Ultrasonic monitoring of zeolite synthesis in real time

Variations of the phase and amplitude of a transmitted ultrasonic wave pack age were monitored in real time during the synthesis of zeolite A and zeoli te X. For both materials, characteristic changes of the measured attenuatio n and the sound velocity of ultrasonic waves traveling in the reaction flui d were observed, correlating with the processes of gel formation and zeolit e crystallization, respectively. Aging effects of the reaction fluids are d emonstrated. The observation of the onset of the zeolite crystallization wa s verified with ex-situ X-ray diffraction (XRD) measurements. (C) 2000 Else vier Science B.V. All rights reserved.