The synthesis, characterization, and structure solution of SSZ-56: An extreme example of isomer specificity in the structure direction of zeolites

Abstract

The synthesis, structure solution, and characterization of the novel zeolite SSZ-56 (Si 54.7B 1.3O 112) are described. SSZ-56 is synthesized under hydrothermal conditions using the trans-fused ring isomer of N, N-diethyl-2-methyldecahydroquinolinium as a structure directing agent. The synthesis of SSZ-56 is sensitive to the isomeric purity of the structure-directing agent. The structure of SSZ-56 was determined from powder diffraction data with the FOCUS Fourier recycling method using peak intensities extracted with the fast iterative Patterson squaring (FIPS) method. SSZ-56 possesses a relatively complex structure with 14 tetrahedral atoms in the asymmetric unit of its topological symmetry. Rietveld refinement of synchrotron X-ray powder diffraction data in space group P2 1/m ( a = 13.9483 (2), b = 19.8958 (1), c = 12.3613 (1)Å, β = 106.68°) confirms the proposed model. SSZ-56 possesses a 12-ring channel system that is intersected by a 10-ring channel system. The two-dimensional projection along the b-axis is similar to the projection along the pores of zeolite beta (polymorph B), and the two-dimensional projection along the c-axis is similar to the projections along the straight 10-ring channels of zeolite ZSM-5.