Kinetic Process Of Spontaneous Liquid-Gas Imbibition On Porous Materials

The porous materials are widely used in catalysis,adsorption and separation due to their abundant pore structure and special surface property,the characterization of them is of great significance.The traditional characterization methods have shortcomings of long time consuming,high cost and poor data repeatability,which can't characterize micropores accurately.The spontaneous liquid-gas imbibition?SLGI?is a method that can characterize the pore structure and surface property simultaneously.The research group has been studying on the SLGI and has made remarkable progress in characterizing the pore structure.However,the research on the microscopic process of SLGI is not deep enough and lack of quantitative analysis of mathematical model,the kinetic model controlled by single factor can't describe the imbibition process very well.In this paper,the kinetics of SLGI on different adsorbents have been investigated,and the kinetic equation was constructed.It was found that the kinetic model was suitable for porous materials rich in micropores.The equilibrium gas recovery volume(1₀)reflected the adsorption capacity,which was related to the micropore volume.The diffusion rate into micropores6)₁ reflected the diffusion rate of gas and liquid molecules into micoropores,which was related to the micropore size.The adsorption rate6)₂ reflected the adsorption rate of liquid molecules on the surface,which was related to the surface property.The factors affecting the SLGI process were investigated.With the increases of temperature,the(1₀)decreases,the6)₁ and6)₂ increases,which is accordance with the theory of physical adsorption and molecular thermal motion.With the decreases of particle size,the(1₀)is constant,indicating that the micropores is the main place for adsorption.In the crushing process,the macropore and mesopores are broken,the channel pores reduce and molecular diffusion accelerate,the surface adsorption on the pores is proportional to the particle size,so the6)₁ increases and the6)₂ decreases.The size,shape and polarity of gas molecules are various,their diffusion,adsorption and accumulate state in micropores is different,which will further affects the imbibition process.Finally,the SLGI method and kinetic equation are used to adjustment of pore structure,modification of surface oxidation and measurement gas density in micropores.