Seed-assisted synthesis of SAPO-34 zeolites: Genetic effect of seeds

Abstract

BackgroundIn the past decades, seed-assisted synthesis of zeolites has become one of the research focuses. Understanding the effect of the seeds on their derived products, and thus tuning the physicochemical properties of those products by selecting suitable seeds is pivotal for synthesizing zeolites via seed-assisted method. MethodsIn this work, four kinds of SAPO-34 with different physicochemical properties were synthesized and used as seeds to prepare their corresponding products via the seed-assisted method. The physicochemical properties of the seeds and the corresponding products were characterized by XRD, SEM, N2 adsorption-desorption, NH3-TPD, and 29Si MAS NMR techniques. Significant FindingsThe results showed that the particle size, textural and acidity properties, and the silicon coordination of the seed-derived products are strongly correlated to their corresponding seeds, exhibiting genetic effects. By investigating the crystallization kinetics, we speculated that the genetic effects should be attributed to the incomplete dissolution of the seeds. During the crystallization process, the incompletely dissolved seed fragments are directly incorporated into the product and serve as models. These models then require the final zeolites to grow according to their patterns, retaining and inheriting their original characteristics.