Molecular Simulation of the Adsorption Characteristics of Methane in Pores of Coal with Different Metamorphic Degrees

In order to study differences in the methane adsorption characteristics of coal pores of different metamorphic degrees, 4 nm pore structure models based on three typical coal structure models with different metamorphic degrees were constructed. Based on the molecular mechanics and dynamics theory, the adsorption characteristics of methane in different coal rank pores were simulated by the grand canonical Monte Carlo (GCMC) and molecular dynamics methods. The isothermal adsorption curve, Van der Waals energy, concentration distribution, and diffusion coefficient of methane under different conditions were analyzed and calculated. The results showed that at the same pore size, the adsorption capacity of CH₄ is positively correlated with pressure and metamorphic degree of coal, and the adsorption capacity of CH₄ in high metamorphic coal is more affected by temperature. The relative concentration of CH₄ in high-order coal pores is low, and the relative concentration at higher temperature and pressure conditions is high. The CH₄ diffusion coefficient in high-rank coal is low, corresponding to the strong Van der Waals interaction between CH₄ and coal. The research results are of great significance for further exploration of the interaction mechanism between CH₄ and coal with different metamorphic degrees and can provide theoretical support for the selection of gas extraction parameters.     

氮气和氧气在膜表面和狭缝孔内平衡吸附的分子模拟

采用巨正则系综的MonteCarlo方法(GCMC)模拟常温(T=303K)下,氮气和氧气在具有狭缝状膜孔的碳膜内的吸附.气体分子之间、气体分子与膜原子之间的相互作用均采用Shifted-Lennard-Jones势能模型.研究了303K和10MPa下,不同膜厚度和膜孔宽度时氧气在膜面和膜孔内的密度分布以及303K和压力从1MPa到10MPa变化时,氮气和氧气在狭缝膜孔内超额吸附等温线.实验结果表明,膜孔端口效应显著,膜厚和膜孔宽度对孔内吸附影响较大,而膜构型对膜面吸附影响显著.     

Numerical Study of Pore Sizes Distribution in Gels

We introduce a new numerical technique for the calculation of the pore size distribution in two-dimensional disordered systems. Our method is based on a triangulation technique which allows a closer measurement of pores surface without any morphological hypothesis.In this work, we focus our calculations in simulated gels. Such materials are modeled in two different conditions: by means of the Diffusion-Limited and Reaction-Limited Cluster-cluster Aggregation algorithms, DLCA and RLCA, respectively. In both situations, when the particles concentration decreases, the average pores size increases. The more compact cluster in RLCA, compared with DLCA, is consistent with the pore size distribution we have calculated. The simulated mean pore size is quantitatively in agreement with experimental data from literature.     

Surface Modification of Bituminous Coal and Its Effects on Methane Adsorption

This paper studied the role of O‐containing groups over the coal surface in methane adsorption. The coal was modified with H₂SO₄, (NH₄)₂S₂O₈ or H₂SO₄/(NH₄)₂S₂O₈), respectively, to introduce O‐containing functional groups, and characterized by proximate analysis, ultimate analysis, Boehm titration, X‐ray photoelectron spectroscopy (XPS) and nitrogen adsorption. The results of ultimate analysis, Boehm titration and XPS indicate that there were increases in terms of both the content of oxygen and the quantities of O‐containing groups over the modified coals surface, especially for the carboxyl. Nitrogen adsorption shows that the modified coals possessed higher surface area and pore volume than that of 0‐XQ. The methane adsorption data were measured at 298 K at pressures up to 4.0 MPa by the volumetric method and fitted well by Langmuir model. Experimental results implied that O‐containing groups and pore structure affected methane adsorption. The adsorption capacities decreased as increasing quantities of O‐containing groups.     

Effect of Pore Size Distribution and Amination on Adsorption Capacities of Polymeric Adsorbents

Polymeric adsorbents with different properties were synthesized via suspension polymerization. Equilibrium and kinetics experiments were then performed to verify the adsorption capacities of the resins for molecules of various sizes. The adsorption of small molecules reached equilibrium more quickly than the adsorption of large molecules. Furthermore, the resins with small pores are easy to lower their adsorption capacities for large molecules because of the pore blockage effect. After amination, the specific surface areas of the resins decreased. The average pore diameter decreased when the resin was modified with either primary or tertiary amines, but the pore diameter increased when the resin was modified with secondary amines. The phenol adsorption capacities of the amine-modified resins were reduced because of the decreased specific area. The amine-modified resins could more efficiently adsorb reactive brilliant blue 4 owing to the presence of polar functional groups.     

Benzene Adsorption Isotherms on MCM-41 and their Use for Pore Size Analysis

This work is focused on the elaboration of methodology for adsorption characterization of porous silicas by using benzene adsorption isotherms measured on good quality MCM-41 materials. Three MCM-41 samples were synthesized by using tetraethyl orthosilicate (TEOS) as silica source and surfactants, octyltrimethylammonium (C8), decyltrimethylammonium (C10) and cetyltrimethylammonium (C16) bromides as templates. A characteristic feature of this synthesis was relatively long hydrothermal treatment (5 days) at 373 K, which gave well ordered samples as evidenced by powder XRD analysis. Benzene adsorption isotherms measured on these MCM-41 samples were used to evaluate such standard quantities as the BET specific surface area, total pore volume, external surface area and the volume of ordered mesopores, and to obtain the statistical film thickness (t-curve) as well as the Kelvin-type relation, which describes the dependence between pore width and condensation pressure for benzene on silica at 298 K. The latter relations were incorporated into the Barrett-Joyner-Halenda algorithm to extend its applicability to calculate the pore size distributions from benzene adsorption data.     

ZIF-8材料中CH4/H2吸附与扩散的分子模拟

采用平衡分子动力学和巨正则系综蒙特卡洛模拟方法对多孔沸石咪唑酯骨架材料(ZIF-8)中CH4和H2分子的吸附与扩散特性进行了比较研究.结果表明,采用柔性力场能够很好地复制ZIF-8在不同压力或温度条件下的晶体结构,也能准确地计算不同温度下CH4和H2分子在ZIF-8中的扩散系数,特别是高温下CH4分子因能够摆脱ZIF-8骨架笼口的空间限制而使其扩散系数出现大幅提升.同时,该力场也能粗略地模拟CH4和H2分子在ZIF-8中的等温吸附曲线,通过自编程序得到吸附和扩散平衡时CH4和H2分子在ZIF-8单元晶胞内的几率密度分布数据,并利用VMD软件可视化.结果显示CH4和H2分子在ZIF-8中的优先吸附位置均在大孔中心靠近咪唑环的区域,但CH4分子的优先吸附位置有两个不同层次,而H2分子的优先吸附位置只有一个层次,说明CH4和H2分子在ZIF-8中存在着不同的吸附机理.     

有机胺修饰具有较大孔径介孔材料的二氧化碳吸附性能

以非离子表面活性剂P123为模板剂,正硅酸甲酯为硅源,通过加入不同的扩孔剂制得具有较大孔径的SBA-15类介孔材料,并采用粉末X射线衍射(XRD)、低温氮气吸附-脱附、扫描电镜(SEM)、傅里叶变换红外(FTIR)光谱等手段对所得样品进行了表征.加入扩孔剂可以明显增大介孔材料的孔容和孔径,而异辛烷为扩孔剂的扩孔效果明显优于四氯化碳.经四乙烯五胺(TEPA)镀饰后,这些样品均表现出良好的CO2吸附性能.其中对于除去模板剂后再镀胺的样品,其CO2吸附能力与介孔材料孔道结构关系不大,而对于未除模板剂的原粉镀胺样品,CO2吸附能力则随孔道的变大而增强.此外,通过吸附等温线和CO2-程序升温脱附(TPD)手段比较了温度和压力对CO2吸附的影响,发现在较高温度下吸附时CO2的吸附能力随压力的变化存在显著差别,因而在这类TEPA修饰的介孔材料上可通过变压吸附的途径来实现对环境气流中CO2的吸附和分离.     

苯酚与对氯酚竞争吸附数学模型研究

对氯苯酚;苯酚与对氯酚竞争吸附数学模型研究     

单宁酸与苯酚在复合功能树脂上的竞争吸附研究

研究了水源水和生化尾水中的代表性模拟背景污染物单宁酸和代表性有机毒物苯酚之间的竞争吸附行为,开展了单组分、同时竞争吸附和预负载竞争吸附实验.研究表明,单宁酸对苯酚在复合功能树脂上的吸附有显著削弱作用.竞争吸附机理包括孔堵塞和吸附质间作用:单宁酸对树脂上微孔的堵塞,减少了苯酚优势吸附位点的数量,降低了吸附剂表面的异质性;吸附质间作用削弱了树脂对苯酚的吸附作用力.     

多孔金属有机骨架材料储氢性能分子模拟

采用优化的DREIDING力场参数, 通过巨正则系综蒙特卡洛(GCMC)模拟方法对H₂在IRMOF-1、IRMOF-61和IRMOF-62共3种金属有机骨架(MOFs)材料中的吸附平衡性能进行了比较研究. 结果表明, 该力场能够在全压力范围内很好地复制H₂在IRMOF-62材料中的等温吸附曲线; 但对低压下H₂在IRMOF-61中的等温吸附曲线预测出现低估. 与IRMOF-1相比, 具有互穿骨架结构的IRMOF-61和IRMOF-62材料在常温下的储氢能力并无明显提高. 进一步比较77 K时100 kPa、3.0 MPa下H₂在上述MOFs材料中达到吸附平衡时的几率密度分布发现, H₂会优先吸附在Zn₄O骨架附近靠近苯环的位置;对具有互穿结构的MOFs材料而言,由于其孔腔尺寸缩小, 使得H₂优先吸附位区域零散化. 适当长度的有机配体形成的互穿骨架结构能增强与H₂分子之间的相互作用, 具备较高的储氢能力; 而有机配体尺寸过长则会增加骨架结构中H₂吸附死角, 对H₂的吸附能力反而出现下降.     

A Facile Method for the Preparation of Monodisperse Beads with Uniform Pore Sizes for Cell Culture

This paper describes a facile method for the preparation of porous gelatin beads with uniform pore sizes using a simple fluidic device and their application as supporting materials for cell culture. An aqueous gelatin droplet containing many uniform toluene droplets, produced in the fluidic device, is dropped into liquid nitrogen for instant freezing and the small toluene droplets evolve into pores in the gelatin beads after removal of toluene and then freeze‐drying. The porous gelatin beads exhibit a uniform pore size and monodisperse diameter as well as large open pores at the surface. Fluorescence microscopy images of fibroblast‐loaded gelatin beads confirm the attachment and proliferation of the cells throughout the porous gelatin beads.     

Competitive Adsorption of Methylene Blue and Rhodamine B on Natural Zeolite: Thermodynamic and Kinetic Studies

A batch system was applied to study the adsorption behavior of methylene blue (MB) and rhodamine B (RB) in single and binary component systems on natural zeolite. In the single component systems, the zeolite presents higher adsorption capacity for MB than RB with the maximal adsorption capacity of 7.95×10^?5 and 1.26×10^?5 mol/g at 55°C for MB and RB, respectively. Kinetic studies indicated that the adsorption followed pseudo‐second‐ order kinetics and could be described by a two‐step diffusion process. For the single component systems, the adsorption isotherm could be fitted by the Langmuir model. In the binary component system, MB and RB exhibit competitive adsorption on the zeolite. The adsorption is approximately reduced to 50% and 60% of single component adsorption systems of MB and RB, respectively at an initial concentration of 6×10^?6 mol·L^?1 at 25°C. In the binary component system, kinetic and adsorption isotherm studies demonstrate that the experimental data are following pseudo‐second‐order kinetics and Langmuir isotherm and kinetic data are fairly described by a two‐step diffusion model. Effect of solution pH on adsorption of MB and RB in both single and binary component systems was studied and the results were described by electrostatic interactions.     

不同孔径的介孔碳分子筛对VB12的吸附性质研究

摘要利用SBA-15为模板, 在不同温度下合成了孔径大小在3.7(CMK-3-100)和6-3 nm(CMK-3-150)之间的介孔碳， 以其作为吸附剂, 研究了它们在水溶液中对VB12的吸附作用. 结果表明, CMK-3-130与CMK-3-100和CMK-3-150相比， 表现出对VB12最大的吸附能力(吸附能力为412.5 mg/g), 这是因为它有比较高的有序结构和比较大的孔容.     

在不同复盖度下二组分气体在硅胶上的吸附规律

通过测定不同复盖度下的丙酮－正己烷、苯－正己烷、甲苯－正己烷和正戊烷－正己烷四个二组分气体在硅胶组成吸附等温线，发现它们有着共同的规律，随着复盖度的增加，各体系的组成吸附等温线都逐渐向下靠近它们各自的气液平衡曲线，因此基本上可以反组分吸附相看成二组分液相，其中除了形成最低人沸点的丙酮－正己烷体系以外，其它三个体系的组成吸附等温基本上都可以理想溶液的相对挥发度议程式模拟得到。     

不同环大小分子筛对钼基分子筛催化剂上甲烷无氧芳构化反应的影响

 钼基分子筛催化剂，由于不同分子筛的孔道大小及孔道形状不同\r\n，对甲烷芳构化反应表现出不同的催化性能．具有8元环孔道结构的小\r\n孔ERS－7分子筛没有催化活性，说明甲烷的芳构化反应离不开分子筛孔\r\n道的择形作用，较小的孔道中不能生成苯等芳烃．具有10元环孔道结构\r\n的ZSM－5，ZSM－11和ZRP－1三种分子筛具有较好的催化性能，但由于\r\n其孔道大小及孔道形状的差别在催化行为上表现出一定的差异．具有1\r\n0元环和12元环孔道结构的MCM－22分子筛，尤其对苯等轻芳烃而言，催\r\n化性能最佳．具有12元环孔道结构的JQX－1以及中孔分子筛SBA－15，\r\n虽然具有一定的催化性能，但活性较低．研究结果表明，孔道大小与苯\r\n分子动态直径相近或孔道稍大的分子筛是催化甲烷芳构化反应的良好载\r\n体，孔道过大或过小都不利于苯和萘等芳烃的生成．     

Adsorption of surfactants onto acrylic ester resins with different pore size distribution

In this study, a series of acrylic ester resins with different pore size distribution were prepared successfully by varying the type and the amount of pore-forming agents. In order to inves-tigate the adsorption behavior and mechanism of surfactants on acrylic ester resins, three kinds of surfactants were utilized as adsorbates that were sodium 6-dodecyl benzenesulfonate (6-NaDBS), sodium 1-dodecyl benzene sulfonate (1-NaDBS) and sodium 1-dodecyl sulfonate, respectively. It was observed that the surface area was available in a particular pore size and an appropriate pore size of resins appeared to be more important for the adsorption of surfactants. As compared to commercial acrylic ester resins XAD-7 and HP2MG, 50# and 38# resins exhibited more excellent adsorption properties toward 1-NaDBS and 6-NaDBS. The experimental equilibrium data were fitted to the Langmuir, and double-Langmuir models. Two models provided very good fittings for all resins over the temperature range studied. The investigation indicated that electrostatic attraction and hydrogen bond between resins and surfactants were the main forces and had an obvious effect on adsorption proc-ess.     

生物金属-有机骨架材料中药物吸附及扩散的分子模拟研究

选用了三种bio-MOFs （bio-MOF-1,bio-MOF-11,bio-MOF-100）材料,采用蒙特卡罗和分子动力学模拟研究了布洛芬分子在bio-MOF材料中的吸附和扩散性质. 结果发现,bio-MOF材料结构对药物分子布洛芬的吸附及扩散有很大影响. 其中,孔径控制着客体分子布洛芬的进入及扩散; 孔隙率大小与布洛芬的吸附量及自扩散系数大小成正比. 静电作用力对布洛芬分子的吸附有较小的促进作用. 另外还研究了布洛芬分子在MOF材料中的最佳吸附位及最优构型,发现布洛芬分子优先吸附在金属角落处,以及不同材料其吸附的布洛芬分子最优构型是不一样的.     

基于压电陶瓷的A型分子筛膜合成与吸附性能

无铅压电陶瓷0.8Na_0.5Bi_0.5TiO₃-0.2K_0.5Bi_0.5TiO₃表面采用化学改性预涂晶种作为基底,分别以微乳和澄清溶液法在基底上水热晶化合成了A型分子筛膜.通过XRD、SEM和FTIR对晶种及分子筛膜进行了表征,通过压电谐振法测量甲烷吸附性能.结果表明:微乳和澄清溶液法均合成单一A型分子筛相,1次合成分子筛膜的时间分别为6、9 h,通过不同镀膜次数生成A型分子筛膜的形貌、膜厚不同.经A型分子筛膜修饰压电振子后,其对甲烷气体的灵敏度可分别达到59 Hz/1%CH₄、68 Hz/1%CH₄.     

Adsorption deformation in the microporous carbon adsorbent-benzene system and porous structure of adsorbents

The relative adsorption deformation of several microporous carbon adsorbents was studied as a function of the benzene adsorption at relative pressure ranging from 1·10⁻¹ to 1.0 and at 293 K. A correlation between the maximum compression of the sample and the characteristic energy of benzene adsorption of the Dubinin-Radushkevich equation was obtained. Using data on the adsorption deformation, it is possible to identify the region with a specific pore size that cannot be evaluated with the help of the Dubinin-Radushkevich equation. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No.6, pp. 1018–1022, June, 2000.