Catalytic Tandem Reaction for the Production of Jet and Diesel Fuel Range Alkanes

Jet and diesel fuels are typically composed of C9-C14 and C12-C20 hydrocarbons, respectively, but the carbon-chain length of sugar-derived aldehydes and furanic compounds is no longer than C6. Here, a cascade catalytic process involving alkylation and hydrodeoxygenation (HDO) of 2-methylfuran (2-MF) with different aldehydes is conducted to directly produce long-chain alkanes with exclusive carbon number of C11-C17 in overall yields of 50-84%.

Preliminary investigations on the alkylation of 2-MF and formalin show that the relative density of Lewis and Brønsted acidic sites of zeolitic materials remarkably affect their catalytic activity and selectivity. Sn-beta(12.5) with pronounced Lewis acidity (including the acid density and strength) exhibits higher catalytic performance in the alkylation than other zeolites, producing long-chain oxygenates in 58-92% yields.

Even in aqueous solution, the Sn-beta(12.5) catalyst can be reused for at least six reaction cycles with almost constant reactivity. More importantly, the co-addition of Hf(OTf)4 with Pd/C greatly promotes C-O bond cleavage of the furan-ring during the HDO process under mild reaction conditions, producing long-chain alkanes in high yields of 84-94%.