气体再燃低NOx燃烧中NO与NHi的反应机理研究

采用量子化学密度泛函理论(DFT)对NO与NH_i自由基的反应机理进行了研究,并结合经典过渡态理论对各反应速率常数进行了计算。结果表明,NO与NH₂自由基的反应体系可通过六个反应通道形成N₂+H₂O、N₂O+H₂和N₂H+OH。从能量变化和反应速率两方面考虑,产物N₂+H₂O最容易生成,其最佳反应通道为NO+NH₂→→N₂+H₂O;NO与NH自由基的反应体系可通过七个反应通道形成N₂+OH、N₂O+H和N₂H+O;其中,N₂+OH最容易生成,最佳反应通道为NO+NH→→N₂+OH。比较发现, NH比NH₂自由基更易与NO发生反应生成N₂。因此,在实际运行中改变操作条件,实现NH₂等向NH方向转化,有利于NO_x的还原。     

The preparation of bimetallic complexes with the ligand 1-oxy-2,6-di[N,N-biscarboxymethyl)aminomethyl]-4-chlorobenzol, and their physico-chemical characterization

With the binucleating ligand 1-oxy-2,6-di [(N,N-biscarboxymethyl)aminomethyl]- 4-chlorobenzol (H₅L) complexes of formulae FeH₂L · 2H₂O; FeH₃L(C1O₄) · H₂O; Fe₂L(OH) · 2H₂O; M₂HL · nH₂O (M = Co, Cu, n = 2; M = Ni, n = 4); FeCuL · 3H₂O; FeCrL(OH) · 3H₂O were prepared and characterized by elemental analysis, IR and electronic spectra and magnetic moment determinations. In addition, thermal analysis data of the complexes and Mössbauer effect spectra of the iron containing complexes are also given and discussed.     

新型磷-钒-氧层状化合物[H2en]2[H3O]6[Co(H2O)2(VO)8(OH)4(PO4)8]的水热合成与晶体结构

金属磷酸盐材料在吸附、离子交换、离子传导和催化剂方面有潜在的应用前景[1～5]. 近年来, 通过水热反应合成了一些A-V-P-O化合物. 在这些化合物中, A一般为碱金属或有机阳离子, 如层状结构的[H2N(C4H8)2NH2][(VO)4(OH)4(PO4)2][6] 和[H2N(C2H4)3NH2][(VO)8(HPO4)3(PO4)4*(OH)2]*2H2O[6], 一维链状结构的 [H2NCH2CH2NH3(VO)(PO4)][7], 手性双螺旋结构的 [(CH3)2NH2]K4[(VO)10(H2O)2(OH)4(PO4)7]*H2O[8]以及具有三维骨架结构的化合物 [H3N(CH2)3NH3K(VO)3(PO4)3][9], [H3N(CH2)3NH3]2[V(H2O)2(VO)6(OH)2(HPO4)3(PO4)5]*3H2O[10]和[H3N(CH2)2NH3][(VO)3(H2O)2(PO4)2(HPO4)4][11].     

非晶态镍硼酸盐结构的EXAFS研究(英文)

由摩尔比分别为1:2和1:8的NiCl2·6H2O和Na2B4O7·10H2O作为反应物,合成两种非晶态镍硼酸盐,同时通过水热法合成β-Ni(OH)2.化学分析和热重-微商热重法(TG-DTG)分析结果确定两种非晶态镍硼酸盐的分子组成分别为NiO·0.8B2O3·4.5H2O和NiO·B2O3·3H2O.激光拉曼(Raman)实验结果表明镍硼酸盐样品中主要存在的硼氧阴离子为B3O3(OH)52-和B2O(OH)62-.同步辐射扩展X射线吸收精细结构(EXAFS)方法对样品进行结构解析,通过数据拟合给出样品中Ni原子周围近邻配位原子种类、配位数以及原子间距离.用不同晶体结构作为标准对两种非晶态镍硼酸盐进行拟合的结果表明,样品中Ni原子周围局域结构与Ni3B2O6晶体(ICSD No.31387)中的吻合较好.Ni原子周围配位原子为O、B和Ni,对于NiO·0.8B2O3·4.5H2O,配位数分别为5.7、3.8和3.8,配位距离分别为0.208、0.263和0.311 nm;对于NiO·B2O3·3H2O,配位数分别为6.0、4.0和4.0,配位距离分别为0.207、0.262和0.310 nm.     

Two-photon excitation of h2o and D2O with a KrF laser (248 nm): photofragment fluorescence from OH and OD(A∑)

Photofragment fluorescence. From OH and OD(A ²∑⁺→X²π), has been observed following two-photon excitation of H₂O and D₂O in the gas phase with a KrF laser (248 nm). The rotational band contour of the OH fluorescence is the same as that observed following single-photon vacuum ultraviolet photolysis of H₂O at 123.6 nm.     

NO reduction and CO oxidation over Cu/Ce/Mg/Al mixed oxide catalyst in FCC operation

Simultaneous NO reduction and CO oxidation in the presence of O₂, H₂O and SO₂ over Cu/Mg/Al/O (Cu-cat), Ce/Mg/Al/O (Ce-cat) and Cu/Ce/Mg/Al/O (CuCe-cat) were studied. At low temperatures (<340 °C), the presence of O₂ or H₂O enhanced the activity of CuCe-cat for NO and CO conversions, but significantly suppressed the activity of Cu-cat and Ce-cat. At high temperature (720 °C), the presence of O₂ or H₂O had no adverse effect on the NO and CO conversions over these catalysts. The addition of SO₂ to NO+CO+O₂+H₂O system had no effect on the reaction of CO+O₂ over Cu-cat, but deactivated this catalyst for NO+CO and CO+H₂O reactions; over Ce-cat, all of these reactions of NO+CO,CO+O₂ and CO+H₂O were suppressed significantly; over CuCe-cat, NO+CO and CO+O₂ reactions were not affected while the reaction of CO+H₂O was slightly inhibited.     

One Dimensional Iron Molybdophosphate Anionic Chains with Different Structural Arrangements Reflecting a Flexibility Character

Structural comparison of a new compound[(bpp)₃H₆]Fe₂^IIIFe₂^IIMo₂₄^V(H₂PO₄)₈(HPO₄)₄(PO₄)₄O₄₈(OH)₁₂· (H₂O)₄·2H₂O(1)[bpp=1,3-di(4-pyridyl)propane] with our previously reported two compounds[(bpy)₃Fe^II]₃· Fe₂^IIIFe₂^IIMo₂₄^V(H₂PO₄)₈(HPO₄)₄(PO₄)₄O₄₈(OH)₁₂(H₂O)₄·12H₂O(2) and[(bpy)₃Fe^II]₂Fe^IIFe^IIIMo₁₂^V(H₂PO₄)₂(H_2-xPO₄)·(H_1+xPO₄)(HPO₄)₂(PO₄)₂O₂₄(OH)₆(H₂O)₂·9H₂O(x=0―1)(3)(bpy=2,2'-bipyridine), which all exhibit one-dimensional mixed-valence iron molybdophosphate anionic chains constructed by alternating connection of Fe^III ions and magic[Fe^II(Mo₆P₄O₃₁)₂] units, reveals that the non-hydrogen atomic ratios of Mo:Fe:P:O within the polymeric anionic chains are the same for all the three compounds, while the polymeric anionic chains of the different compounds bear different numbers of negative charges. And therefore there exist different numbers of counter cations per {Fe₂^III[Fe₂^II(P₁₆Mo₂₄^VO₁₂₄)]} unit found in the titled compounds. It discloses that not only are the spatial assembling of counter cations and polymeric inorganic chains of three compounds quite different, but also the O―Fe^III―O bond angles and Fe^III―O bond lengths of the three different inorganic chains exhibit small differences. What is more important is that such small changes in bond length and bond angle in the assemblage of Fe^III―O bonds lead to the considerable fluctuations of inorganic chains in their structural conformation within the three compounds, reflecting an interesting phenomenon of “flexibility" in the pure inorganic one dimensional mixed-valence iron molybdophosphate chains.     

Syntheses,Crystal Structures and Luminescent Properties of Three New Gallium Complexes Containing Pyridine-2,6-dicarboxylic Acid

Three new gallium complexes formulated as [Ga(PDA)₂][Ga(H₂O)(PDA)(phen)]·4H₂O(1), [Ga(PDA)₂]· (H₂IN)·2H₂O(2) and [Ga(OH)(PDA)(H₂O)]₂(3)(H₂PDA=pyridine-2,6-dicarboxylic acid; phen=1,10-phenanthroline; HIN=isonicotinic acid) have been synthesized under hydrothermal conditions. In the mixed-ligand system of complex 1, PDA^2? and phen are connected to the central Ga³⁺ cation as tri- and bi-dentate ligands, respectively. In complex 2, each Ga³⁺ cation is six-coordinated by two PDA^2? anions octahedrally. Complex 3 shows a binuclear structure, with the bond distance of Ga1-Ga2 being 0.30061(3) nm. The 3D supramolecular structures of the three complexes are constructed via hydrogen bonds and aromatic π-π packing interactions. All the three complexes exhibit intense blue emission at room temperature in the solid state, which are attributed to π^*-π transition centered on the ligands.     

Criegee中间体CH3CHOO与H2O反应机理及酸催化效应

采用CCSD（T）//B3LYP/6-311+G（d,p）方法研究了H₂O及甲酸等6种有机酸对CH₃CHOO与H₂O加成反应的催化作用。结果表明,非催化反应存在双质子迁移和加成反应2条通道,其中加成反应为优势通道。其加成机理为H₂O中OH加到CH₃CHOO的α-C上,同时H₂O中另一个H迁移到CH₃CHOO的端O上。催化剂H₂O及有机酸以氢键复合物的形式参与反应促进了H质子转移,可降低基元反应能垒和表观活化能,且催化效应与有机酸的强度成正比。例如,当分别用H₂O（pK_a=15.7）、甲酸（pK_a=3.75）和草酸（pK_a=1.23）催化时,生成syn-HAHP的基元反应能垒由非催化的69.12 kJ·mol^-1分别降至40.78、18.88和10.61 kJ·mol^-1。非催化反应具有正的表观活化能,而所有催化反应则均具有负的表观活化能。     

Ab initio study of the two competitive channels HO2 + H → H2 + O2 and HO2 + H → H2O + O

Saddle point geometries and barrier heights have been calculated for the H abstraction reaction HO₂(²A″)+H(²S) → H₂(¹Σ⁺_g)+O₂(³Σ⁻_g) and the concerted H approach-O removing reaction HO₂ (²A″)+H(²S) → H₂O(¹A₁)+O(³P) by using SDCI wavefunctions with a valence double-zeta plus polarization basis set. The saddle points are found to be of C_s symmetry and the barrier heights are respectively 5.3 and 19.8 kcal by including size consistent correction. Moreoever kinetic parameters have been evaluated within the framework of the TST theory. So activation energies and the rate constants are estimated to be respectively 2.3 kcal and 0.4×10⁹ ℓ mol⁻¹ s⁻¹ for the first reaction, 20.0 kcal and 5.4.10⁻⁵ ℓ mol⁻¹ s⁻¹ for the second. Comparison of these results with experimental determinations shows that hydrogen abstraction on HO₂ is an efficient mechanism for the formation of H₂ + O₂, while the concerted mechanism envisaged for the formation of H₂O + O is highly unlikely.     

NiMo(O)物相结构与电解水析氢反应活性的关联（英文）

在电催化析氢反应中,Ni Mo(O)催化剂在高电流密度下通常表现为极低的过电位。然而,该优异电催化性能的真正起源尚不明确。一个新的角度,即研究钼镍催化剂结构/性能演变的规律,能够帮助深入理解镍钼催化剂具有高活性的本质原因。基于此,本文详细阐述了含有结晶水的钼酸镍的脱水和氧化过程,在随后的还原处理中,该演变过程也被证实对于衍生不同的催化剂相结构具有重要作用。文中通过热重-差热分析以及程序升温氢气还原的方法探究电催化剂的特征相结构演变过程。同时,借助X射线衍射仪、拉曼光谱和高分辨透射电子显微镜分析确认催化剂物相。原位电化学X射线衍射分析提供了电催化剂在反应过程中的晶相结构。本文合成了具有不同主体相结构的钼镍催化剂：MoNi₄,β-NiMoO₄和α-NiMoO₄,它们的析氢反应活性具有显著差异。其中,β-NiMoO₄作为主体相结构的NiMoO₄-400air-H₂催化剂在碱性水还原反应中显现出最差的析氢性能;与之相比,α-NiMoO₄作为主...     

四元体系H3BO3-MgSO4-MgCl2-H2O在273.15K的溶解度等温线

作者考察了H₃BO₃-MgSO₄-MgCl₂-H₂O四元体系在273.15±0.05K温度下的溶解度等温线。四元体系共饱和点的液相组成为33.44%(重量)MgCl₃,1.77%MgSO₄和0.65%H₃B0₃。     

气相中CrO2+和H2反应的理论研究

用密度泛函UB3LYP/6-311++G(3df, 3pdpd)//6-311G(2dd, p)方法计算研究了在二重态和四重态两个势能面上的气相反应：CrO₂⁺ + H₂→CrO⁺+ H₂O. 对影响反应机理和反应速率的势能面交叉进行了讨论, 并运用Hammond 假设和Yoshizawa 等的内禀反应坐标(IRC)单点垂直激发计算的方法找出了势能面交叉点(crossing point (CP)). 运用碎片分子轨道(fragment molecular orbital(FMO))理论, 对初始复合物2IM1和4IM1的轨道相关进行了分析, 解释了CrO₂⁺活化H—H σ键及H₂迁移的机理.     

La3+-NaY型沸石的水热交换反应

作者根据在100℃、180℃时La³⁺-NaY型沸石交换反应等温线的测定和十三种单一稀土(Ln)元素在180℃时的交换度与相应Ln³⁺离子水合焓关系的研究以及在不同温度下交换反应速率常数、反应级数与交换反应表观活化能的测定,比较系统地研究了La³⁺-NaY型的水热交换反应,从而比较有据地提出这类交换反应的机理。     

Crystal Engineering of Multiple-component Organic Compound:Organic co-Crystals of the Functional Groups of Carboxyl and Amino with Persistent Hydrogen Bonding Motifs

Three small organic molecular co-crystal compounds (C₃N₆H₆)·(C₆H₁₀O₄)·H₂O(1), C₃H₈N₂O(3) and (H₄btec)₂·(4,4'-bipy)(4)(H₄btec=1,2,4,5-benzenetetracarboxylic acid, 4,4'-bipy=4,4'-bipyridine) and one coordination supramolecular compound [Mn(C₂O₄)(H₂O)₂]·C₆H₁₁NO₂(2) were synthesized by hydrothermal reaction. They were characterized by elemental analysis, infrared(IR) spectroscopy and single crystal X-ray diffraction(XRD). Structural analyses reveal that these 2D or 3D supramolecular networks of the compounds were formed by C―H···O, N―H···O, N―H···N, O―H···O and O―H···N hydrogen bonds. Therein, the functional groups of ―COOH, ―NH₂ and ―OH play important roles in constructing supramolecular architectures.     

Synthesis and enthalpy of formation of SrB4O7·3H2O

Hydrated strontium borate, SrB₄O₇·3H₂O, has been synthesized and characterized by XRD, FT-IR, DTA-TG and chemical analysis. The molar enthalpy of solution of SrB₄O₇·3H₂O in 1 mol dm⁻³ HCl(aq) was measured to be (21.15 ± 0.29) kJ mol⁻¹. With incorporation of the previously determined enthalpies of solution of Sr(OH)₂·8H₂O(s) in [HCl(aq) + H₃BO₃(aq)] and H₃BO₃ in HCl(aq), and the enthalpies of formation of H₂O(l), Sr(OH)₂·8H₂O(s) and H₃BO₃(s), the enthalpy of formation of SrB₄O₇·3H₂O was found to be −(4286.7 ± 3.3) kJ mol⁻¹.     

Infrared study of νOD modes in isotopically dilute (HDO) isostructural compounds M(HCOO)2·2H2O (M=Mn,Fe,Co,Ni,Cu,Zn) with matrix-isolated guest ions (Cu in M(HCOO)2·2H2O and M in Cu(HCOO)2·2H2O)

The infrared spectra of isotopically dilute (matrix-isolated HDO molecules) isostructural compounds M(HCOO)₂·2H₂O (M=Mn,Fe,Co,Ni,Zn,Cu) are presented and discussed in the region of the OD stretching modes. According to the structural data the compounds under study are divided into two groups: in M(HCOO)₂·2H₂O (M=Mn,Ni,Zn) the H₂O(1) molecules form stronger hydrogen bonds as compared to H₂O(2); in M(HCOO)₂·2H₂O (M=Fe,Co,Cu) the H₂O(2) molecules form stronger hydrogen bonds as compared to the H₂O(1) molecules. The influence of the metal–water interactions (synergetic effect) and the unit-cell volumes (repulsion potential of the lattice) on the hydrogen bond strength within the isostructural series is discussed. The wavenumbers of the uncoupled OD stretching modes of the HDO molecules influenced by guest ions (Cu²⁺ ions matrix-isolated in M(HCOO)₂·2H₂O and M²⁺ ions matrix-isolated in Cu(HCOO)₂·2H₂O) are presented and commented. For example, the analysis of the spectra reveals that when Cu²⁺ ions are included in the structure of M(HCOO)₂·2H₂O the hydrogen bonds of the type M–OH₂OCHO–Cu are considerably weaker as compared to those of the same type formed when M²⁺ ions are included in the structure of Cu(HCOO)₂·2H₂O if the cations remain unchanged.     

Preparation and x-ray diffraction characterization of the kambaldaite-like sodium cobalt carbonate hydroxide hydrate, Na2Co8(CO3)6(OH)6·6H2O

A new sodium cobalt carbonate hydroxide hydrate, Na₂Co₈(CO₃)₆(OH)₆·6H₂O, has been prepared at room temperature by treatment of Co(OH)NO₃·H₂O with a concentrated aqueous solution of NaHCO₃. X-Ray powder diffractometry and the results of the chemical analyses show that the compound is isotypical to Na₂Ni₈(CO₃)₆(OH)₆·6H₂O —kambaldaite, a unique mineral with no known synthetic or natural analogues.     

The electrolyte NRTL model and speciation approach as applied to multicomponent aqueous solutions of H2SO4, Fe2(SO4)3, MgSO4 and Al2(SO4)3 at 230–270 °C

This work presents chemical modeling of solubilities of metal sulfates in aqueous solutions of sulfuric acid at high temperatures. Calculations were compared with experimental solubility measurements of hematite (Fe₂O₃) in aqueous ternary and quaternary systems of H₂SO₄, MgSO₄ and Al₂(SO₄)₃ at high temperatures. A hybrid model of ion-association and electrolyte non-random two liquid (ENRTL) theory was employed to fit solubility data in three ternary systems H₂SO₄–MgSO₄–H₂O, H₂SO₄–Al₂(SO₄)₃–H₂O at 235–270 °C and H₂SO₄–Fe₂(SO₄)₃–H₂O at 150–270 °C. Employing the Aspen Plus™ property program, the electrolyte NRTL local composition model was used for calculating activity coefficients of the ions Al³⁺, Mg²⁺ Fe³⁺ and SO₄²⁻, HSO₄⁻, OH⁻, H₃O⁺, respectively, as well as molecular species. The solid phases were hydronium alunite (H₃O)Al₃(SO₄)₂(OH)₆, hematite Fe₂O₃ and magnesium sulfate monohydrate (MgSO₄)·H₂O which were employed as constraint precipitation solids in calculating the metal sulfate solubilities. A correlation for the equilibrium constants of the association reactions of complex species versus temperature was implemented. Based on the maximum-likelihood principle, the binary interaction energy parameters for the ionic species as well as the coefficients for equilibrium constants of the reactions were obtained simultaneously using the solubility data of the ternary systems. Following that, the solubilities of metal sulfates in the quaternary systems H₂SO₄–Fe₂(SO₄)₃–MgSO₄–H₂O, H₂SO₄–Fe₂(SO₄)₃–Al₂(SO₄)₃–H₂O at 250 °C and H₂SO₄–Al₂(SO₄)₃–MgSO₄–H₂O at 230–270 °C were predicted. The calculated results were in excellent agreement with the experimental data.     

Synthesis of Mg5(CO3)4(OH)2·4H2O with Flower-like Microstructure and Its Catalytic Activity for Transesterification of Dimethyl Carbonate with Phenol

A novel flower-like hydrated magnesium carbonate hydroxide,Mg_5(CO_3)_4(OH)_2·4H_2O,with micro-structure composed of individual thin nano-sheets was synthesized using a facile solution route without the use of template or organic surfactant.Reaction time has an important effect on the final morphology of the product.The micro-structure and morphology of Mg_5(CO_3)_4(OH)_2·4H_2O were characterized by means of X-ray diffractometry(XRD),field-emission scanning electron microscopy(FE-SEM).Brunauer-Emmett-Teller(BET)surface areas of the samples were also measured.The probable formation mechanism of flower-like micro-structure was discussed.It was found that Mg_5(CO_3)_4(OH)_2·4H_2O with flower-like micro-structure was a novel and efficient catalyst for the synthesis of diphenyl carbonate(DPC)by transesterification of dimethyl carbonate(DMC)with phenol.