Optimization of Pretreatment and Hydrothermal Process of Na-X Zeolite from Kaolin and Metakaolin

Abstract

Synthesis of Na-X zeolite was conducted from kaolin and metakaolin. Synthesis varied in its pretreatment method and hydrothermal conditions. The pretreatment methods used were: conventional alkaline, alkaline fusion and conventional fluoride. Hydrothermal conditions for the experiments were gradual temperature 40 o C (6h), 60 o C (6h), 80 o C (12h), and constant temperature 80 o C for 24 h, 100 o C for 24 and 100 o C for 48 h. Synthesized products were characterized by X-Ray Diffraction (XRD), Fourier Transform InfraRed (FTIR), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), and N 2 Isotherm Adsorption/Desorption method. The result showed that pre-treatment by conventional fluoride could not produce Na-X zeolite, synthesis by conventional alkaline and alkaline fusion with hydrothermal at 100 o C (48h), 100 o C (24 h), and gradual temperature produce Na-X zeolite with Na-P1 or Na-A zeolite as impurities, while synthesis from metakaolin by conventional alkaline with hydrothermal at 80 o C for 24 hours produced pure Na-X zeolite. Na-X zeolite and Na-P1 zeolite with hierarchical pores were synthesized through alkali fusion with hydrothermal at 100 o C for 24 hours.

Green and low-cost synthesis of zeolites from kaolin: a promising technology or a delusion?

“…21 The process time also varies. Usually, metakaolinisation is carried out in a muffle furnace for 2 h, 72,80,111 but there are studies where it has been carried out for 8 h. 70 Metakaolinisation in a microwave oven can reduce the process time to half an hour. 85,88,143 In our opinion, the main problem with metakaolinisation is that researchers often do not explain the choice of temperature and time.…”

“…The alkali fusion method usually includes mixing kaolin or its derivatives powder with alkali in the ratio necessary to obtain the required gel formula, grinding these reagents together and reacting kaolin with molten alkali at high temperatures. 70 Thus, the reaction that would occur in the initial stages of hydrothermal synthesis is carried out simultaneously with metakaolinisation. Often, routes that include a fusion step yield products with higher relative crystallinity than those that use metakaolinisation.…”

Application of Zeolite in the Catalytic Cracking of Waste Vegetable Oil for the Production of highly Volatile Liquid Fuel

“…The process of calcining pre-treated clay involved heating 200g of the sample, which was deposited in 100 ml crucibles. The crucibles were placed in a muffle furnace and heated to about 900°C for four hours (Hartati et al, 2019). The process of calcination aids in bringing the clay's chemical constituents back to life.…”