Synthesis of jet fuel and diesel range cycloalkanes with 2-methylfuran and benzaldehyde

Abstract

Jet fuel and diesel range C₁₂ and C₁₇ cycloalkanes were synthesized for the first time by a two-step process with 2-methylfuran and benzaldehyde, two platform compounds which can be derived from lignocellulose. In the first step, 5,5′-(phenylmethylene)bis(2-methylfuran) was obtained by the acid-catalyzed hydroxylalkylation/alkylation (HAA) of 2-methylfuran and benzaldehyde. Among the investigated commercial acidic resins, Nafion resin demonstrated the highest activity for the HAA of 2-methylfuran and benzaldehyde, which can be rationalized by the highest acid strength of Nafion resin. In the second step, the 5,5′-(phenylmethylene)bis(2-methylfuran) from the HAA reaction was further hydrodeoxygenated to jet fuel and diesel range C₁₂ and C₁₇ cycloalkanes. Among the investigated catalyst systems, the combination of H-ZSM-5 and Ru/hydroxyapatite (denoted as H-ZSM-5 + Ru/HAP) exhibited the best hydrodeoxygenation (HDO) performance. Over it, a high total carbon yield (87.3%) of jet fuel and diesel range C₁₂ and C₁₇ cycloalkanes was obtained under mild conditions (453 K and 4 MPa H₂). According to our measurements, the mixture of C₁₂ and C₁₇ cycloalkanes obtained from the HDO process has high density (0.816 g mL⁻¹) and low freezing point (240 K). Therefore, it can be blended into current bio-diesel and bio-jet fuel to increase their volumetric heat values. As another option, the C₁₂ and C₁₇ cycloalkanes can also be dehydrogenated to produce alkylbenzenes that can be used as feedstock in the production of surfactants.