Résumé
The physical and chemical effects of power ultrasound derive from acoustic cavitation. Ultrasound-assisted synthesis and treatment under hydrothermal conditions using a sonohydrothermal (SHT) reactor has been developed in our group during the last decade.1 Recently, ultrasonic treatment has received much attention for the preparation of zeolites due to a significant acceleration of their growth/crystallization, which considerably reduces the overall synthesis time.2–4 Herein we propose the use of power ultrasound as an alternative to LTA zeolite synthesis and conventional reflux cation substitution methods. LTA synthesis was first carried out in hydrothermal conditions under ultrasound in a sonohydrothermal reactor at 20 kHz. The cation exchange of Na-LTA to the proton form (H-LTA) was then investigated for the first time under ultrasound in a glass reactor (US-GR) with a plunging sonotrode and in the SHT reactor. We have also studied the ultrasonic-assisted cation exchange of Na-LTA against another extra-framework cation (Ca2+) at 20 kHz in both US-GR and SHT reactors. The reflux cation substitution procedure was used as a benchmark method. Ca2+ exchanged LTA zeolite is indeed extensively used as an adsorbent in petroleum and gas purification applications.