Plasma-Activated Solid Base Carbon Monolith Catalyst for Continuous Synthesis of High-Density Aviation Fuel Precursors

Cyclopentanone (CP), a cyclic hydrocarbon, is a potential biobased platform chemical for the synthesis of high-density jet fuel range cycloalkanes. The base-catalyzed self-condensation of CP yields 2-cyclopentylidene cyclopentanone (2-CP) and 2,5-dicyclopentylidene cyclopentanone (3-CP). 2-CP has applications in fuels, fragrances, and flavors, and 3-CP is used as a precursor for diesel-grade products. In this study, solid base activated carbon monolith (ACM)-supported hydrotalcite catalysts (HT/ACM) were synthesized using traditional thermal calcination, rehydration, and air plasma techniques and demonstrated for continuous cyclopentanone self-condensation. Among the ACM-supported hydrotalcites, the HT/ACM activated by air plasma at 100 W for 1 min (PHT/ACM-100W) displayed a higher 2-CP space time yield of 641 g L-cat^–1 h^–1 and selectivity of 27% (220 °C, 1 atm, 0.73 min vapor phase contact time). PHT/ACM-100W displayed a higher CP conversion (42%) compared to the unsupported calcined (34%, 500 °C for 4 h) and rehydrated (39.5%, 8 h at 105 °C) hydrotalcite catalysts yet significantly lower space time yields, suggesting low hydrotalcite distribution and loading on the carbon monolith. The plasma-activated carbon monolith-supported hydrotalcite catalysts synthesized in this work are promising alternatives to the thermally activated and rehydrated hydrotalcites for the catalytic upgrading of biobased cyclic and linear ketones.