Structure analysis of a BEC-type germanosilicate zeolite including the location of the flexible organic cations in the channelsElectronic supplementary information (ESI) available: Results of the TGA and 19F NMR, and crystallographic information file (cif) of the refined structure of Ge-BEC. See DOI: 10.1039/c5ce00731c

A BEC -type zeolite (polymorph C of zeolite beta) with low germanium content (Si : Ge = 5.1) has been synthesised using the flexible linear diquaternary cationic form of pentamethyldiethylenetriamine (2,2′-(methylazanediyl)bis( N , N , N -trimethylethanammonium) as the organic structure-directing agent (SDA). The distribution of germanium within the framework and the location of the SDA within the pores have been determined by analysing synchrotron X-ray powder diffraction data collected on the as-synthesised form. The findings, which are corroborated by 13 C and 19 F NMR data, indicate that the structure of the SDA is retained during the synthesis and that the Ge atoms occupy only sites in the double 4-ring. Although the BEC framework structure has a three-dimensional 12-ring channel system, the SDA molecules are found to orient themselves in two dimensions along the channels running parallel to the a and b axes. A BEC -type zeolite with low Ge content has been synthesised using a flexible SDA. The locations of the Ge and SDA were determined using XPD techniques.