浅淡气相反应的速率常数与温度之间的关系

气相反应的速率常数与温度之间一般满足阿累尼乌斯方程式,但当用分压pi、浓度ci和摩尔分数yi来表示反应物系的组成时,相应阿累尼乌斯方程式中的反应活化能可能不相等,文章推导了气相反应活化能Ec和Ep之间及Ec和Ey之间的关系.     

Excel软件应用于化学反应速率与活化能的测定

化学反应速率和活化能的测定是大学化学、药学和医学专业学生都要求掌握的实验内容,该实验结果涉及到大量的数据、图形和计算处理。利用Excel软件的函数和自动计算功能可以大大缩短计算时间,而利用其作图和曲线拟合功能可以提高图形处理的速度和准确性。将Excel软件应用于实验教学对引导学生掌握计算机处理数据的方法有重要意义。     

不同氧化温度和升温速率下煤的活化能研究

采用热重分析技术,利用Coats-Redfern积分法对同种煤样不同处理方法条件下煤的燃烧反应活化能进行研究。解算活化能的结果表明,利用Coats-Redfern积分法只能求解煤的高温段活化能。煤高温段活化能值的大小受多种条件影响,多种条件下煤的活化能值呈现规律的不一致。复杂条件下处理的煤能够降低其活化能,进而加大煤的自燃倾向性。研究多种条件下煤的活化能大小能够为矿井防灭火提供有力的依据。     

基元反应的活化能与复杂反应历程的关系

本文通过对复杂反应的研究，提出反应可能采取的历程及其采取该历程的依据。     

几种不同PE和PP树脂的粘流活化能研究

测试了几种常用PE和PP树脂在一系列温度下的流变曲线,研究剪切速率对粘流活化能的影响。结果发现,相同剪切速率下,PP、LDPE、LLDPE的粘流活化能相对较高,HDPE树脂的粘流活化能相对较低,说明PP、LDPE和LLDPE对温度的敏感性较高,即升温有利于LDPE和LLDPE的加工;PP树脂的粘流活化能随剪切速率的增加而减小的幅度较大,表现出切力敏感性;剪切速率对PE树脂的粘流活化能的影响较小,在较宽的剪切速率范围内,温度对其流变性能的影响更明显。     

过渡态理论速率系数与标准态和热力学函数

用热力学方法推导了选择标准浓度c~$Euclid Math Oned@@(1 mol/dm~3)和标准压力p~$Euclid Math Oned@@(10~(5 )Pa)两种热力学标准状态时过渡态理论的速率系数表达式,及对于生成活化络合物反应的标准摩尔活化热力学函数在这两种热力学标准状态时的相互关系,这些结果对常见物理化学教材过渡态理论部分忽略之处给予了补充,并用研究案例说明了其应用,有利于物理化学过渡态理论的教与学和加深其应用的理解。     

水性环氧-二乙烯三胺固化剂的合成研究--固化剂胺值与表观活化能的关系

通过对合成的环氧-二乙烯三胺的凝胶时间测试,和由此而得来的表观活化能以及它与胺加成物的胺值之间的关系来考察固化剂的反应活性规律。研究了不同摩尔比、反应时间、反应温度、溶剂种类等对反应活性的影响。     

含两种不同共聚组分改性聚酯的结晶速率

添加己二酸、间苯二甲酸,聚乙二醇对PET进行改性,合成样品。用DSC法研究合成共聚物的等温结晶动力学。结果表明,在所选择的温度范围内,共聚物很好的符合Avrami方程。随温度的升高,共聚物的结晶速度常数K和Avrami指数n逐渐减小,结晶速度G逐渐降低。含2种柔性组分的共聚酯随着一种柔性组分含量的增加,结晶速率G上升;含一种刚性一种柔性组分的共聚酯随刚性组分含量的增加,结晶速率G下降。     

两种新型席夫碱的合成与表征

以对羟基苯乙醇为原料,首先经过三步反应得到中间体5-碘乙基水杨醛,然后分别与邻苯二胺、4'-乙烯基-3,4-联苯二胺反应,得到两种不同的新型席夫碱,分别对各步反应中间体以及两种目标席夫碱进行红外、核磁表征,确定结构。     

两种三苯胺氰基取代二苯乙烯类席夫碱衍生物的合成及性质

以三苯胺、对硝基苯乙腈等为原料,采用亲核取代反应、Vilsmeier甲酰化、Knoevenagel反应等合成了三苯胺基氰基取代二苯乙烯类席夫碱衍生物Y1,Y2。运用质谱、核磁共振谱进行了表征,同时研究了目标分子的聚集诱导发光效应、电化学性质和在六种不同极性溶剂中的紫外可见吸收、荧光发射性质。为寻找新的发光材料进行了有益的探索。     

Impressive Rate Raise of the Hydrosilation Reaction Through UV‐Activation: Energy and Time Saving

Silicone materials are widely used in many fields such as electrical or food industries and their consumption is constantly growing. They are generally cured by vulcanization reaction for long time at high temperatures which requires high energy consumption. The possibility to achieve the polymerization of silicone rubbers by UV‐activation promotes the reduction of both time and temperature leading to an impressive energy saving. Indeed, this process is more than 30 times faster than the thermal one. Moreover, the properties of the two resulting materials are comparable, indicating that the low time of UV‐activated hydrosilation reaction is suitable for the formation of crosslinked silicone polymers.

     

A Simple Approach to Measuring the Gas Phase Heat and Mass Transfer Coefficients in a Bubble Column

A simple experimental approach was developed to measure the gas phase volumetric heat and mass transfer coefficients in a bubble column and a slurry bubble column employing a single gas nozzle. The experimental technique was based on a transfer model that simulates humidification and direct contact evaporation models in the case of a gas bubble rising in a liquid of uniform temperature. The temperature and relative humidity of the inlet and outlet gas in the column are the only measurements required in this technique. Experiments were carried out in a 0.15 m inner diameter column using water as the liquid phase, air as the gas phase, and cation resins of 0.1 mm diameter and a specific gravity of 1.2, as the solid phase. The results showed that, when using solid concentrations in the range of 7–10 wt %, both the volumetric gas‐phase heat and mass transfer coefficients increased with an increase in the gas superficial velocity and were further enhanced by increasing the solid load after a certain minimum superficial velocity had been reached in the column (0.044 m/s in the system used). Increasing the solid load beyond 10 wt %, did not contribute to a further increase in these coefficients. Furthermore, the gas holdup in the column increased with the superficial gas velocity and was further enhanced when the solid‐phase load was in the range of 7–10 wt %. These observations agree well with previously reported findings by other investigators.     

分布活化能模型计算噻吩在NaY上的脱附活化能

采用程序升温脱附（TPD）技术测定了噻吩在NaY上以不同升温速率升温时的TPD谱图。采用活化能分布模型和一阶微分方法解析了噻吩在NaY上的非等温热重曲线。结果表明,NaY表面对噻吩是均匀的,脱附活化能大约为54 kJ/mol;较低的升温速率有助于提高对TPD曲线的分辨率。     

Intermediates in the Methanol-to-hydrocarbons (MTH) Reaction: A Gas Phase Study of the Unimolecular Reactivity of Multiply Methylated Benzenium Cations

In order to reach a deeper insight into the reaction mechanism of the zeolite catalyzed methanol to hydrocarbons reaction (MTH), the proposed reaction intermediates, i.e., a series of multiply methyl-substituted benzenium ions has been generated in the gas phase by chemical ionization. The fragmentations of the corresponding long-lived (metastable) ions have been investigated. While expulsion of H₂ dominates for the lower homologues, elimination of methane dominates for the higher homologues, accompanied by increasing amounts CH₃^·. Loss of larger fragments relevant to the MTH-reaction, in particular ethene, propene and even butene, is also observed in minor amounts. This latter finding is consistent with a proposed reaction cycle in the MTH reaction known as the paring mechanism, and the feasibility of this mechanism has thus been demonstrated. The metastable gas-phase ions studied here are considerably more energetic than those residing in a zeolite catalyst, but they were found to decompose with markedly higher selectivity towards alkenes as compared to those activated by collision-induced dissociation (CID).     

Calculating the Reaction Order and Activation Energy for the Hydrothermal Carbonization of Fructose

The development of accurate kinetic models for hydrothermal carbonization (HTC) faces major difficulties. This is related to the fact that the formation of the solid hydrochar can be regarded as a formation of a second phase from a homogenous solution. The reaction mechanism is not fully understood. From the current state of art, it is obvious that the reaction mechanism is some sort of polymerization reaction, thus, having reaction order higher than one. In order to gain more knowledge about the HTC reaction, fructose is used as a model substance, as it can be regarded as a key intermediate during the hydrothermal processing of carbohydrates. The results indicate that the reaction order is a highly sensitive parameter varying with temperature, reaction time and initial concentration. It can be concluded that the model itself is a strong simplification of the real reaction mechanism, thus more research is necessary to complete the actual knowledge.     

Structural Characterization of the Spinel Phase in the Kaolin-Mullite Reaction Series Through Lattice Energy

Kaolinite undergoes structural transformation on heating. X-ray photographs reveal the existence of a spinel-type phase when kaolin is heated at 980°C. The kaolinite decomposes into a spinel phase with the expulsion of silica. A controversy arises as to whether the spinel phase is γ-Al₂O₃ or Si-Al spinel. Calculating the lattice energies of the structures confirms that the spinel phase is γ-Al₂O₃ and not Si-Al spinel, as proposed earlier. The heat involvement in phase transformation, as obtained from experimental observation at 980°C, is also explained in the light of lattice energies.     

p(BAMO-AMMO)热塑性高能推进剂燃烧转爆轰试验研究

采用燃烧转爆轰(DDT)管法研究了p(BAMO-AMMO)热塑性推进剂主要固体组分RDX和AP含量、AP粒度及级配等对其燃烧转爆轰响应规律的影响。结果表明,在相同试验条件下,含质量分数65%AP的p(BAMOAMMO)推进剂发生了燃烧转爆轰响应,而含等量RDX的p(BAMO-AMMO)推进剂仅发生了燃烧反应。当RDX质量分数从65%增加到85%时,样品由燃烧反应变为燃烧转爆轰反应。含等量细粒度(d50=1.0μm)AP的推进剂发生燃烧转爆轰的倾向较含粗粒度AP(d50=105μm)的低。当粗、细AP以质量比为10∶3级配时,p(BAMOAMMO)推进剂未发生燃烧转爆轰反应。     

Reaction Kinetics of Ozone Gas in Green Gram (Vigna radiate)

This study was carried out to evaluate the reaction kinetics of ozone gas in different height (5 and 10 cm), moisture content (10.6 and 13.4% (d.b.)) and gas flow rate (2 and 4 L/min). The decomposition kinetics obtained was first-order model. As far as the half-life of ozone is considered, the highest value obtained was equivalent to 8.72 min for grains ozonated at 5 cm height, 10.6% (d.b.) moisture content and 2 L/min gas flow rate. In the process of ozone reaction rate in green gram grains, height (p < 0.01) and moisture content (p < 0.01) were found to be the key factor for the effectiveness of ozone fumigation.     

The Use of Inverse Gas Chromatography (IGC) to Determine the Surface Energy of RDX

The surface properties of RDX play an important role in enhancing mechanics performances of the propellants and explosives. In this work, thereby, inverse gas chromatography (IGC) using various probe liquids as the medium was used to determine the surface energy components of RDX containing both dispersive and polar components, which were acquired respectively from neutral probe liquids (such as n‐hexane, n‐heptane, n‐octane) and polar probe liquids (such as chloroform, benzene, methanol). The results show that RDX located in different column temperatures has difference in the surface energy and possesses more surface energy when there is high temperature. The calculated formula of the total surface energy with temperature is: , and it is also found that dispersive, polar, electron acceptor, and electron donor components of RDX are , , , and , respectively. These results demonstrate that the dispersive component is the primary part of the total surface energy, and RDX has an acid performance.