CuO/PSSF复合催化剂的制备及其在苯酚降解中的应用

以纸状不锈钢微纤材料（paper-like sintered stainless steel fibers,PSSF）为载体,采用化学气相沉积法（chemical vapor depositon,CVD）制备CuO/PSSF复合催化剂并在固定床反应器上进行苯酚湿式催化氧化降解研究。采用SEM、XRD、XPS等技术对催化剂的表面形态、物相结构、元素价态进行分析,改变流量及床层高度考察停留时间对湿式催化氧化降解苯酚过程中苯酚转化率、H₂O₂转化率、TOC转化率及Cu²⁺浸出浓度的影响规律。催化剂表征结果表明,活性组分CuO成功负载在PSSF微纤材料上;活性评价测试结果表明,低流量条件对各活性指标变化影响十分明显;随床层高度增加各活性指标均显著提高,4cm床层高度下达到最高苯酚转化率和TOC转化率,分别为96.5%和47.4%,同时没有高毒副产物产生。本文初步探究了复合催化剂与固定床反应器结合的工艺可行性,旨在为工业化含酚废水的降解提供一些思路。     

固相催化湿式氧化高浓度苯酚废水的试验研究

以高浓度苯酚废水为对象,采用CuO/γ-Al_2O_3负载型催化剂进行催化湿式氧化试验,通过正交试验方法得出各工艺参数对固相催化湿式氧化反应结果影响的重要程度,试验结果表明,各工艺操作条件对反应速率及处理效果的影响程度为反应温度物料表观流速废水初始pH值反应压力,最优工艺条件为:废水初始pH值为8,反应温度为220℃,反应压力为2.8 MPa,催化剂床层表观流速为0.9 m/h。     

Cu0.5-xFexZn0.5Al2O4尖晶石型复合氧化物催化剂在苯酚催化湿式氧化中的性能研究

采用溶胶-凝胶法制备了具有尖晶石结构的Cu0.5-xFexZn0.5Al2O4系列复合氧化物催化剂,考察了催化剂在苯酚催化湿式氧化反应中的活性和稳定性.结果表明,苯酚的CODCr去除率和抗积炭能力随Fe含量的增大而提高,在催化剂中引入Fe能在一定程度上抑制Cu的溶出,Culeached/Cutotal从9.19%(x=0)降低到了4.31%(x=0.25);Fe的溶出量随x值增大而减小.对反应后产物的色谱分析说明在含组分Fe量较高的催化剂上苯酚氧化中间产物的进一步转化速率较快.     

Fe/AC催化过氧化氢降解双酚A

传统Fenton反应存在对液相pH要求较高、Fe³⁺回收困难以及难以重复使用等问题。基于"活性离子固载化,酸性环境局部化"的设计思路,通过对活性炭(AC)表面酸化改性,制备得到载铁活性炭(Fe/AC)催化剂。研究了Fe/AC制备工艺与其性能之间的关系,结果表明,在载Fe³⁺量44.05 mg·g^-1、煅烧温度200℃的制备工艺下可得到催化活性较高、稳定性好的Fe/AC催化剂。用性能优良的Fe/AC催化H₂O₂降解双酚A(BPA),其较佳催化反应条件为:反应时间60 min、反应温度20℃、溶液pH值为4.0≤pH≤8.0、Fe³⁺/H₂O₂摩尔比为0.007～0.012、30% H₂O₂用量为0.04 ml H₂O₂·(mg BPA)^-1。本工作制备得到的Fe/AC催化剂具有较好的重复使用性能,在实际废水处理领域具有较大的应用前景。     

Fe/AC非均相Fenton体系降解废水中苯酚研究

采用浸渍法制备了活性炭载铁(Fe/AC)非均相Fenton催化剂,研究了铁负载量、初始pH值、反应时间和H_2O_2用量对催化剂降解模拟废水中苯酚的影响,结果表明,在苯酚废水体积为50 mL,催化剂铁负载量为7.76%, H_2O_2投加量为4 g/L, pH值为3,反应时间为120 min的条件下,苯酚的降解率约为95%。催化剂的稳定性试验表明,重复使用5次后,该催化剂对苯酚的降解率仍能达60%左右。该催化剂具有良好的活性和较强的稳定性,以及良好的实际应用前景。     

用CuO/AC催化氧化降解水中LAS的研究

LAS是一类广泛使用的阴离子表面活性剂,具有一定的毒性,且不易降解.文章以CuO/活性炭(AC)为催化剂,H2O2为氧化剂催化氧化降解LAS.结果表明:在H2O2浓度为4.9 mmol/L,温度=70℃,pH在5～6,反应时间为2.5 h的条件下,LAS降解率67.7%,COD去除率54.1%.     

Pd-Ru/CeO2催化降解高浓度苯胺废水的研究

以Pd-Ru/CeO2为催化剂,以苯胺去除率和降解生成N2的选择性为目标,研究了高浓度苯胺模拟废水湿式催化氧化降解的工艺条件。在220℃,2.4 MPa和pH为4～7条件下处理浓度为600 mg/L的苯胺废水,在2 h内,苯胺去除率可达95%以上,降解生成N2的选择性可达到85%以上,催化剂有较好的重复利用性。     

Fe/AC湿式催化过氧化氢氧化法处理印染废水的研究

以商品活性炭为原料,先用稀盐酸浸泡预处理,然后采用浸渍—微波法制备了负载型Fe/AC催化剂,对酸性品红模拟印染废水进行催化湿式过氧化氢氧化处理(CWPO),研究处理工艺条件对Fe/AC催化活性的影响.结果表明,对商品活性炭进行预处理能显著提高Fe/AC的催化活性,同时Fe/AC的CWPO工艺对酸性品红的脱色效果优于其吸...     

Cu/TiO2催化湿式氧化甲醛废水

甲醛废水排放入水体后,破坏生态系统,影响人们的身体健康。考察了以自制的Cu/TiO2为催化剂,用催化湿式氧化的方法降解甲醛废水的情况。通过优化反应条件,在180℃、pH=5、0.5 MPa、催化剂量为6 g/L时反应2 h,TOC的去除率高达85%,且Cu2+和Ti4+基本没有流失。此外还检测了甲醛溶液中甲醇变化情况和经处理后甲醛废水的降解产物甲酸。结果表明,以Cu/TiO2为催化剂的催化湿式氧化能有效地降解甲醛废水。     

活性炭载体对TiO2/AC光催化降解苯酚影响研究

分别以典型煤基活性炭和椰壳活性炭为载体,采用溶胶-凝胶法制备了TiO2/AC复合光催化剂,采用低温氮气吸附、X射线衍射、扫描电镜等对其性能进行了表征,分析了活性炭载体对复合光催化剂性能的影响.结果表明:TiO2在椰壳活性炭载体上的负载率高于煤基活性炭,TiO2负载使椰壳活性炭的比表面积和微孔容明显减小,TiO2溶胶对微...     

陕北中低温煤焦油提酚工艺废水的处理

为了确定通过浸渍法制备的载铜活性炭的焙烧温度,并了解其催化氧化的处理效果,利用热重-红外光谱联机分析方法对载铜活性炭(Cu-AC)前驱物Cu(NO3)2/AC进行分析,确定Cu-AC的最佳焙烧温度为700℃。并以自制的Cu-AC为催化剂,H2O2为氧化剂,在m(H2O2)∶m(COD)=1.4,m(Cu-AC)∶m(H2O2)=1.5条件下,对中低温煤焦油提酚废水进行催化湿式过氧化法处理,COD去除率达到91.8%,取得了良好效果。     

Influence of preoxidizing treatments on the preparation of iron‐containing activated carbons for catalytic wet peroxide oxidation of phenol

BACKGROUND: Iron species were heterogeneously supported over activated carbons (AC) after different oxidizing pre‐treatments. The influence of the oxidizing method on the iron yield and the physicochemical properties of the iron‐containing activated carbons (Fe/AC) were studied. Thereafter, the activity and stability of Fe/AC catalysts for the wet peroxide oxidation of phenol as model pollutant was evaluated. RESULTS: The pre‐oxidizing treatment with HNO₃ was the most appropriate for iron incorporation, providing a Fe/AC catalyst with the highest TOC removal and oxidant efficiency. A high stability of the catalysts was observed with low values of iron leaching (below 1.5% of their initial iron contents). The best Fe/AC catalyst was studied at different reaction temperatures and initial phenol concentrations. CONCLUSION: The promising results for the Fe/AC catalyst using HNO₃ pre‐oxidizing treatment lay in the remarkable adsorption capacity of the carbon matrix and the potential activity of the iron species as Fenton‐like catalyst for the generation of oxidizing hydroxyl radicals. Copyright © 2012 Society of Chemical Industry     

催化湿式氧化法在苯酚废水预处理中的应用研究

与湿式空气氧化相比，催化湿式氧化可以在温和条件下达到较好的废水处理效果。考察了CuO/η－Al2O3和活性炭两种催化剂处理苯酚废水的催化效果，结果表明在温和条件下可以达到较高COD去除率：在140℃下，催化湿式氧化1h，CODcr去除率分别达到93．2％和88．4％。在160℃下，催化湿式氧化1h，CODcr去除率分别达到93．4％和90．1％。在140℃下，苯酚废水经过湿式空气氧化1h后，BOD5／CODcr仅仅达到0．08，不适合后续生物法处理；使用活性炭催化剂，BOD5／CODcr达到了0．18，而使用CuO／η－Al2O3催化剂，BOD5／CODcr达到了0．30，因此，用CuO／η－Al2O3催化剂处理苯酚废水可以在较低温度下达到预处理效果。     

基于AC/SnO2-Sb粒子电极的苯酚电催化氧化

采用热分解法,以活性炭(AC)颗粒为基体,利用Sn-Sb固溶特性制备具有催化活性的AC/SnO₂-Sb粒子电极,并通过N₂吸附法、扫描电镜(SEM)、X射线衍射(XRD)及电化学测试对其微孔结构、微观形貌、物相组成和电催化活性进行表征.结果表明,SnO₂-Sb活性组分减少了AC介孔但未破坏高孔隙结构,且以固溶体形式广泛分布于AC孔道表面,不仅增强了AC孔隙内部降解有机物的活性,还增加了电催化活性位点,有助于提升催生羟基自由基的能力;同时只有AC/SnO₂-Sb粒子电极的循环伏安曲线(CV)在1.10V存在明显的苯酚氧化峰,说明SnO₂-Sb固溶体在电催化氧化的作用下,可直接参与苯酚的催化降解.以模拟苯酚废水考察粒子电极的电催化活性以及稳定性,结果表明,在电流密度12.0mA/cm² 和反应时间3h条件下,AC/SnO₂-Sb粒子电极的COD和苯酚去除率分别为78.43%和79.52%,均高于AC粒子电极的去除率.此外,AC/SnO₂-Sb在30天连续水处理中表现出较好的电化学稳定性.     

ACF/漆酶复合材料降解苯酚废水的研究及超声优化

采用活性炭纤维(ACF)固定化漆酶处理模拟废水中的苯酚,通过SEM、FTIR、DSC及TG表征,研究不同因素对苯酚去除效果的影响,确定了最佳工艺参数:最佳反应温度为50℃,最适pH为4.0~7.0,且循环使用7次后去除率仍有63.4%,去除效果明显好于ACF和漆酶。通过超声协同作用的方法,提高了固定化漆酶处理苯酚废水的效果,去除率最高能达到95.1%。     

Effect of surface acid groups associated with amorphous and structured carbon on the catalytic hydrodechlorination of chlorobenzenes

BACKGROUND: Catalytic hydrodechlorination (HDC) is a progressive approach to treating chlorinated waste streams. While carbon is widely used as a catalyst support, the influence of carbon surface functionality on HDC performance has not been established. This work sets out to assess the impact of surface acid groups associated with activated carbon (AC), graphite and graphitic nanofibers (GNF) on Pd promoted gas phase HDC of chlorobenzene (CB) and 1,3‐dichlorobenzene (DCB). RESULTS: The acid groups were introduced by HNO₃ washing and the HDC reaction performed over bulk Pd and Pd physically mixed with each carbon. The carbon was subjected to a thermal treatment to remove the surface acidity. Characterization was by temperature programmed decomposition (TPD), temperature programmed hydrogen treatment (TPH), BET area, acid‐base titration, scanning and transmission electron microscopy. TPD, TPH and titration analyses served to establish the presence of surface oxygen groups after acid washing and facilitated an evaluation of the effectiveness of the thermal treatment to remove these groups. CONCLUSIONS: The surface acid groups inhibited HDC activity, a response most pronounced for Pd + AC, less so for Pd + graphite, while the effect was slight for Pd + GNF. HDC inhibition is attributed to chloroarene interaction with the surface functional (notably carboxylic) groups that impedes HDC. Fractional dechlorination of DCB was equivalent to or lower than CB HDC; there is some evidence of DCB interactions with heat treated graphite and GNF that served to raise HDC activity. Effective HDC over carbon based catalysts requires removal of surface acid groups. Copyright © 2008 Society of Chemical Industry     

Influence of pH on the wet oxidation of phenol with copper catalyst

This work reports the influence of pH on the catalytic wet oxidation (CWO) of phenol performed with a commercial copper-based catalyst. The results obtained show that pH is a critical parameter able to modify the chemical stability of the catalyst, the significance of the oxidation reaction in the liquid phase, the reaction mechanism and, consequently, the oxidation route of phenol. Experiments have been carried out to study the mentioned aspects. Stirred basket and fixed bed reactors (FBRs) have been employed, at 140 °C and at 16 bar of oxygen pressure. Three initial pH values have been used: 6 (the pH of the phenol solution), 3.5 (adjusted by H₂SO₄) and 8 (by addition of Na₂CO₃). Furthermore, some phenol oxidation runs without solid catalyst but with different concentrations of copper in solution have been accomplish at pHo=3.5. At acid pH, important leaching of copper from the catalyst to the solution was achieved, finding this negligible at pH 8. It was found that the major contribution to the phenol conversion reached at acid pH by using the solid catalyst was due to the catalytic activity of the leached copper. Both oxidation mechanisms at acid and basic conditions have been elucidated to explain the differences in the type and distribution of the intermediates obtained. The catalytic phenol oxidation route found at pH=8 comprises intermediates less toxic than phenol while at acid pH the cyclic intermediates formed as first oxidation intermediates are far more toxic than phenol.