Structure–performance relationships in ethanol dehydration to ethylene over zeolite catalysts

Catalytic dehydration of bioethanol offers a sustainable route to renewable ethylene, while the use of aqueous ethanol feeds is particularly relevant to processes where extensive ethanol purification is undesirable. In this study, five structurally distinct industrial-grade zeolites, H-ZSM-5, H-Beta, H-Mordenite, H-Y, and H-USY, were comparatively evaluated for ethanol dehydration at 300 °C using a 50 vol% aqueous ethanol feed. The catalysts were characterized with respect to their structural, textural, and acidic properties, and their catalytic performance was assessed in terms of ethanol conversion, ethylene selectivity, ethylene space-time yield (STY ethylene ), and the formation of gaseous and liquid by-products. Significant differences in catalytic behavior were observed among the investigated zeolites. The FAU-type H-Y catalyst exhibited approximately 95% ethanol conversion and 90C-mol% ethylene selectivity, achieving STY ethylene values of up to 48 mmol g cat −1 h −1 while exhibiting comparatively low formation of diethyl ether, acetaldehyde, and acetic acid. H-Mordenite also exhibited high ethylene selectivity despite its one-dimensional pore system, whereas H-ZSM-5 showed lower ethanol conversion and ethylene selectivity together with greater formation of DEE and oxygenated by-products under the investigated conditions. TGA of the spent catalysts revealed substantial catalyst-dependent differences in deposit formation, although no direct correlation between deposit accumulation and short-term catalytic performance was observed. The differences in catalytic performance were associated with concurrent variations in framework architecture, SiO 2 /Al 2 O 3 ratio, textural characteristics, and acid-site properties. Because these descriptors vary simultaneously among the investigated materials, their individual contributions cannot be independently resolved from the present catalyst series. Thus, the results provide a comparative assessment of industrial-grade zeolites for ethanol dehydration under aqueous-feed conditions and highlight the importance of considering catalyst composition, pore characteristics, and acidity collectively when selecting zeolite catalysts for renewable ethylene production.