An integrated method for producing sustainable aviation fuel

Abstract

A process for producing sustainable aviation fuel (SAF) or components thereto is described, wherein the integrated process comprises in the first arm providing a renewable feedstock comprising triglycerides, hydrolyzing the triglycerides into free fatty acids which are subjected to a decarboxylation and / or decarbonylation (DCO) reactions to produce hydrocarbon intermediate A. As second arm of the integrated process, any carbon oxides and glycerol released in the first arm are refined into further hydrocarbons, hydrocarbon intermediate B, which together with hydrocarbon intermediate A are isomerized and a sustainable aviation fuel or components thereto are provided. The process increases carbon efficiency and yield in sustainable aviation fuel production.

Description

[0001] AN INTEGRATED METHOD FOR PRODUCING SUSTAINABLE AVIATION FUEL

[0002] TECHNICAL FIELD

[0003] The present invention generally relates to fuel production. The invention relates particularly, though not exclusively, to production of sustainable aviation fuel or a sustainable aviation fuel compound, from a renewable feedstock, wherein sub-processes are integrated to maximize the product yield.

[0004] BACKGROUND

[0005] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0006] Presently, there is an ongoing need to reduce greenhouse gas emissions and / or carbon footprint in transportation, especially in aviation. Accordingly, the interest towards sustainable aviation fuels and aviation fuel components is and has been growing.

[0007] Processes for producing aviation fuel components from renewable raw materials have been proposed. However, the carbon efficiency of aviation fuel components, as well as yield of aviation fuel has been relatively low in said processes. Specifically, processes where oxygen containing raw materials are hydrodeoxygenated suffer from significant hydrogen consumption and costs thereof. Therefore, there is an ongoing need to improve the yield of sustainable aviation fuel (SAF) components in the processes producing sustainable aviation fuel components that could be used in aviation fuels.

[0008] Many of the renewable feedstocks of biological origin comprise C18+ fatty acids, which restricts their efficient use in a sustainable aviation fuel production, due to the properties of formed n-paraffins and i-paraffins affecting, for example, the boiling point range, cold flow properties, density, and cold viscosity of the final aviation fuel component.

[0009] Therefore, there is an ongoing need to utilize renewable feedstocks comprising C18+ fatty acids in sustainable aviation fuel production without unnecessary yield losses.

[0010] The availability of renewable feedstocks providing hydrocarbons with carbon numbers readily suitable for fuel applications are limited. Further, in some processes light hydrocarbons, and carbon dioxide, are produced and released excessively. Renewable fuel production involving synthesis from low carbon number components, such as carbon oxides, has been studied, but still fails to provide satisfying solutions.

[0011] As an example, the Fisher-Tropsch (FT) synthesis produces wax from synthesis gas. Nevertheless, it tends to yield a wide range of hydrocarbon products, which is inefficient and requires recycling or refining undesirable carbon number paraffins. Even though high-quality products are obtainable thereof, the economics require attention. Attempts have been made to control the FT process so that light and heavy ends of the carbon number range would be diminished. The development is still ongoing.

[0012] There is a need to combine current processes and production facilities in a new manner to improve overall energy efficiency and hydrocarbon yields starting from renewable feedstock comprising triglycerides.

[0013] SUMMARY

[0014] In view of the above, an object of the invention is to provide a process for producing a sustainable aviation fuel component as a main product from a renewable feedstock. An aim is to increase carbon and hydrogen efficiency of the sustainable aviation fuel component production process, and to enable increasing the yield of the aviation fuel component in the process. Another aim is to improve utilization of all the carbon present in the feed, more specifically any gases in addition to the carboxylic acids and / or any esters thereof in the renewable feedstock comprising also hydrocarbons with a carbon number C18 or longer, for production of an aviation fuel component. Another aim is to minimize hydrogen consumption in the process for producing a sustainable aviation fuel component. A further aim is to use the feedstock as efficiently as possible through process integration.

[0015] Yet another aim is to minimize losses of any carbon present in the feed, and instead, direct any side streams to different unit operations within the overall process to eventually refine them to intermediates suitable to be converted to the sustainable aviation fuel component or otherwise valuable products. Hence, the overall yield is further increased. In practice this means refining glycerol, carbon oxides, any C1-C4 hydrocarbons, any heavy fractions and water, preferably in gas phase, through a series of further reactors. The series of further reactors can be integrated / linked through said streams of glycerol, carbon oxides, any C1-C4 hydrocarbons, any heavy fractions, and water (H2O). However, as minor amounts, further highly refined hydrocarbon fractions from renewable sources may be recovered in addition to the sustainable aviation fuel component. Another aim is to make the best use of the SAF components.

[0016] Accordingly, there is provided a process for producing fuel components for sustainable aviation fuel from a renewable feedstock comprising triglycerides, wherein sub-processes A and B have been integrated to share at least step i), wherein the sub-process A for converting the renewable feedstock to a hydrocarbon intermediate A comprises: h) subjecting the renewable feedstock comprising triglycerides to hydrolysis in the presence of water to obtain an oil phase comprising fatty acids and a phase comprising glycerol and water; d) subjecting the oil phase obtained from the hydrolysis in step h) comprising fatty acids to decarb-reactions to obtain carbon oxide(s) and the hydrocarbon intermediate A suitable for isomerization; wherein the sub-process B for converting the carbon oxide(s) to a hydrocarbon intermediate B comprises: r) reforming the glycerol into carbon oxides and hydrogen; c) subjecting carbon oxides from step d), and optionally carbon oxides and hydrogen from step r), to carbon refining to obtain a gas mixture; s) subjecting the gas mixture comprising the carbon oxide(s) to hydrocarbon synthesis step comprising a Fischer-Tropsch process, an isosynthesis process or a methanol synthesis and upgrading process, and recovering the hydrocarbon intermediate B comprising C8-C16 hydrocarbons from the hydrocarbon synthesis effluent; wherein step i) comprises isomerizing the hydrocarbon intermediate A from step d) and the hydrocarbon intermediate B from step s) to obtain the sustainable aviation fuel (SAF) or components thereto comprising isomerized C9-C17 hydrocarbons.

[0017] In the above process disclosure, the steps are denoted by letters referring to the process initials instead of referring to the alphabetical order of letters. Considering each step individually is chosen to distance the disclosure of the present sequence from strict numerical order wherein one step would follow another but rather to emphasize the coexisting nature of sub-processes A and B and connecting streams therebetween. To help to comprehend the sub-processes and streams the steps are named in table 1.

[0018] Table 1. The steps constituting the sub-processes A and B, which together with the shared isomerization step form the overall process of the present disclosure. Surprisingly, the present inventors have found that the now disclosed production integrating subprocesses A and B with shared isomerization and linked by the carbon refining step according to the first example aspect provides increased carbon yield from the renewable feedstock comprising triglycerides. In particular, the carbon yield is improved compared to prior art processes proceeding through hydrodeoxygenation of said renewable feedstock comprising triglycerides or prior art processes involving processes comprising decarb-reactions, or hydrocarbon synthesis selected from a Fischer-Tropsch process, an isosynthesis process or a methanol synthesis and upgrading process alone. Further, hydrogen consumption is decreased compared to processes refining renewable feedstock comprising triglycerides through hydrodeoxygenation reaction.

[0019] Additionally, the process provides feasible routes for recycling compounds having carbon number from C1 to C4, which otherwise would have no or little use as commercial products, particularly in purities obtainable from the prior art processes.

[0020] In the schematic examples of the present disclosure, it is presented how the process for producing sustainable aviation fuel or components thereto is executed with enhanced carbon and energy efficiency and minimal losses.

[0021] Different non-binding example aspects and embodiments have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in different implementations. Some embodiments may be presented only with reference to certain example aspects. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

[0022] DETAILED DESCRIPTION

[0023] All standards and guidelines referred to herein are the latest revisions available at the filing date, unless otherwise mentioned.

[0024] By sustainable aviation fuel (SAF) is herein meant renewable aviation fuel which is produced sustainably and is able to reduce GHG emissions, preferably at least 70 percent, such as about 80 percent, compared to fossil jet fuel baseline, and helps the aviation industry to meet the ambitious CO2 reduction targets for the future. The present SAF composition contributes to reducing the GHG emissions at least 50 percent, such as at least 70 percent, or even such as at least 90 percent, by gCO2eq / MJ calculated according to the EU Renewable Energy Directive 2009 / 28 / EC.

[0025] As used in the context of this disclosure, the properties of the sustainable aviation fuel component comply with the requirements as set out in the ASTM D7566-22 Annex A2. It is understood that the chemical composition is dependent on the composition of the renewable feedstock comprising triglycerides. In an embodiment, the sustainable aviation fuel component obtained from the process comprises mainly C9-C16 isoparaffins, with minor amounts of C8 and C17-C18 isoparaffins and some further C9-C17 n-paraffins or cycloparaffins present. Preferably the sustainable aviation fuel or sustainable aviation fuel component obtained in the present process is of renewable origin.

[0026] Unless otherwise stated, regarding distillation characteristics and boiling ranges, reference is made to EN ISO 3405:2019. For boiling point distribution, reference may also be made to gas chromatography -based methods like ASTM D2887-19e1. Fatty acid distribution for the feed may be determined according to ISO 12966-4:2015, or measured using known analysis methods based on e.g. GC-FID or GC-AED.

[0027] The disclosure relates to a process comprising subjecting a renewable feedstock comprising triglycerides to decarboxylation and / or decarbonylation reactions (DCO) for removal of covalently bound oxygen with one carbon from carbon chains of carboxylic acids of the renewable feedstock. As used herein, the term “decarboxylation / decarbonylation” means the removal of one carbon atom together with covalently bound carboxyl oxygen through CO2 (decarboxylation) or through CO (decarbonylation) from a carboxyl group of an organic acid. Decarboxylation / decarbonylation reaction can take place completely without the influence of molecular hydrogen. Decarboxylation and decarbonylation reactions either together or alone are referred to as decarb-reactions (DCO). A liquid product, comprising mainly odd or uneven carbon number hydrocarbons, is recovered from the DCO reaction.

[0028] It is acknowledged that in many prior art processes, the removal of carboxyl oxygen is conducted by removal of water using hydrogen, in which case it is referred to as hydrodeoxygenation (HDO). From an HDO reaction, a liquid product, comprising mainly even carbon number n-paraffins, is recovered. However, the present process differs from HDO in that it is designed to produce carbon oxide(s) and minimize hydrogen consumption in this stage and accordingly hydrogen may only be required for the reductions of the catalyst, hence, not being consumed in the deoxygenation reaction as such. Hence, the sub-process A is especially beneficial regarding its relatively low hydrogen consumption compared to HDO processes.

[0029] As used herein, the term ’’hydrotreatment (HT)” or “hydroprocessing”, means a catalytic process for treating organic material by means of molecular hydrogen. In the context of the present disclosure, hydrotreatment can comprise at least one or more of removal of oxygen from organic oxygen compounds as water i.e. hydrodeoxygenation (HDO), removal of sulfur from organic sulfur compounds as dihydrogen sulphide (H2S), i.e. hydrodesulfurisation, (HDS), removal of nitrogen from organic nitrogen compounds as ammonia (NH3), i.e. hydrodenitrogenation (HDN), removal of halogens, for example chlorine from organic chloride compounds as hydrochloric acid (HCI), i.e. hydrodechlorination (HDCI), removal of metals by demetallization, removal of phosphorous through dephosphorization, hydroisomerization (HI) of the feed, hydrodearomatisation (HA) to saturate aromatic structures to cycloparaffins, and / or hydrogenation of olefinic bonds, if present in the feed. As used herein, the term ’’hydroisomerization” refers to isomerization process in the presence of hydrogen, wherein the properties of the feedstock are improved by transforming normal / linear hydrocarbons to branched ones having essentially the same carbon number.

[0030] As used herein, the term ’’hydrocracking” refers to catalytic decomposition of organic hydrocarbon materials using molecular hydrogen at high pressure. In hydrocracking, the feedstock is catalytically converted to lower molecular weight compounds (i.e. , lower MW) than in the compounds of the initial feedstock. The cracking conversion to lower molecular weight compounds is relatively unselective, and therefore carbon chains with various chain lengths are obtained through hydrocracking reactions.

[0031] As used herein, the “Fischer-Tropsch process” refers to catalytic FT-synthesis from synthesis gas to a product mainly consisting of hydrocarbons, and necessary separations and possible further refining thereof to yield a hydrocarbon intermediate B. As such the catalytic FT-synthesis is known (see e.g. https: / / en.wikipedia.org / wiki / Fischer%E2%80%93Tropsch_process) in the art and discussed in detail in e.g. Arno de Klerk, University of Pretoria, South-Africa, February 2008, a PhD thesis titled Fischer-Tropsch Refining, and further in view of upgrading in FI20236222, the contents of which are herein incorporated by reference.

[0032] As used herein, the term “isosynthesis process” refers to isosynthesis and necessary separations and possibly further refining thereof to yield a hydrocarbon intermediate B. Isosynthesis reaction as such refers to catalytic hydrogenation of carbon monoxide under isosynthesis reaction conditions, leading principally to production a branched olefinic hydrocarbon, of isobutene which is further oligomerized to trimers and tetramers. Additionally, some paraffinic hydrocarbons and trace amounts of some higher alcohols can be produced in an isosynthesis reaction. As such the catalytic isosynthesis is described in detail in e.g. FI20235260.

[0033] As used herein, the “methanol synthesis and upgrading process” refers to reacting a gas comprising CO2 with H2 or CO with H2, to produce methanol, followed by conversion of methanol to olefins to obtain by oligomerization the desired carbon numbers for eventual SAF components. The methanol synthesis and upgrading process further comprises necessary separations and possible further refining thereof to provide the hydrocarbon intermediate B. The methanol synthesis and upgrading processes are known to a man skilled in the art (see, e.g. https: / / en.wikipedia.org / wiki / Methanol or Gogate, M., Methanol-to-olefins process technology: current status and future prospects, Petroleum Sci and Tech., (37) 2019 559-565). Some processes are currently commercially available.

[0034] As used herein, the term ’’selectivity” or ”DCO deoxygenation selectivity” in context of a DCO reaction refers to a wt-% of deoxygenated product undergone deoxygenation through DCO reactions from the total amount of said deoxygenated product. In practice this means, the remaining wt-% of deoxygenated product / hydrocarbons have undergone deoxygenation through HDO reactions. For example, the specific DCO selectivity wt-% for C18 carboxylic acids can be calculated from the wt- %:s of the C17 and C18 hydrocarbon components (i.e. C17 and C18) in the deoxygenated product with the formula HC17 / (HC17 + HC18) * 100, thereby indicating the wt-% portion of C18 carboxylic acids which have undergone DCO reaction and converted to C17 hydrocarbons. The total DCO selectivity for both C18 and C16 carboxylic acids can be calculated from wt-%:s of the C15 - C18 hydrocarbon components in the deoxygenated product with the formula (HC15 + HC17) / (HC15 + HC16 + HC17 + HC18) * 100.

[0035] As used herein, “degassed” refers to an effluent that has been subjected to gas-liquid separation and from which at least species that are gaseous at NTP (normal temperature and pressure) have been separated or removed. For example, such degassed effluents include degassed hydrotreated effluent. Further, for the purpose of analyses, any stream, effluent, product or sample analyzed for any physico-chemical or a compositional characteristic, is in practice degassed prior to conducting any analysis. In practical language, they would be understood as a “liquid” stream, effluent, product or sample, respectively. The fraction separated from said degassed effluents, typically C1- C4 such as propane, may be referred to as “gaseous phase” or “gaseous fraction” of the respective effluent. Further, where any stream, effluent, product or sample is characterized by corresponding parameters, the numbers are given relative to the degassed weight or volume.

[0036] As used herein, the term ’’feed” or “feedstock” means any feedstock which is fed into a particular reaction. The renewable feedstock comprising triglycerides is the starting material of the overall process and counted as the primary origin for any streams containing carbon, for example when carbon efficiency is of interest. In view of the carbon efficiency, the present process is remarkable in a sense that through the present multistep process, even the carbon cleaved in the decarb-reactions as carbon oxides are refined into the desired end product components through carbon refining, hydrocarbon synthesis and isomerization steps (steps c), s) and i) respectively).

[0037] The renewable feedstock comprising triglycerides is renewable by origin, oily by appearance, comprises triglycerides and is more specifically defined and exemplified in e.g. Fl 130345, FI20216369 or EP1741768. As used herein, the term ’’renewable” refers to compounds or compositions that are obtainable, derivable, or originating from plants and / or animals, including compounds or compositions obtainable, derivable, or originating from fungi and / or algae, in full or in part. As used herein, renewable compounds or compositions may comprise gene manipulated compounds or compositions. Renewable feeds, components, compounds or compositions may also be referred to as biological compounds or compositions, or as biogenic compounds or compositions.

[0038] As used herein, the term “fossil or mineral” refers to compounds or compositions that are obtainable, derivable, or originating from naturally occurring non-renewable compositions, such as crude oil, petroleum oil / gas, shale oil / gas, natural gas, or coal deposits, and the like, and combinations thereof, including any hydrocarbon-rich deposits that can be utilized from ground / underground sources. The term circular refers to recycled material typically originating from non-renewable sources, but which may also be of biogenic origin. For example, the term circular may refer to recycled material originating from waste plastics.

[0039] Said renewable, circular, and fossil compositions are considered differing from one another based on their origin and impact on environmental issues. Therefore, they may be treated differently under legislation and regulatory framework. Typically, renewable, circular, and fossil compositions are differentiated based on their origin and information thereof provided by the producer.

[0040] Chemically, the renewable or fossil origin of any organic compounds, including hydrocarbons, can be determined by suitable method for analysing the content of carbon from renewable sources e.g. DIN 51637 (2014), ASTM D6866 (2020), or EN 16640 (2017). Said methods are based on the fact that carbon atoms of renewable or biological origin comprise a higher number of unstable radiocarbon (14C) atoms compared to carbon atoms of fossil origin. Therefore, it is possible to distinguish between carbon compounds derived from renewable or biological sources or raw material and carbon compounds derived from non-renewable or fossil sources or raw material by analysing the ratio of12C and14C isotopes. Thus, a particular ratio of said isotopes can be used as a “tag” to identify a renewable carbon compound and differentiate it from non-renewable carbon compounds. The isotope ratio does not change in the course of chemical reactions. Therefore, the isotope ratio can be used for identifying renewable compounds and compositions and distinguishing them from non-renewable, fossil materials in reactor feeds, reactor effluents, separated product fractions and various mixtures thereof.

[0041] Numerically, the biogenic carbon content can be expressed as the amount of biogenic carbon in the material as a weight percent of the total carbon (TC) in the material (in accordance with ASTM D6866 (2020) or EN 16640 (2017)). In the present context, the term renewable refers to a material having a high biogenic carbon content, typically more than 80 wt-%, preferably more than 85 wt-%, more preferably more than 90 wt-% or more than 95 wt-%, even more preferably about 100 wt-%, based on the total weight of carbon in the material (EN 16640 (2017)).

[0042] As used herein hydrocarbons, unless otherwise specified, refer to compounds consisting of carbon and hydrogen, and comprise e.g. paraffins, n-paraffins, isoparaffins (monobranched and / or multiple- branched isoparaffins), olefins, naphthenes, and aromatic hydrocarbons. Oxygenated hydrocarbons refer herein to hydrocarbons comprising covalently bound oxygen.

[0043] As used herein paraffins refer to non-cyclic alkanes, i.e. non-cyclic, open chain saturated hydrocarbons that are linear (normal paraffins, n-paraffins) or branched (isoparaffins, i-paraffins). In other words, paraffins refer herein to n-paraffins and / or isoparaffins.

[0044] In the context of the present disclosure, isoparaffins (or i-paraffins) refer to branched open chain alkanes, i.e. non-cyclic, open chain saturated hydrocarbons having one or more alkyl side chains. Herein, isoparaffins having one alkyl side chain or branch are referred to as monobranched isoparaffins and isoparaffins having two or more alkyl side chains or branches are herein referred to as multiple-branched isoparaffins. In other words, isoparaffins refer herein to monobranched isoparaffins and / or multiple-branched isoparaffins. The products from isomerisation are here also referred to as isomerized CX-CXX hydrocarbons. The alkyl side chain(s) may for example be CI- 09 alkyl side chain(s), preferably methyl side chain(s). The amounts of monobranched and multiple- branched isoparaffins may be given separately. The term “isoparaffins” refers to sum amount of any monobranched isoparaffins and multiple-branched isoparaffins, if present, indicating the total amount of any isoparaffins present regardless the number of branches. Correspondingly, “paraffins” refers to sum amount of any n-paraffins, any monobranched isoparaffins, and any multiple-branched isoparaffins, if present.

[0045] In the context of the present disclosure, olefins refer to unsaturated, linear, branched, or cyclic hydrocarbons, excluding aromatic compounds. In other words, olefins refer to hydrocarbons having at least one unsaturated bond, excluding unsaturated bonds in aromatic rings.

[0046] As used herein, cyclic hydrocarbons refer to all hydrocarbons containing cyclic structure(s), including cyclic olefins, naphthenes, and aromatic hydrocarbons. Naphthenes refer herein to cycloalkanes (cycloparaffins) i.e. saturated hydrocarbons containing at least one cyclic structure, with or without side chains. As naphthenes are saturated compounds, they are compounds without aromatic ring structure(s) present. Aromatic hydrocarbons refer herein to hydrocarbons containing at least one aromatic ring structure, i.e. cyclic structure having delocalized, alternating TT bonds all the way around said cyclic structure.

[0047] In the context of this disclosure, CX+ carboxylic acids, CX+ fatty acids, CX+ hydrocarbons, CX+ paraffins, or CX+ isoparaffins refer to carboxylic acids, fatty acids, hydrocarbons, paraffins, or isoparaffins, respectively, having a carbon number of at least X, where X is any feasible integer. The same is meant when referring to corresponding compounds giving the lower limit, i.e. CX and higher carbon number compounds respectively.

[0048] As used herein, the term ’’free fatty acids (FFAs)” refers to an organic acid that contains a carboxyl group (-COOH) attached to an R alkyl group which has one or more carbons. Esters of fatty acids refer to fatty acid derivatives derivative of fatty acids in which the hydrogen atom of the hydroxyl group has been replaced with an alkyl group R’, the ester having the structure R-COO-R’, wherein the R’ is an alkyl chain comprising one or more carbons. As used herein, the term ’’triglycerides” refers to an ester derived from glycerol and three fatty acids.

[0049] In the context of the present disclosure, the “overall process” refers to combination of sub-processes A and B, which are integrated to share at least an isomerization step. As used herein, streams from neighboring processes e.g from the same refinery, preferably low-value streams, may be combined with those originating from different parts of the overall process and which chemically and reactively resemble one another. Such low-value streams from neighboring processes are referred to as “additional” feeds or streams to unit processes, such as "additional” glycerol to reforming refers to glycerol originating from another process which is combined with glycerol separated from the hydrolysis step h) of sub-process A.

[0050] According to the present invention, herein is provided a process for producing sustainable aviation fuel or components thereto from a renewable feedstock comprising triglycerides. The overall process comprises sub-processes A and B, which have been integrated to share at least an isomerization step, here referred to as isomerization step i). The integration of sub-processes A and B also encompasses the sub-process B utilizing carbon oxide(s) from the step d) of the sub-process A, to obtain through several reactions further hydrocarbons to be fed to isomerization i).

[0051] The Integration eventually provides increased yield of the main product, the sustainable aviation fuel or sustainable aviation fuel component.

[0052] According to certain embodiments of the process, the sub-processes A and B may be further integrated through further unit operations, wherein streams originating from one sub-process are refined, utilized and / or upgraded in the other sub-process advantageously reducing loss of carbon and hydrogen, and at the same time increasing the yield of most valuable products. The greatest interest is to utilize carbon streams as effectively as possible. Accordingly, at least one carbon stream comprising CO, CO2 or combinations thereof, glycerol stream, a heavy fraction comprising C17 and higher carbon number linear hydrocarbons (i.e C17+ hydrocarbons) obtained from step s), a light fraction comprising C1-C2 hydrocarbons obtained from step i) are exchanged between subprocesses A and B. Said exchanges are discussed in detail in relation to appended figures.

[0053] As used here, “the sub-process A” refers to a sequence of reactions converting the renewable feedstock comprising triglycerides to a “hydrocarbon intermediate A”, hence reacting the triglycerides through hydrolysis and decarb-reactions to hydrocarbons. This is considered to be the main route of the process disclosed herein, because it produces the majority (by mass) of the sustainable aviation fuel or SAF component obtainable from the overall process. Regarding mass flows, sub-process A is the most significant route producing about 90 %-wt of the SAF or SAF component recovered from isomerization. In addition to step h) hydrolysis and step d) decarb-reactions, sub-process A may contain further steps, such as separations and / or hydrogenation of saturated fatty or organic acids or olefins.

[0054] The step h) of sub-process A comprises subjecting the renewable feedstock comprising triglycerides to hydrolysis. As to chemistry, hydrolysis of triglycerides (diglycerides and monoglycerides as well) eventually releases free fatty acids and glycerol. Hydrolysis contributes to the decarb step by providing fatty acids as the predominant feed instead of triglycerides. Hydrolysis takes place in the presence of water, typically excess water. From the reactor an aqueous phase comprising glycerol and water and an oily phase comprising fatty acids and any further lipid or oily compounds may be recovered. The oil phase and the phase containing glycerol and water are separable by conventional means for liquid-liquid separation. In an embodiment, the step h) comprises also separation of the oil phase and the aqueous phase. Means for said separation are known in the art.

[0055] The aqueous phase comprises water, glycerol and any water soluble or miscible impurities from the renewable feedstock comprising triglycerides. Hence, hydrolysis and subsequent liquid-liquid separation contribute to the purification of the renewable feedstock comprising triglycerides. Pretreatment needs of a renewable feedstock will be reduced since hydrolysis step of triglycerides will simultaneously purify renewable feedstock. A further advantage of hydrolysis step h) is that separation of glycerol from the main route of the sub-process A enables it to be directed to the subprocess B, subjected to reforming and further steps and eventually contributing to the yield of the overall process.

[0056] The basis for hydrolysis as a part of the present process is that fats and oils are made up of triglycerides (triacylglycerols). Triglycerides contain 3 ester functional groups. Hydrolysis is a reaction with water. Hydrolysis is an equilibrium reaction. Acid hydrolysis of a triglyceride produces glycerol and three fatty acids. Reaction is acid catalytic but can be done also with enzymes. If base is used as a catalyst, it results in soaps of fatty acids, which have to be acidulated with strong acid (such as sulfuric acid) afterwards back to free fatty acids. Typical hydrolysis reactions are depicted in the following scheme 1 .

[0057] Scheme 1 . Hydrolysis reactions.

[0058] Preferably the hydrolysis is conducted according to the Colgate-Emery process, in which typical temperature and pressure conditions are around 250 °C and 5 MPa. Using a two hour reaction time, typical FFA yield is 97 %.

[0059] Hydrolysis as such is known as an exothermic process. Nevertheless, vaporizing the water for the hydrolysis process consumes energy, as does the oil / water separation after hydrolysis.

[0060] For the hydrolysis step h), several methods have been developed including acidic / alkaline-catalyzed, lipase-catalyzed, and catalyst-free methods. Another option is a so-called subcritical water hydrolysis, as it carries out efficient hydrolysis of triglycerides, but also simultaneously purifies the treated oil, therefore helping further catalytic processing. The conditions can be between 270 to 350°C and 10 to 20 Mpa and residence time 20-30 min. Additional benefit of this method is to achieve the hydrolysis of amides, which can be difficult to hydrotreat.

[0061] The composition of the oil phase recovered from hydrolysis is characterized by comprising free fatty acids having the carbon number mainly from C14 to C22 and / or other organic acids having carbon numbers from C10 to C22. Further organic acids are for example resin acids. Residues from incomplete hydrolysis can be seen in the oil phase as glycerides (mono, di and / or tri). However, said composition is dependent on the initial feedstock comprising triglycerides, eventual further feedstocks or cofeeds and the hydrolysis conditions. In an embodiment, the oil phase comprises at least 70 wt-%, preferably at least 80 wt-%, more preferably at least 90 wt-% of organic acids, preferably free fatty acids (FFAs), of the total weight of the oil phase.

[0062] After step h) the oil phase comprising fatty acids obtained therefrom, is subjected to decarb-reactions at the step d) to obtain carbon oxide(s) and the hydrocarbon intermediate A suitable for I. Decarbreactions of the step d) refer to decarboxylation and decarbonylation reactions as defined in this application. Preferably the decarb-reactions comprise decarboxylation wherefrom carbon dioxide is recovered.

[0063] In decarboxylation, one fatty acid / fatty acid ester is transformed to hydrocarbon that has one carbon less compared to original chain length of fatty acid / fatty acid ester and carbon dioxide is released. One pathway for decarboxylation uses heterogeneous catalysts containing platinum, palladium, nickel, iridium, ruthenium and rhodium on oxides, zeolites, mesoporous materials, on carbonaceous supports or structured catalyst supports, like Ru / C or Pd / C (see e.g. EP1681337B1 or FI20225933A. The reaction temperatures are from 300-370 °C. Any deactivation of the catalyst can be overcome with continuous regeneration or with added hydrogen during the reaction.

[0064] Another pathway includes metal carbonyl catalyst with added sodium hydroxide and carbon monoxide. The reaction temperatures are between 200-300 °C. In further detail, this method is defined in WO2010043765.

[0065] Theoretically, in terms of carbon number (n), in the predominant reaction, which is decarboxylation, a Cn fatty acid is converted to a C(n-1 ) hydrocarbon with release of CO2. Some CO is also released as side reactions occur on a minor scale.

[0066] In practice in terms of carbon numbers, the oil phase typically comprises a range of different fatty acids. Further, the fatty acids may be saturated or unsaturated. The fatty acids and / or organic acids entering the decarb-reaction of the step d) have carbon numbers typically from C14 to C22. As minor amount, some triglycerides, diglycerides and / or monoglycerides may be present as well. Nevertheless, the carbon number distribution is dependent on the renewable feed comprising triglycerides and properties thereof. In one embodiment, carbon oxide(s) may be obtained from fatty acids by decarb-reactions during a hydrodeoxygenation process. Depending on the reaction conditions the amount of decarboxylation and carbon dioxide generation during hydrodeoxygenation may vary. For example, the WHSV (weight hourly space velocity) of a process can be increased by increasing the flow rate of the feed or decreasing the amount of catalyst. Increased WHSV raises the ratio of decarboxylation to hydrodeoxygenation reactions. Contrary to the DCO reactions HDO reactions require added, external hydrogen, thus increasing the hydrogen consumption. However, it may be also beneficial to carry out a DCO / HDO reaction in the presence of a low amount of H2, as hydrogenation of the feedstock allows hydrogenation of possible double bonds present in the feedstock which also releases heat to be utilized in the endothermic DCO reaction. Therefore, in certain embodiments, the DCO / HDO reaction is carried out in the presence of a H2feed ratio of 50 - 500 nl H2 / liter of the feedstock, or 50 - 350 nl \-\J liter of the feedstock, or 50 - 250 nl \-\J liter of the feedstock. Typically, reactions are carried out in the presence of a sulfided hydrogenation catalyst comprising Ni, NiMo, CoMo or NiW, on a support comprising alumina, silica and / or zeolite. Preferably, at least 10 %, such as at least 20 %, or even at least 40 %, of the deoxygenation reactions occur through DCO reactions during the hydrodeoxygenation process.

[0067] The hydrocarbon intermediate A obtainable from the decarb-reactions comprises linear hydrocarbons having carbon numbers typically from C13 to C21. Said hydrocarbons comprise predominantly from C13 to C21 n-paraffins and possibly n-olefins with carbon number from C13 to C21 as minor amounts. According to an embodiment, the hydrocarbon intermediate A comprises at least 70 wt-%, preferably at least 80 wt-%, more preferably at least 90 wt-% of C13 to C21 n- paraffins, of the total weight of the hydrocarbon intermediate A. When eventually isomerized, such hydrocarbon intermediate provides an advantageous sustainable aviation fuel component composition.

[0068] In case the oil phase comprises unsaturated fatty acids, the hydrocarbons formed thereof comprise unsaturated hydrocarbons, typically in minor amounts. However, a further step hydrogenating said unsaturated hydrocarbons into saturated hydrocarbons could be added. Such hydrogenation has relatively low hydrogen consumption.

[0069] According to specific embodiments, hydrogenation to saturate any carbon-carbon double bonds present may take place before step d), after step d) or both before and after decarb-reactions of step d). Hydrogenation is advantageous in case the fatty acids recovered from hydrolysis comprise a significant amount of unsaturated fatty acids. When hydrogenating before step d), the unsaturated fatty acids are converted into saturated fatty acids. When hydrogenating after step d), the olefins formed in decarb-reactions are converted into n-paraffins. Hence, according to such embodiments, step d) is preceded or followed by a hydrogenation step. Some synergisms can be seen in both options. Should step d) be conducted after hydrogenation, any hydrogen residues thereof contribute to the activation of the decarb-reaction catalyst. However, should the hydrogenation take place after decarb-reactions, any excess hydrogen fed to hydrogenation may contribute to the subsequent hydroisomerization step, which also is conducted with a H2 feed thereto. Minimizing the presence of unsaturated hydrocarbons in the isomerization reaction contributes to avoidance of premature catalyst deactivation.

[0070] The sub-process B can be seen complementing the sub-process A and providing further appropriatesized hydrocarbons in the hydrocarbon intermediate B to the isomerization reaction. Its main purpose is to convert at least the carbon oxide(s) from step d) to a hydrocarbon intermediate B. Its further purpose is to convert at least the glycerol from step h) to a hydrocarbon intermediate B.

[0071] The sub-process B comprises at least steps r) reforming, step c) carbon refining, and step s) hydrocarbon synthesis yielding a hydrocarbon intermediate B. In addition to step r) reforming and step c) carbon refining and s) hydrocarbon synthesis, sub-process B may contain further steps.

[0072] Step r), the reforming precedes said step c) carbon refining. As a preferred feed to said reforming, glycerol recovered from hydrolysis is used. Glycerol reacts to provide carbon oxides and hydrogen as products of the reforming. Further, according to an embodiment, it could be advantageous to add at least part of the decarboxylation reaction gases, carbon oxide(s) to the step r) as well. Thereby, two side streams of sub-process A are processed together to increase the overall carbon yield. The reforming, such as steam reforming, will have beneficial yield to the subsequent hydrocarbon synthesis step s) gas, when the reforming feed comprises both, the glycerol from step h) and decarboxylation reaction gases, carbon oxides from the step d).

[0073] Alternatives for glycerol reforming are known in the art. Reforming may include steam reforming (SR) or dry reforming (DR), and for example partial oxidation reforming (POR), autothermal reforming (ATR), aqueous phase reforming (APR), and supercritical water reforming (SCWR). Preferably, the reforming is steam reforming.

[0074] SR is employed industrially for the production of hydrogen, but it also produces a syngas mixture that is rich in hydrogen (CH4+ H2CX-XDO + 3H2). H2 production may be enhanced, when the resultant gas is separated and CO is reacted further with water via water-gas shift reaction CO + H2O<-> CO2+ H2.

[0075] DR i.e. carbon dioxide reforming, is an endothermic reaction (0^+002^200+2^) between hydrocarbons, such as methane, and carbon dioxide for the production of a mixture of CO and hydrogen, syngas, with the aid of metal catalysts, such as Fe, Co, Ni, Pt, Pd, Ru, Rh and Ir. Typically, syngas is produced by steam reforming reaction or coal gasification. However, present concerns on the contribution of greenhouse gases to global warming have increased interest in the replacement of steam as reactant with carbon dioxide. Besides hydrogen, carbon monoxide and carbon dioxide are produced as well in said reforming. Steam reforming and auto reforming are commercial reforming technologies and known as such, although glycerol is not the current feedstock therein. Aqueous phase reforming and supercritical reforming are under development. Each of these technologies when glycerol is used as a feedstock have its advantages and disadvantages. According to an embodiment, glycerol reforming may be conducted according to processes known from e.g. a review by Schwengber, and coworkers, (C.A. Schwengber et al., Overview of glycerol reforming for hydrogen production, Renew Sustain Energy Rev (2016)).

[0076] According to further embodiments, further feed to the reforming step r) may comprise one or more of carbon oxides obtained from step d), and a light fraction comprising C1-C4 hydrocarbons obtained from step s). Yet as further streams for reforming, any water and / or oxygenates forming as side or co-products in step s), for example when the synthesis is conducted as a FT synthesis and producing light oxygenates as side or co-products thereof, may be recovered and recycled to reforming in step r). Further carbon monoxide may be obtained therefrom. Further, FT light gases when fed to reforming unit will enhance the production of hydrogen.

[0077] According to an embodiment, at least one of additional carbon oxide(s), additional glycerol and / or additional light hydrocarbons comprising C1-C4 hydrocarbons, is fed in step r) to the reforming. Said additional light hydrocarbons comprising C1-C4 hydrocarbons may originate for example from hydrodeoxygenation of triglycerides, hydrocracking, or other reactions capable of producing light hydrocarbons in neighboring processes. Preferably said additional light hydrocarbons comprising C1-C4 hydrocarbons are renewable.

[0078] A relevant step of the sub-process B is step c), subjecting carbon oxides from step d) and optionally the carbon oxides and hydrogen from step r), to carbon refining to obtain a gas mixture. Preferably, carbon refining is carried out by water gas shift reaction or carbon capture. The aim of this step is to adjust the composition of the gas to suit best the hydrocarbon synthesis in next step s). Effective use of the carbon oxides originating from the renewable feedstock comprising triglycerides contributes to the overall carbon management of the present process. Dependent on the synthesis applied, the requirements for the adjusting and the composition of the gas mixture thereby obtained may vary. Further, the reforming and the water gas shift are equilibrium reactions which means that gases from the other side of the reaction equation are present in addition to the gas components most desirable as products.

[0079] In an embodiment, the carbon refining in step c) further comprises adjusting a hydrogen / carbon monoxide ratio of said gas mixture by a water gas shift reaction. Said reaction is known in the art and details thereof can be found in the art. In an embodiment, the carbon refining in the step c) comprises reverse water gas shift (RWGS). for adjusting the hydrogen / carbon monoxide ratio of said gas mixture from step r). In an embodiment, step c) comprises feeding additional hydrogen to the adjusting of the hydrogen / carbon monoxide ratio. Said additional hydrogen may be produced e.g. by electrolysis, such as sustainable hydrogen produced by water electrolysis.

[0080] Where the hydrocarbon synthesis step s) is a Fischer-Tropsch process, the gas fed thereto from step c) should comprise hydrogen gas and carbon monoxide (CO) gas, preferably in such proportions that the hydrogen to carbon monoxide ratio is about 1.7 or higher.

[0081] Where the synthesis is isosynthesis, the gas fed thereto is a mixture of carbon monoxide (CO) gas and hydrogen gas. More specifically, the synthesis gas for isosynthesis comprises primarily carbon monoxide and hydrogen but may further include also carbon dioxide and / or minor amounts of other gases such as methane, as well. Preferably the syngas for isosynthesis comprises 20 mol-% - 60 mol-% of carbon monoxide and 40 mol-% - 70 mol-% of hydrogen.

[0082] Where the synthesis is conducted through a methanol synthesis and upgrading process, the gas fed thereto comprises CO2 with H2 or CO with H2.

[0083] In the hydrocarbon synthesis step s) the gaseous compounds comprising carbon oxide(s) from carbon refining c) are subjected to hydrocarbon synthesis wherefrom C8-C17 hydrocarbons may be recovered as hydrocarbon intermediate B. The side streams otherwise of low value can thus be refined to contribute to the overall sustainable aviation fuel yield.

[0084] The step s) is here defined as subjecting the gas mixture comprising at least carbon monoxide to hydrocarbon synthesis step. The synthesis step comprises a Fischer-Tropsch process, an isosynthesis or a methanol synthesis and upgrading process, and recovering the hydrocarbon intermediate B comprising C8-C16 hydrocarbons from the hydrocarbon synthesis effluent.

[0085] Additional synthesis gas from other sources can be fed to the synthesis unit beside gaseous compounds comprising carbon oxide(s) from carbon refining c). Hence, according to an embodiment additional gas mixture is fed to the hydrocarbon synthesis step s).

[0086] Fischer Tropsch (FT) as the synthesis reaction converts synthesis gas to hydrocarbons and water. The reaction is exothermic. The technology is available commercially. Where the synthesis is a Fischer-Tropsch process, the reaction conditions may be selected from typical reaction temperatures 200-300 °C and typical pressures below 100 bar. In case of FT synthesis, the hydrocarbon synthesis effluent comprises n-paraffins within broad carbon number range. According to a preferred embodiment, the FT conditions are set to provide increased productivity within a JET selective product range, which increases the yield of said fraction from fractionation. The fraction comprising n-paraffins having carbon numbers from C8-C16 can be readily fed to the isomerization step i) as hydrocarbon intermediate B.

[0087] Further fractions recoverable from said FT synthesis, namely heavier hydrocarbons, hence n- paraffins having carbon numbers C17+ may be recovered and preferably also fed to isomerization reaction to increase the SAF yield. However, in case the carbon number distribution of the hydrocarbon intermediate A is inclined to the heavier end of the desired SAF product range, the FT product with wider carbon number distribution may complement at the lighter end.

[0088] As a part of the overall process, the light hydrocarbons, predominantly C1-C4 n-paraffins may be fed to the reformation step r). With the glycerol from hydrolysis, they contribute to further yield via sub-process B to the SAF yield.

[0089] In an embodiment, where the hydrocarbon synthesis comprises isosynthesis, the hydrocarbon synthesis step s) comprises reacting the gas mixture catalytically to produce an isosynthesis reaction product comprising isobutene monomers. In the present isosynthesis process, the isobutene is further oligomerized to produce olefin trimers and tetramers to provide carbon numbers suitable for SAF components after 17ustain17a17ion. For instance, FI20216108 or FI20235260 disclose in detail processes for manufacturing olefin trimers and tetramers by oligomerizing olefin monomers.

[0090] The isosynthesis reaction is carried out in the presence of an isosynthesis catalyst and the reaction conditions may be selected from a temperature from 300 to 500 °C, and a pressure from 20 to 100 bar. Preferably the reaction is carried out as an isosynthesis single pass conversion within the range from 20 % to 80 %.

[0091] The isobutene monomers are further reacted into an oligomerized product containing at least trimers of isobutene and tetramers of isobutene, which are hydrogenated thereby obtaining the hydrocarbon intermediate B.

[0092] In case of isosynthesis, hydrocarbon intermediate B comprises n-paraffins, predominantly within a carbon number range from C12 to C16.

[0093] Where the synthesis is conducted through a methanol synthesis and upgrading process, the reaction proceeds through ethene and propene formation which then are oligomerized to provide hydrocarbons with desired carbon numbers. The methanol synthesis and upgrading process conditions are known to a man skilled in the art (see, e.g. https: / / en.wikipedia.org / wiki / Aviation_biofuel or https: / / en.wikipedia.org / wiki / Methanol or Gogate, M., Methanol-to-olefins process technology: current status and future prospects, Petroleum Sci and Tech., (37) 2019 559-565). Certain processes are currently commercially available.

[0094] Additional synthesis gas from other sources can be fed to the synthesis unit beside gaseous compounds comprising carbon oxide(s) from carbon refining c).

[0095] From the hydrocarbon synthesis effluent, a hydrocarbon intermediate B is recovered by conventional means. In case further fractions are recovered, they can be directed or recycled to appropriate steps. For example, when the hydrocarbon synthesis step is Fischer-Tropsch reaction to obtain hydrocarbons, at least one further hydrocarbon fraction selected from a light fraction comprising CI- 02 or C1-C4 hydrocarbons, optionally a fuel gas product comprising C3-C4 hydrocarbons, a naphtha fraction comprising C3-C7 hydrocarbons, heavy fraction comprising C17+ hydrocarbons, may be recovered in addition to the hydrocarbon intermediate B. Said hydrocarbons when obtained from FT are predominantly n-paraffins.

[0096] According to an embodiment, said heavy hydrocarbon fraction comprising C17+ hydrocarbons, obtained in step s) is fed to the isomerization step i). Feeding this stream to the step i) contributes to the overall sustainable aviation fuel yield. The hydroisomerization reactions together with hydrocracking as a minor side reaction, the heavy end hydrocarbons, especially C17 and even C18, are converted either to i-paraffins fitting into SAF component composition or if higher carbon numbers, to i-paraffins having added value as isomerized heavy hydrocarbons.

[0097] The hydrocarbon intermediate B recovered from the synthesis reaction effluent from step s) comprises carbon numbers typically from C8-C16. Said hydrocarbons comprise predominantly C8- C16 n-paraffins. According to an embodiment, the hydrocarbon intermediate A comprises at least 70 wt-%, preferably at least 80 wt-%, more preferably at least 90 wt-% of C8-C16 n-paraffins, of the total weight of the hydrocarbon intermediate A. As minor components, the hydrocarbon intermediate B may contain some olefins, oxygenates or C18+ paraffins.

[0098] When eventually isomerized, such hydrocarbon intermediate provides an advantageous sustainable aviation fuel component composition.

[0099] In an embodiment, water obtained in at least one of the steps c) and s) is recycled to reforming in step r) and / or hydrolysis in step h). Said steps c) and s) provide water in gaseous phase, as steam, which may be fed to processes where water is needed in the stoichiometry of the reaction and / or where the energy of the steam advances the reaction. Savings in water vaporization / steam production provide a considerable advantage. As used herein, H2O(g), water vapor and H2O vapor refer to water vapor in gaseous phase and in sufficient purity for the reactions where it is used. For example, the synthesis processes as discussed herein, the FT process, the isosynthesis process and the methanol synthesis and upgrading process, release water from reaction thereof as very pure water vapor, which is excellent for use in e.g. reforming in the sub-process B and / or hydrolysis in the sub-process A.

[0100] In the overall process the sub-processes A and B have been integrated to share an isomerization step, the step i). As used herein, isomerization refers to reactions where long chain n-paraffins are isomerized to long chain i-paraffins. In theory, the number of carbon atoms does not change in the reaction. Said step i) comprises isomerizing the hydrocarbon intermediate A from step d) and the hydrocarbon intermediate B from step s) to obtain a SAF component comprising isomerized C9-C17 hydrocarbons.

[0101] In addition to the main product, the SAF component comprising isomerized C9-C17 hydrocarbons, at least one further hydrocarbon fraction selected from naphtha fraction comprising isomerized C3- C7 hydrocarbons and isomerized heavy hydrocarbon fraction comprising isomerized C18+ hydrocarbons, is recovered from step i). Both further products are of high value, the recovery of which improves the overall yield from the renewable feedstock and enables fractionation of the isomerization effluent with desired optimization.

[0102] In an embodiment, in the isomerization step i), hydrocarbon intermediate B comprising C8-C16 hydrocarbons from step s) and hydrocarbon intermediate A from step d) are isomerized separately, nevertheless in the same isomerizing unit(s). Separate isomerization enables specific adjusting of the reaction conditions to provide best conversion and selectivity into the SAF component comprising isomerized C9-C17 hydrocarbons. For example, if one of the intermediates comprises a significant amount of heavy hydrocarbons or in case heavy hydrocarbons recovered from other parts of the process or even recycled from the effluent of the isomerizing itself, are fed to step i), isomerizing reaction conditions allowing mild hydrocracking in addition to isomerization reactions serve the end purpose of good SAF component yield and quality. Further, in some embodiments, a separate isomerizing of hydrocarbon intermediate B and hydrocarbon intermediate A could be feasible timewise.

[0103] According to another embodiment, in the isomerizing step i), hydrocarbon intermediate B comprising C8-C16 hydrocarbons from step s) and the hydrocarbon intermediate A from step d) are combined and isomerized together. Combined isomerizing is favored when both the hydrocarbon intermediate A and hydrocarbon intermediate B are relatively similar to one another in their chemical composition. Advantages are then related to economics of scale.

[0104] In addition to the mass flow integration of different streams as defined herein, the overall process may further comprise energy integration wherein energy recovered from exothermic reactions is used for endothermic reactions. Requirement for external energy is thereby decreased. Accordingly, energy formed in step s) is used for at least one of steps selected from hydrolysis in step h), adjusting the hydrogen / carbon monoxide ratio in step x), decarboxylation in step d) and isomerizing in step i).

[0105] The isomerization treatment of the hydrocarbon intermediate A or the hydrocarbon intermediate B converts at least a certain amount of n-paraffins to i-paraffins, especially to mono-branched i- paraffins. By (further) raising the isomerization degree, for example by increasing severity of the isomerization, more n-paraffins can be converted to i-paraffins, and mono-branched i-paraffins to multiple-branched i-paraffins, such as di-branched, tri-branched i-paraffins, even i-paraffins comprising more than three branches. A catalytic hydroisomerization is preferred.

[0106] The hydroisomerization treatment is preferably conducted at a temperature within a range from 200 °C to 500 °C, preferably from 230 °C to 500 °C, more preferably from 250 °C to 450 °C, even more preferably from 280 °C to 370 °C, a pressure within a range from 1 Mpa to 10 Mpa, preferably from 2 Mpa to 8 Mpa or from 3 Mpa to 10 Mpa, a H2 partial pressure within a range from 1 Mpa to 10 Mpa, preferably from 2 Mpa to 8 Mpa, a weight hourly space velocity within a range from 0.1 to 10, preferably from 0.2 to 8, more preferably from 0.4 to 6 kg n-paraffinic hydrocarbon feed per kg catalyst per hour, and a H2 to n-paraffinic hydrocarbon feed ratio within a range from 10 to 2000, preferably from 50 to 1000 normal liters H2 per liter n-paraffinic hydrocarbon feed.

[0107] Severity of the isomerization may be increased by at least one or more of: decreasing WHSV, increasing temperature, and / or increasing pressure. The isomerization treatment may be performed in the presence of known isomerization catalysts, for example, catalysts containing a molecular sieve, and / or a metal selected from Group VIII of the Periodic Table, and a carrier. Preferably, the isomerization catalyst is a catalyst containing SAPO-11 or SAPO-41 or ZSM-22 or ZSM-23 or ferrierite, and Pt or Pd or Ni, and AI2O3 or SiO2. Typical isomerization catalysts are, for example, Pt / SAPO-11 / AI2O3, Pt / ZSM-22 / AI2O3, Pt / ZSM-23 / AI2O3, and / or Pt / SAPO-11 / SiO2. The isomerization may be conducted for example as described in prior art publications, such as FI100248B, EP1741768A1 , EP2155838B1 , or Fl 129220 B1 , Fl 130345B or Fl 130344B.

[0108] In some embodiments the isomerization conditions are selected to allow mild hydrocracking. In hydrocracking, the fatty acid molecules will split to hydrocarbons that are from carbon number lower compared to fatty acid in the presence of hydrogen and a catalyst. Depending on the choice of the catalyst, the hydrocarbon distribution can be adjusted. Besides hydrocarbons, water and carbon oxides are formed. Typical hydrocracking catalysts are sulfurized NiMo / NiW or noble metal on zeolite-based catalysts on acid support. The hydrogen pressure is typically above 5 Mpa and reaction temperatures are above 350°C. With the selection of reaction conditions and catalyst properties, hydrocracking reactions can be enhanced and the distribution of hydrocarbons to broaden carbon number range is achieved. Further, Hydrocracking of fatty acids forms cyclic (naphthenic and aromatic) compounds that have beneficial impact to SAF properties.

[0109] The main product recovered from the isomerization effluent is a sustainable aviation fuel or fuel component(s) for sustainable aviation fuel (SAF). The sustainable aviation fuel or components thereto may be separated from the isomerization effluent as a fraction having a T5 temperature (5 vol-% recovered) within a range from 170 to 280 °C, preferably within a range from 220 to 260 °C, and a T95 temperature within a range from 250 to 340 °C, preferably within a range from 270 to 320 °C, according to EN ISO 3405-2019, and preferably a difference between T5 and T95 temperatures within a range from 40 to 100 °C.

[0110] The main product, the sustainable aviation fuel or fuel component(s) for sustainable aviation fuel may be defined as a fraction comprising renewable C9-C17 hydrocarbons, mainly branched COCIT hydrocarbons which are suitable for use in aviation fuel applications, such as jet fuel or components thereto. The separated hydrocarbon fraction has preferably an initial boiling point at atmospheric pressure of at least 150 °C and a final boiling point of up to 290 °C.

[0111] The fraction comprising renewable isomerized C9-C17 hydrocarbons is especially rich in renewable isomerized C10-C16 hydrocarbons. As defined herein, a fraction “rich in” means in the context of the present disclosure that the wt-% amount of the hydrocarbons in the fraction, based on the total weight of the fraction, is higher than the wt-% amount of the hydrocarbons in the hydroisomerized stream, or optionally in the stabilized hydroisomerized stream, based on the total weight of the hydroisomerized stream, or the optionally stabilized hydroisomerized stream.

[0112] As additional product(s), further fuel(s) or fuel components and / or renewable chemical(s) may be recovered from the present process, from hydrolysis, from isomerization, or from a synthesis.

[0113] From the hydrocarbon synthesis step different renewable chemicals may be recovered depending on the synthesis selected. In case the synthesis is conducted as a FT-process, a fraction of C3-C7 n-paraffins may be recovered as a product suitable as renewable naphtha component.

[0114] From the isomerization and product separation thereof, in addition to the sustainable aviation fuel or fuel component(s) for sustainable aviation fuel, further products recovered may comprise renewable naphtha, renewable (winter) diesel and / or another product comprising isomerized heavy hydrocarbons, such as hydrocarbons having the carbon number above C18 (i.e. C18+ isomerized hydrocarbons). The heavy hydrocarbons can optionally be separately upgraded.

[0115] Example embodiments are next discussed with reference to appended figures presenting schematic outline of the overall process. In figure 1 , the unit operations and units therefor are referred to corresponding to the steps of the claim 1 . In said figure, sub-process A runs from left to right through steps h) and d). Correspondingly, sub-process B runs from left to right through steps r), c) and s). The final step i), isomerization, integrates said sub-processes producing a sustainable aviation fuel (SAF) or components thereto comprising C9-C17 hydrocarbons as the main product.

[0116] Typical examples of the compositions of streams corresponding to the numbers used in said figures are as defined in the following table 2.

[0117] Table 2. Example stream compositions

[0118] In the beginning of sub-process A, a renewable feedstock comprising triglycerides 10 is fed to the hydrolysis unit h) with water 110. From the hydrolysis unit h), the effluent comprising fatty acids and glycerol as the reaction products is subjected to separation. Suitable separation methods are known in the art. After separation the oil phase 20 is conducted to decarb processes d) and the aqueous stream, i.e. , the aqueous phase comprising glycerol 30 to the reforming unit r).

[0119] Further to the oil phase 20, hydrogen 210 may also be fed to the decarb processes d). Nevertheless, hydrogen addition is modest and only needed to maintain the catalyst in active form. The main product from decarb processes of unit d) is a stream comprising linear hydrocarbons 40, preferably comprising predominantly n-paraffins having carbon number from C13 to C21 , with some n-olefins (C13-C21 ) as a minor amount present as well. As a side stream, carbon oxide(s) released from the decarboxylation and decarbonylation reactions are directed via line 50 to carbon refining c).

[0120] The main product from decarb processes unit d), the stream comprising linear hydrocarbons 40 is directed to hydroisomerization unit i) together with hydrogen 410. Said stream comprising linear hydrocarbons 40, preferably comprises n-paraffins having carbon number form C13 to C21. The first step of the sub-process B is the reforming in unit r). The main feed to the reforming is the glycerol 30 obtained from hydrolysis unit h). Further feeds comprise a stream of any light hydrocarbons 810, such as C1-C2 from the synthesis unit s). Yet further, additional feed(s) to the reforming may be provided. Optionally additional glycerol may be provided via line 350 and / or additional light hydrocarbons via line 550 to the reforming. According to an embodiment, carbon oxide(s) released from the decarb-reactions of the step d) may at least partly be directed via line 55 to the reforming.

[0121] From the reforming unit r) a gas stream 60, an effluent form reforming comprising H2, CO, CO2, and H2O is fed to carbon refining c). Together with the carbon oxide(s) fed via line 50, they are subjected to carbon refining in unit c) in order to adjust H2 / CO ratio to be suitable for the hydrocarbon synthesis as the next step. Depending on the choice of the carbon refining method and unit c) therefore, further H2 may be fed thereto through line 560. Should gaseous water be removed via line 720 from the gas stream, it may be combined with stream 820 from synthesis s) and recycled back to reforming unit r) or alternatively fed to hydrolysis unit h), where the gaseous water contributes to the energy efficiency.

[0122] As the last step of the sub-process B, the gas stream 70 comprising H2, CO, CO2, and H2O is subjected to synthesis conditions in synthesis unit s). Dependent on the synthesis applied, the hydrocarbon end product from synthesis is fractionated to recover C8-C17 hydrocarbons or in some embodiments C12-C22 hydrocarbons to be directed via line 80 to isomerization unit i). Further eventual fractions recovered from the hydrocarbon synthesis step may comprise C1-C4 hydrocarbons, such as C1-C2 hydrocarbons, which are directed to the reforming unit via line 810. Any eventual gaseous water removed via line 820 may be directed to reforming unit r) or alternatively fed to hydrolysis unit h). According to an embodiment, a fraction comprising C3-C7 hydrocarbons, preferably C3-C7 n-paraffins may be recovered as a side product from synthesis unit s) via line 920. Such fraction is usable as a renewable naphtha component.

[0123] The isomerization i) converts linear hydrocarbons to i-paraffins. From the effluent of the isomerization, a SAF component comprising isomerized C8-C17 hydrocarbons 90 is recovered as the main product. Further possible products comprise naphtha 910 comprising paraffins, predominantly i-paraffins within carbon number range from C3 to C7, and / or isomerized heavy hydrocarbons 930 comprising paraffins, predominantly i-paraffins within carbon number range from C18 to C22. Such fraction is usable as a renewable diesel component.

Claims

CLAIMS1 . A process for producing sustainable aviation fuel (SAF) or components thereto from a renewable feedstock comprising triglycerides, wherein sub-processes A and B have been integrated to share at least step i), wherein the sub-process A for converting the renewable feedstock to a hydrocarbon intermediate A comprises: h) subjecting the renewable feedstock comprising triglycerides to hydrolysis in the presence of water to obtain an oil phase comprising fatty acids and a phase comprising glycerol and water; d) subjecting the oil phase obtained from the hydrolysis in step h) comprising fatty acids to decarb-reactions to obtain carbon oxide(s) and the hydrocarbon intermediate A suitable for isomerization; wherein the sub-process B for converting the carbon oxide(s) to a hydrocarbon intermediate B comprises: r) reforming the glycerol into carbon oxides and hydrogen, c) subjecting carbon oxides from step d), and optionally carbon oxides and hydrogen from step r), to carbon refining to obtain a gas mixture, s) subjecting the gas mixture comprising the carbon oxide(s) to hydrocarbon a synthesis step selected from a Fischer-Tropsch process, an isosynthesis process or a methanol synthesis and upgrading, and recovering the hydrocarbon intermediate B comprising C8-C17 hydrocarbons from the hydrocarbon synthesis effluent; wherein step i) comprises isomerizing the hydrocarbon intermediate A from step d) and the hydrocarbon intermediate B from step s) to obtain the sustainable aviation fuel (SAF) or components thereto comprising isomerized C9-C17 hydrocarbons.

2. The process according to claim 1 , wherein at least one further hydrocarbon fraction selected from naphtha fraction comprising isomerized C3-C7 hydrocarbons and isomerized heavy hydrocarbon fraction comprising isomerized C18+ hydrocarbons is recovered from step i).

3. The process according to claim 1 or 2, further comprising, in step s), feeding additional gas mixture to the hydrocarbon synthesis step.

4. The process according to any of the preceding claims, wherein in step r), the feed to reforming further comprises one or more of• carbon oxides obtained from step d),• a light fraction comprising C1 - C2 hydrocarbons obtained from step s).

5. The process according to any of the preceding claims wherein any water and / or oxygenates formed as side or co-products are recovered from the step s) and recycled to reforming in step r).

6. The process according to any of the preceding claims, further comprising, in step r), feeding at least one of additional carbon oxide(s), additional glycerol and / or additional light hydrocarbons comprising C1-C4 hydrocarbons, to the reforming.

7. The process according to any of the preceding claims, wherein the carbon refining in step c), further comprises adjusting a hydrogen / carbon monoxide ratio of said gas mixture,8. The process according to claim 7, wherein said adjusting in step c), is carried out by water gas shift reaction or carbon capture.

9. The process according to claim 7 or 8, further comprising, in step c), feeding additional hydrogen to the adjusting of the hydrogen / carbon monoxide ratio.

10. The process according to any of any of the preceding claims, wherein the step s) comprises a Fischer-Tropsch process, and wherein at least one further hydrocarbon fraction selected form a light fraction comprising C1 - C2 hydrocarbons and a heavy fraction comprising C17+ hydrocarbons, is recovered in addition to the hydrocarbon intermediate B.11 . The process according to claim 10, wherein the heavy hydrocarbon fraction comprising C17+ hydrocarbons, obtained in step s) is fed to the isomerization step i).

12. The process according to any of the preceding claims, wherein said sub-processes A and B have been further integrated through at least one carbon stream, selected from carbon oxide(s) stream, CO-stream, CO2-stream, glycerol stream, a heavy fraction comprising C17+ hydrocarbons obtained from step s), a light fraction comprising C1-C2 hydrocarbons obtained from step i).

13. The process according to any of the preceding claims, wherein step d) comprises decarboxylation wherefrom carbon dioxide is recovered.

14. The process according to any of preceding claims, wherein energy recovered from the step s) is used for at least one of steps selected from hydrolysis in step h), adjusting the hydrogen / carbon monoxide ratio in step c), decarboxylation in step d) and isomerizing in step i).

15. The process according to any of preceding claims, wherein any water obtained in at least one of the steps c) and s) is recycled to reforming in step r) and / or hydrolysis in step h).

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