CRYSTAL CHEMICAL STUDIES ON THE GROWTH SIZE PROBLEM OF Y ZEOLITE Der Naturwissenschaftlichen Fakultät der Gottfried Wilhelm Leibniz Universität Hannover Zur Erlangung des Grades Doktorin der Naturwissenschaften Dr. rer. nat. genehmigte Dissertation von Nada Salman geboren am 21. Oktober 1976 in Hreissoun, Syrien November 2006 Referent: Prof. Dr. Josef-Christian Buhl Institut für Mineralogie, Universität Hannover Koreferent: Prof. Dr. Sameh H. Rahman Tag der Promotion: 13. Februar 2007 ABSTRACT Synthesis of (if possible large sized) pure zeolite Y crystals of high Si : Al ratio (n /n ) was Si Alperformed in the first part of the present work. Therefore, the reproducibility of important procedures, given in the literature was checked and modifications like the use of a nucleation solution were worked out to obtain pure phase products with high n /n . The characterization showed that no high Si Alsilica zeolite Y crystals of sizes bigger than 1 µm could be prepared and a systematical decrease in size with increasing n /n was found. Si Al For a better understanding of the relation of growth behavior and the n /n ratio of the products an Si Alinvestigation of Y-type formation mechanism was performed in a further experimental section.