Ultrasonic studies of zeolites during dehydration

Abstract

The synthetic zeolites of the heulandite group were prepared using the microwave hydrothermal method at 120°C for 30 min. The powders were characterised using X‐ray diffraction. The zeolites were annealed at 60, 80 and 100°C for 1 h. Dehydration studies were conducted on prepared zelolite in the temperature range 300–800 K using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). A conventional ultrasonic pulse transmission technique was used to measure the longitudinal ultrasonic velocity and attenuation at 1 MHz in the temperature range 300–500 K. The accuracy of ultrasonic velocities and attenuation measurements was 0·01 and 0·2% respectively. The observed ultrasonic velocity changes were compared with FTIR, DSC and TGA studies, and it was found that the one can study dehydration studies in zeolites by carrying out ultrasonic studies.