改性镍基催化剂催化增强次氯酸钠氧化性的性能研究

次氯酸钠具有强氧化性，但因性能极不稳定，大大降低了其氧化性能的利用率。采用混捏法制备改性的镍基催化剂催化氧化次氯酸钠，生成的原子氧具有极强的活性，特别是在次氯酸钠浓度不高时，可大大提高次氯酸钠的氧化性能和利用率。采用混捏法制备的改性镍基催化剂用于催化分解次氯酸钠产生活性氧。通过FT-IR、SEM和BET等方法对催化剂的物化性能及催化性能进行了研究，考察了改性镍基催化剂催化分解次氯酸钠溶液反应动力学和活性氯的变化情况。结果表明，添加Fe₂O₃的镍基催化剂具有较高的活性，在改性镍基催化剂作用下，反应活化能大大降低，次氯酸钠活性氯的转化率达到90％以上。在初步处理有机废水的实验中，COD的去除率达到92.5。     

基于碰撞理论的次氯酸钠水溶液稳定性的研究

以碰撞理论为模型,对次氯酸钠溶液的分解机理进行了研究,得出次氯酸钠溶液在无催化剂影响条件下的主要分解方程式。研究表明,在强碱性条件下次氯酸钠的分解主要是通过CIO水解生成HCIO引发的一系列反应;歧化反应是通过HCIO的分解生成的[O]实现的;在强碱条件下,次氯酸钠的分解速率与溶液的初始浓度有关,而反应前后溶液pH值、游离碱含量却几乎不发生变化;升高温度会增加有效碰撞,从而提高反应速率。次氯酸钠溶液添加0．2％、0．6或1．O％的硅酸钠后,体系稳定度变化不大。     

温度和氧浓度对PX氧化的影响

根据不同温度、氧浓度下实测的PX液相催化氧化各中间组分浓度 时间关系,采用双曲型的动力学模型拟合实验数据,得到了各步反应活化能数据和速率常数与氧浓度的关系式。结果说明,PT酸氧化为4 CBA这一步的活化能最大,是整个连串反应过程的速率控制步骤;反应有一个氧浓度门槛值,在此值以上,反应速率不再明显增大,在此值以下,反应速率随氧浓度增大而增大。工业尾氧体积分数一般在4%～5%,相应的反应速率在最大速率的90%左右。     

铁卟啉催化叔丁基过氧化氢分解

采用Adler法合成了四苯基卟啉铁,应用于催化叔丁基过氧化氢(TBHP)分解反应。详细考察了温度、催化剂浓度及TBHP初始浓度等反应条件对分解速率、产物组成的影响。研究结果表明,TBHP分解是由四苯基卟啉铁配位引发的直链型连锁反应,提高温度或催化剂浓度均能增大分解速率、提高反应对叔丁醇及丙酮的选择性;TBHP分解速率与其初始浓度成正比且在一定浓度范围内基本不变。     

环己烷液相非催化/催化氧化反应动力学特性比较

分别以不同氧浓度气体及纯氧作为氧源,利用鼓泡塔反应器在1.1 MPa、不同温度、不同气体流量条件下比较了环己烷液相非催化氧化和催化氧化反应特性。通过比较分析,讨论了环己烷液相氧化的链式反应机理。理论分析和实验数据表明,环己烷液相催化氧化反应诱导期短,其表观速率与环己烷浓度和氧气浓度都为一级;而非催化氧化反应诱导期长,是由烃直接氧化引发过程控制,只有当过氧化氢积累到一定浓度以后,过氧化物分解产生自由基速率变得显著,反应才表现出自催化反应特征。而在催化剂存在的情况下,环己基过氧化氢分解非常迅速,环己基过氧化氢浓度在整个反应过程中稳定在一个很低的水平,反应由氧化生成酮的链传递反应过程控制。     

硫酸催化合成邻苯二甲酸二甲酯的动力学

在工业生产过程所涉及的温度条件下对浓硫酸催化合成邻苯二甲酸二甲酯的化学反应动力学进行了实验研究,测定丫两个实验温度(90℃,100℃)下硫酸催化剂浓度为0.2%～0.9%时反应中各物质的浓度变化,获得了该温度下和催化剂浓度范围内的反应动力学表达式和反应速率常数.实验结果表明,实验条件下的反应速率对邻苯二甲酸单甲酯,甲醇...     

用原子矩阵法对工业级次氯酸钠水溶液分解反应宏观动力学的研究

用原于矩阵法探讨了次氯酸钠水溶液不稳定的原因及其影响因素，结果表明：NaC1O水溶液的强氧化性主要是靠NaClO分解出的原子氧[O]而得以体现的，反应时间越长，分解越彻底。次氯酸钠水溶液分解反应为准一级反应，浓度和温度不同程度地影响了次氯酸钠水溶液的稳定性。     

浅析次氯酸钠水溶液的稳定性

次氯酸钠作为一种低廉、高效、广谱消毒剂、杀菌剂、漂白剂被广泛用于各个领域,市场巨大。但因其本身易分解、不稳定,大大限制了其应用和发展。本文论述了次氯酸钠的性质和生产工艺,分析了温度、光照、溶液pH值、溶液浓度、金属离子等因素对次氯酸钠稳定性的影响。实验表明,低温、适当降低次氯酸钠的浓度、控制溶液中金属离子含量、保持pH值在12.0以上和添加稳定剂是提高次氯酸钠溶液稳定性的有效途径。溶液中添加0.6%的NaCl或1%的Na2SiO3可使次氯酸钠的稳定性显著提高。     

烟气脱硫产物亚硫酸铵非催化氧化动力学

采用搅拌反应器,通过改变初始亚硫酸铵浓度、pH值、空气流量、温度以及硫酸铵浓度、不加催化剂,对氨法烟气脱硫产物亚硫酸铵氧化反应动力学进行了研究。实验结果表明:在硫酸铵浓度为0.15 mol/L、温度为35～60℃的溶液中、氧化空气流量为150～400 L/h时,亚硫酸铵的氧化速率随着pH值增加而下降,随着温度和空气流量的增加而增大;当硫酸铵浓度增大时,亚硫酸铵的氧化速率下降;在pH值为5.5时反应的活化能为31.88 kJ/mol。     

磷钼酸催化合成乙酸乙酯的动力学研究

在反应精馏过程所涉及的温度范围内对磷钼酸催化合成乙酸乙酯的化学反应动力学进行了实验研究,测定了两个温度(110℃,120℃)和四个磷钼酸浓度(0.20%,0.40%,0.60%,0.80%)下的反应速率数据,获得了该温度和催化剂浓度范围内的反应动力学表达式和反应速率常数.实验结果表明,实验条件下的反应速率对乙醇和乙酸均为一级反应.反应速率常数随磷钼酸浓度呈线性增长.     

Oxidation of Hydroxyethyl Cellulose with Sodium Hypochlorite

Oxidation of water-soluble hydroxyethyl cellulose with sodium hypochlorite has been studied under a variety of conditions. Variables studied included the concentration of sodium hypochlorite, pH, temperature, and catalyst. It was found that the rate of oxidation was increased by increasing the hypochlorite concentration and/or reaction temperatures. The rate is very slow in an alkaline medium and very rapid in neutral medium. The effect of catalyst on the rate of oxidation was also investigated. The apparent viscosities of the oxidized samples at various rates of shear were also investigated.     

Soy fatty acid oxidation with sodium hypochlorite monitored by nuclear magnetic resonance spectroscopy

The oxidation process of soy fatty acids by sodium hypochlorite with ruthenium trichloride catalyst was examined at different temperatures and active chlorine:fatty acid molar ratios. ¹H and ¹³C distortionless enhancement by polarized transfer nuclear magnetic resonance (NMR) spectroscopy techniques were used to monitor oxidation of the double bonds in unsaturated lipids by measuring the peak integration ratio of double-bond peaks:methylene-methyl peaks. This NMR monitoring technique proved to be an excellent means to quantify double-bond reactions. Gas chromatography-mass spectrometry was used to identify mono- and diacid products, separated by hexane/methylene chloride extraction, as well as other oxidation products. While the presence of ruthenium catalyst increased the initial rate of oxidation, it also catalyzed the decomposition of hypochlorite, decreasing the available reactive chlorine, resulting in a delay in complete oxidation. A 9:1 molar ratio of active chlorine to fatty acids completely oxidized all double bonds of soy fatty acids. However, the yield of low-molecular-weight monoacid oxidation products was only 17%, indicating the probable formation of hydroxy fatty acids.     

次氯酸钠处理弱酸性艳红B的试验研究

利用次氯酸钠溶液的氧化作用对偶氮类染料弱酸性艳红B废水进行处理。考察了弱酸性艳红B初始浓度、次氯酸钠投加量、反应时间对弱酸性艳红B去除率的影响,结果表明:在反应时间为3.5 h,次氯酸钠投加量为0.8 mg/mL,弱酸性艳红B的质量浓度为40 mg/L条件下,弱酸性艳红B的脱色率可达96.12%,CODCr的去除率达87.94%,反应近似呈现一级反应动力学特征。     

KINETIC STUDY OF BENZYL ALCOHOL OXIDATION UNDER PHASE TRANSFER CATALYSIS CONDITIONS

In this work, benzyl alcohol oxidation to benzaldehyde by sodium hypochlorite (NaOCl) in the presence of quaternary ammonium salt was successfully carried out in an organic solvent/aqueous solution two-phase medium. An aqueous solution of low pH value is found to be favorable for the oxidation of benzyl alcohol by sodium hypochlorite. However, certain amounts of hypochlorite ions are converted to chlorines in a solution of low pH value simply by adding sulfuric acid. It is thus our goal to find a method for the production of benzaldehyde of high yield in a solution at low pH value and the prevention of chlorine production from sodium hypochlorite. Therefore, the primary purpose of this work is to search for a favorable condition for the production of benzaldehyde. It is effective to adjust the pH value by adding KCl/HCl solution rather than by adding sulfuric acid solution. Under this circumstance, the reaction follows a zero^th order rate law. Kinetics of the oxidation by sodium hypochlorite under phase transfer catalysis condition, including the effect of the agitation speed, the amount of TBAB catalyst, quaternary ammonium salts, the amount of sodium hypochlorite, the amount of sodium hydrogen carbonate, organic solvents, the pH value, the amount of dichloromethane, and the temperature on the conversion were investigated in detail. Reasonable explanations were made to satisfactorily account for the results.     

KINETIC STUDY OF BENZYL ALCOHOL OXIDATION UNDER PHASE TRANSFER CATALYSIS CONDITIONS

In this work, benzyl alcohol oxidation to benzaldehyde by sodium hypochlorite (NaOCl) in the presence of quaternary ammonium salt was successfully carried out in an organic solvent/aqueous solution two-phase medium. An aqueous solution of low pH value is found to be favorable for the oxidation of benzyl alcohol by sodium hypochlorite. However, certain amounts of hypochlorite ions are converted to chlorines in a solution of low pH value simply by adding sulfuric acid. It is thus our goal to find a method for the production of benzaldehyde of high yield in a solution at low pH value and the prevention of chlorine production from sodium hypochlorite. Therefore, the primary purpose of this work is to search for a favorable condition for the production of benzaldehyde. It is effective to adjust the pH value by adding KCl/HCl solution rather than by adding sulfuric acid solution. Under this circumstance, the reaction follows a zero^th order rate law. Kinetics of the oxidation by sodium hypochlorite under phase transfer catalysis condition, including the effect of the agitation speed, the amount of TBAB catalyst, quaternary ammonium salts, the amount of sodium hypochlorite, the amount of sodium hydrogen carbonate, organic solvents, the pH value, the amount of dichloromethane, and the temperature on the conversion were investigated in detail. Reasonable explanations were made to satisfactorily account for the results.     

Dehydrogenation and aromatization of methane in the absence of oxygen on Mo/HZSM-5 catalysts before and after NH4OH extraction

A phosphorus-modified electrolytic silver catalyst was prepared and used as catalyst in the oxidative dehydrogenation of glycoto glyoxal. The yield of glyoxal was observed as high as 82% at 98% conversion for the Ag-P catalyst, while 62% at 89% conversion for the pure electrolytic silver. The formation of the surface compounds between the phosphorus additives and the silver surface was demonstrated by means of XPS and SEM. It caused the decrease of the surface concentration of atomic oxygen species, and restrained the decomposition and total oxidation of adsorbed glycol to C₁ products.     

合成4,4′-二硝基二苯乙烯-2,2′-二磺酸钠反应机理探讨

4,4-二硝基二苯乙烯-2,2′-二磺酸钠制备过程是对硝基甲苯邻磺酸氧化生成4,4 ′-二硝基二苯乙烷-2,2′-二磺酸钠;4,4′-二硝基二苯乙烷-2,2′-二磺酸钠再氧化生成4,4'-二硝基二苯乙烯-2,2′-二磺酸钠.通过对硝基甲苯邻磺酸次氯酸钠氧化合成4,4′-二硝基二苯乙烯-2,2′-二磺酸钠的反应实验,研究...     

催化裂化汽油催化氧化及萃取脱硫的研究

以分子氧为氧化剂,将催化氧化与萃取分离相结合,开展催化汽油氧化萃取脱硫研究。结果表明,与直接萃取相比,汽油经过氧化及溶剂萃取,汽油脱硫率有所提高,并且随着氧化温度的提高而增大,氧化过程对催化汽油脱硫有贡献。催化剂能够加速硫化物氧化反应,几种催化剂的汽油脱硫率从大到小顺序为：氧化铈＞碳酸锰或四硼酸钠或氧化锌＞硼酸或过硼酸钠。使用氧化锌或碳酸锰催化剂时,随着催化剂用量的增加,汽油脱硫率总体呈现降低的变化趋势。以硼酸为催化剂时,脱硫率随着催化剂用量的增加先增加后降低,认为催化汽油中硫化物的氧化反应符合连串反应机制。     

Double bond oxidation of unsaturated fatty acids

Different oxidizing agents for performing the cleavage oxidation of the double bond of the unsaturated fatty acids are presented, and their economic performance is analyzed. Ozone and sodium hypochlorite are the most commercially efficient oxidants. Laboratory work for the oxidation of oleic acid to azelaic and pelargonic acids using hypochlorite as oxidant is described. The advantages of working in an emulsion system and using RuCl₃ as a catalyst are discussed, and a possible mechanism of the reaction is presented. A flow sheet for an industrial process based on this concept is proposed. A simulation of a plant using this technology is made by a computerized model, and the economic parameters obtained permit us to conclude that the sodium hypochlorite can be an interesting reagent for industrial oxidations of double bonds in fatty acids.