氨基硫脲与4-氯查尔酮亲核加成-缩合反应的理论研究

对氨基硫脲与4-氯查尔酮亲核加成-缩合反应的反应物和生成物,用量子化学密度泛函方法在B3LYP/6-31G水平上进行了几何构型全优化,从获得的4-氯查尔酮分子中主要原子的Mulliken净电荷,可以推测该化合物具有较高的亲核加成反应活性。对优化后的构型进行了振动分析,得到了不同温度下反应物和生成物的热力学性质,据此计算了相应温度下该反应的焓变、吉布斯自由能变和平衡常数。实验结果表明,在298～1000K内,氨基硫脲与4-氯查尔酮的亲核加成-缩合反应是一个放热反应,吉布斯自由能变为负值,平衡常数很大,说明反应在温和条件下即能自发进行。在此基础上采用含时密度泛函方法计算了分子激发态的电子跃迁能,得到对应激发态的吸收波长,所得结果与文献值基本吻合。     

复合锂基润滑脂制备反应的密度泛函理论

 采用传统方法制备了复合锂基润滑脂,用红外光谱对其进行分析。采用密度泛函理论研究了复合锂基润滑脂的制备反应,并用B3LYP/6-31+G方法计算了制备反应的反应物、产物的总能量,用B3LYP/6-31+G*方法计算了制备反应的反应物、中间体、过渡态和产物的总能量与零点振动能。结果表明,在复合锂基润滑脂制备中,氢氧化锂与12-羟基硬脂酸、氢氧化锂与癸二酸的反应均为放热反应,活化能均较低,中间体处于势能面的最低点,过渡态比反应物的能量要低。     

Quantum-Chemical Studies on TATB Processes

Quantum chemical studies have gained paramount importance in screening of thermodynamically feasible chemical processes. The current investigation attempts to select an appropriate process for the synthesis of 1,3,5-triamino-2,4,6-trinitro benzene (TATB), a reasonably powerful insensitive high explosive (IHE) through density functional theory (DFT) calculations. Although, 1,3,5-trichlorobenzene (TCB) and 1,3,5-trihydroxybenzene (THB) routes for synthesis of TATB have been well established, this article demonstrates the predictive capability of thermochemical computations for the identification of a viable process. Thermochemical parameters of reaction species have been obtained from DFT B3LYP/6-31G? calculations and feasibility of the process has been worked out on the basis of free energies of reactions and equilibrium constant as derived from standard enthalpy and entropy of the reaction species. The detailed computational studies have revealed that the THB route is thermodynamically feasible and the same has been supported experimentally.     

密度泛函理论在催化领域的应用

密度泛函理论作为一种高效的理论研究方法,大大缩短了催化剂的研制周期,降低了开发成本,在石油化工的催化领域得到广泛应用。简要介绍了密度泛函理论的基础,通过介绍反应物在催化剂表面的吸附、催化剂分子结构的设计、催化反应机理和修饰剂的筛选及修饰机理等方面的研究,综述了密度泛函理论在催化裂化、催化异构化、催化加氢与脱氢、催化脱硫和催化氧化等领域的应用,并讨论了密度泛函理论在石化工业催化领域应用中存在的问题和发展方向。     

Cu 和ZSM-5沸石相互作用的理论研究

首次采用密度泛函理论方法,并结合模型簇法研究了Cu^ 和ZSM-5沸石的相互作用。所有模型簇采用B3LYP混合方法对氢原子在3—21G基组水平上,对硅、铝、氧原子在6—31G(d)基组水平上进行了全优化和频率分析。考虑到过渡金属Cu的内层电子相对论效应比较明显和计算速度因素的影响,采用有效核势法(ECP)处理了Cu原子。对Cu^ 与沸石分子筛模型簇的两种配位方式的结构与能量进行了着重比较研究。研究结果表明,Cu^ 与沸石分子筛骨架以二配位的键合方式结合在结构上是最优的、能量上是有利的,是研究NO分子在Cu改性沸石分子筛上优先选择的模型簇。     

二苯并噻吩直接加氢脱硫过程的理论研究

用量子化学中的密度泛函理论,在B3LYP/6-31G*水平上,对二苯并噻吩（DBT）的直接加氢脱硫（DDS）过程进行了理论研究。通过对DBT分子在反应过程中的中间体以及过渡态的量子化学计算,得到各中间产物的能量以及其它参数,从而证明DBT在酸性催化剂上C－S键可自行断裂,完成开环过程。能量差的分析结果表明,C-S键的断裂需要较大能量,是反应过程中的决速步骤,一旦C-S键断裂,在后续的反应过程中硫的脱除相对容易,活泼氢在反应中起到重要作用。     

Cr~(+3)对乙醛C—C键激发脱羰基反应的量化计算研究

利用密度泛函理论对了Cr+3对乙醛脱羰反应中反应路径进行了研究。反应中所有静态点的几何结构和相应能量均是在B3LYP(Cr原子使用Lanl2dz基组,C、H、O使用6-31+G*基组)理论水平上计算得到,优化了势能面[Cr,O,C2,H4]上的中间体和过渡态的几何构型,计算了它们的能量和频率参数,得到了该反应的势能面以及基元反应过程的详细信息。计算表明反应经历开始吸附结合、C—C激发、H原子转移和分子解离四个阶段完成,脱羰基过程主要是由C—C激发的。     

马来酸二丁酯催化合成用新型催化剂的研究

液相法酯化合成马来酸二丁酯是典型的酸催化反应。本论文研制了系列γ Al2O3系、硅铝系催化剂,用于马来酸二丁酯的合成;考察了催化剂种类和制备工艺,以及反应工艺条件的影响。实验结果表明:以并加法制备的SiO2/Al2O3(x(Si)/x(Al)=1/1,沉淀pH值6 0)催化效果最好,在120℃、催化剂用量为1 0g、n(酸)/n(醇)=1/4下,反应3h,马来酸转化率达73 31%。     

Theoretical Study on Adsorption of Methanol on Zeolite and Phosphorus Modified Zeolite

Methanol adsorption in zeolite and phosphorus modified zeolite has been investigated within the cluster model framework of quantum chemical calculation. Full optimization and frequency analysis of all cluster model have been carried out using Gaussian 94 soft package with Hartree-Fock method and B3LYP, B3P86 hybrid methods of density functional theory at 3-21G, 6-31G basis set level for hydrogen atoms and 6-31G (d) basis set level for the other atoms performed on small cluster model for CH3OH, H3Al(OH)SiH2(H2PO4), H3Al(OH)SiH2(H3SiO4), H3Al(OH-CH3OH)SiH2(H2PO4) and H3Al(OHCH3OH)SiH2(H3SiO4). The results show that phosphorus grafting in the zeolite framework has modified the chemical environment in the vicinity of the zeolite bridging hydroxyl. Phosphorus modification can enhance the acid strength of zeolite bridging hydroxyl, which was suggested by the lengthening of zeolite bridging hydroxyl O-H bond and the increasing methanol adsorption energy. This may be favorable to the initial CH3OCH3 formation in the methanol to gasoline (MTG) process.     

咪唑类离子液体催化四氢噻吩氧化脱硫机理*

离子液体作为催化剂在石油脱硫过程中有独特优势,特别是对噻吩类硫化物。本文以四氢噻吩为模型化合物,过氧化氢为氧化物,根据密度泛函理论,研究了咪唑氯铝酸盐离子液体催化四氢噻吩（THT）氧化为砜类的反应机理,探讨了不同阳离子的离子液体催化性能的差异。通过离子液体在催化过程中与反应物、产物的作用结构,发现离子液体与产物砜具有更强的相互作用,阳离子侧链越长作用结构越稳定;根据作用后稳定结构的电荷布局、前线轨道性质,发现作用后THT上S原子有电荷富集现象,电子整体上从THT转移到离子液体,并在分子层面解释了离子液体对反应物键能、键长、电荷布局的作用机理;最后计算氧化反应能垒,证明了加入离子液体可使得反应能垒降低55%以上,且阳离子侧链越长,效果越显著。     

Pd掺杂Fe催化剂上邻甲酚加氢脱氧理论研究

应用密度泛函理论计算研究了邻甲酚在催化剂Fe(211)表面上的吸附活化行为和加氢脱氧反应性能.在此基础上,探究了过渡金属Pd掺杂以及表面水对Fe催化剂活性和产物选择性的影响.结果表明,邻甲酚通过苯环与催化剂表面发生吸附相比于通过羟基与表面相互作用更具能量优势,有利于活化苯环及CAr—O键.Fe(211)表面上邻甲酚脱羟...     

C/O杂化调变Ni催化苯分子脱氢及开环反应性能的理论研究

基于密度泛函理论计算,对比研究了Ni,Ni/O,Ni/C,Ni/C/O杂化体系的电子特性以及催化苯分子脱氢和开环反应的性能.实验结果表明,单独C或O原子对Ni外层轨道的杂化降低了Ni的化学活性,而C/O同时与Ni外层轨道杂化促进了Ni外层电子的离域,提高了Ni/C/O杂化体系与苯分子的键合作用.不同催化剂催化苯分子脱氢...     

DFT Calculation of Room Temperature Ionic Liquid 1-Ethyl-3-Methyl-Imidazolium Chlorocuprate (Ⅰ)

The density functional theory (DFT) has been employed to investigate the electronic structures of EMIM ( 1-ethyl-3-methylimidazolium ), CuCl2-, Cu2Cl3- and EMIM -CuCl2-, EMIM -Cu2Cl3- pairs.Full optimization and frequency analyses of EMIM , CuCl2-, Cu2Cl3-, eight initial EMIM -CuCl2-, and six initial EMIM -Cu2Cl3- geometries have been carried out using Gaussian-94 software-package at 6-31 G (d,p) basis set level for hydrogen, carbon, nitrogen, chlorine atoms and the Hay-Wadt effective core potential for copper atoms. The electronic structures of the lowest energy of EMIM -CuCl2-, EMIM -Cu2Cl3-pairs, single EMIM , CuCl2-, and Cu2Cl3- have been comparatively studied. The calculated results showed that the optimized EMIM -CuCl2- pair conformer of the lowest energy was five ring moiety parallel to CuCl2- plane with a distance of around 3.5A, while EMIM -Cu2Cl3- pair conformer of the lowest energy was five ring moiety of EMIM perpendicular to Cu2Cl3- plane with a distance of around 3.0 A between terminal chlorine atoms and 5-ring plane of EMIM~. The cohesion between cation and anion is electrostatic interaction and C-H-Cl hydrogen bonds are reinforced by charge assistance. The frequency analyses suggested that all stationary points are minimum points because of absence of imaginary frequency. The low energy of interaction caused by bulky asymmetry of EMIM , and charge dispersion of cation and anion give rise to low melting point of ionic liquids EMIM -CuCl2-, and EMIM -Cu2Cl3-. The interaction energy caused by the distance between cations and anions was investigated by single point energy scan.     

密度泛函理论计算研究丙烯聚合中阻聚剂的作用

以Cl2Ti+C4H9和Cl2Ti+H为活性中心,利用密度泛函理论计算研究了CO,CO2,O2阻聚剂对丙烯聚合的阻聚机理。计算结果表明,丙烯在Cl2Ti+H上的配位和插入反应比在Cl2Ti+C4H9上更容易;CO与两种活性中心的配位能力均很强,CO通过和活性中心配位产生稳定的配合物降低催化剂的聚合活性;CO2在两种活性中心上的配位能力较弱,CO2主要通过在Cl2Ti+C4H9上进行插入反应生成羧基金属化合物达到阻聚作用;O2在活性中心上的插入反应能远大于丙烯的插入反应能,O2插入后通过形成更稳定的金属过氧化物阻碍丙烯的反应。     

The Density Functional Study of Thiophene Adsorption on Zeolite Clusters

The density functional theory and the cluster model methods have been employed to investigate the interactions between thiophene and the HZSM-5 zeolites. The molecular complexes formed by the adsorption of thiophene on silanol H3SiOH with two coordination forms, and the model Brrnsted acid sites of zeolite cluster H3Si（OH）AI（OH）2SiH3 upon the interaction with thiophene have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using the B3LYP hybrid method at 6-31G basis level for hydrogen atoms and 6-31＋G（d） basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The calculated results showed that the nature of interactions leading to the formation of the zeolite cluster-thiophene and silanol-thiophene complexes was associated with the van der Waals force confirmed by a slight change of geometric structures and properties. Thiophene is adsorbed on bridging hydroxyl group prior to silanol OH group judging from the magnitude of adsorption heat. The cluster model calculation reproducing the experimental prediction to form the experimental adsorption spectra of thiophene in HZSM-5 zeolite has illustrated the validity of the proposed adsorption models.     

基于密度泛函理论的量子化学方法研究仪长管输油渣油中金属卟啉化合物

基于密度泛函理论(DFT)的量子化学计算方法,对仪长管输油渣油中几种含量最丰富的金属卟啉化合物进行分子模拟,并对其空间分子结构进行结构优化及计算,得到键参数、偶极矩以及电子吸收光谱等信息。通过分子的键参数和偶极矩发现,镍卟啉化合物的极性小于钒卟啉化合物,DPEP型卟啉分子的极性略大于ETIO型卟啉分子。计算了4种典型金属卟啉分子紫外吸收光谱的Soret吸收带和Q吸收带特征吸收峰,并得到4种卟啉化合物的稳定性由强到弱的顺序为ETIO型镍卟啉C₃₅-(ETIO-Ni)、DPEP型镍卟啉C₃₅-(DPEP-Ni)、ETIO型钒卟啉C₃₄-(ETIO-VO)、DPEP型钒卟啉C₃₁-(DPEP-VO)。     

基于分子模拟技术的Cu(Ⅰ)Y分子筛对硫化物及烯烃选择性吸附行为的分析

依据密度泛甬理论(DFT)研究了硫化物及烯烃在Cu(Ⅰ)Y分子筛上的化学吸附.利用广义梯度近似方法,采用6T分子筛团簇模型,对硫化物和烯烃在Cu(Ⅰ)Y分子筛上的吸附行为进行了模拟计算.计算结果表明,在Cu(Ⅰ)Y分子筛上烯烃分子的吸附能大于噻吩分子,与实验结果一致.通过Mulliken布居数分析硫化物和烯烃在Cu(Ⅰ)Y分子筛上的吸附行为发现,吸附剂与烯烃双键的丌_络合作用强度强于与硫化物的作用强度,进而导致烯烃对硫化物的脱除效果有明显的影响.     

甲烷在钯基催化剂上脱氢的分子模拟

为探明甲烷在钯基二聚体催化剂上脱氢反应过程的微观机理,对甲烷燃烧催化剂的设计与使用提供指导。在M06L/6-311++G(d,p)+SDD//M06L/6-311G(d,p)+LANL2DZ基组水平上,采用密度泛函理论(DFT)对甲烷在钯基二聚体催化剂(Pd2、PdPt和PdNi)上的脱氢过程进行了研究。对比了甲烷在催化剂Pd2、PdPt和PdNi上反应的能垒(Eb)、活化能(Ea)及反应速率常数(k),结果表明:CH2→CH是甲烷在二聚体Pd2反应的速率控制步骤(RDS),而CH3→CH2是催化剂PdPt和PdNi反应的RDS;钯基二聚体催化剂对甲烷脱氢的催化活性顺序为PdPt>Pd2>PdNi;抗积炭性能顺序为PdNi>Pd2>PdPt。PdPt适用于要求催化效率较高的项目,而抗积炭性能较好的PdNi催化剂可用于大型工业催化。