Transformation of kanemite into silicalite 1: parameters affecting the cation exchange reaction

The optimum crystallization conditions for the transformation of kanemite i nto silicalite 1 have been determined by X-ray powder diffraction, thermal analysis and Si-29 NMR spectroscopy. The synthesis of silicalite 1 was favo red by the use of TPAOH template, in preference to TPABr template, highly b asic conditions during stirring of the suspension at 70 degreesC and the ad justment of the pH to 8.5 after stirring. The more the layered structure of kanemite disintegrated after the cation exchange reaction, the higher the amount of incorporated template and the higher the crystallinity of silical ite 1 after solid-state transformation. The dissolution process that occurs during the cation exchange reaction with short-chain alkylammonium cations was different from that which occurs in the case of long-chain alkylammoni um cations which are used for the synthesis of mesoporous materials.