In case of inorganic materials which characterized by positive
tetrahedron with Na+ central body in his positive tetrahedral model,
Na+ plays a role as positive templating agent instead of organic
templates through enhancing nucleation process which leads to
forming smaller crystals [24,25]. It was investigated that adding
a certain amount of Na+ cation can stimulate the growth of crystals
and the crystal size was decreased with the increase of Na2Ocontent [26,27]. It was reported that the Al content in the framework
of zeolite is normally observed to be less than that in the
starting gel when template is used. Therefore, it was concluded
that minimum Al (Si/Al = 100/1) should be required to form zeolite
in the absence of organic template [28,29].