Multiple synergistic roles of Zr modification on ZSM-5 in performant and stable catalyst for ethanol conversion to propene

Abstract

Bioethanol to propene is a promising avenue to produce propene by non-fossil routes. In this study, the ethanol conversion on metal-modified ZSM-5 catalysts is systematically investigated under catalyst preparation conditions and reaction parameters. Among all metal modified ZSM-5, Zr modification significantly improves the propene selectivity and catalyst durability. On the Zr/ZSM-5 catalyst (Zr/Al molar ratio is 0.4, reaction temperature 500 °C, and contact time 0.005 g⋅min/mL), the maximum yield of propene reaches up to 32.5 %, which can be maintained above 20.0 % within 20 h. Zr modification changes the acidity and electronic structure of the active sites, improves the adsorption stability of the reactant ethanol on Zr/ZSM-5, facilitates easier desorption of the product propene, benefiting propene production. Moreover, Zr modification is found to increase the activation energy of the ethene protonation, inhibit the ethene dimerization reaction, further inhibits the carbon deposition, and extends the lifetime of ZSM-5. In addition to its synergistic and effective role in the conversion of ethanol to propene, the Zr modified catalyst also exhibits high selectivity and stability in the conversion of bioethanol. According to above significant characteristics, Zr modified ZSM-5 will emerge as a promising catalyst for the conversion of bioethanol to propene.