低阶煤半焦利用热重在O2/CO2、O2/N2和O2/Ar气氛下燃烧特性研究

利用热重研究了两种中国西北典型低阶煤半焦的燃烧特性。探究了不同气氛（O₂/CO₂、O₂/N₂和O₂/Ar）和不同氧气浓度对其燃烧特性的影响。实验结果表明,无论是反应气氛还是氧气浓度都会对低阶煤半焦的燃烧产生影响。相比于N₂和Ar,CO₂明显有利于燃烧反应进行：当反应气氛由O₂/CO₂变为O₂/Ar时,两种不同低阶煤半焦的燃尽温度分别升高了63.7和68.8℃;而当反应气氛由O₂/CO₂变为O₂/N₂时,两种不同低阶煤半焦的燃尽温度分别升高了135.9和129.6℃。在研究范围内,氧气浓度的提高也能明显提高半焦的燃烧性能。与此同时,半焦燃烧特性的动力学分析表明,随着氧气浓度提高,两种半焦燃烧反应的表观活化能E和指前因子A均呈增大趋势。通过对E和A两者关系的分析结果表明,半焦富氧燃烧的活化能和指前因子存在动力学补偿效应。     

单核Cu（H）配合物C18H12CuN402的密度泛函研究

用量子化学从头算方法，在R0B3LYP／LANL2MB水平上，对单核配合物C18H12CuN402进行了理论计算，优化得到了该配合物的平衡几何构型，并计算了它的谐振动频率．结果表明：该配合物分于是可以稳定存在的，电子自旋布居主要集中在Cu原于及配体原于上，Cu原于和配体原于的自旋布居符号相同，说明体系中存在较强的自旋离城效应．体系的前沿轨道主要由cu原于的d轨道和配体原于的p轨道组成，这种组成有利于配体与磁中心之间的电子转移．计算结果与实验符合得较好。     

Oxygen analysis of O2MF6 and O2M2F11 salts

The dioxygenyl salts O₂MF₆ or O₂M₂F₁₁ where M = As, Sb, Bi, Nb, Ta, Ru, Au, and Pt, were hydrolysed aqueous base (40% NaOH) to evaluate their purity and to gain further information about their thermal instability. Compounds containing As, Sb, Bi, Nb and Ta yielded 1.25 moles O₂ per mole of starting material whereas for compounds containing Ru, Au and Pt, 1.5 moles of O₂ per mole of salt was produced. The difference is a consequence of the greater oxidizing power of the RuF^-₆, AuF^-₆ and PtF^-₆ anions. All of the dioxygenyl salts are intrinsically unstable at room temperature in vacuum.     

The absolute partial photoionization cross section for the production of the X 2B1 state of H2O+

The absolute partial photoionization cross section for the production of the ground state of the water molecule ion has been measured from threshold up to an equivalent photon energy of 34 eV using dipole (e,2e) spectroscopy. This data obtained from a constant ionic state scan is consistent with earlier dipole (e,2e) measurements obtained from photoelectron branching ratios and the total photoabsorption measurement. The new data which extends to lower energy is compared with two recent independent measurements obtained using tuneable synchrotron radiation. These two synchrotron radiation measurements are in disagreement with each other in the region between 18 and 22 eV where the two data sets overlap. While good agreement is obtained with the work of Truesdale et al. above 22 eV significant differences exist at lower energies. In contrast good agreement is found with the work of Dutuit et al. from threshold up to 17.5 eV and at 20 eV but not in the intervening region. The measurements are also compared with the results of a variety of earlier reported theoretical calculations.     

Lifetimes of the A O−u state and quenching cross sections of Bi2

The radiative lifetime and self-quenching cross section of the v = 10 level of the BI₂ A state have been measured from laser-induced fluorescence experiments. The values obtained are 639 ns and 101 A² respectively A systematic investigation of lifetimes has been earned out at fixed pressure, showing strong decreases of lifetime owing to predissociations near v' = 28 and v' = 37. A comparison with previous results has been attempted.     

The photoionization cross section for H2 from threshold to 30 eV

The photoionization cross section of H₂ is calculated from threshold to 30 eV. The initial state is the self-consistent-field ground state of H₂ and the final states are the ground electronic state of H⁺₂ and single-center continuum states calculated in the field of H⁺₂. Exchange and screening effects are included.     

Li1.2Mn0.54Ni0.13Co0.13O2正极材料的Ga2O3包覆改性及电化学性能

首先采用共沉淀方法制备富锂锰基正极材料 Li_1.2Mn_0.54Ni_0.13Co_0.13O₂原始样品(P-LRMO), 然后通过简单的湿化学法以及低温煅烧方法对其进行不同含量 Ga₂O₃原位包覆。透射电子显微镜(TEM)以及 X射线光电子能谱(XPS)结果表明在 P-LRMO表面成功合成了 Ga₂O₃包覆层。电化学测试结果表明:含有 3 %Ga₂O₃的改性材料 G3-LRMO具有最优的电化学性能, 其在 0.1C倍率(电流密度为 25 mA·g^-1)下首圈充放电比容量可以达到 270.1 mAh·g^-1, 在 5C倍率下容量仍能保持 127.4 mAh·g^-1, 优于未改性材料的 90.7 mAh·g^-1, 表现出优异的倍率性能。G3-LRMO在 1C倍率下循环 200圈后仍有 190.7 mAh·g^-1的容量, 容量保持率由未改性前的 72.9 %提升至 85.6 %, 证明 Ga₂O₃包覆改性能有效提升富锂锰基材料的循环稳定性。并且, G3-LRMO在 1C倍率下循环 100圈后, 电荷转移阻抗(R_ct)为 107.7 Ω, 远低于未改性材料的 251.5 Ω, 表明 Ga₂O₃包覆层能提高材料的电子传输速率。     

Rate coefficients for CS reactions with O2, O3 and NO2 AT 298 K

CS radicals have been produced by photodissociation of CS₂ at 193 nm and their disappearance monitored by LIF. The vibrationally excited CS radicals rapidly relax to CS(ν = 0). At 298 K, the rate coefficients for CS(ν = 0) reactions with O₂, O₃ and NO₂ are (2.9 ± 0.4) × 10_?19, (3.0 ± 0.4) × 10^?16 and (7.6 ± 1.1) × 10^?17 cm³ molecule^?1 s^?1 respectively. The quenching of CS(A ¹II)_ν=0 by He has a rate coefficient of (1.3 ± 0.2) × 10^?12 cm³ molecule^?1 s^?1.     

Deactivation of vibrationally excited N2 by H2O

The VV exchange rate for the N₂H₂O system is determined using a hard-core repulsive potential. It is found that the rapid deactivation rate arises from near-resonant VR exchanges involving non-dipole changes in the rotational states. Furthermore, a classical-path approximation is used and the resulting rate found to be critically dependent on the path chosen.     

CH2+O2反应的反应机理

The mechanisms of the CH2＋ O2→ H2O＋ CO and CH2＋ O2→ H2＋ CO2 reactions have been studied by performing ab initio CAS(8,8)/6-31G(d,p) calculations, and five intermediates(IMn) and eight transitions(TSn) have been located along the reaction paths. The predicted path for the CH2＋ O2→ H2O＋ CO is: CH2＋ O2→ TS1→ IM1→ TS2→ IM2→ TS3→ IM3→ TS4→ IM4a→ TS5→ H2O＋ CO. For the CH2＋ O2→ H2＋ CO2 reaction, there are two paths: (i) CH2＋ O2→ TS1→ IM1→ TS2→ IM2→ TS3→ IM3→ TS6→ H2＋ CO2 and (ii) CH2＋ O2→ TS1→ IM1→ TS2→ IM2→ TS3→ IM3→ TS4→ IM4a→ TS7→ IM4b→ TS8→ H2＋ CO2, with the latter path more favorable energetically.     

Very long vibrational lifetimes in liquid O2 and N2

Via stimulated Raman scattering the first vibrational energy level is excited above the thermal equilibrium value. Using an optical Schlieren method the vibration-translation relaxation times are measured to be 50 μs and 1 ms in liquid O₂ and N₂, respectively.     

Intermolecular forces for D2, N2, O2, F2 and CO2

The intermolecular potentials for D₂, N₂, O₂, F₂ and CO₂ are determined on the basis of the second virial coeffincients, the polarizabilities parallel and perpendicular to the molecular axes, and the electric quadrupole moment. The repulsive parts of the potentials are taken from the corresponding Kihara core-potentials. Effects of the octopolar induction are taken into consideration in a unique way. The potential depends on relative orientations of the two molecules as well as the distance r between the molecular centers. This dependence is shown in graphs. A measure of the anisotropy of the potential depth is 0.72 for CO₂ 0.36 for D₂, and smaller than 0.27 for N₂ O₂ and F₂. The remarkable anisotropy for CO₂ and D₂ is due to strong electrostatic quadrupole interactions.     

Reactions and photochemistry of vibrationally excited Cl−2

Endothermic reactions and photodestruction of Cl^?₂ below the thermodynamic limit have been observed in the gas phase. These results suggest that Cl^?₂ formed by electron impact is vibrationally excited.     

Possible production of O2(1Δg) and O2(1Σ+g) in the reaction of NO with O3

High-resolution spectra of the NO₂ continuum emission produced from the reaction NO + O₃ → NO₂ + O₂ have been investigated to detect any possible emission from O₂(¹Δ_g) at 1270 nm or O₂(¹Σ⁺_g) at 762 nm. The photolysis of O₃/O₂ mixtures at 253.7 nm, which produces both states of O₂ with known quantum efficiency, has been used as an internal standard. From the results it is concluded that less than 1/300 and 1/200 of the NO + O₃ reactive collissions result in production of O₂(¹Δ_g) or O₂(¹Σ⁺_g), respectively, at room temperature.     

Vibrational spectra of the peroxotantalates (NH4)3[Ta(O2)4], K3[Ta(O2)4], Rb3[Ta(O2)4] and Cs3[Ta(O2)4] and the crystal structure of Rb3[Ta(O2)4]

The compounds (NH₄)₃[Ta(O₂)₄], K₃[Ta(O₂)₄], Rb₃[Ta(O₂)₄] and Cs₃[Ta(O₂)₄] have been prepared and investigated by X-ray powder methods as well as Raman- and IR-spectroscopy. In the case of Rb₃[Ta(O₂)₄] the structure has been solved from single crystal data. It is shown that all these compounds are isotypic and crystallize in the K₃[Cr(O₂)₄] type (SG , No. 121). The infrared- and Raman spectra (recorded on powdered samples) are discussed with respect to the internal vibrations of the peroxo-group and the dodecahedral [Ta(O₂)₄]³⁻ ion. Symmetry coordinates for the [Ta(O₂)₄]³⁻ ion are given from which the vibrational modes of the O-O stretching vibrations of the O₂²⁻ groups, the Ta-O stretching vibrations and the Ta-O bending vibrations are deduced.     

Collision-induced absorption of infrared radiation by N2, O2 and CO2

The collision-induced absorption of the symmetric vibration of CO₂ has been observed in the pure gas at densities from 20.0 to 40.0 amagat and at temperatures of 273, 298, and 323 K using infrared techniques. From the integrated intensities of the bands and using the (exp ?4) model of van Kranendonk, it is possible to deduce a value for the first derivative of the quadrupole moment with respect to the vibrational coordinate. For CO₂ the contribution from quadrupole distortion to the binary absorption coefficient is reported for several temperatures. The (exp ?4) model of van Kranendonk is used to calculate the binary absorption coefficients for the fundamental vibrational bands of N₂ and O₂ at temperatures from 70 to 340 K. The parameters λ and p/σ describing the magnitude and range of the short-range collision-induced dipole moments were determined using the known experimental absorption coefficients. The contributions from atomic distortion and quadrupole distortion to the binary absorption coefficient are calculated for N₂ and O₂.     

Solid state photodecomposition studies of K4Ti(O2)4·2H2O, K3Ta(O2)2F4 and K2V2O3(O2)2F2

The compounds K₄Ti(O₂)₄·2H₂O, K₃Ta(O₂)₂F₄ and K₂V₂O₃(O₂)₂F₂ undergo photolysis in the solid state. The photolysis kinetics obey the parabolic rate equation p = kt^1/2 and indicate a monoexcitation process for the photolysis. These features are similar to those reported previously for peroxo complexes. The mechanism of evolution of oxygen reported earlier appears to be the same in all these solids.     

Conversion of NO in NO/N2, NO/O2/N2, NO/C2H4/N2 and NO/C2H4/O2/N2 Systems by Dielectric Barrier Discharge Plasmas

An experimental study on the conversion of NO in the NO/N₂, NO/O₂/N₂, NO/C₂H₄/N₂ and NO/C₂H₄/O₂/N₂ systems has been carried out using dielectric barrier discharge (DBD) plasmas at atmospheric pressure. In the NO/N₂ system, NO decomposition to N₂ and O₂ is the dominating reaction; NO conversion to NO₂ is less significant. O₂ produced from NO decomposition was detected by an on-line mass spectrometer. With the increase of NO initial concentration, the concentration of O₂ produced decreases at 298 K, but slightly increases at 523 K. In the NO/O₂/N₂ system, NO is mainly oxidized to NO₂, but NO conversion becomes very low at 523 K and over 1.6% of O₂. In the NO/C₂H₄/N₂ system, NO is reduced to N₂ with about the same NO conversion as that in the NO/N₂ system but without NO₂ formation. In the NO/C₂H₄/O₂/N₂ system, the oxidation of NO to NO₂ is dramatically promoted. At 523 K, with the increase of the energy density, NO conversion increases rapidly first, and then almost stabilizes at 93–91% of NO conversion with 61–55% of NO₂ selectivity in the energy density range of 317–550 J L⁻¹. It finally decreases gradually at high energy density. A negligible amount of N₂O is formed in the above four systems. Of the four systems studied, NO conversion and NO₂ selectivity of the NO/C₂H₄/O₂/N₂ system are the highest, and NO/O₂/C₂H₄/N₂ system has the lowest electrical energy consumption per NO molecule converted.