Adsorption and diffusion of mesitylene on MCM-22 and MCM-56 molecular sieves

Using the adsorption and diffusion of large molecular hydrocarbon mesitylene in MWW type molecular sieves as the probe,the properties of MCM-22 and MCM-56 molecular sieves were studied.The molecular sieves were characterized by the techniques of XRD,N2 adsorption and TEM in order to investigate the relationship between the structure of molecular sieves and adsorption and diffusion.The results showed that the adsorption and diffusion of mesitylene were in the external surface(external cups) of MWW-type molecular sieves.MCM-56 molecular sieve possessed more acid sites in its external surface than MCM-22 molecular sieve due to its monolayer structure and staggered layer structure.Compared with MCM-22 molecular sieve,more acid site and curled surface of MCM-56 molecular sieve after calcination prevented mesitylene from diffusion on the molecular sieve.