Adsorptive properties in toluene removal over hierarchical zeolites

Three kinds of hierarchical Mordenite Framework Inverted (MFI)-type nanozeolites including Si-MFI, Al-MFI and Ti-MFI were successfully synthesized by two-stage varying temperature hydrothermal treatment. Taking toluene as the probe molecule, a series of methods were used to evaluate the adsorption properties of as-synthesized hierarchical zeolites samples including the adsorption breakthrough curves, simulation of adsorption isotherms as well as kinetics models and toluene-TPD (the temperature programmed desorption of toluene). The dynamic adsorption results showed that Al-MFI exhibited the highest adsorption capacity for toluene (58 mg/ g(ads) ) under dry gas condition while Ti-MFI had the optimal toluene adsorption performance (45 mg/g(ads) ) under the wet gas condition (the relative humidity was 50%). The simulation results indicated that the adsorption behavior of toluene on hierarchical MFI nanozeolites conformed to the Freundlich principle, and the pseudo-first-order adsorption model was suitable to elucidate the adsorption process. Moreover, the fitting result of intraparticle diffusion model indicated that the adsorption process was affected by multiple adsorption steps and the intraparticle diffusion was not the control step.