can simulate the adsorption process of different components of VOCs in Cu-Mn-Ce/5A adsorption bed. It is shown that there is a fixed relationship between the outlet concentration of VOCs and the adsorption time in Cu-Mn-Ce/5A adsorption bed, which is of practical significance for industrial amplification and application in production.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X701;O647.3

【相似文献】