Adsorption and diffusion of n-butane in mordenite crystals

The effects of the premixed time of silicic acid powder with NaOH solution and the crystallization time on the crystal size of the synthesized mordenite were systematically investigated. Additionally, the study was conducted on the adsorption and diffusion of n-butane in the synthesized mordenite (MOR) crystals with a uniform size of about 8 μm. The results showed that the adsorption of n-butane in the parent Na-MOR zeolite was extremely slow and within 160 min the adsorption could not reach equilibrium under the applied conditions. The adsorption could be significantly improved after the parent Na-MOR zeolite transferred into its H-form, and within 2 min the adsorbed amount reach to ca 70% of its equilibrium adsorption capacity (0.70 mol/kg). However, after the NH4-MOR (precursor of H-MOR) zeolite transferred into its Na-form, the adsorption of n-butane was almost the same as that in the parent Na-MOR. It is concluded that the Na species remaining in the synthesized mordenite channels caused the blockage of MOR micropores, resulting in the limitations of molecule diffusion.