Accurate structure determination of a borosilicate zeolite EMM-26 with two-dimensional 10 × 10 ring channels using rotation electron diffraction

Abstract

A new borosilicate zeolite |N₂H₃₆C₁₆|[Si₂₂B₂O₄₈]·H₂O, denoted as EMM-26, has been synthesized by employing a linear dicationic organic structure directing agent 1,6-bis(N-methylpyrrolidinium)hexane (OSDA). EMM-26 has a novel zeolite framework and contains two-dimensional (2D) intersecting 10 × 10-ring channels. Its structure was solved from sub-micrometer sized crystals using rotation electron diffraction (RED) and refined against both the RED and synchrotron powder diffraction data. We have shown for the first time that RED data alone can be used to accurately determine zeolite structures. The OSDAs can be removed from the framework generating permanent pores. EMM-26 shows good CO₂ uptake and CO₂/CH₄ selectivity.