Aldol condensation of biomass-derived compounds offers a sustainable route to jet fuel precursors. This study explores catalysts based on nanocrystalline ZSM-5 zeolite (n-ZSM-5) modified with various metals (Ca, Mg, Sn, Ti, Zr) for the aldol condensation of furfural (FFL) and cyclopentanone (CPO). While both reactants can enter the ZSM-5 micropores, the resulting C10 (FC) and C15 (F2C) adducts are too large to be formed within or to exit the microporosity, being instead produced over the external acid sites. Metal modification significantly impacts catalytic activity: Ca and Mg reduce conversion, Sn is neutral, whereas Zr and Ti leads to enhanced performance. The TiO2/n-ZSM-5 catalyst shows by far the best behavior, doubling FFL conversion and sharply increasing the FC + F2C yield, which is attributed to a synergistic effect arising from the generation of accessible weak Lewis acid sites by highly dispersed TiO2 that complement the external Brønsted acidity of ZSM-5.
Keywords: Jet fuel; Lignocellulosic biomass; Metal oxides; Titanium oxide; Zeolite.
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