SYNTHESIS AND CHARACTERIZATION OF HEXAGONALLY PACKED MESOPOROUS TANTALUM OXIDE MOLECULAR-SIEVES

The synthesis and characterization of Ta-TMS1, a new member of a growi ng family of hexagonally packed transition-metal oxide mesoporous mole cular sieves (termed TMS1) is described. Ta-TMS1 exhibits a hexagonal array of pores which can be varied in size from 20 to 40 Angstrom and surface areas of over 500 m(2)/g. The thermal and hydrothermal stabili ties of Ta-TMS1 are 500 and 450 degrees C, respectively, making this s ystem the most stable transition metal oxide molecular sieve yet isola ted. The high hydrocarbon adsorption capacities of this material make it a promising candidate as a catalyst support for hydrocarbon re-form ing processes. The synthesis of this material was achieved by a novel approach involving the careful hydrolysis of long-chain primary amine complexes of Ta(OEt)(5). This ligand-assisted templating mechanism rep resents a new approach to the synthesis of porous materials in that th e inorganic precursor is covalently bonded to the template throughout synthesis. The high thermal stability, ease of synthesis and doping, a nd high surface areas of this material make it competitive with zeolit ic molecular sieve materials and may lead to a wide variety of commerc ial applications.