Hi,
I came across the lattice parameter values of Linde Type A zeolite and LTA hydrated zeolite in IZA-SC database. LTA is having the value of 11.91Angstroms ( http://asia.iza-structure.org/IZA-SC/framework.php?STC=LTA) and LTA hydrated is having 24.61Angstroms. What is the difference between these frameworks? And also the lattice parameter values of LTA hydrated (http://asia.iza-structure.org/IZA-SC/pow_pat.php?STC=LTA&ID=LTA_0) and dehydrated (http://asia.iza-structure.org/IZA-SC/pow_pat.php?STC=LTA&ID=LTA_1) are slightly different. Here, How water can influence the slight change in lattice parameter values?
Dear Murukutti. I remember the case of FAU.
The water cause the hydration of the cations that are in zeolite cage. Because of this there are an ASTM series about DRX in zeolite FAU in FCC catalyst that ask for a special preparation before perform the DRX. One have to dry at 105 oC for 2 hours and set the materials into for at least 16 h in a disecator filled with a solution of saturated CaCl2 (instead of silica gel pearls) which has a relative umidity of about 35% with the purpose of stabilize the umidity in the gaseous enviroment and the water content in zeolite before doing DRX.
In relation of the decrease of cell parameter in high content of water, it is expected that free volume decreases in zeolitic cage in this case LTA.
The cations changed its positions with variations of humidity in the enviroment.
Thank you for your response Mr. Joao. But, is it cause to this much difference in lattice parameter value? Nearly half the difference is there, LTA is ~12 A0 and LTA hydrated is ~24.55A0. That to, It is not clear the difference between LTA and LTA hydrated (LTA dehydrated is different from LTA).
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