Use of Ultrasonic Processing at Early Stages of LTA Zeolite Synthesis from Metakaolin

Аннотация

The influence of ultrasonic processing (22 kHz) of a suspension of metakaolin, aluminum oxide, and sodium hydroxide with molar ratio Al₂O₃ · 2SiO₂: NaOH : Al₂O₃ = 6 : 12 : 2, followed by heat-treatment and hydrothermal crystallization on LTA zeolite synthesis, is investigated. It is found that by increasing the S : L ratio at the ultrasonic processing stage it is possible to increase the yield of the desired product. The optimal conditions of ultrasonic processing are determined (amplitude 8 μm, time about 10 min). It is shown that under the optimal conditions the degree of crystallinity of LTA zeolite equals 98%. The mechanisms of LTA zeolite synthesis by means of ultrasonic processing and mechano-chemical activation are compared.