Statistical Optimization of Faujasite Zeolite Synthesis from Bauxite Alumina and Rice Husk Silica

Abstract

Faujasite, a molecular sieve zeolite Y aluminosilicate mineral, has excellent catalytic strength and is employed in various industries. The study therefore, seek to synthesize a faujasite zeolite with a hydrothermal treatment of local clay alumina and rice husk silica using central composite design (CCD) of experiment in response surface methodology (RSM) in a 1000ml 2-neck flat bottom flask on a constant temperature magnetic stirrer at 120^oC for 6 hours. SiO₂, Al₂O₃, and NaOH were coded at three levels at various masses and Si/Al mole ratios. A significant model with an F-value of 142.27 and a Predicted R² of 0.9558 was developed using statistically optimized hydrothermal synthesis. 3.07g NaOH, 10.50g SiO2, and 2.61g Al2O3 were needed to synthesize FAU zeolite with Si/Al mole ratio > 2. At 1095.8cm^-1 in IR spectrum, silicone (Si – O – Si) was the most abundant functional group in the zeolite. EDS and XRD revealed a faujasite zeolite-Y with 85.60wt% Si and 17.50wt% Al. Octahedral modified zeolite Y crystals were seen in SEM topography. At low relative pressures (P/P0 < 0.056), BET showed significant N₂ absorption, indicating micropores. The zeolite's BET study indicated a specific surface area of 1750.0m²/g and a pore diameter of 1.847nm. Transesterification of high-free fatty acid triglycerides can be catalyzed by microporous faujasite zeolite.