Open AccessA Novel Zeolite MCM-22: Sorption Characteristics
Author(s) -
R. Ravishankar,
P.N. Joshi,
Shubhada Tamhankar,
S. Sivasanker,
V. P. Shiralkar
Publication year - 1998
Publication title -
adsorption science and technology
Language(s) - English
Resource type - Journals
eISSN - 2048-4038
pISSN - 0263-6174
DOI - 10.1177/026361749801600803
Subject(s) - sorption , mesitylene , chemistry , zeolite , microporous material , cyclohexane , adsorption , molecule , benzene , inorganic chemistry , chemical engineering , organic chemistry , catalysis , engineering
Synthetic zeolites of MCM-22 type with different framework SiO 2 /Al 2 O 3 ratios (ranging from 40 to 140) obtained by direct hydrothermal crystallisation were studied using different probe molecules. The influence of framework aluminium content on the BET surface area and on the micropore void volume was examined using low-temperature argon sorption. Sorption uptake using different probe molecules such as water, n-hexane, cyclohexane, m-xylene and 1,3,5-trimethylbenzene (mesitylene) was measured at 298 K. Considerable sorption (> 7.5 wt%) of bulky molecules such as m-xylene and mesitylene was observed suggesting the possible access from the crystal surface to some 12 membered-ring cages. The sorption energetics in zeolite MCM-22 as a function of the framework SiO 2 /Al 2 O 3 ratio were discussed on the basis of NH 3 sorption isotherms in the temperature range 303–453 K. The sorption data were analysed in terms of different sorption isotherm equation models. The ammonia sorption studies indicated that the acid sites were not uniform and were distributed heterogeneously.