The Physicochemical Properties Of Vpi-7: A Microporous Zincosilicate With Three-Membered Rings

Abstract

ABSTRACTThe synthesis of materials with void volumes in excess of 50% is an ongoing challenge in molecular sieve science. It has been shown that a correlation exists between the minimum framework density (FD) and the smallest ring in which all tetrahedral atoms reside (MINR). Based on this evidence it appears that materials containing 3-membered rings (3MR) will be necessary in order to obtain FDs lower than those currently attainable. Several framework beryllosilicate minerals including the natural zeolite, lovdarite, contain 3MRs. Unfortunately, beryllium can form highly toxic compounds that limit its suitability for many applications. Thus, in this study we have searched for a replacement for Be and have found that zinc is a suitable substitute with respect to the formation of three-membered rings.We report here VPI-7, a novel zincosilicate molecular sieve which contains three-membered rings. The VPI-7 framework contains rings composed of 3–, 4– and 5 T-atoms which form unidimensional 8– and intersecting 9MR channels.