Hydrothermal Synthesis and Characterization of ZSM-5 Zeolite from Nigerian-Origin Kaolin: Effects of Crystallization Temperature on Structure and Morphology

Abstract

This study investigates the hydrothermal synthesis and characterization of ZSM-5 zeolite from Ajebo kaolin in Nigeria, with a focus on the effects of crystallization temperature on the structure and morphology. ZSM-5 zeolite was synthesized at crystallization temperatures of 100°C, 120°C, and 150°C, with a fixed crystallization time of 6 hours. Characterization techniques, including XRF, FTIR, XRD, EDX, and SEM, were employed to analyze the composition and structure of the synthesized zeolites. The results confirmed the synthesis of ZSM-5 at all temperatures, with the sample crystallized at 150°C achieving the highest crystallinity (85%) and a distinct hexagonal prismatic morphology. XRF analysis revealed high SiO₂ (50–60%) and Al₂O₃ (40–45%) content. FTIR analysis confirmed the absence of -OH vibrations (3600–3700 cm⁻¹) in metakaolin, indicating successful dihydroxylation. A prominent peak at 1078 cm⁻¹ validated the formation of ZSM-5. XRD patterns substantiated the phase transformation from kaolin to ZSM-5, with improved crystallinity at higher temperatures. SEM images showed that the ZSM-5 synthesized at 150°C exhibited well-defined hexagonal prisms. The higher the crystallization temperature, the better the crystallinity of the synthesized zeolites. This study demonstrates Ajebo kaolin as a sustainable and cost-effective source for producing ZSM-5 zeolite, highlighting its potential applications as a catalyst in the breakdown of hydrocarbons and other industrial processes.