Production of Hydroprocessed Esters and Fatty Acids (HEFA) – Optimisation of Process Yield

Abstract

-Both Fischer-Tropsch (FT) and Hydroprocessed Esters and Fatty Acids (HEFA) Synthetic Paraffinic Kerosine (SPK) fuels are considered as leading alternative replacements for conventional jet fuel. To satisfy the requirements of Civil Aviation Authorities (CAA), their drop-in incorporations have been subjected to a rigorous certification process. To reach the ambitious incorporation targets, new routes for biofuels incorporation may need to emerge, involving optimizing the production processes and the blending strategies. This paper focuses on a new strategy for incorporating HEFA, allowing the process yield to be optimised. One of the major steps limiting the process yield for HEFA remains the isomerisation that allows production of a biofuel with very good cold flow properties. But this step introduces a substantial decrease of the overall yield (fuel component per kg of starting material) due to the production of light compounds, unsuitable for conventional jet fuel. In this work relaxing the freezing point requirement for the neat HEFA component (by decreasing the severity of the isomerisation step) is proposed in order to minimize the production of less valuable light compounds. This strategy could lead to a significant additional biofuel yield with respect to the oil compared to a process making a better freezing point component. This allows the land surface area necessary for HEFA feedstock cultivation to be reduced for a given amount of bio-jet fuel produced. Re´sume´-Production d'huiles ve´ge´tales hydrotraite´es (Hydroprocessed Esters and FattyAcids, HEFA) -Optimisation du rendement -Le de´veloppement des carburants alternatifs est en plein essor, notamment dans le domaine ae´ronautique. Cela se concre´tise par la possibilite´, d'incorporer jusqu'a`50 % de carburants de synthe`se de type Fischer-Tropsch (FT) ou Hydroprocessed Esters and Fatty Acids (HEFA) dans du carbure´acteur. Ces cibles d'incorporation sont ambitieuses. C'est pourquoi, l'objectif de cet article est d'e´tudier une strate´gie innovante pour l'incorporation des carburants alternatifs, et plus pre´cise´ment des carburants de type HEFA, dans le domaine ae´ronautique en optimisant les strate´gies de me´langes c'est-a`-dire en cherchant a`optimiser les rendements des proce´de´s. En effet, l'un des moyens d'action permettant d'ame´liorer les rendements des proce´de´s HEFA est d'agir sur l'e´tape d'hydrotraitement. Cette e´tape permet d'ame´liorer les proprie´te´s à froid. Cependant la contre partie est l'impact que cela peut avoir sur le rendement : ame´liorer les This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Bio‐Based Cycloalkanes: The Missing Link to High‐Performance Sustainable Jet Fuels

“…In addition, the unique structures of these spirocycloalkanes dramatically reduced the freezing points compared to the isomeric decalins or bicycloalkanes. The freezing point of spiro [5,6]dodecane (À 51°C) was 59 and 28°C lower than BCH and dimethyldecalins, respectively, while spiro [4,5] decane exhibited a freezing point 41 and 35°C lower than BCP and decalin, respectively. In contrast, the kinematic viscosity suffered for the spiro compounds due to increased shear stress.…”

“…[198] Low valent titanium catalyzed reductive coupling of either cyclopentanone or cyclohexanone generated the corresponding pinacols (Scheme 18). [199] Pinacol rearrangement in the presence of SnCl 4 proceeded smoothly to provide spiro [5,6] dodecan-7-one and spiro [4,5]decan-6-one with quantitative conversions and yields of 79.4 % and 94.4 %, respectively. [200,201] Reduction of the ketone via a Wolff-Kishner-Huang reduction afforded spiro [5,6]dodecane and spiro [4,5]decane in 52.0 % and 64.7 % yields, respectively (Scheme 18).…”

“…Compared to the corresponding bicyclic hydrocarbons BCP and BCH (Scheme 10, Table 3), the spirocycloalkanes displayed slightly higher densities (0.893 g mL À 1 for spiro [5,6] dodecane and 0.870 g mL À 1 for spiro [4,5]decane) compared to BCH (0.887 g mL À ) and BCP (0.867 g mL À ), respectively. In addition, the unique structures of these spirocycloalkanes dramatically reduced the freezing points compared to the isomeric decalins or bicycloalkanes.…”

“…A prominent approach is the hydrotreatment of esters and fatty acids (HEFA). [5][6][7][8] HEFA-Jet, which can be derived from waste vegetable oils, is a complex mixture of normal and lightly branched alkanes. Another approach, that can take advantage of lignocellulosic feedstocks and solid municipal waste, is the conversion of biomass substrates to synthesis gas (a mixture of CO and H 2 ) followed by Fischer-Tropsch catalysis and isomerization to generate an SPK.…”

Aviation Fuels and Biofuels

“…The n-paraffins formed in the process have properties suitable for diesel, with high cetane number and high viscosity, which do not yet have properties desired for HEFA for n-paraffin obtention [52].…”