一种新型有机-无机杂化微胶囊及其渗透性

通过细乳液聚合,在正辛烷液滴外包覆一层苯乙烯与甲基丙烯酸-3-三甲氧基硅丙酯（MPS）的共聚物,得到一种新型有机-无机杂化纳米微胶囊.用透射电镜（TEM）和原子力显微镜（AFM）表征了其形态;用气体吸附仪（BET）研究了其微观结构,发现其具有多孔结构.利用多孔介质中的孔道扩散理论对其渗透过程进行建模,微胶囊渗透过程中的主体扩散系数主要由其孔隙率和曲折因子决定.用紫外可见分光光度计（UV）研究了微胶囊在不同体系中的渗透动力学,计算得到了各种条件下渗透的主体扩散系数和曲折因子,发现溶质的扩散速率随微胶囊中MPS用量增加造成的孔隙率增大而增加;曲折因子在甲酚红-甲醇体系中比在蒽-四氢呋喃体系中小,且基本不随微胶囊中MPS用量变化,与用孔道扩散理论分析结果一致.用红外光谱（IR）证实了示踪剂确实装载进入了微胶囊,但示踪剂的释放速率比装载速率小得多,且主体扩散系数随MPS用量变化不大.     

多孔球形催化剂颗粒的随机网络模型

提出了一种多孔球形催化剂颗粒随机网络构造方法,并以等温一级不可逆反应为例,对催化剂孔道网络内发生的反应扩散过程进行了模拟计算。模拟结果表明,计算出的曲折因子既是孔网络配位数的函数,又随Thiele模数的变化而不同,在纯扩散条件下测得的有效扩散系数只能应用于扩散影响不严重的反应扩散区域。同时对在不同的网络模型上的模拟结果进行了分析,并对各自得出的结论之间存在的分歧进行了解析。     

多孔介质干燥的孔道网络试验及模拟

结合孔道网络及侵入渗流理论。试验并模拟研究了刚性多孔介质的干燥过程。观察了孔道网络内部湿组份的分布状态，孔道网络干燥前沿的形成及发展过程。验证了多孔介质在干燥过程出现的蒸发前沿及其具有的不规则特征。模拟研究了多孔介质在等温条件下不考虑重力时的干燥过程。通过模拟给出了多孔介质在干燥过程内部相的动态分布。模拟结果显示，干燥前沿具有非常不规则的特征。通过相图分析。干燥中内部涅分的迁移不仅是一个从里到外的过程。也同时存在逆向扩散。     

气体有效扩散系数的分形模型

多孔介质中杂乱无序的孔分布结构特性显示了多孔介质具有孔分形结构。气体扩散在孔道中的分形模型是建立在分形理论和气体扩散特点的基础上。在考虑孔的大小分布、连通性分布和2种气体扩散机理的影响下,推导出了气体有效扩散系数和结构参数的关系。从参数分析中,可以得出有效扩散系数与孔的面积分形维数、孔隙率、联通数、气体自由扩散路径、孔最大最小直径比值成正比,与孔道迂曲度、迂曲分形维数成反比。通过实验数据与模型预测值对比验证了分形模型的正确性。     

砂粒堆积床恒温缓慢干燥的孔道网络模拟

对砂粒堆积床这一自然多孔介质的结构特性及孔道网络干燥模型进行了描述，并对砂粒堆积床结构参数与孔道网络模型参数进行了对应分析；建立了堆积床的孔道网络模型，并利用该模型进行了砂堆积床干燥过程的孔道网络模拟；模拟的结果与干燥实验数据进行了验证。     

多孔氧化铝中气体的有效扩散系数

在两种氧化铝中 ,分别采用C₂H₄ 、Ar和CO₂ 进行了两组分和三组分的Wicke -Kallenbach定态扩散实验 .由尘气模型和Stefan -Maxwell方程建立起的扩散通量方程 ,对实验结果加以处理 ,得到了两组分扩散的有效扩散系数及三组分扩散的虚拟两组分有效扩散系数 .同时 ,针对过渡区扩散推出了等温下两组分扩散的有效扩散系数为常数应满足的基本条件 ,所得结论和实验结果相吻合 .而对三组分扩散中的虚拟两组分有效扩散系数不能按照常数处理 .此外 ,无论是两组分或三组分扩散 ,对每一种氧化铝而言 ,有着相近的曲折因子 ,从而证实了曲折因子是与多孔介质结构密切相关的参数     

干燥过程原理研究概况

介绍了多孔介质湿分迁移的液相流动、毛细流动、蒸汽流动、液相扩散、蒸汽扩散等理论的基本论点及其存在的不足。认为借用侵入渗流理论及孔道网络方法研究多孔介质的干燥问题，有望取得新突破。     

气体、溶液中的非电解质和电解质在多孔颗粒内扩散的对比研究

实验测量了气体、溶液中的非电解质以及电解质三类性质相差较大的体系在相同的多孔颗粒内(孔隙率0.234～0.632)的有效扩散系数,并计算出曲折因子.探讨了由D_(?)=D_oε/τ定义的曲折因子对孔隙结构和扩散组分特性的依赖关系.     

气体、溶液中的非电解质和电解质在多孔颗粒内扩散的对比研究

实验测量了气体、溶液中的非电解质以及电解质三类性质相差较大的体系在相同的多孔颗粒内(孔隙率0.234～0.632)的有效扩散系数,并计算出曲折因子.探讨了由D_(?)=D_oε/τ定义的曲折因子对孔隙结构和扩散组分特性的依赖关系.     

分形多孔介质中气体的非稳态扩散

通过引入平均修正系数修正Fick第二扩散定律得到了描述分形多孔介质气体非稳态扩散的理论方程。基于“塞状流”扩散实验法建立了分形多孔介质非稳态扩散实验系统,对3个孔隙结构不同的分形多孔介质样品进行了非稳态扩散实验,通过实验对理论方程进行验证和修正。结果表明,Fick第二扩散定律不适用于分形多孔介质中气体非稳态扩散,分形多孔介质中气体非稳态扩散存在一定规律,且多孔介质孔隙结构不同其扩散规律不同。     

多孔介质中三组分气体扩散的网络分析

采用有效介质理论和平滑域近似的方法 ,对乙烯、氩气和二氧化碳在γ -Al2 O3 内的三组分扩散进行了网络分析 ,同时又用定态扩散实验加以验证 .研究结果表明 ,在确定了多孔介质孔结构参数 (平均配位数 )和孔尺寸参数 (孔径分布 )的前提下 ,通过网络分析的方法就可以获得有关多孔介质中多组分气体扩散的信息 .从而 ,建立起了用多孔介质微观性质描述宏观扩散过程的基本方法     

Mass transfer for dissolving solids in supercritical carbon dioxide Part II: Resistance in the porous layer

The internal mass transfer resistance was measured by dissolving naphthalene from a porous insoluble rod in a stream of supercritical carbon dioxide. Initially the pores of the porous medium (sintered bronze) were filled with naphthalene. During dissolution the naphthalene surface retreats into the porous rod and the length of the diffusion path increases. The tortuosity factor for the porous material was determined from experimental data. The temperature was varied from 35 to 55 °C, the pressure from 118 to 226 bar and the mean pore diameter was either 8 or 20 μm. The results show that the tortuosity factor does not depend on the pressure and pore diameter. This result was to be expected since the mean free path of the molecules is much smaller than the pore diameter. The average tortuosity factor, however, decreased with increase of temperature. From this temperature dependence surface diffusion of the solute absorbed on the pore wall is concluded to take place and thereby to contribute to the observed overall rate of mass transfer.     

确定多孔介质孔结构参数的渗流网络分析法

According to the simulation of nitrogen sorption process in porous media with three-dimensional network model, and the analysis for such a process with percolation theory, a new method is proposed to determine a pore structure parameter--mean coordination number of pore network, which represents the connectivity among a great number of pores. Here the “chamber-throat“ model and the Weibull distribution are used to describe the pore geometry and the pore size distribution respectively. This method is based on the scaling law of percolation theory after both effects of sorption thermodynamics and pore size on the sorption hysteresis loops are considered. The results show that it is an effective procedure to calculate the mean coordination number for micro- and meso-porous media.     

Determination of the effects of the pore size distribution and pore connectivity distribution on the pore tortuosity and diffusive transport in model porous networks

An efficient computation method to study flow and transport process of small molecules in porous media using a dual site-bond lattice model, DBSM, is described. The microscopic properties of the porous network take into account the influence of local heterogeneities during the simulations. The numerical experiments demonstrated the combined effect of pore size distribution and connectivity distribution on the mass transport properties and the structural tortuosity. The results indicate that the pore size distribution and percolation phenomena related with pore shielding effects, influence significantly the tortuosity and the effective diffusivity of the porous network. Also, the simulations raise the important role of the connectivity distribution among the various pores in the gas diffusive properties of the poorly connected networks.     

Transport properties of gas-expanded liquids in bulk and under confinement

Diffusion properties of carbon dioxide-expanded toluene in bulk and confined to nanoporous glasses have been assessed using pulsed field gradient technique of NMR. In the bulk phase the diffusivity of toluene is found to increase significantly with increasing carbon dioxide content. The same dependence is observed in the mesoporous glass with large pore size, but with lower absolute values resulting from the tortuosity of the porous matrix. In contrast, in the porous glass with small pore size, strong confinements lead to different behavior due to an altered equilibrium phase composition in the pore space affecting the mass transfer rates.     

Some observations on the variation of tortuosity with Thiele modulus and pore size distribution

Stochastic pore networks have been used to interpret the effects of pore structure on simultaneous diffusion and reaction in a porous catalyst. A stochastic pore network is a square network of pores, each pore segment having a radius assigned at random from any stipulated pore size distribution. The equations for diffusion and reaction within the network are solved rigorously for first order irreversible kinetics. The model is used to predict effectiveness factors and tortuosities for a hypothetical catalyst having one of four pore size distributions. The analysis predicts that tortuosity will vary with the Thiele modulus, the strength of this variation depending on the pore size distribution. It is further observed that the concentrations experienced by pores in a network are markedly different to those predicted by the parallel bundle model. This is relevant to the question of selectivity in complex reaction schemes.     

Effect of the coordination number of the pore-network on the transport and deposition of particles in porous media

Effect of the coordination number of the pore-network structure on the transport and deposition of colloidal particles in porous media was investigated. Applying with the orthogonal collocation principle and the pseudo-spectral method based on the Chebyshev polynomial, the complete solutions of the population balance equations describing the deposited particles, the suspended particles and the unblocked pore throats of porous media were obtained for the simple square network and the capillary tube network. It is shown that the network structure of porous media may significantly affect filtration rate, and therefore the effluent concentration and pressure drop. The filter with a capillary tube network structure owns higher filter coefficient than that of the filter with a simple square network structure. Theoretical predictions for different influent concentrations of particles, different flow rates and the case of blocking occurred in the filter bed are in agreement with the available experimental data.     

Microporous Substructure of Porous Glasses: Dynamic and Equilibrium Approaches

Porous glasses produced by the leaching of two-phase alkali borosilicate glasses have been studied by dynamic and equilibrium methods for diagnostics of pore morphology. It has been detected the availability of microporous substructure with some kinds of adsorbing micropores of diameter 0.3–2 nm including ultramicropores of molecular size in porous glasses with transporting pores of mean diameter from 4 to 15 nm. The multimodal nanoporous structure of porous glasses detected by kinetic mass spectral method of gas diffusion diagnostics (DD-method) at low temperatures is consistent with the results obtained from analyzing equilibrium desorption isotherms of nitrogen, oxygen and argon at 77.5 K by different calculation techniques including an equilibrium method of gas desorption at low partial pressures (LPED-method). Micropore volume in porous glasses is equal to 6–18% from total pore volume. The dependence of nanoporous morphology of porous glasses on conditions of their production and composition has been established. The diffusion and equilibrium characteristics of different molecules (nitrogen, oxygen, argon) varying in molecule size and quadrupole moment value have been determined for primary and secondary porous substructures of porous glasses at liquid nitrogen temperature at the first time.