Synthesis of an IWW-type germanosilicate zeolite using 5-azonia-spiro[4,4]nonane as a structure directing agent

• Published in: New journal of chemistry Vol. 40; no. 5; pp. 4319 - 4324
• Main Authors: Yuan, Ruting, Claes, Nathalie, Verheyen, Elke, Tuel, Alain, Bals, Sara, Breynaert, Eric, Martens, Johan A., Kirschhock, Christine E. A.
• Format: Journal Article
• Language: English
• Published: 2016
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C5NJ03094C

An IWW-type zeolite with a Si/Ge ratio of 4.9 is obtained using 5-azonia-spiro[4,4]nonane as a template in fluoride-free medium under hydrothermal conditions at 175 °C. In an otherwise identical synthesis, using related 5-azonia-spiro[4,5]decane as a structure directing agent, a mixture of IWW and NON zeolite types was formed. In the absence of GeO 2 from the reactant mixture, pure NON formed. The IWW zeolite was characterized by XRD, SEM, and HRTEM. The IWW zeolite displayed a unique morphology and could be calcined at 600 °C without the loss of crystallinity. The Si/Ge ratio of the IWW zeolite was increased by postsynthesis modification. Part of germanium could be eliminated from the as-synthesized IWW zeolite by acid leaching using 6 M HCl solution. Also the calcined material could be degermanated. Here the presence of a silicon source in the acidic leaching solution minimized structural damage. In this way the Si/Ge ratio of the IWW zeolite was increased from 4.9 up to 10.