Lun-Teh Yuen

Merlinoite synthesis studies with and without organocations

A novel synthesis of zeolite W (MER phase) was carried out combining the use of an organocation ‘template’ molecule and zeolite K-Y as the aluminium source. The reaction was carried out at lower than usual OH– /SiO2 reactant ratios and that translated into an exceptionally high SiO2 /Al2O3 ratio (SAR) of 7.7. This novel synthesis was contrasted with a recently described, wholly inorganic route to zeolite W, and with some previous organocation mediated zeolite syntheses. There is less template found inside the pores of W than in other syntheses to products like chabazite. For the wholly inorganic route, a novel synthesis strategy of removing the initial crystallization products, and then letting the crystallization proceed, was found as a successful route to W. The role of OH–/SiO2 ratios was studied in an effort to bridge the inorganic chemistry for W vs. LTL crystallization and the role the template can play. A surprising outcome of the study was that the unit cell volumes are quite close for the W zeolites produced by the different syntheses routes we describe, even though their SAR values differ.