Work

Further Investigations of Racemic and Chiral Molecular Sieves of the STW Topology

Year: 2021

Type: article

Abstract: Large single crystals of pure-silica STW-type molecular sieves are prepared using 1,2,3,4,5-pentamethylimidazolium (12345PMI) and 2-ethyl-1,3,4-trimethylimidazolium (2E134TMI) as organic structure-directing agents (OSDAs) and α-amino acid additives. The effects of the amount and type of amino acid on the crystallization of pure-silica STW materials are investigated. Room-temperature single-crystal X-ray diffractometry shows that 12345PMI better fits the STW cage than 2E134TMI and is fully consistent with computed simulations. The synthesis of an enantioenriched R-STW-type molecular sieve having a Si/Ge ratio of 2.2 is achieved using a chiral, dicationic OSDA that contains two stereocenters. The conformation of the chiral OSDA in the chiral framework has been obtained from a Rietveld refinement using synchrotron powder diffraction data and is the first structure refinement of an enantioenriched, inorganic molecular sieve prepared from a pure, asymmetric OSDA.

Source: Chemistry of Materials

DOI: 10.1021/acs.chemmater.0c04573

Authors: Jong Hun Kang, Lynne B. McCusker, Michael W. Deem, Christian Baerlocher, Mark E. Davis

Institutions: California Institute of Technology, Seoul National University, ETH Zurich, Rice University

Language: English

Topic: Zeolite Catalysis and Synthesis

Subfield: Inorganic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funders: U.S. Department of Energy, Chevron

Award: GAS SEPARATIONS BY NOVEL, DESIGNED, COST-EFFECTIVE ZEOLITES