Abstract
Hydrocarbon fuels can be produced from a wide range of carbonaceous materials, including biomass and waste plastics, through the Fischer-Tropsch (FT) process. As sustainable aviation fuel (SAF) becomes increasingly important, selective production of a jet fuel fraction from FT wax is required; however, this has not yet been achieved. In this study, hydrocracking of n-heptadecane (n-C17) as a model diesel fuel fraction of FT wax was estimated to obtain a jet fuel fraction selectively using Hβ-zeolite-Al(2)O(3) composite-supported Pt catalysts. The Hβ-zeolite (25 wt%, SiO(2)/Al(2)O(3) = 100)-Al(2)O(3) (60 wt%)-binder (alumina-sol, 15 wt% as Al(2)O(3)) composite-supported Pt (0.5 wt%) catalyst (0.5Pt/β(100)60A) was tested for hydrocracking of n-heptadecane using a fixed-bed flow reactor under the following conditions: 0.5 MPa H(2) pressure, H(2) 300 mL min(-1), WHSV 2.3 h(-1) and 2 g catalyst weight. After hydrocracking of n-C17 to form gaseous hydrocarbons at 300 °C without pre-reduction of 0.5Pt/β(100)60A, the reaction was performed at 250 °C. A conversion of 97% and a selectivity of 79% for the C8-C14 fraction of the jet fuel range were achieved. The sum of the selectivity for the C7 and C8 fractions was higher than 50%. To confirm reproducibility, when the hydrocracking of n-C17 using the catalyst pre-reduced at 270 °C was performed at 300-304 °C, a conversion of 93% and a selectivity of 55% for C8-C14 were achieved at 302 °C, with high selectivity for C8 and C9, although significant amounts of gaseous products were observed simultaneously. Finally, when the hydrocracking of n-C17 using a catalyst pre-reduced at 310 °C was performed at 300-308 °C, a conversion of 99% and a selectivity of 63% for C8-C14 were achieved at 308 °C, and the selectivity for gaseous products reduced to 16%. However, the high selectivity for C8 and C9 was lost, and the same amount of each fraction of C8-C12 was simultaneously observed. It was suggested that the high selectivity of the β-zeolite-containing catalyst for the C8 and C9 fractions could be attributed to C-H bond activation of the carbon at position 9 of n-C17 on reduced Pt within the micropores of β-zeolite.