HYDROTHERMAL SYNTHESIS OF ORDERED ULTRA-LARGE PORE MOLECULAR-SIEVES

Semiconductor nanoparticles assembled within a zeolite is an example t o create quantum confined system. The present studies are focused on t he hydrothermal synthesis of ultra-large pore (ULP) molecular sieves. Molecular sieves can be prepared under hydrothermal condition from Cat apal alumna, aluminosilicate, silicate and ethylsilicate gels respecti vely, under carefully chosen conditions of pH, temperature and crystal lization time. It is very important to note that co-added alkali metal cations, quaternary alkylammonium cation and surfactant species funct ion as charge balancing agent, spacing-filling and structure-directing to obtain a ULP molecular sieve. TEM and electron diffraction pattern conform the periodicity of the structure. X-ray diffraction pattern o f the powder sample shows that there are two peaks in the low-angle 2 theta, the larger d value is 47.4 Angstrom. The formation of these mat erials takes place by means of a liquid-crystal templating mechanism i s also discussed.