Bi2O3电极的制备及其选择性氧化苯甲醇性能研究

采用滴凃法和电沉积法制备了Bi2O3薄膜电极,运用场发射扫描电子显微镜和X射线衍射仪对其进行了表征。在水相中以苯甲醇选择性氧化合成苯甲醛为模型反应,研究Bi2O3薄膜的催化性能。其中电沉积法制备的Bi2O3薄膜电极在水相溶液中表现出优异的电催化选择性氧化性能,苯甲醇的转化率最高,并且在外加偏压为2 V时达到了最高的苯甲醛选择性和苯甲醛收率。     

O3/H2O2高级氧化法预处理酒精废水的实验研究

实验探讨了O3/H2O2高级氧化法预处理某制药酒精废水过程中H2O2投加量、pH值、反应时间、臭氧发生器氧气流量等因素对CODCr去除率的影响。实验得出的最佳反应条件是：H2O2投加量98 mmol/L,pH值11,氧气流量60 L/h,反应时间90 min,在最佳条件下反应后废水CODCr去除率46.3%,TOC去除率50.5%,B/C从0.08提高到0.32,废水可生化性明显提高,能够满足后续生化处理的需要。     

MoO3—Fe2O3 catalysts: Characterization and activity for isopropyl alcohol decomposition

The vapour-phase dehydration and dehydrogenation of isopropyl alcohol (IPA) have been carried out over pure MoO₃ and Fe₂O₃, produced by calcination of ammonium heptamolybdate and of iron (III) nitrate respectively, as well as MoO₃ mixed with 0·5 and 50 mol% Fe₂O₃, prepared from the same materials. All catalysts were calcined in air, in the temperature range 200–600°C for 5 h, and were characterized by thermal analysis (TG, DTA), XRD, IR and S_BET. Surface areas decreased with increasing calcination temperature, and the catalytic activity of the pure oxides MoO₃ and Fe₂O₃, as well as of MoO₃–0.5 mol % Fe₂O₃, increased with their S_BET. The activity of MoO₃–50 mol % Fe₂O₃, which was independent of its S_BET, could be attributed to the increased intensity of terminal Mo—O bonds as shown by IR spectra. The activation energies for the decomposition of IPA over catalysts calcined at 250 and 500°C are tabulated.     

不同尺寸反应器内H2O2热分解氧化NO特性与氧化产物分析

采用实验方法研究了不同尺寸滴管炉反应器内H₂O₂热分解氧化NO特性。对比了不同H₂O₂蒸发条件对NO氧化率的影响规律。分析了气体温度、H₂O₂溶液浓度、H₂O₂：NO摩尔比、NO初始浓度及气体流量对NO氧化率的影响。检测了氧化产物并分析了产物的生成路径。结果表明：H₂O₂的快速蒸发是其热分解氧化NO的前提。减小H₂O₂液滴尺寸或液膜厚度可加速H₂O₂蒸发与分解,提高NO氧化率,扩宽NO氧化的温度范围。保证蒸发速率可削弱H₂O₂浓度对NO氧化率的影响。当H₂O₂：NO < 10时,NO氧化率随H₂O₂：NO的增加而增加;当H₂O₂：NO>10时,NO氧化率几乎不随H₂O₂：NO变化。H₂O₂热分解对于较高浓度的NO具有更高的氧化效率。H₂O₂热分解氧化NO的主要产物为NO₂。HO₂·直接将NO氧化为NO₂,·OH则先将NO转化为HONO,然后进一步氧化为NO₂。     

臭氧-过氧化氢氧化预处理H酸废水

采用工业生产中排放的H酸废水作为研究对象,探讨了臭氧-H2O2氧化的预处理方法对该废水的处理效果。结果表明：在单独臭氧氧化反应体系中,初始CODCr的质量浓度为1 200 mg/L,pH值为7,臭氧氧化时间在20 min（通量为1 L/min）时,CODCr和色度去除率分别为36.7%和95%。单独H2O2氧化反应体系中,H2O2投加量为8 mL/L时,CODCr去除率为7.7%,H2O2投加量达到60 mL/L时,CODCr去除率最高仅达到25.6%。臭氧-H2O2联用体系中,相同初始CODCr浓度、pH值、臭氧氧化时间及臭氧通量条件下,质量分数为3%的H2O2溶液投加量为8 mL/L时,CODCr和色度去除率分别可达48.8%和98%。因此,臭氧-H2O2氧化的预处理方法对H酸废水降解效果良好,且明显优于单独臭氧氧化以及单独H2O2氧化。     

钛盐光度法测定O3/H2O2高级氧化系统中的过氧化氢

采用钛盐光度法测定O3/H2O2系统中的/H2O2,考察了pH值、O3/H2O2摩尔比、钛盐用量和显色时间的影响,确定了最佳的测定条件;通过加标回收率实验和对比实验,证明了该方法的可靠性.结果表明,pH值为3.0、λ=385nm、草酸钛钾浓度2.5mmol·L-1和显色时间8min条件下,H2O2浓度0～45mg·L-...     

Effect of Mn/Al ratio in Co–Mn–Al mixed oxide catalysts prepared from hydrotalcite-like precursors on catalytic decomposition of N2O

The Co–Mn–Al mixed oxide catalysts were prepared by thermal decomposition of hydrotalcite-like precursors with Co/(Mn + Al) molar ratio of 2 and Mn/Al molar ratio varying from 0 to 2. The obtained catalysts were characterized by powder XRD, XPS, BET surface area and TPR measurements and tested in N₂O decomposition. The most active Co4MnAl catalyst exhibited both the optimum Mn/Al molar ratio and the optimum amount of components reducible in the temperature region in which the catalytic reaction proceeds (350–450 °C).     

H2O2氧化法去除水体中亚硝酸盐和氨的研究

本文用H2O2氧化法和UV（紫外光）-H2O2催化氧化法研究了水体中N煤^-与NH4^ 的氧化,结果表明：NO2^-能被H2O2有效氧化,而NH4^ 几乎不能被H2O2氧化;在UV催化下NO2^-的氧化率有显著提高,NH4^ 的氧化率也有一定程度的提高;共存NH4^ 和NO2^-的氧化没有影响,而在浓度较大时,共存NO2^-对NH4^ 的氧化起着一定的促进作用。     

A5微孔分子筛负载V2O5催化氧化对硝基甲苯

将A₅微孔分子筛浸渍于偏钒酸铵溶液,过滤,120 ℃干燥2 h,550 ℃焙烧6 h,制备了含有V₂O₅的A5微孔分子筛催化剂。采用X射线衍射、N₂吸附-脱附和扫描电镜等进行表征,并将其用于以H₂O₂为氧化剂、乙酸酐为溶剂的对硝基甲苯催化氧化生成对硝基苯甲醇的反应。在反应温度40 ℃和反应时间4 h条件下,以质量分数35%的H₂O₂为氧化剂和V₂O₅质量分数8.5%的V₂O₅/A₅为催化剂,能够获得较好的对硝基甲苯转化率（35.54%）和较高的对硝基苯甲醇选择性(67.16%)。反应结束后,在母液中通过电感耦合等离子体原子光谱仪没有检测到V₂O₅。V₂O₅/A₅催化剂连续使用3次,对硝基甲苯转化率为34.21%,对硝基苯甲醇选择性为63.39%,催化剂活性无明显降低。     

The effect of the nature of vanadium species on benzene total oxidation

The nature of the vanadium species present on V₂O₅/Al₂O₃ catalysts was investigated by using solid state ⁵¹V NMR, diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD) and temperature programmed reduction (TPR). ⁵¹V NMR and DRS analyses indicated the presence of V⁵⁺ in tetrahedral symmetry at low vanadium loading. A surface polymeric vanadium species and/or the bulk crystalline V₂O₅ were mainly observed at high vanadium loading as also detected by XRD. The positions of the absorption edges determined through the UV–VIS spectra allowed distinguishing between various tetrahedral symmetries. After TPR, the average oxidation state of vanadium depended on the vanadium content. The nature of vanadium species was related to the catalyst behavior on the benzene oxidation reaction. The catalysts containing high vanadium content were more active suggesting that a high amount of V⁴⁺ is responsible for the higher activity.     

Preliminary study on the TS-1 deactivation during styrene oxidation with H2O2

The deactivation of the TS-1 zeolite during styrene oxidation with H₂O₂ has been investigated by a series of kinetic experiments and further characterisation of the spent catalysts. A decline of the TS-1 activity with time has been observed, especially during the first hours of reaction. TG and TPD–MS analyses of the spent catalysts show that the main products occluded within the zeolite pores are styrene, phenylacetaldehyde and benzaldehyde. The presence of styrene oligomeric compounds has also been detected, although it is postulated they are formed mainly in the solution outside the zeolite pores. Diffusional hindrances due to the high degree of occupancy of the TS-1 pores, as well as, a strong adsorption of styrene, phenylacetaldehyde and benzaldehyde on the Ti sites are proposed as the main reasons for the TS-1 deactivation. These phenomena are enhanced at lower reaction temperatures, which cause a faster initial deactivation. Likewise, longer reaction times favour preferential chemisorption of aldehydes versus styrene.     

双氧水氧化乙二醛合成乙醛酸的研究

在催化剂存在下,用双氧水氧化乙二醛溶液快速合成了乙醛酸.优化的合成条件为:n(H2O2)∶n(乙二醛)=1.10∶1.00、反应温度3～8℃、反应时间3 h,此时,乙二醛转化率为85%、乙醛酸产率为70.3%.     

Mechanistic Study of Carbon Oxidation with NO2 and O2 in the Presence of a Ru/Na‐Y Catalyst

The oxidation of model soot by NO₂ and O₂ in the presence of a Ru/Na‐Y catalyst under conditions close to automotive exhaust gas after‐treatment systems is investigated. Isothermal oxidation experiments of a physical mixture of carbon black and catalyst were performed in a temperature range of 300–400 °C. A remarkable increase of the oxidation rate by NO₂ and O₂ in the presence of the Ru/Na‐Y catalyst was observed. An overall mechanism involving oxygen transfer from the Ru catalyst to the carbon surface leading to an increase of C(O) complexes is proposed. These C(O) complexes are destabilized in the presence of NO₂ increasing the carbon oxidation rate.     

几种低阶煤的过氧化氢氧化解聚性能研究

在40℃利用5％H2 O2水溶液分别对神府次烟煤（ SF）、准东次烟煤（ ZD）、胜利褐煤（ SL）和先锋褐煤（ XF）四种低阶煤进行了氧解,计算其氧解转化率和CO2生成率,结合元素分析、红外光谱以及酸性官能团测定结果比较了四种低阶煤的氧解性能以及其结构特征对氧化解聚性能的影响。结果表明,煤的氧化解聚与变质程度密切相关,变质程度越高,氧化反应性降低。另外煤的氧含量越高,特别是羧基以及酚羟基含量较高时,氧化解聚程度增大。     

Azo-dye Orange II degradation by heterogeneous Fenton-like reaction using carbon-Fe catalysts

In this work, the degradation and mineralization of the non-biodegradable azo dye Orange II (OII) was studied, making use of a heterogeneous Fenton-like oxidation process. For that, hydrogen peroxide activation was achieved by means of two different carbon-based catalysts, which have been impregnated with 7 wt% of iron. The carbon supports employed are quite different, one of them being an activated carbon prepared from agricultural by-products (olive stone), while the other one is a carbon aerogel, prepared by carbonization of an organic resorcinol–formaldehyde polymer. The solids have been characterized using several techniques, namely N₂ and CO₂ adsorption at −196 and 0 °C, respectively, mercury porosimetry, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Then, the catalyst's performance in the Fenton-like oxidation of OII was compared, and the effects of the most relevant operating conditions (pH, catalyst concentration, H₂O₂ concentration and temperature) analyzed for the most promising one (the carbon aerogel based catalyst). In this catalyst, characterization data point for a very good iron dispersion on the carbon surface. This sample showed very good catalytic performances, with mineralization degrees as high as 90%. However, iron leaching from the support is also considerable leading to a progressive deactivation in consecutive reaction cycles.     

超临界水在废旧塑料处理方面的应用

本文论述了超临界流体特别是超临界水在处理废旧塑料中的应用,分析了超临界流体的特性,介绍了国内外超临界流体降解废旧塑料的工艺和进展,分析并比较了以超临界流体为介质分解废旧塑料与常规分解方法的优缺点。     

Characterization and catalytic activity of Pd/V2O5/Al2O3 catalysts on benzene total oxidation

The role of vanadium oxide and palladium on the benzene oxidation reaction over Pd/V₂O₅/Al₂O₃ catalysts was investigated. The Pd/V₂O₅/Al₂O₃ catalysts were more active than V₂O₅/Al₂O₃ and Pd/Al₂O₃ catalysts. The increase of vanadium oxide content decreased the Pd dispersion and increased the benzene conversion. A strong Pd particle size effect on benzene oxidation reaction was observed. Although the catalysts containing high amount of V⁴⁺ species were more active, the Pd particle size effect was responsible for the higher activity.