Adsorption and Textural Properties of LSX Zeolite at the Initial Stages of Destruction

Alteration of adsorption properties and porous structure (texture) of the KNaLSX zeolite at the initial stages of its destruction during ion-exchange modification in solutions of NH₄Cl and thermal shock under vacuum degassing has been studied. Transmission electron microscopy, X-ray diffraction, low-temperature nitrogen adsorption and adsorption of CO₂ and CH₄ at 273 K were applied for characterization of the obtained materials. Conversion of the predominantly microporous material to the material with threemode pore-size distribution is shown. Significant fraction of the faujasite phase and corresponding micropores are preserved in the material. This is accompanied with formation of pores of two types: quasi-spherical mesopores with the characteristic size of 5 nm and the meso-macropores with typical size exceeding 40 nm. Basing on the obtained results, a mechanism of textural changes in the LSX zeolite treated under applied conditions is proposed.