Characterization On Adsorption Behavior Of Porous Materials By Spontaneous Liquid-Gas Imbibition Method

Low temperature gas adsorption method has been widely used in characterize the properties of the materials’pore structure due to its complete theories. However, this method can’t be used to characterize the ultramicropore (<0.7nm) of adsorbent, like carbon molecular sieve and some activated carbon, which have abundant fine pores. Meanwhile, most industrial production processes were carried out at ambient temperature; therefore, studying the property of the ultramicropore and the behavior of porous materials at room temperature will have an important impact on guiding the product of industry.Considering the suction fluid dynamic thought which has been widely used in assessment of the pore texture of cement and concrete and the phenomenon that gases’ density increases in the micropore structure of the adsorbent, this paper put forward a Liquid-Gas Imbibition method. The topic of these works focus on the equilibrium adsorption capacity of the porous material under the condition of ambient temperature, the pore size distribution on the influence of equilibrium adsorption and the dynamic process, meanwhile, the pore structure of the porous material characterization was also discussed. In this work, carbon molecular sieves (CMS), activated carbon (AC) and mesoporous materials like Al2O3and MCM-41were choosed as adsorbent, different gas adsorption process such as N2, CH4, O2,Ar was discussed and the dynamic process was investigated by using Liquid-Gas Imbibition method; Different molecular diameter of the liquid (water, benzene, cyclohexane, isooctane and alpha pinene) was employed to obtain the influence of pore size of activated carbon on gas adsorption capacity; N2and CH4adsorption isotherms of CMS-A were measured at303K,and the volume of these two gases was measured by using Liquid-Gas Imbibition method, respectively. The result shows that the adsorption data measured by these two methods is in consistent.Since most of the gases were in supercritical state under the condition of normal temperature, the property of porous materials adsorption may be different compared with the low temperature condition. The equilibrium adsorption capacity of supercritical gas N2, CH4was tested by Liquid-Gas Imbibition method and adsorption isotherm under the condition of303K,respectively. the result shows that mesopore has no effect on the adsorption of supercritical gases at ambient pressure; In order to investigate the influence of specific surface area as well as micropore volume on the adsorption capacity of supercritical gases like N2, CH4,five types of activated carbons were made which have different activation time, the results indicated that adsorption capacity of porous materials doesn’t grow with the increase of specific surface area as well as micropore volume, while micopore size distribution plays an major role on supercritical adsorption.