Abstract: To study the correlation between the mass transfer performance and pore structure characteristics of industrial catalysis, ZSM-5 zeolites were treated with different concentrations of NaOH solutions to prepare a series of zeolite samples with different degrees of mesoporous(Z5/0.05Na, Z5/0.10Na, Z5/0.20Na, Z5/0.30Na). The pore structure and hydroxyl characteristic of the samples were characterized by means of X-ray diffractometer, scanning electron microscope, transmission electron microscope and in-situ infrared spectrometer, etc. Using toluene as a probe molecule, the influence of the mesoporous formation of samples on its diffusion behavior was evaluated. The results show that the ZSM-5 zeolites treated with NaOH solution exhibit obvious mesoporous characteristics. When the concentration of NaOH is in the range of 0.05-0.20 mol/L, the average pore diameter increases with the increase of alkali concentration. The desorption diffusion rate of toluene is positively correlated with the degree of mesoporous formation of the sample and desorption temperature. With the increase of the degree of mesoporous formation, the desorption diffusion rate of toluene accelerates, and the desorption activation energy decreases.

Key words: ZSM-5 zeolite, alkali treatment, diffusion, zero-length column method, mesoporousization