Zeolite synthesis in the tetraethylammonium-tetramethylammonium mixed-organic additive system

Abstract

The synthesis of zeolites UZM-5, UZM-9, and offretite in the tetraethylammonium-tetramethylammonium two-organic component system, with or without some monovalent inorganic ions present, and their characterization results are described. The phase selectivity of the crystallization was found to differ notably according not only to the synthesis temperature, but also to the type of inorganic cations replacing half of tetramethylammonium ions in the synthesis mixture. A combination of elemental analysis and C-13 MAS NMR measurements allows us to reasonably estimate the intrazeolitic locations and populations of the two organic additives encapsulated within as-made UZM-5 and UZM-9, as well as within as-made offretite, which are further altered by the presence of additional inorganic cations. When a small amount of Na+ ions is used as a supplementary crystallization agent in UZM-9 synthesis, unexpectedly, it is observed that the average size of crystals obtained increases continuously with increasing the autoclave rotation speed up to 150 rpm at the crystallization temperature. (c) 2009 Elsevier Inc. All rights reserved.