Production of renewable long-chained cycloalkanes from biomass-derived furfurals and cyclic ketones

Abstract

Developing renewable long-chain cycloalkanes from lignocellulosic biomass is of significance because it offers huge resource storage, wide applications in aviation/diesel fuels and mitigation of CO₂ emissions. In this paper, cycloalkanes with carbon chain lengths of 13-18 were produced from biomass-derived furfural species (furfural and 5-hydroxymethylfurfural) and cyclic ketones (cyclopentanone and cyclohexanone) via aldol condensation, followed by hydrogenation to saturate the C[double bond, length as m-dash]C and C[double bond, length as m-dash]O bonds, and hydrodeoxygenation to remove oxygen atoms. The aldol condensation of the furfural species with cyclic ketones was catalyzed by NaOH and the target condensation intermediates were obtained in yields of more than 90% at room temperature (30 °C) with a short reaction time (40 min). By using amorphous zirconium phosphate combined with Pd/C as the catalyst, liquid cycloalkanes were produced at the optimal conditions with a yield of 76%. When the combined solid catalyst was reused, the target products reduced after the second run but the initial yield could be largely recovered by recalcination of the spent zirconium phosphate. Considering that cyclopentanone and cyclohexanone can be easily produced from furfural (originating from hemicellulose) and phenol (originating from lignin), respectively, this condensation has the potential to achieve the integrated conversion of biomass-derived cellulose, hemicellulose and lignin to jet fuel and/or diesel additives.

Scheme 1. Routes for long-chained cycloalkane production from furfural species and cyclic ketones.

Fig. 1. XRD patterns of fresh ZrP and NbP (a), and fresh Pd/C (b).

Fig. 2. SEM images of fresh NbP (a) and ZrP (b). TEM images of Pd/C (c) and ZrP (d). N₂ adsorption–desorption curve of ZrP (e). The inset in (c) shows the HRTEM image of Pd/C.

Fig. 3. NH₃-TPD profiles of fresh ZrP and NbP.

Fig. 4. FT-IR spectra of fresh, hydrothermally treated, and regenerated ZrP.

Fig. 5. Hydrodeoxygenation of the FF-CP-FF intermediate to hydrocarbons over different solid acids and metals supported on activated carbon catalysts (a), with different ZrP loadings (b), and with different Pd/C loadings (c). Reaction conditions: 1.0 mmol FF-CP-FF, 15 mL H₂O, 0.05 g metal supported on carbon, 0.10 g solid acid, 4 MPa H₂ pressure, 300 °C, 3 h.

Fig. 6. The influence of reaction temperature (a) and time (b) on the hydrodeoxygenation of the FF-CP-FF intermediate over ZrP and Pd/C. Reaction conditions: 1.0 mmol FF-CP-FF, 15 mL H₂O, 0.05 g Pd/C, 0.10 g ZrP, 4 MPa H₂ pressure.

Fig. 7. The influence of reaction temperature on gas product distribution in FF-CP-FF hydrodeoxygenation. The reaction conditions are as stated for Fig. 6(a).

Fig. 8. Catalytic stability of ZrP and Pd/C in the hydrodeoxygenation of FF-CP-FF to cyclic alkanes. Reaction conditions: 1.0 mmol FF-CP-FF, 15 mL H₂O, 0.05 g Pd/C, 0.10 g ZrP, 4 MPa H₂ pressure, 300 °C, 3 h. Bars 1–3 show successive cycles, bar 4 represents the regenerated ZrP combined with fresh Pd/C and bar 5 represents the regenerated Pd/C combined with fresh ZrP.

Fig. 9. XRD patterns of hydrothermally treated ZrP and Pd/C followed by recalcination.

Fig. 10. C₁₃–C₁₈ cycloalkane production from various condensation intermediates. Reaction conditions: 1.0 mmol condensation intermediates, 15 mL H₂O, 0.05 g Pd/C, 0.1 g ZrP, 4 MPa H₂ pressure, 300 °C, 3 h.