Catalytic cascade acetylation-alkylation of biofuran to C17 diesel precursor enabled by a budget acid-switchable catalyst

Lignocellulosic biomass is a promising feedstock for the synthesis of value-added chemicals and biofuels. However, one of the biggest challenges for producing high-quality diesel fuels is the lack of sufficient carbon-chain length in biomass derivatives. In this study, a C17 diesel precursor 1,1,1-tris(5-methyl-2-f uryl)ethane (TEMF) with a yield of ca. 70% was synthesized from the cascade acetylation-hydroxyalkyla tion/alkylation of bio-based 2-methylfuran (MF) with acetic anhydride (AA) catalyzed by acid-treated montmorillonite with enhanced acidity and improved porosity. The catalytic mechanism of the cascade reaction process was investigated over different types of acid species (Brønsted acid and Lewis acid), and the influence of in situ formed acetic acid was also examined. A synergistic effect was observed to enable the synthesis of TEMF from the trimerization of MF with AA, in which Lewis acid and weak Brønsted acid species mainly catalyze the acetylation and hydroxyalkylation processes, while the subsequent alkylation step is mainly catalyzed by strong Brønsted acid.