Thermal Decomposition Mechanism and Non Isothermal Kinetics of Complex of [La_2(P-MBA)_6(PHEN)_2]2H_2O

Ｏｗｉｎｇｔｏｔｈｅｖａｒｉａｔｉｏｎｏｆｃｏｏｒｄｉｎａｔｅｄｍｏｄｅｓｆｏｒｃａｒｂｏｘｙｌａｔｅａｎｉｏｎｓ ,ｍａｎｙｄｉｆｆｅｒｅｎｔｔｙｐｅｓｏｆｃｒｙｓｔａｌｓｔｒｕｃｔｕｒｅｓｆｏｒｔｈｅｒａｒｅｅａｒｔｈｃｏｍｐｌｅｘｅｓｗｉｔｈａｒｏｍａｔｉｃａｃｉｄａｎｄｎｉｔｒｏｇｅｎ ｃｏｎｔａｉｎｉｎｇｌｉｇａｎｄｓｗｅｒｅｏｂｔａｉｎｅｄ[1～ 4 ] .Ｔｈｅｉｒｔｈｅｒｍａｌｄｅｃｏｍｐｏｓｉｔｉｏｎｂｅｈａｖｉｏｒｈａｄｂｅｅｎｒｅ ｐｏｒｔｅｄｉｎｐｒｅｖｉｏｕｓｐａｐｅｒｓ[5～ 8] .…     

二甲醚燃烧用催化剂BaO·MnO·6Al_2O_3的热分解动力学

采用反相微乳法制备和超临界干燥获得前驱体BaO.MnO.6Al2O3。利用TG-DTA曲线和XRD分析对前驱体的热分解过程进行研究,并用Coats-Redfern法和Kissinger法进一步研究前驱体的热分解动力学,获得六铝酸盐催化剂前驱体热分解的机制函数为:积分式G(α)=[-ln(1-α)]4,微分式为:f(α)=(1/4)(1-α)[-ln(1-α)]-3,反应为随机成核和随后生长控制,计算出的活化能Ea=187.80kJ.mol-1。     

[Eu2(p-MOBA)6(phen)2](H2O)2配合物热分解动力学研究

采用ＴＧ－ＤＴＧ技术研究了「Ｅｕ２（ｐ－ＭＯＢＡ）６（ｐｈｅｎ）２」（Ｈ２Ｏ）２（ｐ－ＭＯＢＡ代表对甲氧基苯甲酸根离子;ｐｈｅｎ表示１,１０－邻啡罗啉）在静态空气中的非温热分解过程及动力学,根据ＴＧ曲线确定了热分解过程的中单产的及最终产物,动用Ａｃｈａｒ法与Ｃｏａｔｓ－Ｒｅｄｌｆｅｒｎ法对非等温动力学数据进行分析,推断出和线步的动力学方程为ｄａ／ｄｔ＝ＡｅｘＰ（－Ｅ／ＲＴ）「－ｌｎ（１－ａ）」＾－     

基于非等温热重法的氟化石墨热分解动力学研究

针对氟化石墨热分解动力学机理不确定和动力学预测信息不足的问题,通过测量多组非等温热重曲线,并利用无模型动力学方法分析（CF）_n热分解反应动力学机理.热重曲线显示（CF）_n热分解经历一步失重,产生的平均气相成分为CF_2.95.动力学分析结果表明机理函数随转化率依次变化:α < 0.1,机理函数为JMA方程f（α）=1.5（1-α）[-ln（1-α）]1/3;0.15 < α < 0.3,机理函数为二维Avrami-Erofeyev方程f（α）=2（1-α）[-ln（1-α）]1/2;0.3 < α < 0.8,机理函数为?esták-Berggren方程f（α）=7.5α1.2·（1-α）2;0.85 < α,机理函数为一维Avrami-Erofeyev方程f（α）=（1-α）.推荐的动力学预测参量活化能为264.23±7.82 kJ/mol,指前因子为（8.70±0.21）×1014/s.另外,动力学机理反映出（CF）_n分解过程存在碳核的链生长以及与分支链的相互作用的特征,这可能是反应产物形成非晶态结构碳的重要因素.      

Oxidation kinetics of ilmenite concentrate by non-isothermal thermogravimetric analysis

The non-isothermal oxidation experiments of ilmenite concentrate were carried out at various heating rates under air atmosphere by thermogravimetry.The oxidation kinetic model function and kinetic parameters of apparent activation energy(Ea)were evaluated by Málek and Starink methods.The results show that under air atmosphere,the oxidation process of ilmenite concentrate is composed of three stages,and the chemical reaction(G(α)=1-(1-α)~2,whereαis the conversion degree)plays an important role in the whole oxidation process.At the first stage(α=0.05-0.30),the oxidation process is controlled gradually by secondary chemical reaction with increasing conversion degree.At the second stage(α=0.30-0.50),the oxidation process is completely controlled by the secondary chemical reaction(G(α)=1-(1-α)~2).At the third stage(α=0.50-0.95),the secondary chemical reaction weakens gradually with increasing conversion degree,and the oxidation process is controlled gradually by a variety of functions;the kinetic equations are G(α)=(1-α)~(-1)(β=10K·min~(-1),whereβis heating rate),G(α)=(1-α)~(-1/2)(β=15-20K·min~(-1)),and G(α)=(1-α)~(-2)(β=25K·min~(-1)),respectively.For the whole oxidation process,the activation energies follow a parabolic law with increasing conversion degree,and the average activation energy is 160.56kJ·mol~(-1).     

六水草酸镝热分解过程机理及动力学研究

稀土草酸盐是目前制备稀土氧化物，尤其是制备具有可控粒度的稀土氧化物常用的前驱体，它具有沉淀物晶型好，易于过滤分解等优点.然而，目前稀土草酸盐热分解的动力学研究较少，因此，采用热重-差热分析法，研究六水草酸镝的热分解过程，通过Kissinger、Ozawa和Crane法计算六水草酸镝的分解动力学参数，通过Coats-Redfern法求出反应的机理函数.结果表明:几种方法计算的分解活化能比较接近，六水草酸镝热分解分2步进行，第1步为1级脱水反应，反应机理函数为F1，表观活化能为62.48 kJ/mol，指前因子为1.84×106；第2步也为1级分解反应，反应机理函数为F2，表观活化能为106.42 kJ/mol，指前因子为2.79×107.      

含锌废渣及贫杂锌矿的碱浸动力学研究

研究了含锌废渣及贫杂锌矿在碱浸过程中的动力学。结果表明,含锌废渣(ZnO)在碱溶液中的浸出过程符合关系式1-(1-η)13=kt,表观活化能为49.22 kJ/mol,说明浸出过程受化学控制;贫杂锌矿(ZnCO3)在碱溶液中的浸出过程可分为两段,在开始段时间内,1-(2/3)η-(1-η)2/3与浸出时间呈直线关系,活化能为19.95 kJ/mol;而在6 min以后则是1-(1-η)13与浸出时间呈直线关系,活化能为46.54 kJ/mol。说明在开始时间段内是受内扩散控制,而随后的浸出过程是受化学反应控制。     

Study on sorption of D155 resin for gadolinium

The sorption behavior and mechanism of a Macroporous weak acid resin, （D155 resin,） for Gd（Ⅲ） were investigated. The statically saturated sorption capacity is 283 mg/g resin at 298 K in HAc-NaAc medium. The Gd（Ⅲ） adsorbed on macroporous weak acid resin, （D155 resin,） could be reductively eluted with the mixed solution of HCl and NaCl, and the elution percentage was as high as 100%. The resin could be regenerated and reused without remarkable decrease in sorption capacity. The apparent sorption rate constant was k298=1.98×10^5 s^-1. The apparent activation energy was Ea=2.78 kJ/mol. The sorption behavior of D155 resin for Gd（Ⅲ） obeyed the Langmuir isotherm. The thermodynamic sorption parameters were △H=33.0 kJ/mol,△S=192 J/mol/K, and △G298=-24.3 kJ/mol. The sorption mechanism of D155 resin for Gd（Ⅲ） was examined by using chemical method and IR spectrometry. The coordination compound was formed between oxygen atoms in the functional group of D155 resin and Gd （Ⅲ）.     

石灰石热分解动力学模型研究

采用TG-DSC方法研究粒径大小为900μm石灰石的热分解过程。根据石灰石热重实验数据,结合Coats-Redfern法,Flynn-Wall-Ozawa法和Kissinger法计算石灰石热分解动力学参数,得到900μm石灰石热分解的活化能E为193.98kJ/mol,指前因子lgA为8.81min-1。根据Malek方法判断石灰石热分解最概然机理函数,得到900μm石灰石热分解属于三维相边界反应模型R3,进一步得到其热分解动力学方程。      

Effects of temperature on the kinetics of the gated electron-transfer reaction between zinc cytochrome c and plastocyanin. Analysis of configurational fluctuation of the diprotein complex

This is a study of the effects of temperature (in the range 273.3-307.7 K) and of ionic strength (in the range 2.5-100 mM) on the kinetics of photoinduced electron-transfer reaction 3Zncyt/pc(II)--> Zncyt+/pc(I) within the electrostatic complex of zinc cytochrome c and cupriplastocyanin at pH 7.0. In order to separate direct and indirect effects of temperature on the rate constants, viscosity of the solutions was fixed, at different values, by additions of sucrose. The activation parameters for the reaction within the preformed complex, at the low ionic strength, are delta H++ = 13 +/- 2 kJ/mol and delta S++ = -97 +/- 4 J/K mol. The activation parameters for the reaction within the encounter complex, at the higher ionic strength, are delta H++ = 13 +/- 1 kJ/mol and delta S++ = -96 +/- 3 J/K mol. Evidently, the two complexes are the same. The proteins associate similarly in the persistent and the transient complex, i.e., at different ionic strengths. In both complexes, however, electron transfer is gated by a rearrangement, as previous studies from this laboratory showed. Changes in the solution viscosity modulate this rearrangement by affecting delta H++, not delta S++. The activation parameters are analyzed by empirical methods. The thermodynamic parameters delta H and delta S for the formation of the complex Zncyt/pc(II) are determined and related to changes in hydrophilic and hydrophobic surfaces upon protein association in three configurations. A difference between the values of delta H for the configuration providing optimal electronic coupling between the redox sites and the configuration providing optimal docking equals the experimental value delta H++ = 13 kJ/mol for the rearrangement of the latter configuration into the former. Enthalpy of activation may reflect a change in the character of the exposed surface as the diprotein complex rearranges. Entropy of activation may reflect tightening of the contact between the associated proteins.     

微型流化床内CO还原铁矿粉动力学试验

 采用微型流化床-过程质谱反应分析仪进行了铁矿粉的CO还原动力学研究。结果表明：微型流化床可抑制外扩散作用,利用等温方法算出的铁矿粉还原反应的活化能为2628kJ/mol,指前因子003946s-1,证明该铁矿粉还原符合气体内扩散控制机制模型,并且采用等温动力学方法可实现反应速率常数与模型函数的分离,极大地简化了计算过程,增加了动力学参数的准确性,为铁矿粉还原动力学的研究提供了一种简单可靠的测试方法。     

微波加热配碳还原分解铁酸锌的工艺及机理研究

研究了利用微波配碳还原焙烧分解铁酸锌的工艺及机理。利用碳气化控制、化学控制及扩散控制模型研究了样品中铁酸锌分解的动力学行为,并考察了微波功率、反应温度、配碳比和粒度对铁酸锌分解率的影响。结果表明,样品的微波加热碳热还原试验的控制步骤为碳气化控制,活化能为39.21kJ/mol,在微波加热温度850℃、C/ZnFe2O4质量比为1∶4、粒径74～89μm、微波功率1.8kW、加热时间60min的条件下,铁酸锌的分解率达到90%。     

Synthesis, characterization and thermostability of tris（2,2,6,6-tetramethyl-3,5- heptanedionato）yttrium（III）

The metal-organic chemical vapor deposition (MOCVD) technique is a promising process for high temperature superconductor YBa2Cu3O7-δ(YBCO) preparation. In this technique, the purity, evaporation characteristics and thermostability of adopted precursors will decide the quality and reproducible results of YBCO film. In the present report, tris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium(III)(Y(TMHD)3) was synthesized by the interaction of yttrium nitrate hydrate with TMHD in methanol solution, and its structure was identified by FTIR, 1 H NMR, 13C NMR and EI-MS spectroscopy. Subsequently, the thermal property and the kinetics of decomposition were systematically investigated by non-isothermal thermogravimetric analysis methods (TGA) at different heating rates in streams of N2,and the average apparent activation energy of evaporation process was evaluated by the Ozawa, Kissinger and Friedman methods. The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 88.9kJ/mol.     

稀土脯氨酸高氯酸盐配合物[RE_2(Pro)_6(H_2O)_4](ClO_4)_6(RE=Pr,Er)的低温热容及热力学性质

合成了两种纯度分别是 99.2 4%和 98.2 0 %的单晶稀土脯氨酸高氯酸盐配合物 [Pr2 (Pro) 6 (H2 O) 4](Cl O4) 6 和 [Er2 (Pro) 6 (H2 O) 4](Cl O4) 6 ,对该配合物进行了热容、热重、差热和标准燃烧热等测定。在 78～ 370 K温度区 ,用高精密全自动绝热量热仪测定了热容值 ,计算机拟合得其热容对温度的多项式方程分别为 :Cp=140 7.0 8 75 1.6 7X 170 .17X2 89.5 9X3- 76 .11X4和 Cp=1317.99 6 33.0 5 X 16 3.82 X2 15 0 .2 3X3- 86 .2 1X4,[Er2(Pro) 6 (H2 O) 4](Cl O4) 6 的 Cp- T曲线有一熔化峰 ,计算熔点为 35 5 .5 5 K,熔化熵为 6 9.5 42 J/(K m ol) ,熔化焓为2 472 5 .81J/m ol。 TG、DTA技术研究了其热分解过程 ,初步分析了配合物的分解机理。燃烧热实验给出了它们的标准燃烧热分别为 1772 0 .41k J/mol和 1810 1.6 5 k J/m ol     

热分析技术在褐铁矿结晶水热分解中应用研究

  利用热分析 (TG、DTG、DSC)技术,在一定升温速率(β=10℃/min)下对褐铁矿结晶水热分解进行非等温动力学研究,采用Coats Redffen法求解了褐铁矿结晶水热分解过程的活化能。结果表明：褐铁矿结晶水热分解过程是一个缓慢—快速—缓慢的过程,其在烧结过程中吸收热量与结晶水含量不成正相关,而与热分解活化能成正相关。     

Reactivity of homocysteine-thiolactone and alpha-methylhomocysteine-thiolactone with e-(aq) and OH-radical: a pulse radiolysis study

The efficient radiation protecting agents homocysteine-thiolactone x HCl (HCTL x HCl) and its alpha-alkylated derivative (alpha-methyl-homocysteine, alpha-MHCTL x HCl) have been investigated in respect to the identification of the primarily formed species after absorption of ionizing radiation using pulse radiolysis technique.The reaction of e-(aq) with the unprotonated form of HCTL (k = 2.1 x 10(9) dm3 mol(-1) s(-1)) is leading to the formation of a radical anion having two absorption bands: at 275 nm (epsilon = 2500 dm3 mol(-1) cm(-1)) and 510 nm (epsilon = 930 dm3 mol(-1) cm(-1)), which decay with 2k = 2.3 x 10(9) dm3 mol(-1) s(-1). The protonated form of HCTL reacts with e-(aq) with k = 4.0 x 10(10) dm3 mol(-1) s(-1). The OH-radicals react with HCTL with k = 1.95 x 10(9) dm 3 mol(-1) x s(-1) resulting in a transient spectrum with lambda(max) = 265 nm (epsilon =2000 dm3 mol(-1) cm(-1)). The transients disappear with 2k = 2.1 x 10(9) dm3 mol(-1) s(-1). The reactivity of e-(aq) with alpha-MHCTL was determined for both forms: for the protonated, k = 1.25 x 10(10) dm3 mol(-1) s(-1) and for the unprotonated, k = 2.6 x 10(9) dm3 mol(-1) s(-1). The transient absorption spectrum at pH = 8.4 shows two absorption bands: lambda = 275 nm (epsilon = 3500 dm3 x mol(-1) x cm(-1)) and 490 nm (epsilon = 1160 dm3 x mol(-1) x cm(-1)). The transients disappear with 2k = 2.2 x 10(9) dm3 x mol(-1) x s(-1). The reaction of OH with alpha-MHCTL x HCl,k = 8.4 x 10(9) dm3 x mol(-1) x s(-1) (pH = 8.6) is resulting in an absorption spectrum with lambda(max) < 260 nm and an absorption band at 350 nm (epsilon = 510 dm3 x mol(-1) x cm(-1)). Up to 50 micros after pulse the transients decay with 2k = 5.5 x 10(9) dm3 x mol(-1) x s(-1) and thereafter by a k = 8.4 x 10(9) dm3 x mol(-1) x s(-1) (pH = 8.6) is resulting in an absorption spectrum with lambda(max) < 260 nm and an absorption band at 350 nm (epsilon = 510 dm3 x mol(-1) x cm(-1)). Up to 50 micros after pulse the transients decay with 2k = 5.5 x 10(9) dm3 x mol(-1) x s(-1) and thereafter by a first order reaction. In addition, the formation of some products was also studied. The yield of ammonia resulting from alpha-MHCTL x HCl strongly depends on pH, e.g. at pH = 5.1 Gi (NH3) = 0.95, whereas at pH = 9.15 it increases to Gi = 3.1. Hydrogen sulphide is formed in airfree solutions, Gi (H2S) = 0.29, whereas in the presence of N2O it is reduced to Gi (H2S) = 0.10. Some probable reaction mechanisms are presented.     

不锈钢尘泥球团煤基直接还原动力学

摘要：研究了不锈钢尘泥球团在温度分别为1100、1150、1200、1250℃时的煤基直接还原反应动力学。采用随机成核和随后生长、化学反应控制、相界面反应和n（n=1、2、3、4）维扩散模型及其相应动力学机制函数对反应过程进行拟合,并结合X-射线衍射（XRD）、扫描电镜（SEM）、能谱分析（EDS）等手段对不锈钢尘泥球团煤基直接还原过程的物相组成、显微结构及元素分布进行表征和分析。研究结果表明：反应初期铁氧化物还原速率较快,随后逐渐减慢,当反应至40min后,反应趋向于平衡。在1100~1250℃温度范围内反应遵从随机成核和随后生长及A1(α)=-ln(1-α)机制函数,碳的气化反应和界面化学反应是尘泥球团煤基直接还原反应的限制性环节,该反应活化能E为47.423kJ/mol,线性相关系数为0996。     

Principles of magnetic resonance angiography

A strongly fluorescing 7-hydroxycoumarin (umbelliferone, U) oxidized in dilute (10 mumol/L-O, 1 mol/L) aqueous solution with CIO- or CIO- + H2O2 (but not with H2O2 alone) produces a strong chemiluminescence (CL). Light emission kinetics depends on the pH of solution (4.0-10.5) and the reaction has a low activation energy Ea = 31 +/- 2 kJ/mol (285-310 K). The spectrum covers the fluorescence of umbelliferone (400-550 nm, lambda max 460 nm). No red emission typical of 1 delta g, 1 sigma g, 1 sigma+g (O2)2 is observed either in the umbelliferone+CIO- or the umbelliferone +CIO- + H2O2 solution. The possible mechanism of CL and concomitant degradative oxidation of umbelliferone is discussed.     

Reduction behavior and mechanism of Hongge vanadium titanomagnetite pellets by gas mixture of H2 and CO

Hongge vanadium titanomagnetite(HVTM)pellets were reduced by H_2-CO gas mixture for simulating the reduction processes of Midrex and HYL-III shaft furnaces.The influences of reduction temperature,ratio ofφ(H_2)toφ(CO),and pellet size on the reduction of HVTM pellets were evaluated in detail and the reduction reaction kinetics was investigated.The results show that both the reduction degree and reduction rate can be improved with increasing the reduction temperature and the H_2 content as well as decreasing the pellet size.The rational reduction parameters are reduction temperature of 1050°C,ratio ofφ(H_2)toφ(CO)of 2.5,and pellet diameter in the range of 8-11 mm.Under these conditions(pellet diameter of 11mm),final reduction degree of 95.51% is achieved.The X-ray diffraction(XRD)pattern shows that the main phases of final reduced pellets under these conditions(pellet diameter of 11 mm)are reduced iron and rutile.The peak intensity of reduced iron increases obviously with the increase in the reduction temperature.Besides,relatively high reduction temperature promotes the migration and coarsening of metallic iron particles and improves the distribution of vanadium and chromium in the reduced iron,which is conducive to subsequent melting separation.At the early stage,the reduction process is controlled by interfacial chemical reaction and the apparent activation energy is 60.78kJ/mol.The reduction process is controlled by both interfacial chemical reaction and internal diffusion at the final stage,and the apparent activation energy is 30.54kJ/mol.     

氢化钛的动态分解行为与规律

通过DSC/TG的热分析试验,研究氢化钛升温过程中分解的动力学规律,利用Coast-Redfern积分法计算了分解过程的动力学参数。结果表明,氢化钛热分解的开始温度为510℃,分解过程中总质量损耗率达3.15%,其中565～660℃温度范围内的质量损耗率占总质量损失的50%左右,分解过程中生成了比氢化钛热稳定性更高的TiHx(0.7相似文献