Synthesis and Monte Carlo Structure Determination of SSZ-77: A New Zeolite Topology

摘要

A new molecular sieve topology has been determined from a multistage Monte Carlo computer simulation procedure using the program ZEFSAII. The material, SSZ-77, consists of alternating layers present in the RUT and AST topologies, and intergrowths may be possible in the way that this material grows. The product first arose from a synthesis where it appears that the degradation of the quaternary ammonium structure directing agent (SDA) produced the viable organo-guest molecule in the structure formation. The synthesis requires the use of Ge as well as Si as lattice components. In the absence of Ge, only RUT forms. An additional study was carried out to determine the suitable size of guest molecules in a series spanning trimethylamine to tetraethylammonium in the presence of benzyltrimethylammonium. It is found from NMR investigations that none of the larger molecules are occluded within the cages of the SSZ-77 structure, and that the primary occluded species is trimethylamine or tetramethylammonium.