Effect of surface etching of ZSM-5 zeolite crystals on the rate of n-hexane sorption

Samples of the as-synthesized zeolite ZSM-5 were purified by etching the surface of crystals with an aqueous-acetone solution of hydrogen fluoride. The solution appeared to be very useful for removing by-products from the samples without affecting morphology or size of the crystals. Measurements of n-hexane uptake with a gravimetric method were performed to verify the effect of the sample treatment. The rates of the n-hexane sorption for the etched samples were up to two orders of magnitude higher than that for the non-etched one. The corrected diffusion coefficient of n-hexane was found to be only several times lower than those obtained with the methods of PFG NMR and FR as reported in the literature. (C) 2003 Elsevier Inc. All rights reserved.