Crystallization and particle size distribution of hydrothermally synthesized SAPO-34: an experimental and population balance study

A population balance-based model was developed to describe the crystallization kinetics of the SAPO-34 zeotype through the hydrothermal method at three distinct temperatures of 180, 200, and 220 °C. The synthesized SAPO-34 catalysts were characterized by XRD, FESEM, BET, and DLS analysis. The model was constructed based on XRD patterns and incorporated established kinetic expressions for homogeneous nucleation and diffusion-controlled crystal growth. The developed model was also employed in a well-mixed batch system to predict the crystal size distribution. To solve the model equations, the Grey Wolf Optimization technique, as a powerful tool for optimizing complex systems, was applied. Then, the experimental data and the model's predictions from zeolite synthesis were compared. Specifically, the nucleation rate, growth rate, crystallization profiles, and mean size of the resulting product crystals of SAPO-34 were evaluated for the first time. Remarkably, a notable agreement between the model and the experimental outcomes, particularly concerning the mean crystal size, was demonstrated. This connection between theory and experiment underlined the effectiveness of the population balance-based model in describing the complex crystallization process of the SAPO-34 zeotype across the range of temperatures. Indeed, this investigation demonstrated valuable insights into the hydrothermal synthesis of SAPO-34, showing the value of population balance modeling in predicting and optimizing crystallization processes. In addition, such findings indicated a great deal of promise for enhancing the precision and control of zeolite crystallization, a key element in several industrial applications, such as catalysis, ion exchange, and adsorption.