非均相湿式催化氧化中H_2O_2的分解

为了考察催化湿式氧化中H2O2分解的影响因素,以CuO/γ-Al2O3为催化剂,模拟苯酚废水为对象,实验研究了该体系中H2O2分解的动力学规律,系统考察了H2O2加入量、催化剂加入量、溶液pH和温度对H2O2分解的影响.研究结果表明,这4个因素对H2O2的分解均有较大影响,在实际过程中应加以控制,以达到最佳效果.     

过氧化氢及其基本有机化学品绿色合成技术

烃类氧化与氮化反应是生产基础有机化学品和高附加值产品的主要反应,在满足和丰富人类物质需求方面贡献巨大,传统的工业氧化与氮化工艺导致严重的环境问题,亟需绿色化转型。作为公认的绿色氧化剂,过氧化氢在烃类氧化和氮化的绿色生产工艺中应用广泛。文章简要介绍了国内外过氧化氢生产现状,重点介绍了中国石化石油化工科学研究院浆态床过氧化氢生产技术,以己内酰胺、环氧丙烷和环氧氯丙烷为例,介绍了过氧化氢在绿色烃类氧化和氮化反应中的应用,汇报了石油化工科学研究院近年来在绿色化工方面的主要研究进展及工业实践结果。多个成套绿色化工技术的成功开发突破了国外对我国的技术封锁,为多个化工生产基地提供全流程绿色生产技术,有力保障了我国化工行业的绿色化转型。     

双氧水绿色合成工艺的进展研究

随着社会经济的发展,环境污染问题也日益的严重。出于环保的理念,在对双氧水进行合成时,也应从环保的角度出发,尽量的做到避免对环境的污染。着重探讨了双氧水的绿色合成的工艺,通过介绍双氧水合成的过程,分析双氧水在合成过程中的特点,并且介绍了相关的绿色合成双氧水的技术等。希望通能够为相关方面的研究提供理论性的参考。     

双氧水氧化塔革新总结

通过对双氧水氧化工序原工艺和氧化塔中存在的问题进行调查分析,提出了新的技改工艺流程和新的氧化塔设备结构,实施后取得了下述的显著经济效果:(1)氧化流程短,工艺简单,产量高,比原工艺产量提高40%,单台产量可达5600t/a,每年多创产值384万元;(2)仪表连锁自控,操作方便,生产稳定,空气消耗量少,能耗小;(3)氧化塔的氧化能力大,结构简单,便于制造,单台造价降低6万元;(4)氧化效率提高6%达到96%,每年可多生产266t,多创利润63.84万元;(5)回收尾气中芳烃,确保废气、废液的排放达到环保要求.     

Full phenol peroxide oxidation over Fe-MMM-2 catalysts with enhanced hydrothermal stability

Iron-containing mesoporous mesophase materials Fe-MMM-2 have been synthesized by a sol–mesophase route under mild acidic conditions and characterized by DRS-UV–vis, XRD, and N₂ adsorption measurements. It was found that pH of the synthesis solution and iron content in the samples affect both the textural characteristics and the state of iron atoms. Isolated iron species predominate in silica framework under Fe < 2 wt% and pH  1.0 or Fe  1 wt% and pH < 2.0. These species are stable to leaching and highly active in full H₂O₂-based phenol oxidation. The increase in iron loading and pH of the synthesis solution lead to the agglomeration and formation of oligomeric iron species, which, in turn, results in the reduction of the catalytic activity of Fe-MMM-2 and the increase of iron leaching.     

对氯苯甲醇绿色催化氧化合成对氯苯甲醛

介绍了一种重要精细化工中间体对氯苯甲醛的绿色合成方法。以对氯苯甲醇为原料,过氧化氢作氧化剂,铜盐作催化剂,通过催化氧化合成对氯苯甲醛。分别考察了铜盐种类及用量、过氧化氢用量及滴加时长和反应温度对收率的影响。得到最佳反应条件为：乙酸铜作催化剂,投料摩尔比n(乙酸铜)∶n(对氯苯甲醇)∶n(过氧化氢) = 1∶100∶300,水作溶剂,96 ℃反应2 h后,转化率为93.1%,生成对氯苯甲醛的选择性为97.7%,最终收率高达91.0%。将含催化剂水相进行循环利用,发现循环5次后,对氯苯甲醛的收率仍可达85%以上。该方法氧化剂绿色环保,催化剂及溶剂可多次循环利用,且不产生废酸,适用于工业生产。     

双氧水的生产方法与应用

介绍了双氧水的５种生产方法及各自优缺点,并介绍了双氧水在纺织、化工行业、造纸、环保、电子、冶金、食品等行业的应用,指出国内企业应加快开发市场急需的Ｈ２Ｏ２及其下游产品。     

Electrochemical oxidation of Crystal Violet in the presence of hydrogen peroxide

BACKGROUND: The combination of electrochemical oxidation using a Ti/RuO₂? IrO₂ anode with hydrogen peroxide has been used for the degradation of Crystal Violet. The effect of major parameters such as initial pH, hydrogen peroxide concentration, current density, electrolyte concentration and hydroxyl radical scavenger on the decolorisation was investigated. RESULTS: The decolorisation rate increased with initial pH and hydrogen peroxide concentration, but decreased with electrolyte and radical scavenger concentration. The decolorisation rate increased with current density, but the increase became insignificant after current density exceeded 47.6 mA cm^?2. On the other hand, hydrogen peroxide decomposition rate increased with initial pH and current density, but decreased with electrolyte and radical scavenger concentration. The amount of hydrogen peroxide decomposed during 30 min reaction increased linearly with hydrogen peroxide dosage. The main intermediates were separated and identified by gas chromatography–mass spectrometry (GC–MS) technique and a plausible degradation pathway of Crystal Violet was proposed. At neutral pH, the electrochemical process in the presence of hydrogen peroxide was more efficient than that in the presence of Fenton's reagent (electro‐Fenton process). CONCLUSION: The anodic oxidation process could decolorise Crystal Violet effectively when hydrogen peroxide was present. Almost complete decolorisation was achieved after 30 min reaction under the conditions 2.43 mmol L^?1 hydrogen peroxide, 47.6 mA cm^?2 current density and pH₀ 7, while 62% COD removal efficiency was obtained when the reaction time was prolonged to 90 min. Copyright © 2010 Society of Chemical Industry     

过氧化氢氧化法制偶氮二甲酰胺工艺的研究

采用过氧化氢(含量50%以上)为氧化剂,以溴化钠为主催化剂、铁基物质为助催化剂氧化联二脲制偶氮二甲酰胺产品,工艺操作简单,且反应母液循环套用,减少三废排放,达到清洁文明生产效果。     

Catalytic wet peroxide oxidation of phenolic solutions over a LaTi1−xCuxO3 perovskite catalyst

LaTi_1−xCu_xO₃ perovskites are efficient catalysts for the oxidation of aqueous solutions of phenol using hydrogen peroxide as precursor of free radicals. The catalytic results have shown that under mild reaction conditions and oxidant contents lower than stoichiometric, phenol was rapidly removed with a final total organic carbon (TOC) conversion of ca. 90%. Initial rate of TOC removal depends dramatically on temperature, catalyst loading and peroxide concentration. Perovskite catalyst after reaction is completely regenerated by calcination and retains a similar catalytic performance. Finally, the catalytic results demonstrate that leaching of active species during the catalytic oxidation seems to proceed by a complex mechanism in which the presence of hydrogen peroxide in combination with phenol plays an essential role.     

An Integrated Process of H2O2 Production through Isopropanol Oxidation and Cyclohexanone Ammoximation

The possibility of the integration of the processes of H₂O₂ production through isopropanol partial oxidation and the direct ammoximation of cyclohexanone with H₂O₂ and NH₃ catalyzed by TS‐1 was investigated. The results of isopropanol partial oxidation showed that around 7.5 % yield of H₂O₂ was obtained at 110 °C, 10 atm, 2 h, and after fractionation, a H₂O₂ solution with the typical composition 25.2 wt.‐% H₂O₂, 10.3 wt.‐% isopropanol, 0.29 wt.‐% acetone, 0.45 wt.‐% phosphoric acid and 0.43 wt.‐% acetic acid was obtained. The presence of these impurities up to the above levels did not appreciably influence the ammoximation of cyclohexanone in terms of the conversion of cyclohexanone and the selectivity to cyclohexanone oxime. The results indicate that the processes of H₂O₂ production through isopropanol partial oxidation and the ammoximation of cyclohexanone can be integrated.     

环己烷氧化液中过氧化物组成剖析

采用对环己烷空气氧化后的氧化液进行水洗和环己烷反萃取的方法,剖析环己烷氧化液中环己基过氧化氢和己酸过氧化氢组成分布。结果表明:环己烷氧化液有质量分数9.57%的过氧化物被洗出,可通过水洗将环己基过氧化氢和己酸过氧化氢分离;己酸过氧化氢占环己烷氧化液中过氧化物的9.4%,而环己基过氧化氢占环己烷氧化液中过氧化物约90.0%。     

Partial oxidation of methane and the effect of sulfur on catalytic activity and selectivity

Partial oxidation of methane into syngas was conducted over fresh and sulfided catalysts at a temperature range of 450–750 °C. The temperature dependence of conversion, H₂/CO ratio, and the CO₂ concentration were measured for both fresh and sulfided catalysts. Regardless of metal type, metal loading, support type, and the methods of preparation it appears that all the fresh catalysts were very active and conversions of higher than 70% with H₂/CO ratio of about 2 were observed at 750 °C. Pulse sulfidation appears to be reversible for some of the catalysts but not for all. Under pulse sulfidation conditions, the Rh(0.5%)/Al₂O₃ and NiMg₂O_x-1100 °C (solid solution) catalysts were fully regenerated after reduction with hydrogen. Rh catalyst showed the best overall activity, less carbon deposition, both fresh and when it was exposed to pulses of H₂S. Sulfidation under steady-state conditions, flowing H₂S/Ar mixture over the catalysts, significantly reduce catalyst activity. The catalysts were characterized before and after reaction with H₂S using temperature-programmed oxidation (TPO) and reduction (TPR), X-ray diffraction, and XPS.     

Direct synthesis of hydrogen peroxide from H2 and O2 using zeolite-supported Au catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using zeolite-supported Au catalysts is described and their activity is contrasted with silica- and alumina-supported Au catalysts. Two zeolites were investigated, ZSM-5 and zeolite Y. The effect of calcination of these catalysts is studied and it is found that for uncalcined catalysts high rates of hydrogen peroxide formation are observed, but these catalysts are unstable and lose Au during use. Consequently, reuse of these catalysts leads to lower rates of hydrogen peroxide formation. However, catalysts calcined at 400 °C are more stable and can be reused without loss of gold. The use of zeolites as a support for Au gives comparable rates of hydrogen peroxide formation to alumina-supported Au catalysts and higher rates when compared with silica-supported catalysts. prepared using a similar method. Zeolite Y-supported catalysts are more active than ZSM-5-supported catalysts for the stable calcined materials. It is considered that the overall activity of these supported catalysts may be related to the aluminium content as the activity increases with increasing aluminium content.     

Direct synthesis of hydrogen peroxide from H2 and O2 using zeolite-supported Au-Pd catalysts

The direct synthesis of hydrogen peroxide from H₂ and O₂ using zeolite-supported Au-Pd catalysts is described using two zeolites, ZSM-5 and zeolite Y, using an impregnation method of preparation. The addition of Pd to Au for these catalysts significantly enhances the productivity for hydrogen peroxide. The use of zeolites as a support for Au-Pd gives higher rates of hydrogen peroxide formation when compared with alumina-supported Au catalysts prepared using a similar method. The addition of metals other than Pd is also investigated, but generally Au-Pd catalysts give the highest activity for the synthesis of hydrogen peroxide. The addition of Ru and Rh have no significant effect, but the addition of Pt does enhance the activity for the selective formation of hydrogen peroxide.     

Chemical oxidation of anthracite with hydrogen peroxide via the Fenton reaction

Solutions of 30% H₂O₂ ranging from pH = 0 to pH = 11.5 have been used to oxidize anthracite at room temperature. The inorganic impurities, primarily pyrite, catalysed the oxidation and reduction of H₂O₂ (the Fenton reaction) to form the hydroxyl radical; the oxidation of the organic matter was minimal and was observed only in strong acidic solutions (pH < 1.5). After acid demineralization, samples of the same anthracite underwent a significant enhancement of oxidation in both acid and alkaline solutions (pH = 0.4–11.5). As all the iron had been removed from the surface and the reactions were completed in a much shorter time, the oxidation mechanism must have been of a different nature than that for the untreated anthracite. A qualitative model based on the catalytic decomposition of H₂O₂ by activated carbon sites in the coal surface is used to explain the oxidation of the demineralized anthracite.     

Catalytic wet peroxide oxidation of phenol with a Fe/active carbon catalyst

A Fe on activated carbon catalyst has been prepared and tested for phenol oxidation with H₂O₂ in aqueous solution at low concentration (100 mg/L). Working at 50 °C, initial pH 3 and a dose of H₂O₂ corresponding to the stoichiometric amount (500 mg/L) complete removal of phenol and a high TOC reduction (around 85%) has been reached. Oxidation of phenol gives rise to highly toxic aromatic intermediates which finally disappear completely evolving to short-chain organic acids. Some of these last showed to be fairly resistant to oxidation being responsible for the residual TOC. In long-term continuous experiments the catalyst undergoes a significant loss of activity in a relatively short term (20–25 h) due to Fe leaching, this being related with the amount of oxalic acid produced. Deactivation may also be caused by active sites blockage due to polymeric deposits on whose formation some evidences were found. Washing with 1N NaOH solution allows to recover the activity although complete restoration was not achieved.     

Hydrogen peroxide promoted wet air oxidation of phenol: influence of operating conditions and homogeneous metal catalysts

The promoted wet air oxidation of phenol has been investigated through the addition of hydrogen peroxide as a source of free radicals. The reaction has been shown to proceed in two stages, an initial fast reaction associated with hydrogen peroxide consumption and a second slower step that occurs at a rate comparable with conventional wet air oxidation. An increase in temperature has a positive effect on both stages, while oxygen partial pressure only influences the second slower stage. The influence of pH on phenol oxidation is shown to be significant with the highest efficiency achieved at very alkaline conditions when phenol is completely dissociated. The catalytic activity of homogeneous metal salts was investigated in both the presence and absence of hydrogen peroxide. The combined addition of hydrogen peroxide and a bivalent metal (ie copper, cobalt or manganese) is shown to enhance the rate of phenol removal. However, in the absence of hydrogen peroxide only copper exhibited catalytic activity. Finally, a reaction mechanism involving different radical species has been proposed. From the experimental results the apparent activation energy (96.9 ± 3.5 kJ mol⁻¹) and pre‐exponential factor (1.6 ± 0.2 10¹⁰ s⁻¹) were calculated for hydrogen peroxide decomposition into hydroxyl radicals. © 1999 Society of Chemical Industry     

湿式过氧化氢催化氧化降解喹啉及其机理

采用浸渍法制备了负载型铜铁氧化物催化剂,并以喹啉为目标污染物,建立了湿式过氧化氢催化氧化(CWPO)体系.研究了反应温度、初始pH、H₂O₂和催化剂投加量对喹啉去除效果的影响,并分析了CWPO体系中 的作用及喹啉的降解路径.结果表明,CWPO对喹啉具有很好的去除效果,反应30 min喹啉的去除率可达到100%,反应60 min矿化率可达到88.34%.确定了最佳反应温度为80℃,初始pH为7,H₂O₂和催化剂投加量分别为29.15 mmol·L^-1和4 g·L^-1. 氧化在CWPO降解喹啉体系中起主导作用,其平均产生速率为1.69×10^-6 mmol·L^-1·min^-1.推测了CWPO降解喹啉的4种可能路径,在中性和酸性条件下,分别生成以吡啶环或苯环为主的中间产物.     

Catalytic wet peroxide oxidation over mixed (Al–Fe) pillared clays

Mixed (Al–Fe) pillared clays are very efficient solid catalysts for oxidation of organic compounds in water by hydrogen peroxide. We have shown that in rather mild experimental conditions (atmospheric pressure, T≤70°C) and with a low excess (20%) of hydrogen peroxide, phenol was rapidly converted, mainly to CO₂, without significant catalyst leaching. The (Al–Fe) pillared clay catalyst (called FAZA) can be used several times without any change of its catalytic properties. According to the low leaching observed and a previous Mössbauer spectroscopy study, the iron species appear to be strongly bonded to the aluminium pillars.