共查询到20条相似文献,搜索用时 14 毫秒
1.
构造了高岭石硅氧层和铝氧层的团簇模型(分别为Si13O37H22和Al6O24H30), 并分别在B3LYP/6-31G(d), MP2/6-31G(d)//B3LYP/6-31G(d)和B3LYP/6-311++G(d,p)//B3LYP/6-31G(d)理论水平上对1,3,5-三硝基苯(TNB)在高岭石表面的吸附性质(如优化的几何构型、 结构参数、 吸附能、 振动频率、 静电势和分子轨道等)进行了研究. 结果表明, TNB和硅氧层表面间的相互作用以静电和范德华相互作用为主; TNB与铝氧层间的相互作用以氢键为主, 且TNB和铝氧层间相互作用的能量更低, 结构更稳定. 相似文献
2.
Li the past decade, the reactivity of carbon containing confounds with single crystal silicon surfaces has received extensive attention from both experimental and theoretical sides owing to its compact relevance to the growth of silicon carbide and diamond films. While considerable interest has been focused on the adsorptions of alkenes, alkanes and some other small organic molecules[1], very few experiments[2,3] can be found in the literature regarding the adsorption of CO2,a greenhouse gas, on Si surfaces. We report herein the results of our recent theoretical study concerning CO2 adsorption on the reconstructed Si(100)-2×l surface. The methods employed in our calculations are the hybrid density functional B3LYP method and a two-layer ONIOM (CCSD(T):B3LYP) approach[4]. 相似文献
3.
CH和CO在油页岩中矿物质结构内部吸附的分子模拟 《燃料化学学报》2017,45(11):1310-1316
利用Materials Studio2017模拟软件构建了蒙脱石、高岭石、方解石和生石膏四种矿物质分子模型。采用巨正则蒙特卡洛(GCMC)方法和分子动力学(MD)方法对四种模型的吸附量和吸附热进行了模拟计算。研究表明,相同温度和压力条件下四种矿物质对CH_4和CO_2分子吸附量大小为:蒙脱石高岭石生石膏方解石;CH_4和CO_2分子的单组分吸附量随压力的增大而增大,两种气体吸附均符合Langmuir吸附规律;四种矿物质对CH_4和CO_2分子的等量吸附热均小于42 k J/mol,即为物理吸附;随着温度的升高,CH_4和CO_2分子的吸附量和吸附热均减小,且CH_4和CO_2分子的等量吸附热和等温吸附量之间呈良好的正相关。 相似文献
4.
J. Onsgaard L. Bech C. Svensgaard P. J. Godowski S. V. Hoffmann 《Progress in Surface Science》2001,67(1-8):205-216
Interest in CO, CO2 and H adsorption on alkali-promoted Cu surfaces stems from the promoting role of alkali metals in heterogeneous catalysis. Adsorption of an alkali metal on a Cu surface causes a substantial decrease in the work function. The change in the electronic structure of the surface has strong consequences for the adsorption and reactive properties of the Cu surfaces. Another important factor for the reaction yields is the corrugation of the surface. The influence of these two parameters, the alkali metal coverage and the corrugation, on the dissociation of CO and the reactions between low-molecular gases like H, CO and CO2 has been investigated on a series of low-index and stepped Cu surfaces. Particularly the synthesis of formate HCOO− from coadsorption of H and CO2 has been studied. The experimental evidence for these findings is synchrotron radiation based measurements of valence band energy distributions, and work function measurements. It is demonstrated in this report that CO dissociates on the potassium-modified stepped surface, Cu(1 1 2), at 125 K. The dissociation process is conditioned by the presence of steps and the alkali metal coverage. Carbonate is formed via the process CO + CO →CO2 + C and reaction with oxygen. Adsorption of atomic hydrogen in the presence of K gives rise to two H-1s-induced states in the valence band. The influence of temperature on the binding energies and the population of these states have been studied. Formate is synthesized when the alkali/Cu surface, precovered with hydrogen, is exposed to CO2. 相似文献
5.
随着二氧化碳(CO2)排放量的不断增加, 全球变暖和气候变化的加剧对人类的生存环境产生了巨大的影响. CO2作为廉价、 可再生的碳氧资源, 将其转化为高附加值化学品是绿色化学及能源领域的重要研究课题之一, 受到广泛关注. Pd基催化剂由于具有优异的加氢能力以及良好的抗烧结、 抗毒化性能, 作为CO2催化转化最有前途的催化剂被广泛应用和研究. 本文主要对Pd基催化剂上CO2加氢制备HCOOH, CO, CH4和甲醇等小分子能源化合物的研究进展进行综合评述, 重点关注Pd基催化剂上CO2分子的吸附/活化位点、 催化剂的金属-载体强相互作用及表界面组成等对催化剂活性和选择性的影响以及催化反应机理. 相似文献
6.
采用基于赝势平面波基组的密度泛函理论方法对CO分子在α-Al2O3(0001)以及γ-Al2O3的(100)、(110C)、(110D)表面上的吸附构型和电子结构进行系统研究.计算结果表明,CO倾向于选取C端吸附在表层Al原子上,并主要通过其5σ轨道与表面发生作用,吸附后部分电子从CO转移到底物,导致各Al2O3表面功函均发生不同程度的下降,与气相相比,吸附后CO分子的C-O伸缩振动频率均发生蓝移.通过对比CO在各表面上的吸附情况,可以看出CO可作为检测Al2O2不同类型表面活性中心的有效探针分子. 相似文献
7.
Corrosion inhibition of three imidazoline derivates with different numbers of benzene rings, namely 2-phenyl-1-ethylamino imidazoline(CI-1), 2-phenyl-1-ethylamino-1-methylbenzyl quaternary imidazoline(CI-12) and 2-phenyl-1-benzoyl ethylamino imidazoline(CI-13), on mild steel in CO2-saturated brine solution was evaluated by mass-loss method and potentiodynamic polarization method. The results show that the three imidazoline derivates can inhibit CO2 corrosion effectively with CI-12 ranking the highest. They mainly restrain the anodic dissolution and act as anodic-type inhibitors. The adsorptions of these derivates on the mild steel surface follow the Langmuir adsorption isothermal equation and belong to chemical adsorption. 相似文献
8.
马季铭 《高等学校化学学报》1986,7(8):729
表面活性剂在氧化物表面上的吸附,因其在浮选中的重要作用而被广泛研究。但迄今为上的工作多是关于表面活性离子在电性相反的氧化物表面上,例如阳离子表面活性剂在带负电的氧化物表面上的吸附,而对电性相同的表面活性离子的吸附则很少涉及,虽然许多实际问题中遇到的是后一种情形。本工作研究了烷基硫酸钠在带负电的TiO2表面上的吸附,根据吸附与电泳的实验结果计算了吸附自由能,并提出了可能的吸附机理。 相似文献
9.
Michalkova A Robinson TL Leszczynski J 《Physical chemistry chemical physics : PCCP》2011,13(17):7862-7881
This computational study performed using the density functional theory shows that hydrated and non-hydrated tetrahedral and octahedral kaolinite mineral surfaces in the presence of a cation adsorb the nucleic acid bases thymine and uracil well. Differences in the structure and chemistry of specific clay mineral surfaces led to a variety of DNA bases adsorption mechanisms. The energetically most predisposed positions for an adsorbate molecule on the mineral surface were revealed. The target molecule binding with the surface can be characterized as physisorption, which occurs mainly due to a cation-molecular oxygen interaction, with hydrogen bonds providing an additional stabilization. The adsorption strength is proportional to the number of intermolecular interactions formed between the target molecule and the surface. From the Atoms in Molecules analysis and comparison of binding energy values of studied systems it is concluded that the sorption activity of kaolinite minerals for thymine and uracil depends on various factors, among which are the structure and accessibility of the organic compounds. The adsorption is governed mostly by the surface type, its properties and presence of cation, which cause a selective binding of the nucleobase. Adsorbate stabilization on the mineral surface increases only slightly with explicit addition of water. Comparison of activity of different studied kaolinite mineral models reveals the following order for stabilization: octahedral-Na-water > octahedral-Na > tetrahedral-Na > tetrahedral-Na-water. Further investigation of the electrostatic potentials helps understanding of the adsorption process and confirmation of the active sites on the kaolinite mineral surfaces. Based on the conclusions that clay mineral affinity for DNA and RNA bases can vary due to different structural and chemical properties of the surface, a hypothesis on possible role of clays in the origin of life was made. 相似文献
10.
利用扫描隧道显微镜、X射线光电子能谱和同步辐射光电子能谱研究了CeO2(111),部分还原的CeO2-x(111) (0<x<0.5)以及Ca掺杂的CeO2模型催化剂的形貌、电子结构以及它们与CO2分子间的相互作用。CeO2(111)和部分还原的CeO2-x(111)薄膜外延生长于Cu(111)单晶表面。不同Ca掺杂的CeO2薄膜是通过在CeO2(111)薄膜表面室温物理沉积金属Ca及随后真空退火到不同温度而得到的。不同的制备过程导致样品具有不同的表面组成,化学态和结构。CO2吸附到CeO2和部分还原的CeO2-x表面后导致表面羧酸盐的形成。此外,相比于CeO2表面,羧酸盐物种更易在部分还原的CeO2-x表面生成,而且更加稳定。而在Ca掺杂的氧化铈薄膜表面,Ca2+离子的存在有利于CO2的吸附,且探测到碳酸盐物种的形成。 相似文献
11.
The adsorption of 2,4-dinitrotoluene (DNT) on the tetrahedral and octahedral surfaces of dickite (a clay mineral of the kaolinite group with a 1:1 dioctahedral structure characterized by the common chemical formula Al2Si2O5(OH)4) was studied using small representative mineral models. The calculations have been performed at the HF/3-21G level of theory. The orientation of DNT on the tetrahedral surface of dickite was found to be coplanar with the surface plane. In the case of the adsorption on the octahedral surface the DNT molecule is placed with an inclination about 30∘ to the surface plane. This type of adsorption results in an electron density redistribution of DNT on the surface of the mineral that is more significant in the case of the adsorption on the tetrahedral surface. The interaction energies of DNT with the octahedral and tetrahedral surfaces corrected by the BSSE energy were found. The adsorption energy of a DNT-tetrahedral fragment amounts to −6.5 kcal/mol, and the interaction energy of the DNT-octahedral fragment system is −17.7 kcal/mol. 相似文献
12.
The adsorption of molecular oxygen at defective edge sites of zigzag and armchair graphite surfaces has been investigated by adopting cluster models in conjunction with density functional theory. Several different types of chemisorbed O2 species are identified. It was found that the defect edge sites exhibit the significant catalytic role toward the adsorption and activation of molecular oxygen. The O2 molecule is not only able to strongly bind to these edge sites, but the O–O bond strength is obviously weakened. Moreover, the calculated adsorption energy for O2 adsorbed on the clean graphite basal surface is fairly consistent with the weak interaction nature of O2 with the surface observed in the experiment, indicating one-layer cluster model is an effective way to study O2 adsorption on graphite surface in terms of accuracy and computational cost, which is in agreement with previous experience. Whereas, we note that the local detailed arrangement of edge carbon atoms can play an important effect on the adsorption of O2 on defect surfaces. 相似文献
13.
Maneerat Ongwandee Glenn C. Morrison Xiaowen Guo Charles C. Chusuei 《Colloids and surfaces. A, Physicochemical and engineering aspects》2007,310(1-3):62-67
Sorptive interactions of volatile organic compounds (VOCs) with indoor surfaces play a major role in inhalation exposure to these species. Using ZrSiO4 and polyethylene (PE) to model mineral surfaces and carpeting, respectively, the adsorption behavior of gaseous trimethylamine (TMA) was examined under conditions of 80% relative humidity (RH) in N2 and in the presence of 1000 ppm CO2 or NH3. TMA adsorption and desorption behavior were studied using attenuated total reflection infrared (ATR-IR) and X-ray photoelectron (XPS) spectroscopies. Spectral data revealed that TMA adsorbed on both surfaces in a protonated state. Stronger adsorption was observed to occur on ZrSiO4. XPS scans indicate that the “dry” ZrSiO4 surface maintains OH groups available for bonding, supporting earlier research showing that partition coefficients increase as RH decreases. 相似文献
14.
利用密度泛函理论研究了气体分子(NH3, H2O, H2S, NO2)吸附在二维M3(HIB)2(M=Ni, Cu; HIB为六亚氨基苯)薄膜上体系的几何结构和电子结构的变化. 结果表明, 2种薄膜对气体分子的响应不同. 其中NH3, H2O和H2S在M3(HIB)2薄膜表面的吸附较弱, 主要与薄膜的亚氨基形成氢键, 吸附能均小于-0.36 eV, 吸附对体系电子性质的影响很小. 但是 NO2分子在薄膜表面形成化学吸附, 吸附能在-0.65~-1.72 eV范围内. 吸附NO2分子使其电子结构发生明显改变, 如Cu3(HIB)2在费米能级处打开带隙, 由金属性质转变为半导体性质. 这是由于NO2分子的pz轨道与金属原子$d_{z}^{2}$ 轨道发生了强烈的轨道杂化. 此外, 研究发现高浓度的NO2分子吸附能够使Ni3(HIB)2薄膜由非磁性变为磁性体系, 由普通金属性质变为半金属性质; 而高浓度的NO2分子使Cu3(HIB)2薄膜由金属性质变为半导体性质, 薄膜电导率降低. 相似文献
15.
SONG Jialong WANG Zitao LIU Yaozu TUO Chao WANG Yujie FANG Qianrong QIU Shilun 《高等学校化学研究》2022,38(3):834-837
Environmental pollution is one of the most severe problems facing today, including water pollution and the greenhouse effect. Therefore, developing materials with high-efficiency dyes adsorption and CO2 uptake is significant. Covalent organic frameworks(COFs), as a burgeoning class of crystalline porous polymers, present a promising application potential in areas related to pollution regulation due to their exciting surface properties. Herein, we report a 3D COF with a high specific surface area(BET about 2072 m2/g) by utilizing tetrahedral and rectangle building blocks connected through[4+4] imine condensation reactions to synthesize. The obtained COF not only can separate dyes from water effectively but also shows a remarkable CO2 uptake capacity. This research thus provides a promising material to remove dyes and adsorb CO2 in environmental remediation. 相似文献
16.
基于密度泛函理论对Hg在纯CeO_2表面的吸附机理进行了理论计算,采用p(3×3)的二维超晶胞模型计算了CeO_23个不同表面上不同位点对汞的吸附能,计算结果表明,Hg在纯CeO_2表面吸附能力较弱,为物理吸附,Hg原子与CeO_2未形成有效化学键。为了进一步研究Hg在CeO_2表面的吸附机理,计算了Hg在Pd掺杂的CeO_2(Pd-CeO_2)表面的吸附机理,结果表明,Hg在Pd-CeO_2表面吸附能较强,为化学吸附,Hg原子与Pd-CeO_2之间形成有效的化学键,说明Pd的掺杂有利于提高CeO_2对汞的吸附能力。为了量化纯CeO_2和Pd-CeO_2的汞脱除效率,对Hg在纯CeO_2和Pd-CeO_2表面的脱除进行了实验研究。实验结果表明,纯CeO_2对汞的脱除效率较低,贵金属Pd的掺杂能够有效提高CeO_2的汞脱除效率,与理论计算的结果相符。 相似文献
17.
采用第一性原理密度泛函计算方法和周期性平板模型系统研究了放射性碘分子在Cu2O三个低指数表面的吸附行为。通过计算若干平衡吸附构型的结构参数和吸附能评估了不同特征吸附位的作用。构型优化计算表明所选晶面存在适度的结构弛豫。计算结果表明,与Cu2O(110)表面相比,Cu2O(100)和(111)晶面表现出更高的碘分子吸附反应活性。其中,表面氧原子位(OS)和配位未饱和铜原子位(CuCUS)分别为Cu2O(100)和(111)晶面的能量最优吸附位点。此外,针对几种典型吸附结构计算分析了其电子结构信息,以进一步阐明吸附体系之间的相互作用机理。 相似文献
18.
基于密度泛函理论的第一性原理和平板模型构造了最稳定的O2/CaO(001)表面,通过优化Se和SeO2在此表面可能的初始吸附结构得到最佳吸附构型,分析了Se原子在O2/CaO(001)表面向SeO2的转化。结果表明,Se原子在O2/CaO(001)表面的稳定吸附构型主要有两种,即O-Se-O和O-O-Se基团,其中,O-O-Se基团的Se终端具有一定化学活性;Se在O2/CaO(001)表面向SeO2转化所需反应能垒小于均相条件下生成SeO2所需反应能垒,表明CaO不仅作为吸附剂,也能促进Se向SeO2的转化;SeO2分子在O2/CaO(001)表面发生化学吸附时,吸附基底的部分价电子转移至SeO2分子轨道中。 相似文献
19.
Nitric oxides (NOx) storage catalyst[1] provides an alternative route for abatement of NO in presence of oxygen by first adsorbing NOx and then desorbing it by temperature swing or pressure swing. YBa2Cu3Oy[2] and Mn-Zr mixed oxides[3] were reported to have large NOx adsorption capacity, but the former suffered from a great amount of coexisting CO2 gases. The author previously reported that high NOx adsorption capacity could be obtained on Ce modified TiO2-pillared montmorillonite without deactivation by CO2[1]. Microemulsion method was reported to be effective to control particle sizes and microstructures of the metal oxides[4]. In this paper, a thermal stable ZrO2 with high surface area was prepared in water-in-oil microemulsion, and NOx adsorption capacity was tested on the above ZrO2 sample after impregnating with manganese nitrate and cerium nitrate. 相似文献
20.
Conjugated porous polymers exhibit considerable advantage as attractive candidate for carbon dioxide(CO2) capture. However, the regeneration of the CO2 still faces the problem of high energy cost. Here we synthesize a near-infrared region(NIR) light responsive conjugated porous polymer(PDPP-Gu) {DPP=3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione} by constructing porous amorphous networks with a side chain engineering strategy to regulate CO2 adsorption and release through photothermal conversion. The PDPP-Gu is featured by a torsional conjugated backbone as well as a functional side chain of guanidino group. The donor-acceptor configuration of PDPP-Gu afforded strong absorption in the NIR and an excellent photothermal conversion capability of up to 48.8%, as well as a high surface energy. Moreover, guanidine modified side chain further enhanced the CO2-polymers interactions, resulting in a high CO2 selective adsorption capacity(0.8 mmol/g) at 273 K, 1 bar(1 bar=105 Pa). The adsorbed CO2 can be released under NIR light irradiation. This strategy of molecule design combined the dual features of photothermal conversion and gas adsorption, which is beneficial for the development of materials to dynamically control the adsorption and release of CO2 through NIR light. 相似文献