日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

In catalytic reactions using porous materials, diffusion of reactant and product molecules within pores of the materials strongly affects overall reaction rates. Therefore, information concerning with diffusion mechanisms is required for catalyst design. In this paper, intracrystalline diffusivities of benzene within a series of porous materials in liquid phase (cyclohexane and iso-propanol were used as solvent) were measured by a constant volumetric method to understand the diffusion mechanism. Within microporous material of which pore diameters are close to benzene molecule, the diffusion mechanism of benzene molecule in liquid phase is the same as vapor phase because benzene molecule independently diffuses within the micro-pore. Intracrystalline diffusivities of benzene within meso-porous materials were almost the same and/or smaller than that within micro-pore, though the pore diameter of mesoporous materials are larger than those of micro-pore. Benzene molecules as well as cyclohexane were adsorbed onto the pore wall of meso-porous materials, leading to a decrease in the effective pore diameter for diffusion. Moreover, effects of affinity between the pore wall of porous materials and the solvent on the benzene diffusivities were investigated and it was found that adsorption amount and intracrystalline diffusivities of benzene are decreased by using hydrophilic molecule as solvent.