环己烷液相无催化氧化模拟计算及动力学的修正

1 模拟计算1.1 动力学和流动模型模拟计算中采用陈纪忠等建立的动力学模型,其反应网络为:描述该6种组分的生成或消失速率的动力学方程式在文献[1]中已有详细报道。从冷模研究得到:液相流动为全混流;u_g≥7 cm/s 时气相流况可视作平推流。若从各种流动模型的计算结果看,气相即使作为全混流,计算结果差异也甚小。本文采用液相全混、气相平推的流动模型。     

Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process

The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation of Ce(IV) in nitric acid media at 80 °C were studied. The current-voltage curves and cerium electrolysis kinetics showed the dependence on number of cell stacks needed to be connected in series for the destruction of a given quantity of organic pollutant. The presence of an optimum region for Ce(III) oxidation with a contribution of oxygen evolution, especially at low Ce(III) concentration (high conversion ratios), was found. The cells were applied for the Ce(IV) regeneration during the organic destruction. The cell and reactor processes were fitted in a simple model proposed and used to calculate the current needed in terms of Ce(III) oxidation rate and the number of cell stacks required for maintaining Ce(IV)/Ce(III) ratio at the same level during the organic destruction. This consideration was based on the kinetic model previously developed by us for the organic destruction in the MEO process.     

Investigation of an Ozone Membrane Contactor System

Ozone mass transfer rates were determined for nine expanded porous Teflon membranes that had different pore size, thickness, and pore volume, a nonporous Teflon membrane, and a PVDF membrane. The mass transfer coefficient was 7.6 ± 0.5 × 10^?5 m/s at Re of 2000 for all membranes tested even though pore sizes ranged from 0.07 to 6 μm and thickness from 0.076 to 0.25 mm. Mass transfer increased with liquid side Reynolds number. Therefore, it is likely that ozone mass transfer is liquid phase controlling and not membrane limited. For a hypothetical case of 4000 m³/d and 2 mg/L ozone transferred, plate and frame membrane and hollow fiber contactors are approximately one and two orders of magnitude smaller, respectively, than fine-bubble diffusers.     

THE ROLE OF LATTICE OXYGEN IN THE DYNAMIC BEHAVIOR OF OXIDE CATALYSTS

The lattice of an oxide catalyst used for oxidation reactions can act as a reservoir for oxygen, storing and releasing it for reactions at the catalyst surface under appropriate conditions. The implication of this oxygen storage property of an oxide catalyst on its dynamic response characteristics has been investigated through an experimental study of 2-butene oxidation over vanadium oxide as a model reaction. Isothermal reaction rate measurements in a differential reactor and nonisothermal studies in a single pellet reactor have been carried out. Following a step increase in the feed butene concentration, isothermal reaction rate overshoot and pellet temperature overshoot were observed. These observations could be modelled in a qualitatively correct way by a very simple model accounting for the participation of lattice oxygen in the catalytic reactions under dynamic conditions. It is demonstrated through model simulations that the ignition characteristics of a catalyst pellet are significantly affected by the participation of the lattice oxygen, when steady state multiplicity is present.     

Glyoxal Ozonation Process in Aqueous Solution

The process of ozonation of glyoxal in aqueous solution has been studied by following its chemical and kinetic evolution. Results show that the oxidative process leads to formation of carboxylic functions and carbon dioxide according to a constant selectivity ratio at varying conversion degree.. Comparison between the oxygen amounts of reaction products and the corresponding ozone consumptions reveals that molecular oxygen takes part in the reaction process. System behavior is explained on the basis of radical reaction mechanism.     

N-氧化烟酸的合成

以烟酸为原料，在冰醋酸溶液中，用双氧水氧化合成N-氧化烟酸。实验发现在合成中加入一种共沸剂，可以降低反应的回流温度，同时，也可将反应生成的水不断带走，使转化率增大，并且具有合成工艺简单，溶剂可以重复使用，无三废等特点。适宜的反应条件为：烟酸：双氧水：冰醋酸的摩尔比为1：1.5:3，共沸剂A或B的用量为30ml，反应时间为5h，收率92.0%。     

Iron Behavior in the Ozonation and Filtration of Groundwater

In Finnish groundwater, the main substances that require treatment are iron and manganese. In addition to this, groundwaters are soft and acidic. Iron removal is usually relatively effective by oxidizing dissolved iron into an insoluble form, either by aeration or chemical oxidization and removing the formed precipitate by sand filtration. Sometimes, if the untreated water contains high amounts of organic matter, problems may arise for iron removal. In Finland, it is quite common that groundwater contains high levels of both iron and natural organic matter, mainly as humic substances. The groundwater of the Kukkala intake plant in Liminka has been found to be problematic, due to its high level of natural organic matter. This research studied the removal of iron from this water by means of oxidation with ozone and filtration. While the oxidation of iron by ozone was rapid, the precipitate particles formed were small, and thus could not be removed by sand and anthracite filtration, and the iron residue in the treated water was more than 2 mgL^?1. And while the filtration was able to remove iron well without the feed of ozone, the iron residue in the treated water was only 0.30 mgL^?1. In this case, iron was led to the filter in a bivalent dissolved form. So, the result of iron removal was the best when the sand/anthracite filter functioned largely as an adsorption filter.     

湿式空气氧化法处理乙烯废碱液装置的技术改造

针对中国石化齐鲁石化公司烯烃厂乙烯装置废碱液处理系统在试运转过程中存在的问题,通过分析原因,提出并实施改进工艺的相关措施,得到一组适宜的工艺操作参数,保证了废碱液湿式空气氧化装置的稳定运行。     

AgBiVMo oxide catalytic membrane for selective oxidation of propane to acrolein

A metal ions (Ag, Bi, V, Mo) modified sol–gel method was used to prepare a mesoporous Ag_0.01Bi_0.85V_0.54Mo_0.45O₄ catalytic membrane which was used in the selective oxidation of propane to acrolein. By optimizing the preparation parameters, a thin and perfect catalytically active membrane was successfully prepared. SEM results showed that the membrane thickness is 5 μm. XRD results revealed that Ag_0.01Bi_0.85V_0.54Mo_0.45O₄ with a Scheelite structure, which is catalytically active for the selective oxidation of propane to acrolein, was formed in the catalytic membrane only when AgBiVMoO concentrations were higher than 40%. Catalytic reaction results demonstrated that the selective oxidation of propane could be controlled to a certain degree, such as to acrolein, in the catalytic membrane reactor (CMR) compared to the fixed bed reactor (FBR). For example, a selectivity of 54.85% for acrolein in the liquid phase was obtained in the CMR, while only 8.31% was achieved in the FBR.     

"反应-吸附法"精制焦化柴油的研究

以物质A为反应物,白土为脱色物质,研究用反应-吸附的方法提高焦化柴油的质量。实验表明:精制油的色度、氧化安定性沉渣、实际胶质均可达到国标合格柴油的要求,焦化柴油中的硫、氮等杂原子化合物和不饱和烃类化合物等不安定组分得到有效脱除,柴油质量大大提高,精制柴油收率在98%以上。