氯化亚铜在活性炭载体表面单层分散的密度泛函理论计算

 应用量子化学计算方法研究了活性炭载体表面CuCl活性组分的单层分散行为. 以C16H10,C13H9和C12H12原子簇模型模拟活性炭表面,用密度泛函理论中的B3LYP方法计算得到了CuCl在活性炭表面分散的活性位、稳定构型、相互作用能以及单层分散阈值. 结果表明,CuCl以铜端垂直附着在活性炭表面的顶位和桥位上,相互作用能为76.84～80.79 kJ/mol,单层分散阈值为0.471 g/g. 而XRD测得的单层分散阈值为0.467 g/g,与量子化学计算的结果一致; 按照密置单层模型计算得出的单层分散阈值为0.941 g/g,远大于实验测定结果. 因此,应用量子化学计算方法可以得到活性炭表面活性组分单层分散的丰富信息,并能确定活性组分的单层分散阈值.     

椅型碳纳米管吸附氧原子的密度泛函理论研究

利用密度泛函B3LYP对有限长扶手椅形单壁碳纳米管(3,3),(4,4)和(5,5)吸附O原子的几何结构、电子属性、反应能和红外光谱进行了系统地理论研究,获得了一些有意义的结果,主要包括如下4个方面:(1)2个O原子吸附在管外壁垂直于管轴的C—C键形成开环的轮烯结构,吸附在管内壁形成环氧结构;(2)O原子吸附在管外壁要比吸附在管内壁具有较大的能隙和吸附反应能;(3)与单壁碳纳米管管外壁吸附1个O原子相比,2个O原子吸附在管外壁具有较大的吸附反应能;(4)B3LYP得到的C—O伸缩振动频率与实验一致.     

Rh(111)表面上CO和O共吸附的密度泛函理论计算研究

采用密度泛函理论对Rh(111)表面上CO和O的吸附和共吸附进行了系统的研究,计算了三类不同的共吸附结构.从吸附能和化学位移的角度,通过与已有实验结果对比,推断出可能存在的吸附构型.CO和O之间存在较大的排斥作用,在表面上竞争吸附.电子结构分析发现,这种排斥作用来源于CO和O之间与Rh的d轨道成键的竞争.用密度泛函理论计算的化学位移与实验测量结果一致,说明化学位移的理论计算能辅助对表面结构的预测.     

锐钛矿型TiO2表面吸附甲醛的密度泛函理论研究

应用密度泛函理论优化了锐钛矿型TiO2（001）,（110）和（100）晶面结构,发现（001）晶面能量最低.通过对甲醛吸附到（001）面的6种初始猜测方式的几何优化,发现从甲醛H—C—O侧面吸附方式为最稳定的吸附方式,吸附能最大,发生了化学吸附.吸附后甲醛中C—H键增长,键变弱,C—O键缩短,键增强.甲醛中C原子与邻...     

密度泛函理论研究CO和 O2在NiFeB2/TiO2表面的吸附

 运用密度泛函理论中广义梯度近似的 PW91 方法结合周期平板模型, 研究了 NiFeB2 合金簇在 TiO2(110) 面的吸附模式. 结果表明, NiFeB2 平行吸附在 TiO2 面的 Ot-Ot 位最稳定, 吸附能为 526.4 kJ/mol. 为了探明 NiFeB2/TiO2 是否具有催化氧化 CO 活性, 进一步研究了 CO 和 O2 在 NiFeB2/TiO2 面的共吸附行为. 结果表明, CO 和 O2 以 Eley-Rideal 机理共吸附在 Fe 上时, 易形成碳酸盐, 而以 Langmuir-Hinshelwood 机理共吸附在 Fe 上时, O2 发生分解, 与 Fe, Ni 和 B 形成稳定的六元环.     

基于密度泛函理论计算的CO2在SrTiO3(100)表面的吸附

通过密度泛函理论的第一性原理,模拟了CO2分子在SrTiO3(100)表面TiO2-和SrO-位点上的吸附行为,获得了CO2在几种不同吸附模型下的结构参数及表面吸附能,进而研究了吸附机理和结构稳定性.计算结果表明,当CO2的C原子吸附在SrTiO3(100)表面SrO-及TiO2-位点的氧原子上时,吸附结构较稳定,尤其是C、O原子共吸附在TiO2-位点时最稳定,而其余吸附模型则不稳定.对吸附稳定模型的Mulliken布局数及态密度分析显示:CO2分子在SrTiO3(100)表面吸附主要是由于SrTiO3(100)面的电子跃迁至CO2分子,CO2分子得到电子形成弯曲的CO2-阴离子结构,并伴随着C-O键的伸长,从而达到吸附活化CO2的目的.     

NH3在硼纳米管表面吸附的密度泛函理论研究

利用密度泛函理论研究了NH₃在完整和含有缺陷的硼纳米管上的吸附行为以及相关电子性质. 计算结果表明, 对于α硼纳米管, 在不同的直径和手性条件下, NH₃均倾向于吸附在配位数为6的顶位上. 电子结构计算结果表明, NH₃能够吸附在纳米管表面主要是由于N和B原子产生了较强的相互作用. 表明硼纳米管是一种潜在的NH₃气气敏材料.     

噻吩在Ni(111)表面吸附的密度泛函理论研究

采用密度泛函理论方法,运用平板模型对噻吩分子在Ni(111)表面的水平吸附进行了结构优化和能量计算.结果表明,hcpA位的吸附最稳定,以bridgeB吸附最不稳定;噻吩吸附在表面上时,S原子向上翘起,4个C原子与边面Ni原子的作用更紧密,表面原子与噻吩的匹配程度决定了吸附的强度和吸附后S—C键的活泼性;噻吩以bridgeA吸附时分子与表面之间的电子给予与反馈最多,分子最活泼,而hcpA位吸附后噻吩分子轨道上电子的能量变稳定,分子并不活泼.     

氢气在碳纳米管内吸附的密度泛函理论研究

本文应用密度泛函理论研究纯流体氢气在单壁碳纳米管内吸附过程,采用硬球状态方程改进的基本测量理论表征硬球的斥力作用,离子吸引项的贡献则用微扰理论描述.在温度为300k,氢气本体对比密度范围为0.2～0.7条件下,计算了三种不同尺寸的碳纳米管氢气吸附的密度分布,其密度泛函计算结果与计算机分子模拟数据完全一致.     

富勒烯C70吸附氧原子的密度泛函理论研究

在密度泛函B3LYP理论下,用6-31G*基函数对富勒烯C70吸附氧原子进行了理论研究。讨论了其几何结构、电子属性、反应能、电离势和电子亲和势。计算结果表明:一个氧原子吸附在C70赤道带上形成具有开环轮烯结构的e,e-C70O是最稳定的。与基态的C70O相比,C70O35具有较大的HOMO-LUMO能隙,较高的电离势和较低的电子亲和势,因此C70O35是稳定的分子。     

Adsorption Study of Methane on Activated Meso-carbon Microbeads by Density Functional Theory

A combined method of density functional theory (DFT) and statistics integral equation (SIE) for the determination of the pore size distribution (PSD) is developed based on the experimental adsorption data of nitrogen on activated mesocarbon microbead (AMCMB) at 77K. The pores of AMCMB are described as slit-shaped with PSD.Based on the PSD, methane adsorption and phase behavior are studied by the DFT method. Both nitrogen and methane molecules are modeled as Lennard-Jones spherical molecules, and the well-known Steele‘s 10-4-3 potential is used to represent the interaction between the fluid molecule and the solid wall. In order to test the combined method and the PSD model, the Intelligent Gravimetric Analyzer (IGA-003) was used to measure the adsorption of methane on the AMCMB. The DFT results are in good agreement with the experimental data. Based on these facts,we predict the adsorption amount of methane, which can reach 32.3ω at 299K and 4 MPa. The results indicate that the AMCMBs are a good candidate for adsorptive storage of methane and natural gas. In addition, the capillary condensation and hysteresis phenomenon of methane are also observed at 74.05K.     

苯在CuCl（111）表面吸附的密度泛函理论研究

采用量子化学的密度泛函理论方法,探讨了苯分子在CuCl(111)表面上不同覆盖度下不同吸附位上的平行吸附行为. 计算结果表明,随覆盖度的减小,吸附作用增强, Cl位上的吸附是稳定的吸附模式,在低覆盖度下吸附能约为74 kJ/mol, 在顶位和穴位上的吸附属于较弱的物理吸附. 同时对吸附前后的电子布居和态密度进行了分析. 吸附过程中,苯分子的π电子向底物转移,同时Cu的 3d轨道的电子反馈给苯的反键π轨道.     

Adsorption of Carbamazepine in All-Silica Zeolites Studied with Density Functional Theory Calculations**

The anticonvulsant drug carbamazepine (−) is an emerging contaminant of considerable concern due to its hazard potential and environmental persistence. Previous experimental studies proposed hydrophobic zeolites as promising adsorbents for the removal of carbamazepine from water, but only a few framework types were considered in those investigations. In the present work, electronic structure calculations based on dispersion-corrected density functional theory (DFT) were used to study the adsorption of CBZ in eleven all-silica zeolites having different pore sizes and connectivities of the pore system (AFI, ATS, BEA, CFI, DON, FAU, IFR, ISV, MOR, SFH, SSF framework types). It was found that some zeolites with one-dimensional channels formed by twelve-membered rings (IFR, AFI) exhibit the highest affinity towards CBZ. A “good fit” of CBZ into the zeolite pores that maximizes dispersion interactions was identified as the dominant factor determining the interaction strength. Further calculations addressed the role of temperature (for selected systems) and of guest-guest interactions between coadsorbed CBZ molecules. In addition to predicting zeolite frameworks of particular interest as materials for selective CBZ removal, the calculations presented here also contribute to the atomic-level understanding of the interaction of functional organic molecules with all-silica zeolites.     

Adsorption of Carbon Dioxide on Activated Carbon

The adsorption of CO2 on a raw activated carbon A and three modified activated carbon samples B, C, and D at temperatures ranging from 303 to 333 K and the thermodynamics of adsorption have been investigated using a vacuum adsorption apparatus in order to obtain more information about the effect of CO2 on removal of organic sulfur-containing compounds in industrial gases. The active ingredients impregnated in the carbon samples show significant influence on the adsorption for CO2 and its volumes adsorbed on modified carbon samples B, C, and D are all larger than that on the raw carbon sample A. On the other hand, the physical parameters such as surface area, pore volume, and micropore volume of carbon samples show no influence on the adsorbed amount of CO2. The Dubinin-Radushkevich (D-R) equation was the best model for fitting the adsorption data on carbon samples A and B, while the Preundlich equation was the best fit for the adsorption on carbon samples C and D. The isosteric heats of adsorption on carbon samples A, B, C, and D derived from the adsorption isotherms using the Clapeyron equation decreased slightly increasing surface loading. The heat of adsorption lay between 10.5 and 28.4 kJ/mol, with the carbon sample D having the highest value at all surface coverages that were studied. The observed entropy change associated with the adsorption for the carbon samples A, B, and C (above the surface coverage of 7 ml/g) was lower than the theoretical value for mobile adsorption. However, it was higher than the theoretical value for mobile adsorption but lower than the theoretical value for localized adsorption for carbon sample D.     

氢气在单壁碳纳米管束的吸附的密度泛函研究

作者利用密度泛函理论（DFT）计算了氢气在单壁碳纳米管束（SWNTs)中管内 和管间的吸附。考察了温度,孔径以及压力对吸附的分子数密度,重量百分比,单 位体积储存能力以及超额吸附量的影响。DFT计算发现,较大的孔径有利于氢气在 SWNTs中的吸附且氢气在管隙中的吸附不可忽略。计算表明在77 K和6 MPa时,氢气 在2.719 mm的SWNTs的总的吸附的重量百分比分别可达到13.2 wt%,这约是美国能 源部（DOE）目标值的两倍,而单位体积储存能力在DOE目标值附近,而在300 K和 6 MPa时,氢气在2.719 nm的SWNTs的总的吸附的重量百分比仅为1.5 wt%。通过实 验结果与计算结果的比较表明,密度泛函理论的计算结果支持SWNTs有较高的吸附 储氢能力的实验结论。     

Density Functional Theory Study of HCN Adsorption on Small Gold Clusters

A theoretical study was carried out on the adsorption of hydrocyanic acid on small Aun （n ≤ 7） clusters using density functional methods. For HCN adsorption on gold clusters, no dependence was found with respect to the even-odd alternation in relation to the number of gold atoms in the cluster. The HCN molecule is adsorbed at simple adsorption sites （1-fold coordination）, perpendicular to the adsorption site. The largest adsorption energy is only about 74.61 kJ·mol^-1, which indicates that the HCN molecule does not decompose and the C-N bond retains triple bond, and that the C-H and C-N stretching frequencies are only weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.     

氧在CuCl(111)表面吸附的密度泛函理论研究

运用广义梯度密度泛函理论的PW91方法结合周期平板模型,在DNP基组下研究了氧分子和氧原子在CuCl(111)表面上的吸附.对氧分子在CuCl(111)表面吸附的相关计算和比较发现,覆盖度为0.25单层时的吸附构型为稳定的吸附构型,氧分子倾斜地吸附在CuCl(111)表面的顶位时比较稳定,吸附后O2分子的伸缩振动频率与自由O2分子相比发生了红移.态密度和Mulliken电荷布居分析结果表明,整个吸附体系发生了由Cu原子向O2分子的电荷转移.氧原子在CuCl(111)表面吸附的计算结果表明,氧原子倾向于以穴位(hollow)吸附在CuCl(111)表面,通过Mulliken电荷布居和态密度分析对氧原子在CuCl表面的吸附行为作了进一步探讨.