Mesoporosos

Chem. Mater. 1999, 11, 2919-2927

2919

Crystal Structure of Zeolite MCM-35 (MTF)
Philip A. Barrett, Marıa-Jose Dıaz-Cabanas, and Miguel A. Camblor* ´ ´ ´ ˜
Instituto de Tecnologıa Quımica (C.S.I.C.-U.P.V.), Universidad Politecnica de Valencia, ´ ´ ´ Avda. Los Naranjos s/n, 46022 Valencia, Spain Received May 17, 1999. Revised Manuscript Received July 15, 1999

Zeolite MCM-35 may be crystallized in its pure silica form in fluoride or hydroxide media at relatively low pH (below 11) in the presence of hexamethyleneimine. Its crystal structure has been solved by direct methods and refined using synchrotron powder diffraction data. Calcined MCM-35, [Si44O88], has a new zeolite topology (monoclinic, space group C2/m, a ) 9.49998 Å, b ) 30.7096 Å, c ) 7.31333 Å, ) 91.7113°) and contains small one-dimensional pores with openings defined by windows of eight tetrahedra.

Introduction Synthetic efforts during the last 40 years have produced a large number of zeolites, and around 100 different zeolite topologies have been determined.1 It is notable that most of the new zeolites discovered recently have been synthesized by the use of relatively complex and sophisticated organic cations employed as structuredirecting agents (SDA). This synthetic approach mainly relies on the believe that new zeolites require rather specific SDA to be used, since zeolites that need little structure-direction specificity (which have been called “default host lattices”)2 should have already appeared over all these years of synthetic effort. The specificity of the SDA, which most frequently are organoammonium cations, has been related to properties such as conformational rigidity, size and hydrophobicity (characterized by the C/N+ ratio).3 While this approach has proved extremely fruitful over the past few years, it is interesting to note that some new, recently discovered zeolites (such as MCM-224 and MCM-35)5 have been synthesized by using an amine (hexamethyleneimine) with a relatively