title: Critical factors in the seed-assisted synthesis of zeolite beta and "green beta" from OSDA-free Na+-aluminosilicate gels.
abstract: Organic structure-directing agent (OSDA)-free synthesis of zeolite beta is a subject of both scientific and industrial interest. Herein, we report a comprehensive investigation into the effects of various parameters on the seed-assisted crystallization of zeolite beta in the absence of OSDA. The crystallization behavior of "OSDA-free beta" is strongly governed by the chemical composition of the starting Na(+)-aluminosilicate gel as well as by the Si/Al ratios of the calcined beta seed crystals, which are prepared using tetraethylammonium hydroxide (TEAOH). Furthermore, OSDA-free beta seed crystals can be used to form zeolite beta, termed "green beta". XRD, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, and ²⁷Al magic angle spinning NMR analyses showed that the OSDA-free beta and green beta were of high purity and crystallinity. The nitrogen adsorption-desorption of OSDA-free beta and green beta revealed higher surface areas and larger volumes in the micropore region than those of the beta seeds synthesized with OSDA after calcination. These results provide a robust and reliable process for the environmentally friendly production of high-quality zeolite beta in a completely OSDA-free Na(+)-aluminosilicate system.
authors.affiliation: Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kamimura
authors.forename: Watcharop
authors.initials: W
authors.lastname: Chaikittisilp
authors.forename: Keiji
authors.initials: K
authors.lastname: Itabashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shimojima
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Okubo