Abstract: A novel topological framework structure of the molecular sieve named CJU-18 is obtained theoretically, which has 18 membered ring open pores.The structure is formed by the assemblage of the second building units: cancrinite cage, according to the hexagonal space groups P₆₃/mmc.It has not only the 18-ring pore channel system which parallels to the c-axis as in VPI-5, but also 10-ring pore channel system along both a and b-axis.The results obtained from calculating the bond distances and angles between the atoms show that the structure may probably exist.By using the POWD-MODELING program and the X-ray powder diffraction pattern the topological structure is described.

Key words: CJU-18, Extra large pore molecular sieve, Topological framework structure, Can-crinite cage