Study On The Dymamics Of Liquid-Gas Imbibition Of Porous Materials

Dynamic of liquid imbibition which have the characterization of simple operation, cheap price and reliable data has been widely used for the assessment the pore texture of cement, concrete and other macro materials. By using the idea of liquid imbibition, combined with gas adsorption in porous materials, the liquid-gas imbibition process of porous material was studied in this thesis, which establish the foundation for the method of liquid-gas imbibition applied to measure the pore characterization of porous materials.The test used AC, γ-Al2O3and zeolite as adsorbent, N2and CH4as adsorbate, water, benzene, cyclohexane, isooctane and a-pinene as liquid probe, and volume of gas displaced was measured. The pore texture of porous materials were characterized by N2adsorption at77K, and the gases adsorption isotherms were measured at303K. Influences of pore structure of AC, types and cations of ZSM-5on the displaced CH4and N2were emphatically investigated. The experimental results show that the volume of gas recovered by liquid-imbibition reflects the adsorption capacity of the porous materials. The gas recovery volume decreases as the molecular dimentions of liquid probe increases giving the pore structure information of sample. Inner specific surface area and pore size distribution seem to be the determining factors affecting the adsorption capacity and separation ability of CH4/N2on activated carbons. For example, the pores in the range of0.59-0.90nm are suitable for CH4/N2separation for AC-1. The gas displaced from powder ZSM-5is higher than that from columnar; The volume of CH4recovered from powder ZSM-5which cation exchanged with alkali metals Group I is higher than that with Group II. Cations exchange have no effect on the N2recovery.Used CMS, ZSM-5and AC as adsorbent, N2as adsorbate, dynamics of the liquid-gas imbibition have been carried out, and the factors affecting the dynamics have been taken into consideration. The experimental results show that liquid-gas imbibiting speed rises as temperature increasing and the contact area between the sample and the liquid increasing. The bigger liquid viscosity and adsorbent size, the bigger resistance of liquid-gas imbibition, and the smaller rate of the process. The rate of liquid-gas imbibitions rises as particle size reducing show that water displacement may be determined by micopore diffusion and macropore diffusion. While the grain size is thinner than0.42-0.85mm and0.85-1.40mm, respectively, the imbibiting speed in CMS and ZSM-5hardly increased, and the resistance of the macropores diffusion can be neglected, and diffusion of the micropore can be the dominant role. Calculated imbibiting rate of CMS and ZSM-5at different temperature using LDF model, and got the activation energy of liquid-gas imbibition. For cylindrical AC which side surface was sealed, dynamics of water displacement may be determined by macroporcs, and volume of the gas displaced against t1/2is a straight line, and, follow up the Washburn equation.