Modification of Synthetic Zeolite from Kaolin for Sustainable Heterogeneous Catalyst in Esterification Reaction

ABSTRACT Zeolites are porous aluminosilicates with a regular crystal structure, high surface area, and tunable acid sites, making them suitable for use as heterogeneous catalysts. In this study, zeolite was synthesized from kaolin as a precursor and subsequently modified via ion exchange to obtain an acidic catalyst. The catalyst was applied in the esterification reaction between isoamyl alcohol and acetic acid to produce isoamyl acetate. The acidity of the zeolite was enhanced by the ion exchange method using an ammonium chloride (NH 4 Cl) solution with a concentration of 1–3 M, followed by calcination at 500°C to produce an H‐zeolite catalyst. Based on SEM analysis, it was found that the synthesized zeolite had the morphological characteristics of Na‐P1 zeolite, which was further confirmed by XRD results. EDX analysis showed that the zeolite synthesized from kaolin had a Si/Al ratio of approximately 3.35. In addition, based on the results of XRF analysis on the zeolite sample, the presence of Na elements of 0.62% by mass and Na 2 O of 2.87% by mass could be identified. FTIR analysis was conducted to determine changes in catalyst characteristics following ion exchange modification. The FTIR spectrum showed an increase in acid sites in the zeolite structure, which was further confirmed by NH 3 ‐TPD analysis with an acidity value of 1.3343 mmol g −1 . Subsequently, the catalytic activity of H‐zeolite was evaluated in an esterification reaction at 60°C–100°C for 60–180 min. The catalytic esterification reaction with a molar ratio of acetic acid to isoamyl alcohol of 1:3, a catalyst loading of 3% (wt/v), and a temperature of 100°C for 180 minutes achieved the highest acetic acid conversion of 97.02%. Based on the results of GC‐MS analysis of the reaction products, it was confirmed that the esterification reaction catalyzed by H‐zeolite successfully produced isoamyl acetate with high selectivity. Furthermore, stability tests showed that the H‐zeolite catalyst could be reused for up to three reaction cycles with relatively stable performance.