Hydrothermal synthesis of kaolin-based ZSM-5 zeolite: Effect of synthesis parameters and its application for bioethanol conversion

Abstract

In petrochemical applications, improving the catalytic activity and stability of Zeolite as a cutting-edge material has gained research interest. Herein, a local South African clay as a source of high silica and alumina with an organic template of tetrapropylammonium bromide (TPABr) was synthesized hydrothermally. The study then examined the effect of crystallization temperature (120–180 °C), crystallization time (24–96 h) and ageing time (0–48 h) on the crystallinity, surface morphology and functional group of the Kaolin-based ZSM-5 Zeolite formed. Characterization results by X-ray diffraction, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed the hydrothermal synthesis of the crystalline powder was successful. The XRD revealed the highest intensity at ∑5 with the most intense peaks at 2Ѳ° and a relative crystallinity from 74.6% to 76.66% at the temperature of 180°C and 48 h of ageing and crystallization time of sampled powder. The crystals' growth and pore structure (openings of 5–5.5 Å) was affirmed by the SEM results. Likewise, the BET revealed the surface area (146.15 m2/g), pore volume (0.056 cm3/g) and pore size (59.12 Å). The FTIR spectra vibration within the wavenumber from 545 to 1224 cm−1 also confirmed the sharpness of the beta and pentasil index peaks. Moreso, the bioethanol conversion at the temperature of 180°C over the synthesized ZSM-5 catalyst yielded 2.03% H2, 1.03% CH4, 37.07% C2H4, and 62.4% liquids. This study has demonstrated the synthesized Kaolin-based ZSM-5 Zeolite has the potential for industrial decomposition of ethanol with good catalyst stability.