Direct Production of Sustainable Aviation Fuel by Deoxygenation and Isomerization of Triglycerides Over Bifunctional Ir−ReOx/SAPO-11 Catalyst

Abstract

Catalytic thermochemical conversion offers a sustainable method to upgrade oil-based feedstocks into highly valuable biofuel, aligning with the modern biorefinery concept. Herein, a series of IrRe/SAPO-11 catalysts with different Ir to Re molar ratios compared to reference Ir/SAPO-11 and Re/SAPO-11 catalysts was prepared using a wetness impregnation method. These catalysts were used for the direct production of sustainable aviation fuels (SAFs) via efficient hydrodeoxygenation and hydroisomerization of triglycerides. The catalyst screening confirmed that the optimum IrRe/SAPO-11 catalyst, with an equivalent Ir to Re molar ratio, exhibited the highest hydrodeoxygenation activity under milder operation conditions than the conditions used in previous studies. Increasing the reaction temperature up to 330 °C enhanced the formation of iso-alkanes in the liquid product, achieving a freezing point of −31.4 °C without additional cold flow improvers. Furthermore, a long-term stability experiment demonstrated that the developed Ir−Re system exhibited exceptional performance over 150 h. This excellent catalytic activity and stability of the bifunctional IrRe/SAPO-11 catalyst was owing to its suitable interface between metallic and oxide sites, mixed mesoporous structures, reduced catalyst size, and increased Lewis acid ratio, as confirmed by our comprehensive characterizations.