Performance of catalytic dehydration of ethanol to ethylene using SUZ–4 zeolite synthesized from rice husk ash in a packed–bed reactor

This work aimed to study the development of ethylene production through the catalytic dehydration of ethanol using SUZ‒4 zeolitesynthesized from rice husk ash. The optimal conditions for zeolite synthesis, which were tested in the catalytic dehydration process, included a molar ratio of 50 R:50 S and a hydrothermal temperature of 150 °C for 4 days. Under these conditions, the SUZ‒4 zeolite exhibited high crystallinity (97.4 %) and a well‒distributed microporous structure on the catalytic surface, with a pore volume of 0.137 cm³/g and pore sizes ranging from 4.33 to 7.65 Å. The multichannel porous structure further enhanced the selectivity of reactant and product molecules. The zeolite also exhibited a high concentration of weak acid sites (0.787 mmol/g), which are crucial for catalyzing the reaction. Additionally, an investigation into a W/F ratio of 4.45–4.96 g_cat./mmol_EtOH·min⁻¹ showed that this range was optimal for efficiency, highlighting the importance of balancing the catalyst amount with ethanol molecules for effective catalysis at 300 °C. Ethanol conversion reached 99.75 %, and the ethylene yield was 81.28 %. Over a 33‒hour period, the stability of the SUZ‒4 zeolite maintained the ethanol percentage above 90 %. After coke formation on the SUZ‒4 catalyst surface, the zeolite was regenerated, and the ethylene yield remained between 70 and 80 % over 4 regeneration cycles, demonstrating the catalyst's reuse efficiency. Finally, under the optimal conditions for SUZ‒4 zeolite synthesis and catalytic dehydration, a scale‒up experiment was conducted using a packed‒bed reactor 250 times the original size. The results showed that both ethylene yield and ethanol conversion remained consistent.