Hydrothermal synthesis of ordered ultra—-large pore molecular sieves

Abstract

Semiconductor nanoparticles assembled within a zeolite is an example to create quantum confined system. The present studies are focused on the hydrothermal synthesis of ultra-large pore (ULP) molecular sieves. Molecular sieves can be prepared under hydrothermal condition from Catapal alumna, aluminosilicate, silicate and ethylsilicate gels respectively, under carefully chosen conditions of pH, temperature and crystallization time. It is very important to note that co-added alkali metal cations, quaternary alkylammonium cation and surfactant species function 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 of the powder sample shows that there are two peaks in the low-angle 2Θ, the larger d value is 47.4Å. The formation of these materials takes place by means of a liquid-crystal templating mechanism is also discussed.