Interference microscopy investigation of the influence of regular intergrowth effects in MFI-type zeolites on molecular uptake

Interference microscopy is applied to carry out investigations of the influ ence of the regular intergrowth effects commonly observed in large silicali te-1 crystals on adsorption/desorption of isobutane. The intracrystalline c oncentration profiles measured by interference microscopy during adsorption of isobutane are compared with those simulated using the Monte Carlo metho d. The comparison of the simulated and the measured profiles allows the pos sibility that the uptake of isobutane from the gas phase into silicalite-1 crystals proceeds through the internal interfaces separating the intergrowt h sections of the crystals to be ruled out. The diffusion coefficient of is obutane obtained by comparing the simulated and the measured concentration profiles is found to be in agreement with the previously reported diffusivi ties of isobutane in silicalite-1.