催化湿式氧化法滴流床反应器处理污水的研究和应用

主要研究催化湿式氧化法滴流床反应器发展过程、研究进展和实际应用,论述了在湿式氧化法中滴流床反应器的特点和影响因素,并且对进一步的深入研究,工艺上的改进及其应用前景提出了参考建议。     

Catalytic wet air oxidation of phenol using active carbon: performance of discontinuous and continuous reactors

Catalytic wet air oxidation (CWAO) of an aqueous phenol solution using active carbon (AC) as catalytic material was compared for a slurry and trickle bed reactor. Semi‐batchwise experiments were carried out in a slurry reactor in the absence of external and internal mass transfer. Trickle‐bed runs were conducted under the same conditions of temperature and pressure. Experimental results from the slurry reactor study showed that the phenol removal rate significantly increased with temperature and phenol concentration, whereas partial oxygen pressure had little effect. Thus, at conditions of 160 °C and 0.71 MPa of oxygen partial pressure, almost complete phenol elimination was achieved within 2 h for an initial phenol concentration of 2.5 g dm^?3. Under the same conditions of temperature and pressure, the slurry reactor performed at much higher initial rates with respect to phenol removal than the trickle bed reactor, both for a fresh active carbon and an aged active carbon, previously used for 50 h in the trickle bed reactor, but mineralisation was found to be much lower in the slurry reactor. Mass transfer limitations, ineffective catalyst wetting or preferential flow in the trickle bed alone cannot explain the drastic difference in the phenol removal rate. It is likely that the slurry system also greatly favours the formation of condensation polymers followed by their irreversible adsorption onto the AC surface, thereby progressively preventing the phenol molecules to be oxidised. Thus, the application of this type of reactor in CWAO has to be seriously questioned when aiming at complete mineralisation of phenol. Furthermore, any kinetic study of phenol oxidation conducted in a batch slurry reactor may not be useful for the design and scale‐up of a continuous trickle bed reactor. © 2001 Society of Chemical Industry     

滴流床反应器催化湿式氧化法处理碱渣废水

在自行研制的滴流床反应器中,以MnOx/γ-Al2O3为催化剂,研究了反应温度、进水有机物浓度、液体流率等主要工艺参数对酸化中和预处理后的碱渣废水催化湿式氧化效果的影响。结果发现反应温度和液体流率对氧化反应效果的影响显著:温度升高,反应速率加快;液体流率越慢,反应效果越好。在滴流床处理碱渣废水最开始连续运转的15 h中出水中金属离子溶出现象比较严重,但随后趋于稳定,催化剂的活性并没有受到影响。由于滴流床中高的催化剂-液相比,废水在滴流床中表现出高的降解速率。     

Carbon supported platinum catalysts for catalytic wet air oxidation of refractory carboxylic acids

Carbon supported platinum (1% wt) catalysts were prepared by the incipient wetness impregnation method and by organometallic chemical vapor deposition. Catalyst characterization was carried out by means of adsorption and thermogravimetric techniques, and by electron microscopy. The catalyst with higher metal dispersion was produced by incipient wetness impregnation. The catalysts were tested in the catalytic wet air oxidation (200°C and 6.9 bar of oxygen partial pressure) of aqueous solutions containing low molecular weight (C₂ to C₄) carboxylic acids. Significant conversions (greater than 60% over 2 h) and 100% selectivity towards water and non-carboxylic acid products were observed for both systems. The initial reaction rate was used to compare the performance of the two catalytic materials and direct correspondence to the metal dispersion was found. No metal leaching was observed during reaction and no significant deactivation occurred in three successive catalytic oxidation runs. A kinetic model based on the Langmuir–Hinshelwood formulation was applied and the results were analyzed in terms of a heterogeneously catalyzed free radical mechanism.     

Catalytic wet oxidation of substituted phenols in the trickle bed reactor

Continual catalytic wet oxidation of phenol and its derivatives as a suitable chemical pretreatment before a biological treatment process was investigated. The evaluation of (i) the influence of amino-, carboxy- and sulfo- phenol substituents on the course of the oxidation of hydroxyl-aromatics, (ii) the catalytic ability of an active carbon, and (iii) the influence of reaction conditions, viz. temperature (120–160°C) and oxygen partial pressure (2–5 MPa) in the continuous trickle bed reactor, is presented. The active carbon type catalyst seems to be active enough for phenol oxidation, but it is not so effective for aromatic acids. The results of trickle bed operation were strongly influenced by hydrodynamics, viz. wetting efficiency. An insufficient catalyst wetting compensates for an effect of residence time in the bed and undesirable fluctuation of conversion appears at the low liquid velocities which are typical for waste water treatment processes. It is possible to achieve an optimal value of reactor productivity. © 1998 SCI     

微波诱导活性炭催化氧化有机废水的研究进展

微波诱导活性炭催化氧化技术为有机废水处理提供了一种新的解决途径。全面阐述了该技术的催化氧化机理、微波反应器类型和处理效果,结合实际工程需求,对目前研究中存在的问题和发展趋势进行系统分析,以期为微波诱导活性炭催化氧化技术的工程化应用提供指导。     

过硫酸盐高级氧化降解水体中有机污染物研究进展

基于硫酸根自由基（sulfate radical,SO₄ ^-·）氧化原理的活化过硫酸盐（persulfate,PS）氧化法是近年来高级氧化工艺（advanced oxidation process,AOP）的研究热点,以经济、高效、环境友好、安全稳定的优势在水处理、环境保护等领域开辟了新的思路。此前,学者们发现过硫酸盐高级氧化根据活化反应条件（如温度、光照、pH、过渡金属及催化剂等）的不同,会产生不同的自由基参与氧化反应,对降解结果也会产生不同程度的影响。本文根据相关自由基氧化机理,从产生硫酸根自由基的单一氧化、复杂活化体系硫酸根自由基与其他自由基复合氧化以及强化降解等方面,分析了近几年国内外学者对过硫酸盐降解典型有机污染物的研究及在催化剂开发方面所做的工作,指出了许多新颖的过硫酸盐活化手段及其降解效果与不足,并就未来的发展进行了展望,以期为过硫酸盐氧化法未来更好地发展和应用探索出路。     

湿式氧化-催化湿式氧化联用处理定影废水

采用湿式氧化(WAO)-催化湿式氧化(CWAO)两段工艺处理定影废水,重点考察了反应时间、温度、压力、pH等因素对WAO处理效果的影响,并进行了CWAO处理WAO出水氨氮的尝试,取得了较好的效果.实验确定WAO适宜的反应条件:温度为160℃、氧分压为1 MPa、反应时间为2 h、进水pH为4.8.该条件下的CODCr去除率达79%,出水pH为1.4.CWAO处理WAO出水时所选定的反应条件:pH为12.9、温度为250℃、氧分压为3 MPa、反应时间为2 h.采用CWAO和WAO联用的方法处理定影废水,CODCr去除率达99.8%,氨氮去除率达97.8%,pH为5.6.     

催化湿式氧化法处理噻螨酮生产废水的试验

采用CuO-MnO2-La2O3为催化剂,以催化湿式氧化技术处理噻螨酮生产过程中产生的的高浓度有机废水.试验结果表明,用该复合催化剂在处理此种有机废水时表现出较好的催化活性.在230℃,氧气分压为2.5MPa和pH值为7.3的条件下,当废水CODCr的质量浓度为15 730 mg/L,在120 min内,CODCr去除率达到96.1%,而在相同条件下未加催化剂的湿式氧化CODCr去除率只有50.3%.     

Mass transfer‐limited wet oxidation of phenol

Catalytic wet oxidation carried out in a continual three‐phase trickle‐bed reactor contributes to the sustainability of chemical technology. It was found that the hydrodynamics and the mass‐transfer of reactants could have a significant impact on the performance of the trickle‐bed reactor. An aqueous phenol oxidation was tested at different temperatures and liquid feed rates and the activities of both the CuO‐supported catalyst and the extruded active carbon were compared. To avoid the impact of liquid maldistribution, a bed of catalyst particles diluted with fine glass spheres was also used. Rate‐limited conditions of both liquid‐ and gas‐phase presented reactants were determined. Under the conditions of gas component transfer limitation, a better wetting of the diluted catalyst bed can lead to a worsening in the reactor performance due to the lower overall reaction rates. © 2001 Society of Chemical Industry     

Kinetics of phenol oxidation in a trickle bed reactor over active carbon catalyst

The wet air oxidation of phenol over a commercial active carbon catalyst was studied in a trickle bed reactor (TBR) in the temperature and oxygen partial pressure ranges of 120–160 °C and 0.1–0.2 MPa, respectively. The performance of the active carbon was compared in terms of phenol and COD destruction. The weight change of active carbon due to reaction was also measured. Finally, oxic phenol adsorption isotherms were assessed in batch conditions at 25, 125 and 160 °C. In order to use the conversion data obtained from the TBR for a kinetic study, special care was taken to check the kinetic control in the TBR experiments. Several kinetic models including power law or Langmuir–Hinshelwood expressions were considered to describe the catalytic oxidation of phenol over active carbon. The simple power law model with first order dependence on both phenol and oxygen concentration predicted satisfactorily the experimental data not only over the entire range of operating conditions studied, but also outside its validity range. Copyright © 2005 Society of Chemical Industry     

催化湿式氧化处理农药废水的研究

利用担载型双金属活性组分催化剂，考察了反应温度、压力、进料空速和V（空气）：V（H2O）（体积比）等反应条件对催化湿式氧化处理某农药废水效果的影响。对于该种废水，在4．2MPa，245℃，空速为2．0h^-1，V（空气）：V（H2O）＝300的反应条件下，废水的COD去除率可达到91．3％。经处理后废水的BOD5／COD＞0．5，说明其可生化性能良好。     

湿式过氧化物氧化技术处理高浓度有毒有机废水研究

采用湿式过氧化物氧化技术(WPO)处理苯酚丙酮装置某化工厂产生的高浓度有毒有机废水,并在WPO的基础上投加活性炭,加强催化氧化效果。通过单因素实验确定反应温度160℃,反应时间1h,进水pH值为3.0,H2O2投送加量控制在H2O2/COD=0.5,FeSO4按照n[Fe2+]/n[H2O2]=0.1的比例投加,在活性炭催化作用的强化下,COD和苯酚的去除率分别可以达到90%和99%以上。     

Numerical simulation of reactive pulsing flow for the catalytic wet oxidation in TBR using a VOF technique

Guided by the intrinsic advantages of the dynamic nature of mass/heat transfer fluctuations in pulsing flow, here we performed volume‐of‐fluid (VOF) numerical simulations to evaluate how liquid flow modulations can improve the detoxification of liquid effluents by catalytic wet oxidation. First, prominent numerical parameters were optimized in terms of mesh aperture and time step. Second, the effect of oxidation temperature and the influence of gas and liquid flow rates have been investigated comparatively under different flow regimes. The VOF computations have correctly handled the experimental observations both in terms of the axial conversion and temperature. The increase of oxidation temperature was found to move the trickling and pulsing intersection point on the conversion toward the top of the trickle bed. Finally, in comparison with trickling flow regimes, these computed and experimental findings revealed a considerable improvement on the detoxification of organic matter highlighting the benefits of process intensification covered by the periodic liquid flow modulations. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

湿法磷酸中有机物的脱除方法

湿法磷酸中含有多种杂质,有机杂质是其中的一种。介绍了采用活性炭和化学氧化相结合脱除湿法磷酸中有机杂质的方法,分别研究了试剂用量、反应温度、反应时间和搅拌速度对脱除湿法磷酸中有机杂质的影响。结果表明,采用活性炭吸附和化学氧化相结合的方法脱除湿法磷酸中的有机杂质,最显著的影响因素为活性炭用量和双氧水用量;在最佳工艺条件下,该法可以脱除湿法磷酸中80.2%的有机杂质,净化后磷酸中残余的有机杂质含量低于食品级磷酸对有机杂质所要求的含量。该方法是脱除湿法磷酸中有机杂质的有效方法。     

Effect of phase maldistribution on performance of two-phase catalytic monolith reactor and its comparison with trickle bed reactor

Monolith reactors are widely considered as an alternative to the conventional trickle bed reactor. For the commercial deployment of monolith reactors, comparative performance studies are required. Reliable comparative and performance studies require a detailed understanding of the effect of phase distribution/maldistribution on the performance studies. In this work, performance and comparative studies were carried out in a relatively large column that was 4.8 cm in diameter. Experiments were performed in the same conditions that were used in studies for which phase distribution data were available. Since the properties of the catalyst used were different in both the reactors, the apparent kinetics were studied to facilitate the comparison. The hydrogenation of alpha-methyl styrene (AMS) was used as a test reaction. From the performance studies, it was found that the effect of maldistribution on the performance was stronger than the catalyst availability. From the comparative studies, it was found that the monolith reactor with maldistributed flow conditions provides higher productivity than the trickle bed reactor.     

新型材料在室内污染治理中的应用

室内污染严重威胁着人们的身体健康,如何祛除室内污染尤其是利用新型材料祛除室内污染和研制新型装修材料成了科技工作者研究的热点。文章针对室内污染物的危害进行了阐述,并对新材料在室内污染治理中应用进行了综述。     

超临界水氧化技术在有机污染物处理中的应用

超临界水氧化是新兴的、有效的有机废物处理技术。介绍了超临界水的特性和超临界水氧化的基本原理与优点,综述了超临界水氧化技术在各种有机污染物处理中的应用,指出了为实现超临界水氧化技术工业化亟待解决的问题。     

高浓度难降解有机废水湿式氧化可行性研究

选择四种高浓度难降解有机废水,在2L高压间歇反应釜中,研究了湿式氧化效果与技术可行性。结果表明:从氧化的容易程度来看,乳化液废水>丙硫咪唑废水>甲胺磷废水>分散蓝废水;各废水湿式氧化后可生化性得到显著改善;Cu2+有不同程度的催化作用;甲胺磷废水和丙硫咪唑废水对不锈钢反应釜腐蚀严重,乳化液废水最适宜湿式氧化。反应温度显著影响废水湿式氧化效果,温度越高氧化率越高。     

高级氧化技术在持久性有机污染物处理中的应用

介绍了持久性有机污染物(POPs)的相关概念和性质,对几种典型的高级氧化技术在POPs处理中的应用现状作了较为详细的阐述,总结了各相关技术的基本原理及研究进展,并对其应用前景进行了评述。