Ga-substituted merlinoite (MER)-type zeolites are hydrothermally synthesize
d using aluminosilicate MER crystals as seeds under wholly inorganic condit
ions. The presence of Ga in tetrahedral positions is evidenced by powder X-
ray diffraction, Si-29 and Ga-71 MAS NMR, and IR spectroscopies. The bulk S
i/(Ga + Al) ratio in the framework determined by elemental analysis is in t
he range 1.9-3.0, depending on the initial Si/Ga ratio of the synthesis mix
ture. An attempt to fully substitute framework Al by Ga was not successful:
a gallosilicate with GIS topology, denoted TNU-2, is produced when alumino
silicate MER seed crystals are not added to the synthesis mixture. This cle
arly shows that the structure-directing ability of Ga is different from tha
t of Al in the synthesis conditions used here. (C) 2001 Elsevier Science B.
V. All rights reserved.