Browsing 化学化工－已发表论文 by Title
Now showing items 9431-9450 of 14235
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V-MCM-41 for selective oxidation of propane to propene and acrolein
(2001)The V-MCM-41 with lower V content catalyzes the oxidation of propane to acrolein with a yield of 3.3% and selectivity of 20%, while that with higher V content mainly produces propene. -
V/P复合氧化物上C–H键活化的密度泛函研究（英文）
(2015-9-20)选择氧化催化剂通常为多组分复合氧化物.一般认为,高价过渡金属的端末双键氧(M=O)是烷烃活化的中心,而非金属端氧(nM=O)与烷烃活化无关.但近期的理论研究发现,复合氧化物中非金属端氧也可能参与烷烃活化.本文采用密度泛函方法(b3lyP)对比V=O和P=O的脱氢活性,并深入揭示二者的差异.H脱除反应可以视为是质子偶联电子传递的过程.对于V/P复合氧化物,V5+充当电子的受体,而V=O和P=O均可接受质子.由于P=O具有更强的质子化能力, ... -
V_2O_5/MPO_4在丙烷氧化脱氢中的催化作用
(1999-03-20)研制了具有不同酸碱性的磷酸盐ＭＰＯ４（Ｍ＝Ａｌ，Ｚｒ，Ｃａ）载体，并用这些载体负载０６％～６０％的Ｖ２Ｏ５。所制备的催化剂在丙烷氧化脱氢反应中具有较好的催化性能，如３％Ｖ２Ｏ５／Ｃａ３（ＰＯ４）２催化剂在丙烷转化率为１７０％时，丙烯选择性可达５５９％，丙烯收率达９５％。考察了不同反应条件下催化剂的性能，表明在高温高空速条件下，３％Ｖ２Ｏ５／Ｃａ３（ＰＯ４）２催化剂的反应活性较好，而３％Ｖ２Ｏ５／Ｚｒ３（ＰＯ４）４催化剂在低温低 ... -
Valence Band Offsets of LiPON/LiCoO(2) Hetero-Interfaces Determined by X-ray Photoelectron Spectroscopy
(ELECTROCHEMICAL SOC INC, 2011-10-26)Interfaces within Li-ion batteries are of interest with respect to stability and transfer resistance. In this paper, we investigated LiPON/LiCoO(2) hetero-interfaces formed at room temperature (RT) and 200 degrees C using ... -
Valence Band Offsets of LiPON/LiCoO2 Hetero-Interfaces Determined by X-ray Photoelectron Spectroscopy
(ELECTROCHEM SOLID ST, 2011)Interfaces within Li-ion batteries are of interest with respect to stability and transfer resistance. In this paper, we investigated LiPON/LiCoO2 hetero-interfaces formed at room temperature (RT) and 200 degrees C using ... -
Valence bond calculations of hydrogen transfer reactions: A general predictive pattern derived from theory
(AMER CHEMICAL SOC, 2004-09)Hydrogen abstraction reactions of the type X-. + H-H' --> X-H + H'(.) (X = F, Cl, Br, l) are studied by ab initio valence bond methods and the VB state correlation diagram (VBSCD) model. The reaction barriers and VB ... -
Valence bond calculations on the transition state for the E2 reaction of fluoride ion with ethyl fluoride - Implications for the More O‘Ferrall-Jencks diagram
(2005-09)A valence bond self-consistent field (VBSCF) calculation has been carried out on the bimolecular elimination (E2) reaction of fluoride ion with ethyl fluoride. The transition state was first optimized at HF/6-31+G and the ... -
Valence bond configuration interaction: A practical ab initio valence bond method that incorporates dynamic correlation
(AMER CHEMICAL SOC, 2002-02-27)A post-VBSCF method, called valence bond configuration interaction (VBCI), is developed here. The method incorporates dynamic correlation, by use of configuration interaction (CI) to improve the energetics after a VBSCF ... -
Valence bond description for the ground state and several low-lying excited states of LiH
(Elsevier Science Publishers, 1992-07)The potential energy curves of the ground and four singlet low-lying excited states of LiH were calibrated using the bonded tableau unitary group approach (BTUGA). The results show that the ground and the first excited ... -
Valence bond Modeling of barriers in the nonidentity hydrogen abstraction reactions, X 'center dot+H-X -> X '-H+X center dot (X ' not equal X = CH3, SiH3, GeH3, SnH3, PbH3)
(AMER CHEMICAL SOC, 2002-10-24)Breathing orbital valence bond (BOVB) computations (Hiberty, P. C.; Humbel, S.; Byrman, C. P.; van Lenthe, J. H. J. Chem. Phys. 1994, 101, 5969) are used to obtain nonidentity barriers for hydrogen transfer reactions between ... -
Valence Bond Perturbation Theory. A Valence Bond Method That Incorporates Perturbation Theory
(AMER CHEMICAL SOC, 2009-07)A post-VBSCF method, called valence bond second-order perturbation theory (VBPT2), is developed in this paper and is shown to be (i) economical and (ii) at par with more sophisticated VB and MO-based methods. The VBPT2 ... -
Valence bond study of dissociation behavior and spectroscopic constants for the ground states of LiF and NaF
(HIGHER EDUCATION PRESS, 1998)Ab initio VB calculations were used to determine the accurate spectroscopic parameters of the ground stated of LiF and NaF. A set of potential energy curves corresponding to the ground states including ionic and covalent ... -
Valence bond study on excited states of molecules - Bonding features of the low-lying states of molecule B-2
(SCIENCE CHINA PRESS, 1997)Based on the correspondence of the molecular orbital theory and valence bond theory to the description of chemical bonds, the ab initio valence bond (VB) calculations of the low-lying slates of diatomic molecules are ... -
Valence bond theoretical study for chemical reactivity
(SCIENCE PRESS, 1998)Based on the symmetry of the valence bond wavefunction and the correspondence between bonding patterns and bonded tableaus for chemical bonds in the ground and excited states, the conservation of orbital symmetry and the ... -
VALENCE-BOND CALCULATIONS OF THE POTENTIAL-ENERGY SURFACE FOR CH4- CH3+H
(1994)A valence bond study of the potential energy surface for methane CH4--> CH3 + H is performed at the 6-31G level using (i) a valence bond self-constituent field (VB-SCF) method; (ii) a valence bond configuration interaction ... -
VALENCE-BOND DESCRIPTION FOR THE GROUND-STATE AND SEVERAL LOW-LYING EXCITED-STATES OF LIH
(1993-07)The potential energy curves of the ground and four singlet low-lying excited states of LiH were calibrated using the bonded tableau unitary group approach (BTUGA). The results show that the ground and the first excited ... -
VALENCE-BOND STRUCTURE-FUNCTION AND BONDED FUNCTION .1. THEORETICAL METHOD AND APPLICATION TO METHANE
(ACTA CHIMICA SINICA, 1995)The bonded tableau is expanded in a series of bonded functions of different order, where the zero-order wavefunction of a system is expressed as an asymmetric product of strong-orthogonal geminals (APSG), moreover, many-order ... -
VALENCE-BOND STRUCTURE-FUNCTION AND BONDED FUNCTION .2. APPLICATION TO WATER MOLECULE
(ACTA CHIMICA SINICA, 1995)The bonded tableau unitary group approach (BTUGA) is used to calculate and analyze the structure of H2O, also the interactions between two bonding electron pairs, a bonding and a lone pairs as well as between two lone pairs ... -
VALENCE-BOND STUDIES OF N2O4
(1994-12-10)A non-empirical valence bond method is used to investigate the conformation of N2O4 Calculations of the planar conformer shows that the pi resonance energy between the two NO fragments is only 3.60 kJ mol(-1), so that the ...