铁系柱撑蒙脱土催化剂的制备及其降解苯酚废水的研究
发布时间：2019-07-01 21:05
【摘要】：苯酚及其衍生物是化工和制药行业的重要原材料,近年来随着这两个行业的不断发展,酚类废水的处理已成为社会关注的焦点问题。酚类分子结构稳定、毒性高、可生化性差,传统技术很难做到经济高效的降解。本文采用新兴的非均相催化湿式过氧化氢氧化技术(CWPO),以代表物苯酚为研究对象,通过聚阳离子交换法制备系列铁,铈,铝-柱撑蒙脱土催化剂(Fe,Ce,Al-MMT)降解苯酚废水,重点优化催化剂的结构和催化性能,针对性地解决废水降解率低、柱撑催化剂易失活的问题。实验考察了制备条件(柱化液Fe/Ce摩尔比、活性组分负载量、焙烧时间)对Fe,Ce,Al-MMT催化剂的影响。以CWPO降解苯酚废水的效果参数(COD去除率、Fe离子溶出量)为指标评价了催化剂的活性及稳定性；同时,以ICP、XRD、N_2吸附-脱附、FTIR、 DR UV-Vis、SEM和H_2-TPR等表征结果为依据分析了催化剂的微观形貌和活性组分的存在形式。综合可知,柱撑过程可以有效改性蒙脱土,当Fe/Ce摩尔比为7/3,活性金属负载量为6%,焙烧温度为450℃时,制备的Fe,Ce,Al-MMT催化剂性能较优,具有层间距高(doo1为2.649nm)、比表面积大(181.2m2/g)、活性组分含量多且分散性好、稳定性强的特点。使用450℃-6%Fe,Ce,Al-MMT降解苯酚5h后,苯酚COD去除率可达94.48%,Fe离子溶出量仅为0.6528mg/L。将优化得到的450℃-6%Fe,Ce,Al-MMT催化剂应用于CWPO降解苯酚废水的研究。结合反应的动力学常数,以溶液COD去除率、Fe离子溶出量为指标考察工艺条件(反应时间、催化剂投加量、催化剂入水pH)对苯酚降解的影响。结果表明,当反应温度为60℃,催化剂投加量为1.0g/L,催化剂入水pH为5.0时,苯酚的降解效果较好(废水的COD去除率达到94.48%,Fe离子溶出0.6528mg/L,表观速率常数0.6529h-1)。此外,采用BET、SEM、DR UV-Vis等表征分析了单次使用后的450℃-6%Fe,Ce,Al-MMT催化剂,发现酸性反应介质并不会对催化剂的结构和活性组分产生较大的影响,并且连续五次重复使用回收的催化剂,苯酚的COD去除率仅下降6%,说明制备的催化剂稳定性良好。实验对CWPO降解苯酚废水的机理进行研究,证明了HO·是非均相CWPO降解体系最主要的活性自由基,其生成速率受介质溶液pH的影响较大。建立的一级动力学模型与实验数据的拟合率较高,计算去除COD的表观活化能Ea=17.64KJ/mol。最后,在催化剂传统制备法的基础上进行改良以减少制备过程中的用水量,在不借助外场能量的前提下,分散介质由蒸馏水替换为介电常数较低的乙醇溶液,重点讨论了不同分散介质对催化剂微观结构和催化活性的影响。结果显示,两种方法所制备的催化剂性能相当,证明了该方法的可行性。
[Abstract]:Phenol and its derivatives are the important raw materials in the chemical and pharmaceutical industry. In recent years, with the development of these two industries, the treatment of phenolic wastewater has become the focus of social concern. The phenolic molecular structure is stable, the toxicity is high, the biodegradability is poor, and the traditional technology is difficult to achieve cost-effective degradation. In this paper, a new heterogeneous catalytic wet hydrogen peroxide oxidation technology (CWPO) was used to study the degradation of phenol wastewater by using a polycation exchange method to prepare series of iron, iron and aluminum-pillared montmorillonite catalysts (Fe, Ce, Al-MMT). The structure and the catalytic performance of the catalyst are optimized, and the problem of low degradation rate of the wastewater and easy deactivation of the column support catalyst is solved. The effects of preparation conditions (Fe/ Ce molar ratio, loading of active component and firing time) on the Fe, Ce and Al-MMT catalysts were investigated. The activity and stability of the catalyst were evaluated with the effect parameters of CWPO-degrading phenol wastewater (the removal rate of COD and the amount of Fe ion). At the same time, ICP, XRD, N _ 2 adsorption-desorption, FTIR, DR UV-Vis, The results of SEM and H _ 2-TPR were based on the analysis of the micro-morphology of the catalyst and the existence of the active components. It is known that the process of column support can effectively modify the montmorillonite, when the molar ratio of Fe/ Ce is 7/3, the loading of the active metal is 6%, and the roasting temperature is 450 DEG C, the prepared Fe, Ce, Al-MMT catalyst has the advantages of better performance, high layer spacing (doo1 of 2.649 nm) and large specific surface area (181.2 m2/ g), The active component has the characteristics of multiple content and good dispersivity and strong stability. The removal rate of phenol was 94.48% after 5 h of phenol degradation by 450 鈩，
本文编号：2508791
[Abstract]:Phenol and its derivatives are the important raw materials in the chemical and pharmaceutical industry. In recent years, with the development of these two industries, the treatment of phenolic wastewater has become the focus of social concern. The phenolic molecular structure is stable, the toxicity is high, the biodegradability is poor, and the traditional technology is difficult to achieve cost-effective degradation. In this paper, a new heterogeneous catalytic wet hydrogen peroxide oxidation technology (CWPO) was used to study the degradation of phenol wastewater by using a polycation exchange method to prepare series of iron, iron and aluminum-pillared montmorillonite catalysts (Fe, Ce, Al-MMT). The structure and the catalytic performance of the catalyst are optimized, and the problem of low degradation rate of the wastewater and easy deactivation of the column support catalyst is solved. The effects of preparation conditions (Fe/ Ce molar ratio, loading of active component and firing time) on the Fe, Ce and Al-MMT catalysts were investigated. The activity and stability of the catalyst were evaluated with the effect parameters of CWPO-degrading phenol wastewater (the removal rate of COD and the amount of Fe ion). At the same time, ICP, XRD, N _ 2 adsorption-desorption, FTIR, DR UV-Vis, The results of SEM and H _ 2-TPR were based on the analysis of the micro-morphology of the catalyst and the existence of the active components. It is known that the process of column support can effectively modify the montmorillonite, when the molar ratio of Fe/ Ce is 7/3, the loading of the active metal is 6%, and the roasting temperature is 450 DEG C, the prepared Fe, Ce, Al-MMT catalyst has the advantages of better performance, high layer spacing (doo1 of 2.649 nm) and large specific surface area (181.2 m2/ g), The active component has the characteristics of multiple content and good dispersivity and strong stability. The removal rate of phenol was 94.48% after 5 h of phenol degradation by 450 鈩，
本文编号：2508791
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