On The Correspondence Between The Sodium
ON THE CORRESPONDENCE BETWEEN THE SODIUM
AND ALUMINIUM IN THE SYNTHETIC FAUJASITES
K. Patrylak, A. Yakovenko, V. Khranovs’ka
Institute of Bioorganic Chemistry and Petrochemistry of National Academy
of Sciences of Ukraine; 1, Murmans’ka vul., Kyiv, 02094 Ukraine
Zeolites are built by an endless polymeric chain consisted of SiO2 and AlO2 tetrahedra. Each of the last bears a negative charge which is compensated by one or another cation, for example Na+, therefore, zeolites are objects of strictly defined chemical composition and theoretically of fully equivalence between Al and Na. But it is well known that the real zeolites practically never are characterized by the strictly defined chemical formulae: they content a certain surplus Na, what allows sometimes to declare even the overequivalent cation contents relatively the Al ones [1].
To examine the possibility of achievement of the proper balance between the zeolite Na and Al on the basis of Na surplus zeolite by means of a long water washing of the last, was the task of the present paper.
Three X zeolite samples were subjected to the washing for 60-160 h by hot bidistilled water using Soxhlet’s extractor: industrially prepared granulated NaX of 75 wt % zeolite phase content as 2-3 mm (sample 1) and 0.5-1 mm (sample 2) fractions as well as the monocrystalline NaX sample 3 of strictly defined formula Na92Al92Si100O384 (0.05-0.1 mm) synthesized under special conditions [2].
It is stated that the process of surplus Na removal transits smoothly in the process of structural Na replacement by water protons. Unfortunately, there is no a clear-cut boundary between these two processes (during 160 h the Na loss made about 1.7 and 3 wt % of total Na for sample 1 and 2 respectively). It was surprising that even sample 3 lost during the 60 h washing about 0.4 wt % of its Na, the Al being lost simultaneously too. Therefore, the obtainment of a surplus-Na-free zeolite sample by means of water washing of surplus Na zeolite is not an easy task.
References
1. Matkovs’ka L.O. Abstract of Thesis. L.V.Pisarzhevsky Institute of Physical Chemistry, Kyiv, 1998.
2. Bogomolov V.N., Petranovsky V.P. Zeolites, 6, 418 (1986).
Related articles::