含氰（腈）类废水湿式催化氧化处理理论分析

通过对现有关于湿式催化氧化法处理含氰（腈）废水的反机理分析研究,剖析了催化剂对WAO工艺的动力学,热力学等方面的影响,讨论了催化剂类型,温度,pH值,反应器类型等因素对氰（腈）类物质氧化过程的影响,并对CWAO工艺处理含氰（腈）废水的特点进行了总结,为建立含氰（腈）废水湿式催化氧化法的工程化实用技术提供一些理论与实验依据。     

水热电催化氧化法处理高浓度苯酚模拟废水的研究

结合催化湿式氧化法和电催化氧化法为水热电催化氧化法处理高浓度苯酚模拟废水((ρCOD)为7500mg/L):以C/Ru作催化剂(w(Ru)为0.5%),自制DSA阳极(釜体为阴极),加入NaCl作支持电解质(w(NaCl)为1%),充入氧气使PO2为3.5MPa,升温至设定温度后:开初0.5h进行苯酚的催化湿式氧化,后0.5h进行电催化氧化,并改变条件进行苯酚的单一催化湿式氧化和电催化氧化。结果表明:85℃时水热电催化氧化条件下,苯酚去除率为100%,COD去除率达92.34%,而单一催化湿式氧化和电催化氧化的COD去除率却依次为68.46%、39.73%,可见水热电催化氧化法利用了催化湿式氧化法和电催化氧化法的协同作用,取得了更佳的效果。该方法是一种新型、低温、高效的废水处理技术,为处理苯酚废水提供了另一种可能途径。     

焦化废水湿式氧化催化剂性能及工艺条件研究

对比Cu-Mn/Al 2O3、Cu-Zn/Al 2O3、Cu-Ti/Al 2O3、Cu-Ce/Al 2O3等系列催化剂的催化性能,优选出Cu-Ce/Al 2O3催化剂,考察催化湿式氧化处理焦化废水的工艺条件、催化剂活性及稳定性,结果显示,利用Cu-Ce/Al 2O3(摩尔比Cu:Ce=3:1)催化剂处理焦化废水时,该催化剂的加入可使焦化废水COD去除率提高40%,处理效果随温度升高明显增强,在保证氧气供应充足的情况下,适当增加氧气分压,对处理效果增加不太明显。其优化工艺条件为:反应温度180℃,总压4.8MPa,氧气分压1.4MPa,氧化反应时间120mi n,焦化废水COD去除率最高可达94.3%,且金属离子溶出量较少,该催化剂持续工作500h内,其催化活性和稳定性良好。     

催化湿式氧化中锰铈催化剂的研究进展

催化湿式氧化技术是一种通过选用适当催化剂,处理高浓度、高毒性以及难生物降解有机废水的有效方法。以Mn、Ce为活性成分的催化剂,具有成本低,活性高、稳定性和选择性好等优点。因此,锰铈催化剂已成为国内外的研究应用的热点。本文评述了锰铈催化剂的制备方法及应用概况,研究了催化剂的失活机理,探讨了催化剂再生措施,以期对有关研究者提供一定的参考。     

Catalytic wet air oxidation of olive oil mill effluents: 4. Treatment and detoxification of real effluents

Olive oil mill wastewater (OMW) generated by the olive oil extraction industry constitutes a major pollutant, posing severe environmental threats. It contains a high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Platinum and ruthenium supported titania or zirconia were studied in the catalytic wet air oxidation (CWAO) of OMWs in a batch reactor and in a continuous trickle-bed reactor. CWAO experiments at 190 °C and 70 bar total air pressure confirmed the effective elimination of the TOC (total organic carbon) and of the phenolic content of actual diluted OMW. Simultaneously, toxicity towards Vibrio fischeri was reduced and a decrease in phytotoxicity occurred. The ruthenium catalysts were found stable over a long period of operation in a trickle-bed reactor.The biodegradability of the oxidized waste has been enhanced and this study also examined the feasibility of coupling CWAO and an anaerobic digestion treatment. The pretreatment of the OMW in the presence of a ruthenium catalyst reduced considerably the total phenolic contents of the wastewater, and produced an effluent suitable to be treated by anaerobic treatment with increased biomethane production compared to the untreated effluent.     

Catalytic oxidation of aqueous methyl and dimethylamines by activated carbon

The catalytic wet air oxidation (CWAO) of methyl and dimethylamines was studied. A commercial peach stones activated carbon and its oxidized and reduced forms were used as catalysts. The observed catalytic behavior is related to the presence of oxygenated surface functional groups on the activated carbons. The N-compounds were selectively oxidized to nitrogen, water and carbon dioxide using these activated carbon catalysts. It is proposed that the quinonic surface groups are responsible for the selective catalytic oxidation of these amines. Carboxylic, lactonic and anhydride groups strongly adsorb the amine compounds producing inhibition of the catalytic activity of the activated carbon in the CWAO process.     

Phenol Catalytic Wet Air Oxidation Over Ru Nanoparticles Formed in Hypercrosslinked Polystyrene

Catalytic wet air oxidation (CWAO) of phenols is an important process of environmental catalysis, allowing one to reach nearly complete oxidation of phenols to non-hazardous compounds. Here we report syntheses of nanocatalysts based on Ru-containing nanoparticles (NPs) formed in the pores of hypercrosslinked polystyrene (HPS) and their catalytic properties in the phenol CWAO under mild conditions. The Ru species were incorporated in HPS using wet impregnation of ruthenium(IV) hydroxychloride in a complex solvent followed by the NaOH and H₂O₂ treatment. The catalysts containing from 0.5 to 2.8 wt% of Ru were studied by X-ray fluorescence analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, and liquid nitrogen physisorption methods. The NP sizes were controlled by the pores of HPS. The two types of Ru species: Ru(IV) and Ru(IV) × nH₂O, constituted the NP composition. The effects of the phenol and catalyst initial concentrations and temperature were investigated in the phenol CWAO. Removal of 97 % of phenol was observed for the most active catalyst containing 2.8 wt% of Ru.     

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。     

废水高温深度氧化处理技术

介绍了多种废水高温深度氧化技术,包括湿式空气氧化技术、催化湿式氧化技术、湿式过氧化物氧化技术、超临界水氧化技术和焚烧技术,其中着重比较了焚烧技术中四种炉型的特点。     

Surface modification of carbon-supported iron catalyst during the wet air oxidation of phenol: Influence on activity, selectivity and stability

Catalytic wet air oxidation (CWAO) of phenol with iron/activated carbon catalysts (Fe/AC) at temperature of 400 K and 8 atm of total pressure is an efficient treatment to oxidize a resistant pollutant such as phenol into biodegradable species, mainly short chain acids. Extended studies employing activated carbon catalysts point out significant changes in the carbon as a consequence of the CWAO process. After the long-term experiments carried out in this work it was concluded that these modifications consist of loss of microporosity, temporary decrease of the mesoporosity, decrease of the carbon/oxygen ratio on the catalyst surface, more acidic pH_slurry values, and aggregation of the -Fe₂O₃ crystallites. The causes that provoke these changes and the reasons why they do not alter significantly the CWAO efficiency were analyzed. The way of exposition of Fe/AC catalyst to the reactants plays an important role in its activity and selectivity towards complete mineralization, namely oxidation to CO₂ and H₂O.     

催化湿式氧化处理头孢氨苄废水

采用催化湿式氧化处理头孢氨苄废水,考察反应温度、进水pH及Cl-含量对RCT催化剂性能的影响,并对液体样品及催化剂进行了HPLC、TOC/TN、GC-MS、N2物理吸附-脱附及XRF表征。通过正交实验,得出最佳的工艺条件为:进水pH=4.8,Cl-浓度1 500 mg·L-1,反应温度260℃;对催化剂进行300 h连续寿命考察,废水TOC及TN去除率均超过90%,催化剂稳定性高,活性组分流失较少;废水经催化湿式氧化处理,水中残留的主要有机物均可生化降解。     

Ru/TiO_2催化剂制备及其在有机酸废水湿式氧化中的应用

以纳米TiO_2为载体,通过优化制备方法,合成了高活性的Ru/TiO_2贵金属催化剂,采用X射线衍射(XRD)、N_2物理吸附、程序升温还原(H_2-TPR)和透射电镜(TEM)等手段对催化剂进行表征,并将制备的催化剂应用到湿式氧化处理3种有机酸模拟废水中。研究表明,氢气还原有助于Ru在TiO_2表面的分散,由此制备的催化剂氧化活性较高。在200℃,初始氧压3 MPa的条件下反应2 h,Ru/TiO_2在湿式氧化处理丙烯酸、丁二酸和乙酸有机酸模拟废水时,化学需氧量(COD)去除率分别达到95.3%,91.6%和70.1%。     

Catalytic wet air oxidation of ammonia over M/CeO2 catalysts in the treatment of nitrogen-containing pollutants

Ammonia, a well-known by-product of chemical, fertiliser and metallurgy industries, is also the most refractory product of nitrogen-containing compound oxidation. Consequently, NH₄⁺ is a key component of waste disposal of conventional processes like anaerobic digestion or nitrification/denitrification. Catalytic wet air oxidation (CWAO) process, able to eliminate organic matter with non toxic by-product formation, was investigated for ammonium ions removal from wastewater. Oxidation of aniline and of ammonia were carried out on mono- and bimetallic noble metal catalysts (Pt, Ru, Pd, etc.) prepared by impregnation and supported on cerium oxides. In liquid phase, at high temperature (150–250 °C) and high pressure of oxygen (20 bar), a Ru/CeO₂ catalyst is able to achieve the elimination of refractory nitrogenous organic products like aniline. The greatest interest of CWAO compared to the classical biological one, is that the selectivity towards molecular nitrogen is much higher (>90%). Indeed, in this process, ammonium ions give essentially N₂, via hydroxylamine and below 200 °C. At higher temperatures the rate of conversion is extremely high but nitrite and nitrate ions appear in the effluent. On a RuPd/CeO₂ catalyst, the optimal temperature for ammonia conversion is then 200 °C. In these conditions, the N₂ selectivity is up to 90%.     

Stable and efficient Ru/TiO2-ZrO2 catalysts for catalytic wet air oxidation of phenolsulfonic acid wastewater treatment

Catalytic wet air oxidation (CWAO) technology can efficiently treat organic wastewater, but the performance of existing catalysts, especially its stability, is far from industrial applications. In this study, ZrO₂ was used to modify TiO₂ support to form the stable Ru/TiO₂-ZrO₂ catalysts. It was found that the Ru/TiO₂-ZrO₂ catalysts showed excellent performance for catalytic wet air oxidation of phenolsulfonic acid wastewater. They gave high total organic carbon (TOC) conversions (>90%) and remained stable in 5 consecutive running in the Ti/Zr ratio range from 9∶1 to 7∶3. On the other hand, TOC conversion decreased from 99.1% to 65.3% in 5 consecutive cycles for the conventional Ru/TiO₂ catalyst. The characterization results of XRD, BET, XPS, H₂-TPR and ICP-OES indicated that ZrO₂ can enter the lattice of TiO₂ to form TiO₂-ZrO₂ solid solution, which prevented the transformation of TiO₂ from anatase to rutile. In addition, the modification of ZrO₂ strengthened the interaction between Ru and the support, which effectively inhibited the leaching of Ru metal. The stable support structure and good anti-loss performance are the main reasons for the excellent reaction performance of Ru/TiO₂-ZrO₂ catalyst.     

稳定高效Ru/TiO2-ZrO2催化剂处理苯酚磺酸废水

催化湿式氧化（CWAO）技术可高效处理有机废水，但现有催化剂的性能，尤其是其稳定性距工业应用还有很大差距。利用ZrO₂对TiO₂载体进行掺杂调变，研制出了具有良好稳定性的Ru/TiO₂-ZrO₂催化湿式氧化催化剂。结果表明， Ru/TiO₂催化剂在进行连续5次催化湿式氧化降解苯酚磺酸（phenolsulfonic acid，PSA）废水的反应后，总有机碳（total organic carbon，TOC）转化率由99.1%降低至65.3%；而Ru/TiO₂-ZrO₂催化剂在Ti/Zr质量比为9∶1~7∶3范围内，能表现出优良的反应性能，在连续5次反应后， TOC转化率稳定保持在90%以上。X射线仪衍射（XRD）、N₂吸脱附（BET）、X射线扫描微探针电子能谱仪（XPS）、氢气程序升温还原（H₂-TPR）和电感耦合等离子体发射光谱（ICP-OES）表征结果表明：ZrO₂能够进入TiO₂的晶格，TiO₂-ZrO₂固溶体的生成阻止了TiO₂由锐钛矿相向金红石相的转变。另外，ZrO₂的调变加强了Ru与载体的相互作用，有效抑制了活性金属Ru的流失。稳定的载体结构和良好的抗流失性能是Ru/TiO₂-ZrO₂催化剂具有优良反应性能的主要原因。     

Catalytic wet-air oxidation processes: A review

Environmental catalysis usually refers to end-of-the-pipe treatment processes that reduce the emissions of hazardous pollutants. Abatement of pollutants in aqueous streams by means of heterogeneous catalysts is an example of such process. This paper reviews the developments in the field of catalytic wet-air oxidation (CWAO). Catalysts are reviewed first, followed by mechanistic speculations and kinetics that have been proposed for the CWAO process. The process is discussed more in detail only in those cases where it is already commercialised or at least foreseen to be in the near future. Particular attention was given to the heterogeneously catalyzed wet-air oxidation of real industrial wastewaters (such as Kraft bleach plant effluents) in batch and continuous-flow oxidation reactors. Finally, the considerable potential of the CWAO process to ultimately destroy organic pollutants in industrial effluents and detoxify them by using novel titania-supported Ru catalysts is presented.     

湿式催化氧化/膜过滤组合工艺膜过滤机理

采用湿式催化氧化/膜过滤组合工艺,以Mo-Zn-Al-O粉末作为催化剂降解阳离子红GTL模拟染料废水,探讨在膜过滤过程中平均孔径为0.1 μm的微滤和0.022 μm的超滤聚偏氟乙烯(PVDF)中空纤维膜的过滤机理。实验结果表明,两种膜过滤组合工艺对染料的降解效果均优于单独湿式催化氧化,0.01 MPa恒压条件下运行120 min后微滤和超滤的膜通量分别衰减了26.63%和16.48%,其原因是粉末催化剂可在微滤膜孔内部沉积形成中间阻塞过滤,后在表面形成滤饼层;而在超滤膜表面仅形成滤饼层。通过实验结果对膜阻力进行计算,可知在相同反应过程后微滤膜产生的不可逆阻力大于超滤膜。在不同反应条件下,催化剂的沉积量与膜阻力呈现线性相关。     

废水催化湿式氧化处理中的催化剂失活问题

活性组分流失和催化剂表面积炭是导致废水催化湿式氧化处理中催化剂失活的主要原因。介绍了催化湿式氧化中催化剂失活的机理和影响其失活的原因。催化剂组分和制备方法、反应条件以及反应器类型会影响催化剂的失活。对提高催化剂稳定性的方法也作了论述。     

Catalytic wet air oxidation of phenol and acrylic acid over Ru/C and Ru–CeO2/C catalysts

Ru/C catalysts promoted, or not, by cerium were prepared by impregnation of an active carbon (961 m² g⁻¹) with chlorine-free precursors of Ru and Ce. They were characterized by chemisorption of H₂ and of CO and by electron microscopy. TEM and H₂ chemisorption gives coherent results while CO chemisorption overestimates Ru dispersion. In Ru–Ce/C, Ce is in close contact with Ru and decreases Ru accessibility.

Catalytic wet air oxidation (CWAO) of phenol and of acrylic acid (160°C and 20 bar of O₂) was investigated over these catalysts and their performance (activity, selectivity to intermediate compounds) compared with that of a reference Ru/CeO₂ catalyst. Carbon-supported catalysts were very active for the CWAO of phenol but not for acrylic acid. Although high conversions were obtained, phenol was not totally mineralized after 3 h. It was shown that acrylic acid was more strongly adsorbed than phenol. Moreover, the number of contact points between Ru particles and CeO₂ crystallites constitutes a key parameter in these reactions. A high surface area of ceria is required to insure O₂ activation when the organic molecule is strongly adsorbed.     

CWPO中催化剂的应用研究现状及趋势

催化湿式过氧化氢氧化技术是一种专门针对高浓度难降解有机废水的处理技术.本文对该技术中使用的催化剂进行了分类评述,其中详细讨论了非均相催化剂的研究状况,并展望了其今后的发展方向.