氯离子柱撑水滑石共沉淀法合成反应动力学

根据氯离子型层状复合氢氧化物(LDH-Cl)制备过程中溶液浓度变化的监测结果和不同反应进程时产物的EDS、IR、XRD、TEM、TG-DTA表征结果,研究了合成LDH-Cl的共沉淀反应动力学特征及机理.实验结果表明, LDH-Cl的生成符合多核层表面反应动力学模型;反应过程中LDH的晶胞参数c从2.421 nm变为2.399 nm,通道高度h由0.3321 nm减小为0.3228 nm,粒子直径Da由6.40 nm增大为15.16 nm, Dc由7.43 nm增大到10.93 nm,纵横比由0.86增大为1.39; IR和TG-DTA特征变化表明了层板对阴离子作用的强度和层板的结构稳定性随反应进程而提高.     

氯离子柱撑复合氢氧化物纳米微晶的制备及属性

用共沉淀法制备前驱体后,在水热、微波和沸热等不同晶化方式下合成了一系列层状氯离子柱撑镁铝复合氢氧化物(LDH-Cl),在EDS,XRD,IR,TG-DTA,TEM和N₂吸附-解吸测试表征的基础上,讨论了LDH-Cl的组成与结构的关系及制备条件对组成、结构和性质的影响.研究结果表明:LDH-Cl具有超分子结构和水滑石型层状结构的特征;微晶生长习性在不同晶化过程中的差异决定了粒子发育程度的不同、组成与结构相关性的不同;微晶粒子在不同合成条件和晶化方式下表现了不同的结晶度水平从而引起红外吸收、热稳定性及比表面积等基本属性的变化.     

四硼酸根阴离子对氯型水滑石前体插层组装的动力学研究

根据四硼酸根对氯型水滑石(LDH—Cl)前体插层组装时溶液浓度的变化和不同反应进程产物的EDS,IR,XRD,TEM和TG—DTA表征研究了四硼酸根插层组装的动力学．结果表明,氯离子的交换溶出符合Stumm模型,四硼酸根的插入受控于扩散过程模型,插层产物保留了前驱体的层状结构及微孔结构,但插入大体积复杂离子B4O5(OH)4^2-引起晶胞c轴向体积和粒子尺寸的变化较大,晶胞参数c由2．399nm增大到2．558nm,通道高度h由0．3228nm增大到0．3756nm,粒子面向直径Da由15．16nm减小到8．92nm,径向尺寸Dc由10．93nm减小到4．55nrn;比表面积由92．63m^2／g增大到111．20m^2／g,LDH热分解特征亦有较大变化．     

牛黄酸及水杨酸系药物对镁铝层状复合氢氧化物的插层组装

通过XRD和IR表征对镁铝层状复合氧氧化物(LDH)与水杨酸、乙酰氨基酚、乙酰水杨酸,以及谷氨酸、色氨酸、牛黄酸反应产物的比较分析,研究了不同药物对有关组装方式的适宜性.结果表明水杨酸类药物均可通过离子交换组装到LDH层间,晶胞参数c由2.3893 nm依次增大为2.4024、2.4110和2.4111nm,通道高度h由0.3194 nm增大为0.3238、0.3267和0.3268 nm;通过离子交换能将谷氨酸组装到LDH层间,产物的IR吸收、热分解行为及TEM形貌与前体有明显区别,晶胞参数c由2.3765nm增大为2.3851nm,h由0.3152nm增大为0.3180nm;共沉淀法适宜制备LDH-牛黄酸插层复合物,但简单的离子交换不能使色氨酸与LDH有效复合.     

高分子修饰Pt/ZnS-CdS/SiO2催化剂表面官能团调变

用丙烯酸酯和环氧树脂将亲水性的-OH和芳香性的苯环修饰到Pt/ZnS-CdS/SiO2催化剂表面,在不同气氛下进行热处理,得到了表面修饰并热处理后的Pt/ZnS-CdS/SiO2光催化剂,考察催化剂的可见光催化分解水产氢活性.结果表明修饰并热处理后催化剂活性不同程度的下降.XRD结果表明,修饰前后ZnS和CdS的特征衍射峰没有改变,但空气热处理致使催化剂晶型由立方晶型的CdS和六方晶型的ZnS向六方晶型的CdS和α-ZnS的转变,氢气气氛热处理致使催化剂的晶型向六方结构的固溶体Zn0.5Cd0.5S转变,未修饰的催化剂在空气和氢气中热处理后晶型发生了同样的转变.HRTEM结果表明表面修饰后催化剂平均粒径由18 nm减小为6 nm,仍以ZnS为外层,CdS为内层的核壳结构形态存在.紫外可见漫反射(UV-Vis DRS)结果表明,经修饰和热处理后的光催化剂在450～800 nm区间的光吸收增加,在空气中773 K煅烧后的催化剂的吸收限由480 nm红移至520 nm,而在氢气中于773 K煅烧后吸收限则由480 nm蓝移至420 nm.修饰后催化剂的羟基吸收强度增大,出现了苯环的特征吸收峰,这些官能团经热处理后发生了显著变化.红外光谱(IR)结果表明空气热处理导致部分含氧官能团发生了脱离,羟基吸收增强;氢气热处理导致C—O和C—O—C的吸收峰增强,同时催化剂表面发生碳化.热重差热分析(TG-DTA)与红外结果均证实了这种变化.产氢活性下降可能归结为表面羟基减少导致的在反应体系中的分散性和光生电荷的分离效率降低;催化剂表面的含氧官能团占据了催化活性位并且降低了颗粒在水溶液中的分散性.     

Studies on Photocatalytic Hydrogen Production Relating to the Surface Functional Groups＇ Modulation of Polymer-modified Pt/ZnS-CdS/SiO2

用丙烯酸酯和环氧树脂将亲水性的-OH和芳香性的苯环修饰到Pt/ZnS-CdS/SiO2催化剂表面,在不同气氛下进行热处理,得到了表面修饰并热处理后的Pt/ZnS-CdS/SiO2光催化剂,考察催化剂的可见光催化分解水产氢活性.结果表明修饰并热处理后催化剂活性不同程度的下降.XRD结果表明,修饰前后ZnS和CdS的特征衍射峰没有改变,但空气热处理致使催化剂晶型由立方晶型的CdS和六方晶型的ZnS向六方晶型的CdS和α-ZnS的转变,氢气气氛热处理致使催化剂的晶型向六方结构的固溶体Zn0.5Cd0.5S转变,未修饰的催化剂在空气和氢气中热处理后晶型发生了同样的转变.HRTEM结果表明表面修饰后催化剂平均粒径由18 nm减小为6 nm,仍以ZnS为外层,CdS为内层的核壳结构形态存在.紫外可见漫反射（UV-Vis DRS）结果表明,经修饰和热处理后的光催化剂在450～800 nm区间的光吸收增加,在空气中773 K煅烧后的催化剂的吸收限由480 nm红移至520 nm,而在氢气中于773 K煅烧后吸收限则由480 nm蓝移至420 nm.修饰后催化剂的羟基吸收强度增大,出现了苯环的特征吸收峰,这些官能团经热处理后发生了显著变化.红外光谱（IR）结果表明空气热处理导致部分含氧官能团发生了脱离,羟基吸收增强;氢气热处理导致C—O和C—O—C的吸收峰增强,同时催化剂表面发生碳化.热重差热分析（TG-DTA）与红外结果均证实了这种变化.产氢活性下降可能归结为表面羟基减少导致的在反应体系中的分散性和光生电荷的分离效率降低;催化剂表面的含氧官能团占据了催化活性位并且降低了颗粒在水溶液中的分散性.     

ZnAl-LDHs热致拓扑转变的理论及实验研究

层状复合金属氢氧化物(LDHs)材料具有纳米尺度的二维层状结构.其晶体结构在煅烧的条件下可发生热致拓扑转变,利用此性质可以LDHs为前驱体制备高分散催化剂.本文采用基于密度泛函的第一性原理分子动力学模拟方法并结合热重分析(TG-DTA)研究了ZnAl-LDHs在升温过程的拓扑转变机理.通过TG-DTA数据明确了发生分解反应的两个关键性温度273和800℃,并在这两个温度进行模拟.在273℃,模拟了LDHs层间阴离子分解及层板脱羟基过程中金属离子的迁移机理,结果表明,层间阴离子CO_3~(2-)通过与主体层板作用形成单齿配体进行分解,产物水分子先于CO_2释放到层间区域内.此时LDHs层板结构已经坍塌,金属离子在层板方向及垂直层板方向都发生了显著的迁移,拓扑不变量(层板方向迁移度)变化明显.因此,ZnAl-LDHs不存在记忆效应.在800℃,模拟发现LDHs结构已经完全坍塌,生成了多孔性的混合金属氧化物,与文献实验结果相符合.本文从原子水平上理解了LDHs整个结构从分解的起始阶段到完全脱水的演变过程,并解释了ZnAl-LDHs没有记忆效应的原因,为认识LDHs热致拓扑转变机理,设计高分散催化剂提供了有益的理论信息和指导.     

正丁胺对晶态层状苯乙烯基膦酸-磷酸氢锆的插层研究

合成了晶态层状有机-无机多功能材料苯乙烯基膦酸-磷酸氢锆(α-ZPPVPA),并研究了正丁胺(BA)对α-ZPPVPA的插层性能。用元素分析、XRD、IR、TG、SEM和TEM等分析方法对α-ZPPVPA及其插层化合物α-ZPPVPA-BA进行了结构表征和形貌分析。结果表明,正丁胺成功地插入了α-ZPPVPA层板之间,层间距为2.41 nm,正丁胺的插入使α-ZPPVPA的层间距(1.66 nm)增大了0.75 nm,插入的正丁胺在α-ZPPVPA中呈双分子层排列,且苯乙烯基侧链不饱和双键的存在不影响α-ZPPVPA与正丁胺的插层反应。     

新型纳米结构V10O24·12H2O的制备及结构表征

以V2O5粉末为原料, 在常压下制备新型纳米结构V10O24·12H2O材料, 并分析了其反应机制. 利用XRD, TEM, TG-DSC, FTIR和XPS对其结构和形貌等进行了表征. 结果表明, V10O24·12H2O的层间距d(002)≈1.43 nm; 微观形貌为球形, 球径40~60 nm; 有V4+和V5+两种化学状态; IR峰的变化主要由晶格膨胀和V4+引起; 存在吸附水、层间水及结晶水.     

纳米(NH4)3PMo6W6O40的室温固相合成及形成机理

以H3PMo6W6O40•23H2O和(NH4)2C2O4•H2O为原料，采用室温固相反应合成出(NH4)3PMo6W6O40•6H2O产物，用元素分析、IR、UV-Vis、XRD、TEM、TG-DTA、BET等手段确定其组成、结构和性能.结果表明，产物为纳米粒子，平均粒径为10 nm.纳米粒子保持着杂多阴离子的Keggin特征结构，比表面积为167.6 m2•g－1，且在465 ℃以下具有良好的热稳定性.反应中反应热能、结晶水和生成物H2C2O4•2H2O对形成小粒径的(NH4)3PMo6W6O40纳米粒子起关键作用.     

Br2+2HI=2HBr＋I2应机理的密度泛函理论

用密度泛函理论(DFT)B3LYP方法，取3-21G**基组研究了气相反应Br2＋2HI=2HBr＋I2的机理，求得一系列四中心和三中心的过渡态.双分子基元反应Br2＋HI→HBr＋IBr和IBr＋HI→I2＋HBr的活化能(81.02和121.08 kJ•mol－1)小于Br2、HI和IBr的解离能(249.21、320.16和232.42 kJ•mol－1)，故从理论上证明了标题反应将优先以分子与分子作用形式分两步完成.同时发现I原子与Br2分子反应生成较稳定的IBr2是一个无能垒过程，IBr2分解为IBr和Br原子的能垒为70.88 kJ•mol－1.     

Theoretical Study on the Reaction Mechanism of F2 ＋ 2HBr = 2HF ＋ Br2

1 INTRODUCTION The replacement reactions between halide and hy- drogen halide, or halide and halide are basic reac- tions in chemistry. Goldfinger et al. have speculated by experiment that the gas reaction between chlorine and hydrogen bromide might be a two-step intermo- lecular reaction[1, 2]. But gas reactions between other halides and hydrogen halides haven’t been reported experimentally so far. About theoretical investiga- tion, colinearity quantum mechanics, vibrational tran- sitio…     

在超音速F-F2-IF与NH3气流中产生IF(B3Π0+)的研究

研究了在超音速F-F_2-IF气流与NH_3气流中通过化学反应与碰撞传能产生IF(B~(3Π_0~+))的过程。用光学多通道分析仪在450-750 nm范围内记录到IF(B~(3Π_0~+)→X~(1∑~+))辐射的33条光谱线。提出了产生IF(B~(3Π_0~+))的机制。     

Cl_2 2HI=2HCl I_2反应机理的理论研究

分别在MP2/3-21G!!、CCSD(T)/3-21G!!//MP2/3-21G!!和B3LYP/3-21G!!3种水平上,计算研究了气相反应Cl2 2HI=2HCl I2的机理,求得一系列四中心和三中心的过渡态.通过比较六种反应通道的活化能大小,得到了相同的结论:双分子基元反应Cl2 HI"HCl ICl和ICl HI"I2 HCl的最小活化能小于Cl2、HI和ICl的解离能,从理论上证明了反应Cl2 2HI=2HCl I2将优先以分子与分子作用形式分两步完成.用内禀反应坐标(IRC)验证了MP2/3-21G!!方法计算得到的过渡态.     

Cl2+2HI=2HCl+I2反应机理的理论研究

分别在MP2/3-21G**、CCSD(T)/3-21G**//MP2/3-21G**和B3LYP/3-21G**3种水平上, 计算研究了气相反应Cl₂+2HI=2HCl+I₂的机理, 求得一系列四中心和三中心的过渡态. 通过比较六种反应通道的活化能大小, 得到了相同的结论：双分子基元反应Cl₂+HIHCl+ICl和ICl+HII₂+HCl的最小活化能小于Cl₂、HI和ICl的解离能, 从理论上证明了反应Cl₂+2HI=2HCl+I₂将优先以分子与分子作用形式分两步完成. 用内禀反应坐标(IRC)验证了MP2/3-21G**方法计算得到的过渡态.     

Investigation on the mechanism and applications of the reaction Cl_2+2HBr=2HCl+Br_2

The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions CI2+HBr→HCI+BrCI and BrCI+HBr→HCI+Br2 is smaller than the dissociation energy of CI2, HBr and BrCI, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous CI2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCI are obtained by cooling the mixtures and further separated by absorption with CCI4. The recovery percentage of Br2 is more than 96%, and the CI2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.     

The born approximation as a simple diagnostic method for direct molecular collisions with applications to Cl + HI and F + H2 reactions

Born approximation computations are presented and discussed for the Cl + HI → I + HCl and F + H₂ → H + HF reactions and their isotopic analogues. Most aspects of the role of reagent energy or the energy disposal in the products previously deduced from experiment or trajectory computations can be accounted for the Born approximation. The procedure used here neglects the interaction between non-bonded atoms. It does thereby provide a very simple computational scheme which requires as input only the spectroscopic constants of the reactants and products. In addition it offers simple qualitative interpretations of the trends in the results. The overall satisfactory agreement between the present results and past studies lends credibility to the basic propensity rule provided by the Born approximation: The most probable transitions are those that minimize the momentum transfer to the nuclei. The principle is discussed with special reference to exothermic (E′_T ? E_T) and endothermic transitions.The computations for Cl + HI indicate a decline of the reaction cross section with increasing kinetic energy and a strong enhancement by HI rotational energy. The surprisal analysis confirms the absence of vibrational population inversion for endothermic transitions. For the F + H₂ (and isotopic variants) reactions, the product-rotational state distribution extends nearly to the energy cut-off. The vibrational state distribution is somewhat different for para- and normal H₂ and, in general, the collision outcome is very sensitive to the initial rotational state of H₂ particularly at low translational energies. The HF/DF branching ratio is F + HD collisions is increasing with increase of the HD rotational state. The vibrational surprisal is essentially isotopically invariant.     

Ti^＋离子和C2H4分子自旋禁阻反应中C—H键活化机理的理论研究

用密度泛函B3LYP方法,研究了二重态和四重态势能面自旋禁阻反应Ti^＋（^4F,3d^24s^1）＋C2H4→TiC2H2^＋（^2A2）＋H2的微观机理．通过自旋．轨道耦合的计算讨论了势能面交叉点和可能的自旋翻转过程．中间体IM1-^4B2处,四重态和二重态间的旋-轨耦合值为59．3cm^-1．自旋多重度必将发生变化,从四重态系间穿越到二重态势能面形成共价型复合物IM1-^2A1,同时导致四重态势能面的势垒明显降低．到插入中间体IM2后,二重态势能面上有两条不同的反应路径,即分步和协同路径,后者在二重态势能面上得到放热产物TiC2H2^＋（^2A2）＋H2具有较低的活化势垒,4．52kcal／mol,其主反应路径为：Ti^＋＋C2H4→^4IC→IM1—^4B2→4.2ISC→IM1—^2A1→[^2TSins]→IM2-^2A”→[^2TSMCTS]→IM5→TiC2H2^＋（^2A2）＋H2．     

Mechanism and kinetics of the reaction of F with trivalent phosphorus iodide using electron spin resonance detection

The reaction of iodobistrifluoromethylphosphine, P(CF₃)₂I, with atomic fluorine was studied by fast-flow ESR methods. The initial stage of the reaction is the abstraction of I by F, to form IF with a bimolecular rate constant of (1.0 ± 0.3) × 10¹⁴ cm³ mol^?1 s^?1 at 297 K. In the presence of excess F, stepwise addition to the phosphorous occurs. In the presence of excess P(CF₃)₂I, the reaction P(CF₃)₂ + IF → P (CF₃)₂F + I appears to take place. This reaction rate is slow relative to P(CF₃)₂ + F → P(CF₃)₂F.     

Investigation on the mechanism and applications of the reaction Cl2+2HBr=2HCl+Br2

The mechanism of reaction Cl₂+2HBr=2HCl+Br₂ has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G^** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions Cl₂+HBr→HCl+BrCl and BrCl+HBr→HCl+Br₂ is smaller than the dissociation energy of Cl₂, HBr and BrCl, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br₂ from HBr. Gaseous Cl₂ directly reacts with HBr gas, which produces gaseous mixtures containing Br₂, and liquid Br₂ and HCl are obtained by cooling the mixtures and further separated by absorption with CCl₄. The recovery percentage of Br₂ is more than 96%, and the Cl₂ remaining in liquid Br₂ is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.