CuO/Ti0.5Zr0.5O2催化剂对NO+CO反应的催化作用

环境治理是当今社会面临的一大主要问题。目前,城市空气污染日趋严重,特别是工厂和汽车排放的大量未燃烧的烃类、CO、NOx是主要的空气污染物。其中,氮氧化物(NOx)排放状况尤其严重,它的排放会给环境和人们生活带来严重危害,因此,如何有效地消除NOx已成为目前环境保护中一个非常     

CH3O·2+NO气相反应的密度泛函理论研究

用密度泛函方法分别研究了单态和三态 CH3 O·2 NO CH3 O· NO2 气相反应 .结果表明 ,反应中 NO进攻 CH3 O·2 经过了一个顺反异构化的过程 ,摘取 CH3 O·2 的端基氧 .整个反应是吸热反应 ,理论计算吸热值为 5 0 .93k J/ mol,单态为多通道多步骤反应 ,决定速度步骤的能垒为 1 90 .6 1 k J/ mol.而三态为单通道反应 ,其决定速度步骤的能垒为 1 6 3.31 k J/ mol.三态反应为最佳反应通道 .该反应的研究将为保护臭氧层及大气环境提供重要的理论依据 .     

羟基取代黄烷酮类化合物与NO的反应研究

羟基取代的黄烷酮与NO反应, 得到了羟基邻位或对位单硝基化产物. 随着反应时间的延长, 有羟基邻位和对位双硝基化以及羟基两个邻位双硝基化产物生成. 多羟基取代的黄烷酮可以生成多硝基化产物.     

Theoretical Studies on Reaction Mechanism of CH3SO with NO

The potential energy surface （PES） of CH3SO radical with NO reaction has been studied at MP2/6-311G（2df, p） and QCISD/6-311G（2df, p） levels. Geometries of the reactants, transition states （TS） and products were optimized at B3LYP/6-311G （d,p） level. The geometries of the transition states were found for the first time. The calculated results show that the reaction can proceed via singlet-state or triplet-state PES. Because of the high energy barrier of triplet surface, the singlet surface reactions are dominant. The topological analysis of electron density shows that there are two kinds of structaral transition states （the bifurcation-type ring structure transition state and the T-shaped conflict structure transition state） in the titled reaction. The total electronic density of the reactants, TS and products and the spin electronic density on the triplet surface were also discussed in this paper.     

Quantum Chemical Calculations on the Structure and Adsorption Properties of NO and N2O on Ag+ and Cu+ Ion-Exchanged Zeolites

Ab initio cluster quantum chemical calculations at the Hartree–Fock (HF/Lanl2dz) and correlated second-order Moller–Plesset perturbation theory (MP2/Lanl2dz) levels were performed for NO and N₂O interactions with Ag⁺ and Cu⁺ ion-exchanged zeolites. The interaction energies were estimated in a conventional way and also corrected for basis set superposition errors. It was shown that the highly dispersed Ag⁺ counterions establish twofold coordination to the lattice oxygens on the zeolite surface, similar to the case of Cu⁺ ions. However, both NO and N₂O bind relatively strongly to the Cu active sites of Cu⁺ ion-exchanged zeolites than those of the Ag⁺ site of the Ag⁺ ion-exchanged zeolites. Based on the results of these calculations, the two different forms of adsorption for these molecules on the catalyst surface, the nature of their binding and characteristics of the adsorption properties have been discussed. Finally, some comparisons with the results obtained by a variety of density functional theory calculations on target systems have been presented.     

MO theoretical studies of electron pair decorrelation processes. I. Pair correlation energy and single bond dissociation

The homolytic dissociation of a single bond involves the decorrelation of one electron pair. Thus, the contribution of electron correlation to dissociation energies is large. In the present paper a new procedure is presented which allows the computation of the (within the given basis) complete correlation energy of one optimized electron pair. The method which requires only modest computational effort has been applied to the calculation of dissociation energies of a number of bonds of different types. The results show that the correlation of the electron pair of the bond which is broken contributes about 50–80% to the change of the total correlation energy occuring during the dissociation process which amounts to 20–70 kcal/mol. The fraction of correlation contributed by the bond electron pair as well as the relative importance of the left-right correlation within the bond depend very much on the type of the bond. In the case of CC and CH single bonds our method yields dissociation energies which are low by only about 5 kcal/mol. Thus, the method seems to be well suited for the calculation of potential surfaces of non-concerted organic chemical reactions which involve diradicals as intermediates.     

CH自由基和NO2反应研究Ⅱ.反应的动力学计算

采用MP2(FULL)/6-31G(d)方法从动力学计算上探讨了CH自由基与NO2反应的可能途径,找到了反应物,中间体及产物之间的能量通道和过渡态,报道了它们的构型、电子态及能量.并通过频率分析和IRC方法对所有的过渡态进行了验证.在此基础上求出了各步反应的活化能.在以前热力学研究的基础上,对于可能的反应通道进一步作了动力学分析,找到了反应主产物通道的分支比,与实验得到的分支比基本吻合.     

Infrared optical constants of aqueous sulfate-nitrate-ammonium multi-component tropospheric aerosols from attenuated total reflectance measurements: Part II. An examination of mixing rules

We examine the performance of several mixing rules that are commonly used in modeling optical constants of aerosol mixtures either in remote sensing or radiation transfer/climate studies employing the new refractive index data reported in Part I. We demonstrate that the optical constants of the considered mixtures are not accurately modeled using pure solute optical constants (e.g., ammonium sulfate optical constants and the optical constants of pure water) due to the complex ion-ion and ion-water interactions. On the other hand, we do find that ternary and quaternary mixtures can be well modeled by applying the mixing rules to lower order multi-component optical constants data, e.g., binary data to determine ternary optical constants, or binary and ternary data to determine quaternary optical constants. By using lower order optical constants data sets, much of the ion-ion and ion-water effects are captured. Both mass-fraction and volume-fraction weighting of the “component” optical constants yield satisfactory results, performing as well or better than the more complicated mixing rules. These findings will be of practical use in remote sensing and radiation transfer/climate studies as well as help guide the decision on what optical constants measurements will be required.     

Templated synthesis and catalytic properties of an Rh/ceria-zirconia catalyst

Ceria-zirconia nanophase with structural defects and high thermal stability was synthesized by a surfactant-templated method. The 0.5 wt.% Rh/ceria-zirconia catalyst shows high activity for NO reduction by CO under an oxygen-rich condition, and the selectivity to 100% N₂ below 200°C was achieved.     

TiO2表面氧空位对NO分子吸附的作用

采用程序升温热脱附(TPD)实验方法测定了NO在TiO₂表面吸附后的脱附谱，利用 分子轨道 理论研究了TiO₂吸附NO的原子簇模型及吸附前后的原子簇能级变化.结果表明， NO在TiO₂表面吸附后可在两个峰值温度450 和980 K脱附出N₂.TiO ₂表面经预覆氧处理后，N₂ 的脱附量降低.吸附时NO中的O能够占据TiO₂表面氧空位并与N脱离，而N原子则 相互结合成 为N₂脱附.分子轨道理论计算证明在TiO₂(110)表面能够存在氧空位 并具备吸附NO的结构条件.