Study of TATP: Influence of Reaction Conditions on Product Composition

The influence of reaction conditions (temperature, catalyst type, catalyst concentration – represented as molar ratio catalyst/acetone n_c/n_a) on the composition of the product formed from the reaction of acetone and hydrogen peroxide (30%) under acid catalysis was studied. 3,3,6,6,9,9‐Hexamethyl‐1,2,4,5,7,8‐hexoxonane (TATP) was found to be the major product when the content of the catalyst in the reaction mixture is low (n_c/n_a ≤ 0.5). A single side product (peak 10.2) in an amount ranging from 1.5 to 8% of the total peak area was present in all the prepared samples. Three other side products were found when catalyzing by hydrochloric and nitric acids. Temperature and catalyst type did not have a significant influence on the composition of the product at low catalyst concentration. Increasing the catalyst concentration led to the formation of 3,3,6,6‐tetramethyl‐1,2,4,5‐tetroxane (DADP) either as a co‐product of TATP or as an exclusive product depending on the concentration of the catalyst.     

二次反应对煤热解产品组成的影响

煤的热妥是煤炭转化过程中的第一步，通过热解可以产生高质量的热解煤气及珍贵的液体产品。然而在实际过程中，对热解产品的组成有不同的要求。因此，研究煤热解二次反应对实际过程有着重要的指导意义。     

Conductivity of Tazheranite Ceramics Synthesized by Controlling Composition

Tazheranite ceramics with controlled compositions were synthesized by solid-phase reaction, and their conductivity was measured using the complex impedance method. The CaO content in tazheranite compositions showed the highest conductivity at around 15 mol%. In particular, Ca_0.81Ti_0.04O_y sintered bodies revealed the highest conductivity, and this value agreed very closely with that of 15 mol% CaO-stabilized ZrO₂.     

Controlling the Oligomeric Composition of Carbon-Fiber Precursors by Dense-Gas Extraction

Dense-gas extraction of M-50 petroleum pitch with the solvent toluene was carried out in a continuous, countercurrent-flow, packed column at temperatures from 330° to 380°C, pressures from 42 to 84 bar, and a solvent-to-pitch ratio of 5:1. Both one- and two-column configurations were used to fractionate raw pitches into top and bottom cuts of controlled oligomeric distribution. Using matrix-assisted laser desorption–ionization mass spectroscopy for absolute molecular weight determination, the effect of changes in pitch oligomeric distribution on both the softening point and the degree of anisotropy (i.e., isotropic–mesophase equilibrium) was established. For example, pitch fractions rich in dimer and trimer species, and with essentially all monomer removed, exhibit the anisotropic microstructure typically found in precursors for high-performance carbon fibers.     

Melting Curves of Triolein Polymorphs

High-pressure treatment is a promising option for improving mechanical properties and processing parameters of fat-containing products. To identify optimum processing windows, melting curves, crystallization kinetics, and pathways for transferring the optimized structures to atmospheric pressure need to be known. Here, we provide melting curves of different polymorphic forms of triolein in the industrially relevant pressure range. The melting points of different polymorphic forms are detected optically in thin samples during stepwise changes of pressure or temperature. For cross-nucleated spherulites, this method allows determining the respective melting points of nuclei and overgrown structures. Tracing the melting curves to atmospheric pressure confirms previous identification of the polymorphic forms at high pressure and enables identifying a previously reported but undefined structure as the β₂-form. Employing Raman spectroscopy, it is confirmed that the polymorph remained unaltered during the pressure release. With increasing pressure, the melting curves of the different polymorphic forms approach each other until they successively merge at the highest pressure levels studied.     

Determination of the Equilibrium Composition of the Product Mixture in the Reaction of Oxidizing Ammonolysis of Methane

Application of the advanced Hook‐Jeeves method for the solution of systems of nonlinear equations has led to determination of the equilibrium composition of the product mixture formed in the reaction of oxidizing ammonolysis of methane (OAM). It is shown that the composition crucially depends on the number of the considered parallel and sequential reactions. It is established that no thermodynamic restrictions exist both for the formation of formic acid in the course of the OAM reaction and for the subsequent conversion of formic acid to hydrogen cyanide.     

蜡产品成型过程中的质量控制

在介绍蜡产品成型生产、工艺原理及特点的基础上,针对过程控制中存在的质量问题,分析出现问题的原因,确定相应的对策,并得出有效控制的结论,达到提高蜡产品成型质量的目的.     

Growth Rate of Pressure-Induced Triolein Crystals

In pressure-induced crystal growth of triolein from melt at pressures up to 300 MPa and at temperatures between 283.16 and 293.16 K, we can distinguish three different crystal morphologies. Raman spectroscopy indicates that they are related to different polymorphic structures. Switching from the most stable to a less-stable structure implies a jump in the growth rate to a maximum value. As pressure increases, the growth rate decreases indicating that the growth is transport limited. Measurements at different temperatures show that the growth rate is mainly governed by pressure. In a certain parameter range, we observe cross-nucleation to crystals with a higher growth rate. These crystals have a Raman fingerprint not yet described in the literature.     

钢筋混凝土梁中碱-硅反应的控制

介绍国外用F级低钙粉煤灰控制钢筋混凝土梁结构变形的试验数据。试验数据表明 ,粉煤灰具有控制砼梁变形和防止由碱 硅反应引起的强度损失双重作用     

通过气泡成分分析解决超白浮法玻璃生产中的气泡缺陷

气泡是玻璃生产中最常见的玻璃缺陷之一,由于它的大小、密度、位置的不确定性,增加了对气泡缺陷来源诊断的难度。超白浮法玻璃生产中气泡更是影响玻璃质量的主要缺陷,通过测定气泡中气体的组成含量,可以较准确、快速地判断该缺陷产生的根源,从而采取有效措施消除缺陷。     

抑制菱镁制品返卤泛霜的实验研究

在以往的研究中,大多采用无机改性剂或有机改性剂进行研究,进而导致菱镁制品的试验研究停留在一定的水平。试验研究采用加入有机高分子改性剂和无机改性剂Na3PO4复合改性剂,先用不同剂量的有机高分子改性剂,找出有机高分子改性剂的最佳含量,再用不同剂量的无机改性剂Na3PO4与其混合使用,从而找出复合改性剂的最佳配方。实验结果表明,磷酸盐可以提高菱镁水泥的抗水性,复合效果更佳。对添加多种新型混合活性改性剂的试验研究,使菱镁制品返卤泛霜的现象得到了明显的抑制。     

控制DVD-9生产成本的有效方法

本文章直接探讨DVD-9的成本工艺。而且,必定从有利的方面去讨论成本问题。重点是DVD-9生产工艺中的3个环节。这对任何一个厂家的生产经理都是一个很好的成本分析案例。无论您使用是什么设备,这种良好的生产工艺必将让光盘复制人员从这个案例研究中学习到有益的成本分析方面的知识。 这个对比将向你展示生产DVD-9的M2 SO2系统在成本节约方面出色的表现。而且节省的最     

玻璃组成的设计与控制技术探讨

玻璃组成决定玻璃特性,根据玻璃性能要求进行科学快速的成分设计,当玻璃组成确定后,商业化生产时如何确保玻璃组成稳定以保证玻璃特性稳定,进而确保玻璃质量稳定十分重要。通过对玻璃用途以及性能要求,探讨组成的设计与控制技术,并利用科学手段实现组成的优化设计和快速控制,达到节省时间和成本、提高效益的目的。     

松弛法求解气相复杂反应体系平衡组成的面向对象编程

介绍一套通用的计算低压气相复杂反应体系平衡组成的软件。采用C Builder5.0面向对象编程语言开发，只要输入反应网络和工艺条件以及初始参数，就能自动进行处理。实例应用表明，计算结果可靠，使用方便。     

Minimizing Bromate Concentration by Controlling the Ozone Reaction Time in a Full-Scale Plant

The latest European Directive 98/83/CE (5 December 1998), concerning the quality of water intended for human consumption, has set a two-stage parametric value for bromate. Bromate concentration will comply with 25 μg/L after December 25, 2003, and with 10 μg/L after December 25, 2008. Bromate formation in water is generally due to bromide oxidation during the ozonation stage. Due to higher temperatures, this latter parametric value is often exceeded in summer. Minimizing bromate levels is thus a crucial problem for drinking water producers. A bromate-minimizing strategy consists of shortening the reaction time between ozone and water. This can be done by neutralizing dissolved ozone residual with bisulfite at the exit of the ozone reactor chamber and/or by managing the introduction of ozone in different chambers depending on the water flow rate. This is only possible if, in our case, the disinfection goal for ozone is respected toward bacteria and viruses. The CT value must comply with 1.6 mg/min/L. In our plants, this value could be very large due to high contact time in and after leaving the ozone reactors.     

不同催化剂对重质油加氢反应产物的影响

采用不同的加氢催化剂,在不同的实验条件下,考察了重质油中四组分的含量变化,烃组成、元素组成。并建立了重质油组成的分离、分析方法,对加氢重质油进行四组分分离,从而探究重质油性质在加氢过程中的转化规律。     

洗衣粉配料自动控制程序

根据生产要求，改进、开发、设计了洗衣粉配料自动控制程序，应用于工厂生产，和前期相比，节约了原料成本，提高了控制精度和产品合格率。     

Enzymatic Incorporation of Selected Long-Chain Fatty Acids into Triolein

Acidolysis of triolein (tri C18:1) with selected long-chain fatty acids (LCFA) was carried out using Candida antarctica (Novozym 435), Rhizomucor miehei (Lipozyme RM IM), Pseudomonas sp. (PS-30), Aspergillus niger (AP-12), and Candida rugosa (AY-30). A better incorporation of stearic acid (SA), α-linolenic acid (ALA), γ-linolenic acid (GLA), arachidonic acid (AA), and docosapentaenoic acid (DPA) was achieved using lipase from Rhizomucor miehei. Lipase from Pseudomonas sp. catalyzed a better incorporation of linoleic acid (LA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) into triolein. Thus, Rhizomucor miehei and to a lesser extent Pseudomonas sp. might be considered as providing the most effective enzymes for acidolysis of triolein with selected LCFA. In general, incorporation of LCFA into triolein (tri C18:1) may be affected by chain length, number of double bonds, and the location and geometry of the double bonds as well as reaction conditions and reactivity and specificity of lipases used. As the ratio of the number of moles of a mixture of equimole quantities of C18 FA to triolein changed from 1 to 3, incorporation of C18 FA into triolein increased accordingly with Rhizomucor miehei lipase. Similarly, incorporation of n-3 FA into triolein increased when ALA, DPA, DHA, and EPA were used. The same trend was noticed for a mixture of n-6 FA (LA + GLA + AA) and triolein.     

对二甲苯与羟胺盐反应体系的产物调控规律

以钼化合物为催化剂,考察了对二甲苯与羟胺盐体系一步合成2,5-二甲基苯酚或2,5-二甲基苯胺的反应.探讨了反应介质、催化剂加入量、反应温度以及时间等因素对该体系反应产物的影响.结果发现,当反应介质为体积比4∶10∶1的水-乙酸-硫酸溶液,催化剂加入量为0.5 g,羟胺/对二甲苯的物质的量之比为1～1.2之间,温度80℃、时间4h的反应条件下,对二甲苯-羟胺盐体系可以生成2,5-二甲基苯酚产物,其选择性为83％.另外,在反应介质为体积比10∶5～13∶2的乙酸-硫酸溶液,对二甲苯使用量为20 mmol,催化剂加入量为0.25 g,反应温度为85℃,反应时间为4h的条件下,对二甲苯-羟胺盐体系可以高选择性地生成2,5-二甲基苯胺,其选择性为88％.     

Fe0/Fe2+去除硫酸根的产物特性及反应机理

在不同的供氧条件下,开展了利用Fe~0/Fe~(2+)复合体系去除硫酸根的实验研究,对反应产物进行了X射线衍射(XRD)、扫描电子显微镜(SEM)及X射线光电子能谱分析(XPS)表征,并剖析了其作用机理。结果表明:供氧条件对硫酸根的去除效果由好到差的顺序依次为:限制供氧好氧厌氧,硫酸根的去除率分别为(93.4±1.3)%、(67.1±3.2)%和(18.8±2.8)%。经表征确定限制供氧条件下产生的墨绿色絮体为硫酸盐绿锈,而好氧条件下的最终产物主要为纤铁矿。限制供氧条件下Fe~0/Fe~(2+)复合体系制备硫酸盐绿锈去除硫酸根实质是传统氧化法和共沉淀法制备硫酸盐绿锈的结合,克服了传统方法的缺点,具有操作简便,成本低廉的特点。