Tumbling approach towards template-free synthesis of EMT zeolite

The zeolite EMT has been synthesized with 18-crown-6/Al2O3 ratios as low as 0.14, by applying continuous tumbling of the synthesis mixture during the entire aging and crystallization period. The crystalline product contained only two crown ether molecules per unit cell, and the mother liquor was ess entially free of crown ether. It was found that the lower the amount of cro wn ether, the slower the rate of crystallization and the smaller the crysta llites of the product, whereas the total product yield remained well above 90% based on aluminum. With lower crown ether content the range of synthesi s conditions under which EMT was obtained became increasingly narrower: pre sumably because of the increasing probability of nucleating of other phases such as cubic faujasite when less 18-crown-6 is present. (C) 1999 Elsevier Science B.V. All rights reserved.