铝及其氮化物表面干法氧化的研究进展

介绍了铝及其氮化物表面干法氧化的研究现状及发展前景.总结了不同氧化方法对铝氧化膜性质的影响,并对采用干法制备铝氧化膜及氮氧化膜技术的发展前景进行了展望,指出采用铝表面的热氧化、多组分等离子氧化制备铝氧化膜或氮氧化膜将成为铝氧化技术新的发展方向.     

废水的深度氧化处理技术研究进展

介绍处理生物难降解有机物的各种深度氧化处理技术--光化学催化氧化、湿式催化氧化、超临界水氧化、电解氧化及其他深度氧化技术,阐述了各种技术的机理及研究进展,探讨了各项技术发展的前景与趋势.     

废水的深度氧化处理技术研究进展

介绍处理生物难降解有机物的各种深度氧化处理技术——光化学催化氧化、湿式催化氧化、超临界水氧化、电解氧化及其他深度氧化技术,阐述了各种技术的机理及研究进展,探讨了各项技术发展的前景与趋势。     

TiC基金属陶瓷的高温氧化行为

研究了以Fe-Cr-Si或Ni-Fe-Cr-Si为粘结相的新型TiC基金属陶瓷在850℃空气中的氧化行为,测定并计算了氧化增重与时间的函数关系及氧化速率.结果表明,这类陶瓷材料的氧化为"钝化型氧化",显示出较好的抗氧化性和力学性能.通过X射线衍射(XRD)、扫描电镜(SEM)等手段,分析了氧化膜的组成与结构,探讨了TiC基金属陶瓷高温下的耐氧化机理.     

Diesel Oxidation Catalysts

The diesel oxidation catalyst (DOC) has been part of diesel exhaust systems since regulations were introduced to limit the amount of harmful emissions released to the environment from diesel engines. The DOC primary functions are oxidation of CO, unburned hydrocarbons, and NO, while active hydrocarbon oxidation can also be used to generate exotherms required for downstream components. This review will describe work that has attempted to understand the reactions, both desired and undesired, that occur over the catalyst. First, the history, configuration, and components of the DOC will be discussed, followed by in-depth coverage of the fundamental reactions that occur over a DOC, including reaction mechanisms, reaction inhibition, and other reactivity effects. Finally, DOC deactivation mechanisms and their effects on the DOC are described. While there is a lot of research literature regarding Pt- and Pd-based catalysts for many different reaction schemes, this review tries to highlight work most relevant to DOC applications.     

Selective oxidation with air on metal catalysts

Oxidation of organic molecules with air on metal catalysts has been known for a long time but there has been a renewed interest in recent years because these catalytic reactions are environmentally safe and could replace stoichiometric oxidations. This paper describes several oxidation reactions conducted either at high temperatures in the gas phase or at moderate temperatures in the liquid phase; in both cases they proceed via a mechanism of oxidative dehydrogenation on the metal surface. Ethylene glycol was converted to glyoxal at 550°C on Ag/SiC catalyst with a 70% yield provided promoters were added to the reaction feed (diethylphosphite or iodine) or deposited on the catalyst (LiPO₄ or H₃PO₄). The promoters improve the conversion and selectivity by modifying the structure and the oxygen concentration on the surface of silver. Oxidation of glyoxal to glyoxylic acid, glucose to gluconic acid and glycerol to various oxygenated derivatives were conducted in water at 60°C in the presence of carbon-supported palladium or platinum catalysts. Bismuth promoter, deposited on the platinum metals by redox reaction, improves the catalyst activity by preventing over-oxidation of the metal surface and favors the oxidation of secondary alcohol functions into keto-derivatives. At higher reaction temperatures, platinum catalysts produce C-C bond rupture with the formation of carboxylic acids with smaller chains. Thus, cyclohexanol was converted into C₆, C₅, and C₄ diacids with a 45% selectivity to adipic acid on Pt/C catalysts at 150°C.     

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。     

甲苯直接氧化制苯甲醛研究进展

简单清洁的甲苯直接氧化法是苯甲醛生产技术的发展方向。对于气相直接氧化法,开发高活性和高选择性的催化剂,提高苯甲醛的选择性和收率是研究的热点。液相直接氧化法易于工业化,而寻找合适的催化剂和溶剂是目前的研究方向。     

生物难降解有机污染物废水深度氧化治理技术进展

本文综述了处理废水中生物难降解有机污染物的深度氧化技术—湿式空气氧化法、超，临界水氧化法、复合空气氧化法、光化学氧化法及其相应的催化氧化法，评论这些方法的特点及应用前景有38篇参考文献。     

苯环侧链烃基氧化研究进展

苯环侧链氧化是有机合成反应中的重要反应类型之一。综述了近年来苯环侧链烃基氧化的各种方法,并阐明了各种方法的优缺点,提出了苯环侧链烃基氧化反应的研究方向。     

催化氧化法处理印染废水的研究进展

印染废水色度深,毒性大,有机污染物含量高且难降解,采用催化氧化法能将污染物氧化分解。主要介绍了催化氧化法处理印染废水的研究进展,包括光催化氧化法、二氧化氯氧化法、电化学氧化法、Fenton试剂氧化法,对各种方法进行了评价,同时对催化氧化法处理印染废水的发展前景做了简述。     

组合氧化法深度处理煤制甲醇污水的实验研究

采用Fenton-NaClO组合氧化法对煤制甲醇污水进行深度处理。确定了最佳的Fenton氧化条件:H_2O_2投加量为90 mmol/L,Fe~(2+)浓度为30 mmol/L,p H=4,反应时间为60 min。最佳的NaClO氧化条件:p H=6,NaClO浓度为40 mmol/L,反应时间为60 min。经Fenton-NaClO组合氧化法处理后,出水COD、氨氮分别从280、130 mg/L降到43、8 mg/L,均可满足《污水综合排放标准》(GB 8978—1996)中规定的一级排放标准。     

Competitive no,co and hydrocarbon oxidation reactions over a diesel oxidation catalyst

The oxidation of NO, CO and hydrocarbons (HC) individually, in mixtures, and with NO₂ were investigated over a monolith‐supported Pt/Al₂O₃ catalyst under oxidising conditions. Although competitive adsorption and inhibition by other species on oxidation reactions is a relatively well‐known phenomenon, this study represents a more comprehensive examination of such effects between key components in vehicle exhaust gases. NO₂ was completely reduced by CO and C₃H₆, under NO₂ limited conditions, at temperatures as low as 110°C and at temperatures above 140°C with dodecane and m‐xylene. NO₂ was then again observed once the extent of oxidation of the other species by oxygen was significant. Under the conditions tested, NO, CO and HC oxidation was inhibited by NO₂ in the feed gas mixture. HC were also found to inhibit the oxidation of NO and other HC species due to site adsorption competition. For CO, HC did not change the onset of oxidation, but did inhibit the extent after their light off began. At low temperatures, CO was initially found to inhibit NO oxidation, but at higher temperatures, once CO oxidation was significant, CO promoted NO conversion to NO₂. The observed inhibition effects of the different gases on HC oxidation were not additive, indicating one species would cause inhibition, but once its inhibition ended, another species could still then cause inhibition. The combined effect of C₃H₆, NO and NO₂ on CO conversion was found to be additive. This is because CO oxidation started prior C₃H₆. © 2011 Canadian Society for Chemical Engineering     

Mechanism of active and passive oxidation of reaction-bonded Si3N4-SiC refractories

The mechanism of the active and passive oxidation of reaction-bonded Si₃N₄-SiC refractories used for six-month in silicon nitridation shuttle has been analyzed. The change of morphology and component of reaction-bonded Si₃N₄-SiC block of saggar have been analyzed. The results show that in Si₃N₄-SiC, Si₃N₄ has a higher activity and is more easily oxidized than SiC in both active and passive oxidation modes. All the fibrous α-Si₃N₄ which exists in a substantial amount in Si₃N₄-SiC before use has transformed to β-Si₃N₄ or was oxidized. The burning side of Si₃N₄-SiC block, which operates in high oxygen partial pressure, is oxidized in passive mode generating SiO₂, Si₂N₂O and carbon. The working side of Si₃N₄-SiC block, who works in low oxygen partial pressure, is oxidized in the active mode generating gaseous SiO. In another stage of service, SiO generated by silicon nitridation in the saggar infiltrates into the block and reacts with nitrogen forming small rods of Si₃N₄ that fill pores, which leads to lower apparent porosity. In the middle section of the block, two different oxidation modes coexist, since there is a gradually variation of oxygen partial pressure.     

Performance of CO preferential oxidation reactor with noble-metal catalyst coated on ceramic monolith for on-board fuel processing applications

On-board fuel processors are being developed to provide hydrogen-rich gas to the polymer electrolyte fuel cell automotive propulsion systems. Whereas the anode catalyst in the fuel cell has low tolerance for carbon monoxide, 10–100 ppm, reforming of gasoline and other hydrocarbon fuels generally produces 1–2% of CO. Of the many methods of removing CO from the reformer gas, preferential oxidation (PrOx) of CO over noble-metal catalysts is practiced most frequently. In this paper, we present experimental data for CO conversion on a Pt-based catalyst that is active at room temperature and was coated on a ceramic monolith. The data is used to develop an empirical correlation for selectivity for CO oxidation as a function of CO concentration and oxygen stoichiometry at 30,000–80,000/h space velocity. The selectivity correlation is used in a model to analyze the performance of multi-stage, adiabatic PrOx reactors with heat exchange between the stages to cool the reformate to 100 °C. An optimization algorithm is used to determine the operating conditions that can reduce CO concentration to 10 ppm while minimizing parasitic loss of H₂ in the reformate stream. It is found that the 10 ppm constraint limits the maximum inlet CO concentration to 1.05% in a single-stage reactor and to 3.1% in a two-stage reactor. The results clearly show the incremental reduction in parasitic H₂ loss by addition of second and third stages.     

湿式空气氧化技术的发展

催化湿式氧化法是一种处理高浓度、有毒有害、生物难以降解废水的方法,近年来在国内外都取得了快速的发展,文章论述了湿式氧化法和催化湿式氧化法的概念和发展,以及应用前景。     

化学氧化法处理抗生素制药废水

应用传统生化法处理抗生素制药废水,出水很难达到行业排放标准.采用光催化氧化法和氯氧化法对抗生素制药废水进行了研究,探讨了上述过程中光照时间、通气条件、初始pH值及投加有效氯量等因素对抗生素制药废水处理效果的影响.试验结果表明,这两种化学氧化法都能够有效地去除抗生素制药废水中的有机物,出水COD值达到<污水综合排放标准>(GB8978-1996)的二级标准.     

臭氧Fenton氧化深度处理合成氨工业废水实验研究

分别采用臭氧氧化和Fenton氧化工艺对合成氨工业废水生化处理后的排放尾水进行深度处理实验研究。结果表明,尾水COD为48 mg/L,BOD5为8 mg/L,当臭氧氧化反应进行120 min后,出水COD最低,为41 mg/L,去除率为14.58%,B/C由0.16提高到0.31。在n(Fe2+)∶n(H2O2)=20.38时,Fenton氧化出水COD为18 mg/L,COD去除率达到64.58%,满足深度处理排放标准要求。研究结果表明Fenton氧化可以作为该尾水的深度处理工艺。     

污染水中氰化物的化学氧化去除处理试验

采用含氰化物(CN-)的试验水样模拟城市取水水源地发生氰化物水污染事故,分别比较Cl2、ClO2和O3处理CN-的氧化效率,初步探讨三种氧化剂氧化降解CN-的机理,并考察投加浓度对CN-去除率的影响。试验表明,Cl2氧化CN-的效率较ClO2和O3高;用浓度为25.6μmmol/L的Cl2处理由原水配制含CN-的试验水样,反应进行20 min,CN-去除率达98.6%,Cl2可用于应急处理氰化物水污染事故。     

芳烃氧化制备芳酸研究的进展

芳酸是多种有机高聚物材料如聚乙烯萘酯（ＰＥＮ）、液晶高聚物（ＬＣＰ）等的重要单体和多种医药、农药、染料等的中间体，可由煤焦油中富含的苯、萘、菲、苊等直接氧化制得．综述了芳烃通过化学氧化、空气氧化、电解氧化、光氧化和微生物氧化制备芳酸的研究进展