MCM-47: A Highly Crystalline Silicate Composed of Hydrogen-Bonded Ferrierite Layers

Abstract

The synthesis, structure solution, and characterization of the layered silicate MCM-47 are described. MCM-47 is synthesized using a diquaternary ammonium salt prepared from the reaction of 1-methylpyrrolidine with 1,4-dibromobutane. The structure solution of MCM-47 using Monte Carlo methods and the FOCUS algorithm shows that the material is composed of ferrierite layers. The Rietveld refinement of synchrotron X-ray powder diffraction data in space group Cmcm gives unit cell parameters a = 7.386 Å, b = 22.454 Å, and c = 14.018 Å and agreement values of Rp = 5.20%, Rwp = 6.99%, and χ2 = 3.01. The results of the structure refinement and the 1H MAS NMR spectrum indicate that the layers of MCM-47 are held together by strong hydrogen bonds. Energy minimization calculations of the organic structure directing agent within the layers of MCM-47 suggest that geometric complementarity between the organic and inorganic components can explain the unusual stacking arrangement of the ferrierite sheets.