排序方式: 共有16条查询结果,搜索用时 31 毫秒
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硫酸化氧化锆固体超强酸 总被引:1,自引:0,他引:1
硫酸化氧化锆(SZ)是一种固体超强酸催化剂,它能高效催化异构化、烷化、酰化、环化、裂解、酯化和酯交换等多种类型的催化反应。1979年,日本科学家Hino和Arata发现SZ能在室温催化丁烷异构化反应,首次提出了SZ是一种酸性比100%浓硫酸还强一万倍的固体超强酸,从而引起了科学家们对SZ研究的浓厚兴趣。经过了三十多年发展,研究者们在SZ的合成、改性、表征和应用等方面取得了许多新的研究成果。本文综述了SZ几十年来的研究进展,内容主要包括SZ的合成方法,表面结构和酸性机理,研究者们对SZ性质的不同看法,SZ的改性及应用。 相似文献
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Based on liquid variational perturbation theory with quantum mechanics correction, the effective exp-6 potential is adopted
to compute the shock Hugoniot of liquid H2 + D2 mixtures at different molar rations. An examination of the confidence of the above computation is performed by comparing
experiments and calculations, in which similar calculation procedure used for H2 + D2 is adopted for H2 and D2 each, since no experimental data are available to conduct this kind of comparison. Good agreement in both comparisons is
found. This fact may look as if an indirect positive verification of calculation procedure was used here at least in the pressure
and temperature domain covered by the experimental data of H2 and D2 used for comparison, numerically nearly up to 20 GPa and 104 K.
Project supported by the Science and Technology Foundation of China Academy of Engineering Physics (Grant No. 97Z011). 相似文献
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本文利用分子动力学方法研究了KCl晶体在ρ=ρ0时的温度相变。面心立方(fcc)和体心立方(bcc)两种结构的径向分布函数随温度的变化的情况说明,在高压下,发生着bcc结构相fcc结构的转变,bcc结构是不稳定的。为了选取合理的势参数,利用了分子动力学程序在T=0时的性质,计算了NaCl和KCl晶体的零温状态方程,研究了它们在压力作用下发生的多形性相变。计算表明,NaCl和KCl晶体将分别于18.8 GPa和5.9 GPa发生从fcc到bcc的多形性相变,这些值相当接近实验结果。着说明本文选用的势参数势有一定精度的。 相似文献
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Molecular dynamics simulation of thermodynamic properties of NaCl at high pressures and temperatures 总被引:1,自引:0,他引:1
Qifeng Chen Lingcang Cai Dongquan Chen 《Journal of Physics and Chemistry of Solids》2004,65(6):1077-1081
The expansivity, constant-pressure heat capacity, and isothermal bulk modulus of sodium chloride (NaCl) have been obtained by using molecular dynamics method. The calculated thermodynamic parameters are found to be in agreement with the available experimental data. At an extended temperature and pressure ranges, these parameters have also been predicted. The thermodynamic properties of NaCl are summarized in the pressure 0-500 kbar ranges and the temperature up to 1000 K. 相似文献
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爆轰产物物态方程及CHBr3相变的理论研究 总被引:4,自引:0,他引:4
由吉布斯自由能最小计算处于化学平衡状态的气体和固体混合系统的平衡组分。以BKW和VLW作为爆轰产物的物态方程对几种炸药爆轰参数作了预言,计算结果与实验值吻合得非常好。另外,还对CHBr3的冲击压缩分解作了化学平衡计算,给出了冲击压缩曲线,对文献[6]中提出的CHBr3在55~60 GPa存在相变的看法提出了质疑。 相似文献
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Compression behavior and structure of dense helium at high temperatures by molecular dynamics simulation 总被引:1,自引:0,他引:1
In this work,the isotherm and energy distribution at T=304 K of dense helium are studied by molecular dynamic (MD) simulations with exp-6 potential r*=2.9673 ? (the position of the well minimum) and ε/kB=10.8 K (ε is the well-depth and kB is the Boltzmann constant) given by Peter et al.,and different values of stiffness parameter α.The optimized value of α=12.7 is deduced that can describe the atomic interactions for dense helium satisfactorily.This optimized α in exp-6 potential is used to conduct MD simulations of two isotherms of dense helium at T=300 K and T=298K.The calculations are in good agreement with the experimental.We further employed this method to investigate the equation-of-state and structure of dense helium at higher temperatures and found that when the density remained 1.6 g/cm3,the second peak of the radial distribution function would disappear in the temperature range from 2000 to 3040 K,demonstrating that a solid-liquid transition or decrystallization had occurred. 相似文献
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Meccanica - Semi Reentrant structures, which exhibit zero Poisson’s ratio and monoclastic curvature, are combinations of hexagonal Honeycomb and auxetic Reentrant structures. Deflections and... 相似文献
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Siwei Xu Hongping Pu Hua Wang Caiyun Han Du Dongquan Yanyan Zhang Yongming Luo 《Journal of Physics and Chemistry of Solids》2012,73(10):1252-1258
Ordered SBA-16-type mesoporous silica materials (MSMs) have been rapidly synthesized under weak acidic media in the presence of phosphomolybdic acid (abbreviated to HPMo) and inorganic salts (NaCl, Na2SO4, KCl and K2SO4) by using nonionic triblock copolymer F127 as a structure directing agent and tetraethylorthosilicate (TEOS) as a silica source. Both HPMo and inorganic salts play a crucial role in promoting SBA-16-type MSMs formation, and the reaction products have still retained an ordered body-centered cubic (Im3m) mesostructure after treated with 100 °C water for 120 h. The high hydrothermal stability of reaction products might be attributed to the higher degree of polymerization and condensation of silanol groups, arisen from the synergistic effect of rapid nucleation with the aid of HPMo and salt effect during the crystallization process. 相似文献
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