Large intraparticle mesoporosity of hierarchical ZSM-5 synthesized from kaolin using silicalite seed: effect of aging time and temperature

The development of a simple, effective, and replicable method for the formation of hierarchically structured materials from natural sources has drawn significant research interest recently. The current study analyzes the two-step hydrothermal synthesis of Indonesian kaolin to hierarchical ZSM-5. The aging temperature and time are the two crucial parameters that contributed to the intraparticle mesoporosity of ZSM-5. The aging step is a decisive step in the nucleation process of zeolite synthesis, this step can affect the crystal and pore structure of the zeolite product. N₂ adsorption–desorption with the NLDFT method was used to determine the intraparticle mesoporosity at P/P₀ = 0.3–0.4. The large intraparticle mesoporosity enables materials to have wide structural functions owing to intensify accessibility and mass transport properties. A statistical experimental design based on the Taguchi method with L9 orthogonal array and analysis of variance (ANOVA) was employed to identify the percentage of contribution for each parameter on the development of mesoporosity. The optimum aging condition at 70 °C for 6 h with the S/N ratio of 49.630, produced intracrystalline mesopore ZSM-5 with the largest mesoporous surface area of 303.067 m²/g and 0.596 cc/g of the pore volume. The relationship between aging time and temperature in the mesostructured creation in hierarchical ZSM-5 was revealed by the data analysis of the interaction plot for the S/N ratio.