Front-end design decisions for a process to produce sustainable aviation turbine fuel from waste materials were presented. The design employs distributed conversion of wastes to oils, which are then transported to a central facility for gasification, syngas cleaning, Fischer-Tropsch synthesis and refining, that is, a spoke-and-hub approach. Different aspects of the front-end design, that is, the steps up to syngas cleaning, were evaluated. The evaluation employed a combination of case studies, calculations, experimental investigations, and literature review. The supply of sustainable aviation fuel (SAF) as a 50:50 mixture of wastederived and petroleum-derived kerosene to meet the demand of an international airport (Pearson, Toronto) was employed as case study. The amount of raw material required made it impractical to make use of only one type of waste. Using the same set of assumptions, it was shown that in terms of cumulative transport distance required, a spoke-and-hub approach was twice as efficient as centralized processing only. Technologies for decentralized production of oils were assessed, and oils produced by pyrolysis and hydrothermal liquefaction (HTL) in pilot-scale and larger facilities were procured and characterized. These oils were within the broader compositional space of pyrolysis oils and HTL oils reported in laboratory studies. The oil compositions were employed to study the impact of oil composition on entrained flow gasification. Thermodynamic equilibrium calculations of pyrolysis and HTL oil entrained flow gasification resulted in H 2 / CO ratios of syngas and O 2 consumption rates in a narrow range, despite the diversity of feeds. At the same time, to produce an equal molar amount of syngas (H 2 + CO), less HTL oil than pyrolysis oil was required as feed. Gas cleaning technologies were reviewed to ascertain types of contaminants anticipated after gasification, their removal effectiveness, and Fischer-Tropsch catalyst poisoning 1763

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.

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Fischer–Tropsch synthesis produces a product that invariably contains C4 and lighter material. The C2–C4 fraction has a high olefin content. The light hydrocarbons in the Fischer–Tropsch tail gas can be separated from the unconverted synthesis gas, but the added cost and complexity of doing so by pressure distillation is often considered unjustified. In this study the possibility of reactive recovery of the C2–C4 olefins from the Fischer–Tropsch tail gas by oligomerization over H-ZSM-5 was investigated. Two specific issues were investigated for this unconventional application of this industrially practiced technology, namely, to determine the impact of low olefin partial pressure on productivity and to determine whether acid catalyzed CO reactions, such as the Koch reaction, were taking place. Catalyst and reactor system performance was evaluated using model propylene oligomerization. A catalyst productivity of 0.42 g·(gcat)−1·h–1 was achieved with a 39% C3H6 feed at 190 °C, 3 MPa, and weight hourly space velocity (WHSV) of 0.9 h–1. These results were comparable to previous reports in the literature. The same catalyst was employed to evaluate conversion of a model Fischer–Tropsch tail gas mixture containing 17.4% H2, 7.5% CO, 68.0% CH4, 0.65% C2H4, and 6.45% C3H6. The operating range 205–278 °C, 3 MPa, and WHSV 1–1.5 h–1 was investigated. At 237–278 °C and WHSV 1.5 h–1, catalyst productivity remained around 0.32–0.36 g·(gcat)−1·h–1. Despite an olefin partial pressure of only 0.22 MPa, better than 85% olefin conversion was achieved. The liquid product was olefinic and contained 70–80% naphtha and 20–30% distillate. No evidence was found that CO reacted with the olefins in the feed, either by the Koch reaction to produce carboxylic acids, or to form ketones. Deposits formed on the catalyst and deactivation was observed over a period of 240 h. The nature of the deposits varied from top to bottom in the packed bed. Analysis of the spent catalyst indicated that liquid filled pores preceded hydrogen transfer and aromatization to form coke-like deposits over time.