Wax Hydrocracking over Pt/SiO₂–Al₂O₃ at 2 MPa: Product Characterization and Its Implications for Catalysis

Abstract

Hydrocracking of Fischer−Tropsch wax can be used to produce kerosene-range products that can be blended in jet fuel. Performing the hydrocracking at pressures near that of Fischer−Tropsch synthesis could be beneficial for some refinery scenarios, as unconverted H 2 from Fischer−Tropsch synthesis can be used for hydrocracking without further compression. At lower pressure, the equilibrium alkene content during hydrocracking is increased and this could affect the product distribution. In particular, the degree of isomerization of the kerosene-range products affects the properties of hydrocracked kerosene to be used for jet fuel. The purpose of this study was to gain a better understanding of the isomer distribution obtained by wax hydrocracking. Hydrocracking of paraffin wax was carried out over a 0.5 wt % Pt/SiO 2 − Al 2 O 3 catalyst at a pressure of 2 MPa. Detailed chromatographic analysis of narrow distillation cuts of the obtained kerosene-range product was used to obtain isomer distributions for the C 8 , C 9 , and C 11 alkanes formed during hydrocracking. While the observed carbon number and isomer distributions were generally what would be expected from the hydrocracking and hydroisomerization mechanism, there were two observations that could not be explained in this way. (i) The isomer distributions were not equilibrated and were dominated by 2-and 3-methylalkanes. (ii) There were also percentage levels of cyclic compounds. An increased contribution of Pt catalysis under the chosen low-pressure conditions contributed to the observed deviations. The formation of cyclic compounds could be attributed to the increased contribution of Pt catalysis at 2 MPa. Although some speculation was offered about what could have affected the isomer distribution, the prevalence of 2-and 3methylalkanes in the product remained unexplained.

Viscosity and Density of Narrow Distillation Cuts from Refined Petroleum- and Synthetic-Derived Distillates in the −60 to +60 °C Range

“…The aromatic volume fractions are shown in Figure S2 in the Supporting Information. The aromatic content in the synthetic distillate was low …”

“…The density, on the other hand, was affected by both changes in the molar mass and compound class compositional changes between different cuts of petroleum kerosene. For the synthetic distillate that was a product of wax hydrocracking, a similar HPLC analysis was not carried out in this study, as the aromatic mass fraction is very low …”

“…The synthetic distillate was the product of hydrocracking of a paraffinic wax over a Pt/SiO 2 –Al 2 O 3 catalyst at 2 MPa . The composition of the parent paraffin wax is shown in Table S2 in the Supporting Information.…”

Direct Production of Jet Fuel by Catalytic Hydrocracking of Glycerol Trioleate over a Ni/Mo Catalyst Supported on Nb2O5–ZrO2

“…but tend to develop for the upgrade of n -alkanes to isoalkanes. − When zeolite catalysts are used for the direct transformation of fatty biomass to jet fuel, small-molecule gas and aromatic hydrocarbons are more easily produced and affect the yield and quality of the liquid products . However, because of the easy deactivation of single metal oxide catalysts, some researchers also combined two or more metal oxides to obtain more active and stable catalysts. , For example, WO 3 –ZrO 2 , SiO 2 –Al 2 O 3 , TiO 2 –ZrO 2 and CrO 3 –ZrO 2 , etc., have been reported to show better catalytic performances in terms of the stability and selectivity than single metal oxides. In general, metal oxides have been widely used as catalyst supports to prepare the biofuel by the catalytic cracking of fatty acids and their derivatization.…”

Hydrocracking of Heavy Fischer–Tropsch Wax Distillation Residues and Its Blends with Vacuum Gas Oil Using Phonolite-Based Catalysts

“…The quality of the cracked products is affected by the type of catalyst and the processing conditions. Production of fuel range hydrocarbons via hydrocracking of FT wax and atmospheric residues has been widely investigated [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. High cetane numbers of fuels help reduce particle matters, NO x , CO, and hydrocarbon emissions.…”