催化湿式氧化处理焦化废水

【作者】 艾先立；

【导师】 赵彬侠；

【作者基本信息】 西北大学 ， 化学工程， 2011， 硕士

【摘要】 本文针对焦化废水中的主要污染物苯酚、喹啉为研究对象,并以焦化废水中苯酚和喹啉的质量比配制了模拟焦化废水；以过渡金属元素铁(Fe)为活性组分,分别以活性炭(AC)和蒙脱土(MMT)为载体,采用不同的方法制备了Fe/AC和Fe-Al-MMT催化剂。并对所制备的催化剂进行了表征,根据表征和实验结果提出了在不同制备方法下催化剂制备适宜的工艺条件。用所制备的催化剂对模拟的焦化废水进行催化湿式过氧化氢氧化(CWPO)法处理,以TOC或COD去除率为评价指标,考察了不同工艺条件下处理焦化废水的效果；同时探讨了不同工艺条件下,催化剂的稳定性；得出采用CWPO处理废水时,工艺条件对TOC或COD去除率影响的一般规律。采用浸渍法制备Fe/AC催化剂,并对所制备的催化剂进行了比表面积(BET)、热重(TG)等方法的表征,考察了Fe/AC催化剂的制备条件和CWPO处理工艺条件对Fe/AC催化剂的稳定性和催化活性的影响。结果表明：铁负载量、焙烧温度、初始pH值、氧化剂(H202)用量对催化剂的催化活性和稳定性有较大影响。铁负载量2%,300℃下焙烧4h制备的Fe/AC催化剂,在初始pH=5,反应温度为60℃,100ml模拟水样,H202加入量2100mg/L,2%Fe/AC催化剂300℃下焙烧4h的催化剂10g/L。在此条件下反应3h,Fe离子溶出量为：5.79mg/L。通过采用柱撑改性蒙脱土的方法所制备的Fe-Al-MMT催化剂,并通过TG、DTG、BET比表面积等表征手段确定了Fe-Al-MMT催化剂的制备工艺,通过实验确定焦化废水CWPO处理工艺对Fe-Al-MMT催化剂的稳定性和催化活性的影响。通过实验结果确定：催化剂的Fe/Al比为2：8,焙烧温度为350℃,在初始pH=3,反应温度为60℃,100ml模拟水样,H202加入量2100mg/L,催化剂投加量为5g/L。在此条件下反应3h,Fe离子溶出量为：1.52mg/L, TOC去除率可达63.04%。探讨了两种不同的催化剂催化H202分解的动力学,经过计算可得：采用Fe/AC催化剂时,在适宜的工艺条件下催化分解H202的反应级数为1.14,活化能Ea为67.46kJ/mol;当采用Fe-Al-MMT催化剂,在适宜的工艺条件下催化分解H202的反应级数为1.39,活化能Ea=80.57kJ/mol。本实验对Fe/AC催化剂与Fe-Al-MMT催化剂在制备方法、制备周期、离子溶出、催化剂寿命方面进行了比较。Fe/AC催化剂具有制备方法简单,制备周期短的优点,但其离子溶出严重,稳定性差不利于长期使用,加之其投加量与Fe-Al-MMT相比过大。整体上,Fe-Al-MMT催化剂在性能上优于Fe/AC催化剂。更多还原

【Abstract】 Phenol and quinoline are the main pollutants in coking waster. According to the mass ratio of the two pollutants, the simulated coke-plant wastewater was prepared. Iron (Fe), the transition metal, as the active component of the catalyst; the activated carbon (AC) and montmorillonite (MMT) as the supporter. In other words the Fe/AC and Fe-Al-MMT catalyst were prepared respectively. According to the characterized and experimental results the preparing process of the catalysts have been taken.The catalysts were used for simulated coke-plant wastewater by the CWPO treatment, under the different process, the stability of the catalyst. When under different process of the coke-plant waster the TOC or COD removal as the evaluation. The coke-plant waster was treated by CWPO process the conditions on COD and TOC removal.Activated carbon-supported Fe catalysts (Fe/AC) have been prepared by incipient impregnation and was characterized by means of BET and TG analysis. Phenol, quinoline, the main pollutants in coking waster, have been treated by CWPO. The preparation of Fe/AC catalyst and the process of CWPO has been studied. The results showed:the loading of Fe, the calcination temperature, the initial pH and the dose of the oxidant(H2O2) have greatly influenced the catalyst’s stability and the catalytic activity. The Fe loading of the catalyst is 2%, the catalyst was calcinated at 300℃for 4h, when the initial pH is 5, the reaction temperature is 60℃; the dose of the hydrogen peroxide is 2100mg/L, the dose of catalyst used 10g/L meanwhile Fe leaching is 5.79mg/L.Clay pillared with Fe-Al was made as a catalyst for CWPO (catalytic wet peroxide oxidation) of simulated coke-plant wastewater (phenol, quinoline). The Fe-Al pillared (Fe-Al-MMT) clays was characterized by BET surface, X-ray diffraction (XRD), thermal gravimetric (TG) and differential scanning calorimetry (DSC), the results shows:the thermal stability of the pillared clays is stronger than the shopping sodium montmorillonite due to the interaction between the iron species and the catalyst support. Then, the catalyst’s performance in CWPO was analyzed under different operating conditions such as the reaction temperature, initial pH and H2O2 dose.Fe-Al-MMT catalyst was reused under considerable operating conditions (reaction temperature is 60℃, pH initial=3, [H2O2]0=2100mg/L, Wcat= 5g/L), the solids shows high stability in the reaction due to strong interaction between the iron species and the catalyst support. The pillared clays were also stable against the leaching out of Fe.H2O2 decomposition kinetics of two different catalysts were studied. Fe/AC catalyst was used at the best processing conditions the reaction order of H2O2 decomposition is 1.14, the activation energy Ea=67.46kJ/mol, however, when the Fe-Al-MMT catalyst was used under the best processing conditions the reaction order of H2O2 decomposition is 1.39, meanwhile the activated energy Ea=80.57kJ/mol.This study also compare the Fe/AC catalyst and Fe-Al-MMT catalyst on preparation method, preparation cycle, Fe leaching, the lives of the catalyst and so on. The Fe/AC catalyst preparation method is easy and simple, also the preparation period is short. However, the iron on the catalysts leaching is large, the catalyst’s stability is not stable enough, the dosage is more large than the Fe-Al-MMT catalyst. Generally speaking, Fe-Al-MMT catalyst is better the Fe/AC catalyst on CWPO as the catalyst.更多还原