抄録
Production of zeolite particles of desired sizes and shapes without addition of other compounds will be beneficial industrially, for example for use of catalysts, adsorbents and ion exchangers. The purpose of this study is to establish a fundamental method of preparing large polycrystalline zeolite A particles in a single operation of crystallization that can be used as catalyst. To obtain polycrystalline particles of zeolite A, continuous feeding of reactant solutions was found to be essential, and the use of a CMSMPR (continuous mixed suspension mixed product removal) crystallizer was also good for the formation of polycrystallites. Furthermore, for the crystallization of zeolite A under the condition of continuous feeding, it was discovered that the two reactant solutions, sodium aluminate and sodium silicate solutions, should be premixed to form aluminosilicates before entering into the crystallizer. The size of the resulting zeolite A particles increased with the decrease of the mean residence time of the solution and with the increase of supersaturation levels of the mother liquor. In summary, zeolite A polycrystalline particles having a mean size of 100 m were successfully produced by controlling the rates of surface nucleation and crystal growth in a CMSMPR crystallizer equipped with a premixer.
