Process for preparing sustainable jet fuels or diesel fuels; and precursors thereof

Abstract

The present invention relates to a process for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels, comprising the steps of: a) converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising C8-18 alcohols by means of a Guerbet reaction; b) dehydrating the mixture comprising C8-18 alcohols to C8-18 olefins and water; and c) hydrogenating the C8-18 olefins to aliphatic hydrocarbons; wherein the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (L)nM(OH)n(H2O)m type complex wherein,  n and m are positive integers;  M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and  L is a ligand.

Description

[0001] PROCESS FOR PREPARING SUSTAINABLE JET FUELS OR DIESEL FUELS; AND PRECURSORS THEREOF

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to the field of jet fuels, diesel fuels, and precursors thereof. In particular, the present invention relates to a process for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels.

[0004] BACKGROUND OF THE INVENTION

[0005] Aviation turbine fuels, commonly known as jet fuels, are typically made from fossil sources through the refining of crude petroleum or other sources such as coal or natural gas (see FIG. 1). Traditionally, these routes have been preferred due to their optimal combination of energy content, performance, availability, ease of handling, and cost, despite their high CO2 footprint. However, growing concerns about consistent supply and environmental impact has prompted governments and industries to seek more sustainable fuel production processes.

[0006] For economic and safety reasons, jet fuels produced through more sustainable processes must have similar performance properties and be suitable for use in conventional turbine engines. In particular, these fuels must comply with the major specifications for commercial jet fuel as issued by ASTM (American Society for Testing and Materials) under ASTM D1655. Key performance properties of jet fuels include high energy content and good combustion quality.

[0007] In response to these challenges, the industry has explored various alternative jet fuels, including biofuels. Among these, alcohol-to-jet (ATJ) fuel processes have gained attention due to their potential to utilize renewable feedstocks. Alcohols such as ethanol and butanol can be derived from biomass, making them attractive starting materials for sustainable fuel production.

[0008] However, despite recent advances, ATJ fuel processes disclosed in the art typically produce a mixture of products that are not suitable for jet fuel applications because they do not meet the aforementioned performance requirements. Moreover, these processes often require high energy inputs and / or involve complex catalytic systems, undermining their sustainability.

[0009] Accordingly, it is an objective of the present invention to provide a process that overcomes one or more of the above issues. More specifically, it is an objective of the invention to provide an improved process for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels. Preferably, the process starts from alcohols derivable from renewable sources, such as bio-ethanol and fusel alcohols. It is also an objective of the present invention to provide a process that produces aliphatic hydrocarbons with a desirable carbon distribution for jet and / or diesel fuel applications.

[0010] SUMMARY OF THE INVENTION

[0011] The present inventors have now found that one or more of the objectives above can be attained by using the process as presently claimed, and (preferred) embodiments thereof.

[0012] An advantage of the present invention is that aliphatic hydrocarbons can be efficiently produced having a desirable carbon distribution (i.e., linear and branched alkanes having carbon chains of varying length) for jet and / or diesel fuel applications. In particular, it has been found herein that a mixture comprising at least two different chain length primary alcohols can be efficiently converted by means of a Guerbet reaction to produce a mixture comprising a broad distribution of Cg.ig alcohols of desired chain length. The Cg.ig alcohol mixture can be further processed into aliphatic hydrocarbons that conforms to partial specifications of an aviation turbine fuel.

[0013] Another advantage of the present procedure is that the composition of the initial mixture of primary alcohols can be tuned to provide a mixture comprising Cg.ig alcohols with a low to high degree of branching, hence providing a direct route to highly branched aliphatic hydrocarbons.

[0014] Another advantage of the present invention is that the process proceeds with good conversions and by-product formation is negligible.

[0015] Another advantage of the present procedure is that readily available primary alcohols may be used as starting materials. Preferably, the primary alcohols are obtained or obtainable from a sustainable source.

[0016] Another advantage of the present procedure is that alcohols derived from renewable biological sources (i.e., bio-based alcohols) may be used, which improves the sustainability and energy security of the present approach.

[0017] Another advantage is that, next to providing alcohols with even carbon numbers (e.g., Cg alcohol, CM alcohol, C12 alcohol, CMalcohol, CM alcohol, Cig alcohol), the present procedure also allows to provide alcohols having odd carbon numbers (e.g., Cg alcohol, Cn alcohol, Cu alcohol, Ci5alcohol, Ci7alcohol), which can be further processed into aliphatic hydrocarbons. This allows to meet specifications of the Jet Fuel Al type.

[0018] According to a first aspect, the present invention relates to a process for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels. The process preferably comprises the steps of: a) converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg.ig alcohols by means of a Guerbet reaction; b) dehydrating the mixture comprising Cg.ig alcohols to Cg.ig olefins and water; and c) hydrogenating the Cg.ig olefins to aliphatic hydrocarbons.

[0019] In some preferred embodiments, the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, Ni, or a combination thereof; preferably wherein the metal catalyst comprises an (L)nM(OH)n(H2O)mtype complex wherein, n and m are positive integers; M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and L is a ligand.

[0020] In some preferred embodiments, the process comprises the steps of: a) converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg.ig alcohols by means of a Guerbet reaction; b) dehydrating the mixture comprising Cg.ig alcohols to Cg.ig olefins and water; and c) hydrogenating the Cg.ig olefins to aliphatic hydrocarbons; wherein the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (L)nM(OH)n(H2O)mtype complex wherein,

[0021] ■ n and m are positive integers;

[0022] ■ M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and

[0023] ■ L is a ligand.

[0024] In some preferred embodiments, the mixture comprising Cg.ig alcohols comprises at least 90.0 wt.%, preferably at least 95.0 wt.%, of Cg.ig alcohols, based on the total weight of the mixture. In some preferred embodiments, the mixture comprising Cg.ig alcohols is purified before step b) to have at least 90.0 wt.%, preferably at least 95.0 wt.%, ofCg.ig alcohols, based on the total weight of the mixture. In some preferred embodiments, the Guerbet reaction in step a) is performed in the presence of at least one base, wherein the base is an alkoxide or hydroxide; and is preferably selected from the group comprising potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium tert-butoxide, sodium tert-butoxide, potassium isoamylate, sodium isoamylate, and mixtures thereof.

[0025] In some preferred embodiments, the different chain length primary alcohols of step a) are primary Ci- 30 alcohols; preferably Ci.g primary alcohols selected from the group comprising ethanol, isoamyl alcohol, methanol, n-propanol, / so-propanol, n-butanol, sec-butanol, / so-butanol, normal amyl alcohol, active amyl alcohol, neopentyl alcohol, hexan-l-ol, 2,2-dimethylbutan-l-ol, 2,3- dimethylbutan-l-ol, 3,3-dimethylbutan-l-ol, 2-ethylbutan-l-ol, 2-methylpentan-l-ol, 3- methylpentan-l-ol, and 4-methylpentan-l-ol.

[0026] In some preferred embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol and isoamyl alcohol; or methanol and isoamyl alcohol; or ethanol, n-propanol, iso-propanol, and isoamyl alcohol; or ethanol, n-butanol, and isoamyl alcohol; or ethanol, 1-hexanol, and isoamyl alcohol; or ethanol and a primary C5-20 alcohol; or ethanol, a first primary C5-20 alcohol, and a second primary C5-20 alcohol; or ethanol, a first primary C5-20 alcohol, a second primary C5-20 alcohol, and a third primary C5. 20 alcohol.

[0027] An advantage of the aforementioned mixtures is that a mixture comprising Cg.ig alcohols may be obtained having a desirable length and degree of branching for various jet fuel applications.

[0028] In some preferred embodiments, the Guerbet reaction of step a) comprises heating the mixture comprising at least two different chain length primary alcohols to a temperature of from at least 120°C to less than 300°C, for a period of from at least 5 minutes to at most 24 hours.

[0029] In some preferred embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is obtained by distilling a fusel alcohol mixture comprising isoamyl alcohol. Advantageously, this allows the use of a renewable, biomass-derived feedstock for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels. In some preferred embodiments, the mixture comprising Cg.ig alcohols of step a) is separated from the reaction mixture, optionally comprising a portion of unreacted different chain length primary alcohols.

[0030] In some preferred embodiments, the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (HL)nM(OH)n(H2O)mtype complex wherein, n and m are positive integers; M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and HL is a protic mono-, di-, or a polydentate organic ligand selected from the group comprising: indole, maleimide, maltol, 5-hydroxymaltol, kojic acid, tropolone, thujaplicin, hinokitiol, stipitatic acid, 2,6-bis[4-isopropyl-2-oxazolin-2-yl]pyridine, imidazole, 2,6-bis[4- phenyl-2-oxazolin-2-yl]pyridine, 2,6-bis[(3,8)-8H-indeno[l,2-d]oxazolin-2-yl)pyridine, pyrrole, pyrazole, 4-hydroxypyrazole, pyrazole-3-carboxyladehyde, pyrazole-3-carboxylic acid, pyrazole-4- carboxylic acid, pyrazole-3,5-dicarboxylic acid, 4-al kyl / aryl pyrazole, 3-alkyl / aryl pyrazole, 5-al kyl / aryl pyrazole, 3,5-alkyl / aryl pyrazole, 1-benzylpyrazole, 3,5-di(2-pyridyl)pyrazole, 2-(lH-pyrazol-3- yl)phenol, 2-(lH-pyrazol-5-yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5-hydroxypyrazole, tris(l-pyrazolyl)methane, tris(3,5-dimethyl-l-pyrazolyl)methane, bis(pyrazolyl)methane, 4- hydroxybenzimidazole, 1-benzylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, 2- alkylimidazole, 2-arylimidazole, 4-alkylimidazole, 2-aminobenzimidazole, 2-alkylbenzimidazole, 4,5- diarylimidazole, 4,5-dialkylimidazole, 2,4,5-triarylimidazole, 2,4,5-trialkylimidazole, 4-arylimidazole, 5-alkylimidazole, 5-arylimidazole, 4-methylimidazole, 1-benzylpyrazole, 4-arylimidazole, 5- methylimidazole, 2-(lH-imidazol-2-yl)pyridine, 2-(l-hydroxyethyl)benzimidazole, 2-(2- pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-lH-benzimidazole, lH-pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2-pyridyl)benzimidazole, 2-(lH-imidazol-2-yl)pyridine, 2,6-bis(2- benzimidazolyl)pyridine, 2-(3-pyridyl)-lH-benzimidazole, 2-(2-pyridyl)benzothiophene, 2-aryl-4H- (l,2,4)triazole, 2-(4-methyl-2-pyridyl)-lH-benzimidazole, 2-arylbenzothiazole, 2,2'-bipyridine-4,4'- dicarboxylic acid, 2, 2'-bipyridine-5, 5' -dicarboxylic acid, 2, 2'-bipyridine-3, 3' -dicarboxylic acid, 4- imidazolecarboxylic acid, 4-pyrozolecarboxylic acid, pyrrole-3-carboxylic acid, 5-oxazolecarboxylic acid, 2,2'-bis(4,5-dimethylimidazole), 2,2'-bisimidazole, imidazole-4-carboxaldehyde, imidazole-4,5- dicarboxylic acid, 4,4'-bisimidazole, 4,4'-bisbenzimidazole, 2,2'-bisbenzimidazole, 4,5- bis(hydroxymethyl)imidazole, 2-(diphenylphosphino)benzenesulfonic acid, 2-[di(2- methoxyphenyl)phosphino]benzenesulfonic acid, and mixtures thereof.

[0031] In some embodiments, the ligand L may be denoted as a ligand L*. In some preferred embodiments, the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (L*)nM(OH)n(H2O)mtype complex wherein, n and m are positive integers; M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and L* is a ligand; and wherein the ligand L* is selected from the group comprising: a halide, a hydride, an alkoxide, an aryloxide, an amide, an acetate, an acetylacetonate, an alkyl, an aryl, CO, NO, phosphine, pyridine, an alkene, an alkyne, N-heterocyclic carbene, cyclopentadiene, a mono-dentate phosphine of formula PR1R2R3, a bidentate phosphine such as R1R2P-PR1R2, a methylene linked R1R2P- CH2-PR1R2, RlR2P-(CH2)n-PR1R2, or R1R2P-(CH2)n-NR4-(CH2)n-PR1R2; wherein each R1, R2, and / or R3is independently selected from alkyl or aryl, with optional variable functionality such as sulfonate, halide, and wherein R1, R2, R3, R4can be identical or different; preferably wherein R1, R2, R3,and R4are all phenyl; and preferably wherein the ligand L* is selected from the group comprising: a monodentate phosphine of formula PR1R2R3, a bidentate phosphine such as R1R2P-PR1R2, a methylene linked R1R2P-CH2-PR1R2, RlR2P-(CH2)n-PR1R2, or R1R2P-(CH2)n-NR4-(CH2)n-PR1R2; wherein each R1, R2, and / or R3is independently selected from alkyl or aryl, with optional variable functionality such as sulfonate, halide, and wherein R1, R2, R3, R4can be identical or different; preferably wherein R1, R2, R3,and R4are all phenyl.

[0032] In some preferred embodiments, step b) of dehydrating the mixture comprising Cg.ig alcohols is performed in the presence of at least one solid acid catalyst; preferably wherein the solid acid catalyst is selected from the group comprising acidic resins, alumina and aluminosilicates, heteropolyacids, W or Mo functionalized oxides, and mixtures thereof.

[0033] In some preferred embodiments, step b) of dehydrating the mixture comprising Cg.ig alcohols comprises heating to a temperature of from at least 120°C to less than 250°C for a period of from at least 5 minutes to at most 24 hours.

[0034] In some preferred embodiments, step c) of hydrogenating the Cg.ig olefins is performed in the presence of at least one hydrogenation catalyst and hydrogen gas, wherein the hydrogenation catalyst comprises Pt, Pd, Rh, Ru, Ir, Ni, Fe, Cu, Co, Cr, or combinations thereof.

[0035] In some preferred embodiments, step c) of hydrogenating the Cg.ig olefins comprises heating to a temperature of from at least 50°C to less than 300°C for a period of from at least 5 minutes to at most 24 hours.

[0036] In some preferred embodiments, the mixture comprising Cg.ig alcohols further comprises C5.g alcohols, and wherein at least some of the C5.g alcohols are isolated from the mixture and dimerized to CIO-IB alcohols. In some preferred embodiments, step a) and / or step b) and / or step c) is performed in the presence of at least one solvent; preferably wherein the solvent is selected from the group comprising aromatic hydrocarbons, poly(ethylene glycol) monoalkyl ethers, aliphatic hydrocarbons, and combinations thereof.

[0037] The invention also relates to the use of the aliphatic hydrocarbons prepared with the process as described herein, and (preferred) embodiments thereof, as a jet fuel and / or as a diesel fuel.

[0038] The invention also relates to a process for preparing jet and / or diesel fuel, comprising the steps of:

[0039] - preparing aliphatic hydrocarbons with the process as described herein, and (preferred) embodiments thereof; and,

[0040] - providing the prepared aliphatic hydrocarbons as jet and / or diesel fuel.

[0041] The invention also relates to a process for preparing a precursor for jet and / or diesel fuel, comprising the steps of:

[0042] - preparing aliphatic hydrocarbons with the process as described herein, and (preferred) embodiments thereof; and,

[0043] - providing the prepared aliphatic hydrocarbons as a precursor for jet and / or diesel fuel.

[0044] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, which illustrate, by way of example, the principles of the invention.

[0045] DETAILED DESCRIPTION OF THE FIGURES

[0046] The teaching of the application is illustrated by the following Figures which are to be considered as illustrative only and do not in any way limit the scope of the claims.

[0047] FIG. 1 illustrates the conversion of fossil sources such as crude petroleum or other sources such as coal or natural gas into jet fuels.

[0048] FIG. 2 is a graph illustrating the distribution of mixtures of hydrocarbons typically found in jet fuels.

[0049] FIG. 3 is a schematic illustration of a suitable system for dimerization of C2-7 alcohols.

[0050] FIG. 4 is a GC chromatogram illustrating the composition of crude fusel alcohol used in the Example section. FIG. 5 is a GC chromatogram illustrating the composition of cut 1 of the distillation of crude fusel alcohol.

[0051] FIG. 6 is a GC chromatogram illustrating the composition of cut 2 and 3 of the distillation of crude fusel alcohol.

[0052] FIG. 7 is a GC chromatogram illustrating the composition of the residue of the distillation of crude fusel alcohol.

[0053] FIG. 8 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising ethanol and isoamyl alcohol.

[0054] FIG. 9 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising 1-propanol and isoamyl alcohol.

[0055] FIG. 10 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising 1-butanol and isoamyl alcohol.

[0056] FIG. 11 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising 1-hexanol and isoamyl alcohol.

[0057] FIG. 12 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising 1-heptanol and isoamyl alcohol.

[0058] FIG. 13 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising 1-octanol and isoamyl alcohol.

[0059] FIG. 14 is a GC chromatogram illustrating the composition of the Guerbet reaction of a mixture comprising 1-dodecanol and isoamyl alcohol.

[0060] FIG. 15 is a graph illustrating the composition of the alcohol mixture obtained in Example 2.

[0061] FIG. 16 is a GC chromatogram illustrating the composition of the dehydration product of Example 3.

[0062] FIG. 17 is a mass spectrum illustrating the composition of CM olefins produced in Example 3.

[0063] FIG. 18 is a mass spectrum illustrating the composition of Cg.u olefins produced in Example 3.

[0064] FIG. 19 is a GC chromatogram illustrating the composition of the dehydration product of Example 4.

[0065] FIG. 20 is a mass spectrum illustrating the composition of hydrocarbons produced in Example 5.

[0066] DETAILED DESCRIPTION OF THE INVENTION Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0067] The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known, or part of the common general knowledge in any country as of the priority date of any of the claims. Throughout this disclosure, various publications, patents, and published patent specifications are referenced by an identifying citation. All documents cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings or sections of such documents herein specifically referred to are incorporated by reference.

[0068] As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a step" means one step or more than one step.

[0069] The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements, or method steps. The terms also encompass "consisting of" and "consisting essentially of", which enjoy well-established meanings in patent terminology.

[0070] Whereas the terms "one or more" or "at least one", such as one or more members or at least one member of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members. In another example, "one or more" or "at least one" may refer to 1, 2, 3, 4, 5, 6, 7 or more.

[0071] The terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the disclosure described herein are capable of operation in other sequences than described or illustrated herein.

[0072] As used herein, the term "and / or" when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0073] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" or "in a particular embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while certain embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art.

[0074] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all subranges subsumed therein. This applies to numerical ranges irrespective of whether they are introduced by the expression "from... to..." or the expression "between... and..." or another expression.

[0075] As used herein, the terms "about" or "approximately" are used to provide flexibility to a numerical value or range endpoint by providing that a given value may be "a little above" or "a little below" said value or endpoint, depending on the specific context. Hence, the terms "about" or "approximately" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, are meant to encompass variations of and from the specified value or endpoint, such as variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1% or less, and still more preferably + / -0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention.

[0076] Unless otherwise stated, use of the terms "about" or "approximately" in accordance with a specific number or numerical range should also be understood to provide support for such numerical terms or range without the term "about". For example, the recitation of "about 30" should be construed as not only providing support for values a little above and a little below 30, but also for the actual numerical value of 30 as well.

[0077] As used herein, the term "substantially" refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is "substantially" enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of "substantially" is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.

[0078] The terms "wt.%," "vol%", or "mol%" refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component.

[0079] All references cited in the present specification are hereby incorporated by reference in their entirety. In particular, the teachings of all references herein specifically referred to are incorporated by reference.

[0080] Whenever the term "substituted" is used in the present invention, it is meant to indicate that one or more hydrogens on the atom indicated in the expression using "substituted" is replaced with a selection from the indicated group, provided that the indicated atom's normal valency is not exceeded, and that the substitution results in a chemically stable compound. Where groups can be substituted, such groups may be substituted with one or more, and preferably one, two or three substituents.

[0081] The term "halo" or "halogen" as a group or part of a group is generic for fluoro, chloro, bromo, iodo.

[0082] The term "alkyl" as a group or part of a group, refers to a hydrocarbyl group of formula CnHjn+i wherein n is a number greater than or equal to 1, with no site of unsaturation. Alkyl groups may be linear or branched and may be substituted as indicated herein. Generally, alkyl groups can comprise from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, more preferably from 1 to 6 carbon atoms, more preferably from 1 to 4 carbon atoms. When a subscript is used herein following a carbon atom, the subscript refers to the number of carbon atoms that the named group may contain. For example, the term "Ci.galkyl", as a group or part of a group, refers to a hydrocarbyl group of formula CnHjn+i wherein n is a number ranging from 1 to 6. Thus, for example, "Ci.galkyl" includes all linear or branched alkyl groups with between 1 and 6 carbon atoms, and thus includes methyl, ethyl, n-propyl, / -propyl, butyl, and its isomers (e.g., n-butyl, / -butyl, and t-butyl); pentyl and its isomers, hexyl, and its isomers, etc. For example, Ci.4al kyl includes all linear or branched alkyl groups having 1 to 4 carbon atoms, and thus includes for example methyl, ethyl, n-propyl, / -propyl, 2-methyl-ethyl, butyl, and its isomers (e.g., n-butyl, / -butyl, and t-butyl), and the like. In particular embodiments, the term alkyl refers to Ci i2al kyl (Ci-i2 hydrocarbons), yet more in particular to Cuoalkyl (Ci-w hydrocarbons), yet more in particular to Ci.gal kyl (Ci-9 hydrocarbons), yet more in particular to Ci.gal kyl (Ci.g hydrocarbons) as further defined herein above. Non-limiting examples of alkyl include methyl, ethyl, 1-propyl (n-propyl), 2-propyl ( / Pr), 1-butyl, 2-methyl-l-propyl(i-Bu), 2-butyl (s-Bu), 2-dimethyl-2-propyl (t-Bu), 1-pentyl (n-pentyl), 2- pentyl, 3-pentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, 3-methyl-l-butyl, 2-methyl-l-butyl, 1-hexyl, 2- hexyl, 3-hexyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl, 3-methyl-3-pentyl, 2-methyl- 3-pentyl, 2,3-dimethyl-2-butyl, 3,3-dimethyl-2-butyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n- dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-icosyl.

[0083] The term "aryl", as a group or part of a group, refers to a polyunsaturated, aromatic hydrocarbyl group having a single ring (i.e. phenyl) or multiple aromatic rings fused together (e.g. naphthyl), or linked covalently, typically comprising 6 to 12 carbon atoms; wherein at least one ring is aromatic, preferably comprising 6 to 10 carbon atoms, wherein at least one ring is aromatic. The aromatic ring may optionally include one to two additional rings (either cycloalkyl, heterocyclyl or heteroaryl) fused thereto. Examples of suitable aryl include Cg-izaryl, preferably Cg-ioaryl, more preferably Cg-garyl. Nonlimiting examples of aryl comprise phenyl, biphenylyl, biphenylenyl, or 1-or 2-naphthanelyl; 5- or 6- tetralinyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8-azulenyl, 4-, 5-, 6 or 7-indenyl, 4- or 5-indanyl, 5-, 6-, 7- or 8- tetrahydronaphthyl, 1,2,3,4-tetrahydronaphthyl, and 1,4-dihydronaphthyl; 1-, 2-, 3-, 4- or 5-pyrenyl. A "substituted aryl" refers to an aryl group having one or more substituent(s) (for example 1, 2 or 3 substituent(s), or 1 to 2 substituent(s)), at any available point of attachment.

[0084] The term "alkoxy" or "alkyloxy" or "alkoxide", as a group or part of a group, refers to a group having the Formula -ORX1wherein RX1is alkyl as defined herein above. Examples of suitable alkyloxy include Ci-2oalkyloxy, or Cugalkyloxy, or Ci.^alkyloxy, or Ci.galkyloxy. Non-limiting examples of suitable alkoxy include, but are not limited to methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy and hexyloxy. The term "aryloxy" or "aryloxide", as a group or part of a group, refers to a group having the formula -ORx2wherein Rx2is aryl as defined herein above. Examples of suitable aryloxy include C5-3oaryloxy, or Cg-soaryloxy, or Cg-uaryloxy,

[0085] The term "hydroxyl" or "hydroxy", as a group or part of a group, refers to the group -OH. The term "amino" refers to the group -NH?.

[0086] Substituents optionally are designated with or without bonds. Regardless of bond indications, if a substituent is polyvalent (based on its position in the structure referred to), then any and all possible orientations of the substituent are intended.

[0087] The terms described above, and others used in the specification are well understood to those in the art.

[0088] In the following passages, different aspects or embodiments of the invention are defined in more detail. Each aspect or embodiment so defined may be combined with any other aspect(s) or embodiment(s) unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0089] According to a first aspect, the present invention relates to a process for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels. The process preferably comprises the steps of: a) converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg.ig alcohols by means of a Guerbet reaction; b) dehydrating the mixture comprising Cg.ig alcohols to Cg.ig olefins and water; and c) hydrogenating the Cg.ig olefins to aliphatic hydrocarbons.

[0090] As indicated above, the compositions of transportation fuels (e.g., jet and diesel fuels) are not defined at a molecular level. Instead, transportation fuels are defined as mixtures of typically aliphatic and optionally aromatic hydrocarbons that meet a collection of physical properties and specifications (e.g., as described in ASTM D 1655 and FIG. 2). All engines and turbines that use these fuels are designed to use mixtures (typically primarily hydrocarbons) with these specific properties. If other fuel composition are to be widely used as a transportation fuel replacement, it must also meet this collection of physical properties and specifications. Extensive experimentation has advantageously revealed that the present process can provide aliphatic hydrocarbons that meet the fuel-defining ASTM specifications for the respective fuel (e.g., jet or diesel fuels). The term "diesel fuel" refers to a mixture typically comprising primarily hydrocarbon compounds that can be used to operate a diesel engine. In practical terms, the mixture of hydrocarbons called diesel fuel must meet key ASTM specifications for diesel fuel listed in ASTM specification D975. Typical petroleum-based diesel fuels consist of primarily linear aliphatic hydrocarbons with C14-15 alkanes as the major component, and lesser amounts of smaller and larger alkanes.

[0091] The term "jet fuel" refers to a mixture typically comprising primarily hydrocarbon compounds that can be used to operate a jet engine. Jet fuel can also include optional non-hydrocarbon additives. In practical terms, the mixture of hydrocarbons and optional additives called jet fuel must at least meet key ASTM specifications for jet fuel listed in ASTM specification D1655. Typical petroleum-based jet fuels consist primarily of straight chain aliphatic hydrocarbons, with C12 alkanes as the major component, and lesser amounts of aromatics and smaller and larger alkanes. A "fuel precursor" refers to a mixture comprising hydrocarbons (aliphatic and / or aromatic hydrocarbons) that does not meet one or more of the respective fuel specifications (e.g., the ASTM requirements described herein applicable to spark ignition fuels, diesel fuels, or jet fuels), but which can be adjusted to meet these specifications by blending an appropriate amount (e.g., typically up to about 10%, up to about 20%, up to about 30%, up to about 40%, or up to about 50%) of the appropriate hydrocarbons. In some embodiments, the aliphatic hydrocarbons produced by the present process may be fuel precursors that can be further modified to meet specific fuel requirements.

[0092] In what follows below, particularities and properties of the process steps, starting materials applied therein, and resulting products and intermediates will be discussed in greater detail.

[0093] In a first step of the process according to the present invention (step a)), a mixture comprising Cg.ig alcohols is prepared by means of a Guerbet reaction. A Guerbet reaction is a chemical reaction which has a well understood meaning within the art. More specifically, the Guerbet reaction involves the conversion of alcohols of lower molecular weight (i.e., lower alcohols) to alcohols of higher molecular weight (i.e., higher alcohols). Said conversion process comprises a series of dehydrogenation (oxidation), aldol condensation, dehydration, and hydrogenation steps wherein the starting primary alcohols are mainly dimerized to p-alkylated analogues. Optionally, minor amounts of higher homologues, such as trimers, may also be formed when the reaction product reacts with some of the starting alcohol(s) in another Guerbet reaction. In the context of the present invention, a mixture of several different primary alcohols is used, which is typically referred to as a "mixed" Guerbet reaction.

[0094] The term "primary alcohol" as used herein refers to an organic compound with a well-established meaning within the art. More particularly, a primary alcohol is an organic compound comprising a hydroxyl (-OH) group attached to a primary carbon atom. The "chain length" of a primary alcohol refers to the number of carbon atoms in the longest continuous carbon chain to which a hydroxyl group is attached. In other words, the mixture comprising at least two different chain length primary alcohols used in the present process refers to a composition comprising two or more primary alcohols, wherein each primary alcohol has a different number of carbon atoms in its longest continuous carbon chain.

[0095] In particular embodiments, the mixture applied in step a) of the present process comprises at least two primary C1-30 alcohols having a different chain length. The expression "C1-30" as used herein refers to the total number of carbon atoms of the primary alcohol, i.e. ranging from 1 to 30. For example, Ci- 30 alcohol includes all saturated, unsaturated, linear, or branched C1-30 alcohols, and thus includes methanol, ethanol, n-propanol, / so-propanol, butanol and its chain isomers (e.g., n-butanol, iso- butanol, sec-butanol), isoamyl alcohol, normal amyl alcohol, active amyl alcohol, neopentyl alcohol, hexan-l-ol, 2,2-dimethylbutan-l-ol, 2,3-dimethylbutan-l-ol, 3,3-dimethylbutan-l-ol, 2-ethylbutan-l- ol, 2-methylpentan-l-ol, 3-methylpentan-l-ol, and 4-methylpentan-l-ol. Preferably, the mixture applied in step a) of the present process comprises at least two primary Ci.g alcohols.

[0096] In preferred embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising one or more linear, primary Ci.g alcohols and one or more branched, primary C3-6 alcohols. Preferably, the mixture comprises from 10.0 to 90.0 wt.% of one or more linear, primary Ci.g alcohols and from 10.0 to 90.0 wt.% of one or more branched, primary C3-6 alcohols; with wt.% relative to the total weight of the mixture.

[0097] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol and fusel alcohol, preferably isoamyl alcohol. Preferably, the mixture comprises an excess amount of fusel alcohol, such as in a weight ratio of ethanokfusel alcohol of from at least 1:2 to at most 1:100, or at least 1:2 to at most 1:50, or at least 1:2 to at most 1:20, or at least 1:2 to at most 1:10, or at least 1:2 to at most 1:8.

[0098] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising methanol and isoamyl alcohol. Preferably, the mixture comprises an excess amount of isoamyl alcohol, such as in a weight ratio of methanokisoamyl alcohol of from at least 1:2 to at most 1:10, or at least 1:2 to at most 1:8.

[0099] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, n-propanol, iso-propanol, and isoamyl alcohol. Preferably, the mixture comprises an excess amount of isoamyl alcohol, such as in a weight ratio of ethanol:n-propanol:iso-propanol:isoamyl alcohol of from at least 1:1:1:2 to at most 1:2:2:10, or at least 1:1:1:2 to at most 1:2:2:8.

[0100] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, n-propanol, iso-propanol, and isoamyl alcohol. Preferably, the mixture comprises an excess amount of ethanol, such as in a weight ratio of ethanokn- propanokiso-propanokisoamyl alcohol of from at least 2:1:1:1 to at most 5:2:2:5, or at least 2:1:1:1 to at most 4:2:2:4.

[0101] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, n-butanol, and isoamyl alcohol. Preferably, the mixture comprises an excess amount of isoamyl alcohol, such as in a weight ratio of ethanokn- butanokisoamyl alcohol of from at least 1:1:2 to at most 1:2:10, or at least 1:1:2 to at most 1:2:8.

[0102] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, n-butanol, and isoamyl alcohol. Preferably, the mixture comprises an excess amount of ethanol, such as in a weight ratio of ethanokn-butanokisoamyl alcohol of from at least 2:1:1 to at most 5:2:5, or at least 2:1:1 to at most 4:2:4.

[0103] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, 1-hexanol, and isoamyl alcohol. Preferably, the mixture comprises an excess amount of isoamyl alcohol, such as in a weight ratio of ethanokl- hexanokisoamyl alcohol of from at least 1:1:2 to at most 1:2:10, or at least 1:1:2 to at most 1:2:8.

[0104] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, 1-hexanol, and isoamyl alcohol. Preferably, the mixture comprises an excess amount of ethanol, such as in a weight ratio of ethanokl-hexanokisoamyl alcohol of from at least 2:1:1 to at most 5:2:5, or at least 2:1:1 to at most 4:2:4.

[0105] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol and a primary C5-20 alcohol. Preferably, the mixture comprises an excess amount of primary C5-20 alcohol, such as in a weight ratio of ethanokprimary C5-20 alcohol of from at least 1:2 to at most 1:10, or at least 1:2 to at most 1:8.

[0106] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol and a primary C5-20 alcohol. Preferably, the mixture comprises an excess amount of ethanol, such as in a weight ratio of ethanokprimary C5-20 alcohol of from at least 2:1 to at most 5:1, or at least 2:1 to at most 4:1. In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, a first primary C5-20 alcohol, and a second primary C5-20 alcohol. In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol, a first primary C5-20 alcohol, a second primary C5-20 alcohol, and a third primary C5-20 alcohol.

[0107] The preferred amount of each different chain length primary alcohol used may depend to some extent upon the desired carbon distribution and degree of branching of the Cg.ig alcohols comprised in the resulting (Guerbet) mixture as apparent to those skilled in the art.

[0108] The mixture applied in step a) of the present process may be of any origin and obtained by any suitable production method. No limitation regarding the particular origin of the primary alcohols used in the process of the invention, although it is contemplated that certain forms of primary alcohols (e.g., biobased ethanol) may be more suitable than others. Preferably, the mixture comprises primary alcohols that are derived or derivable from a renewable feedstock. At least a part of the primary alcohols may be bio-based.

[0109] Ethanol as described herein may encompass any primary C2 alcohol, including of fossilized and nonfossilized or biological origin. For instance, ethanol may be rectified spirit, i.e., first product of the distilleries that is collected from rectifier column and contains 94.5% alcohol. Alternatively, it may be classified as ordinary denatured spirit (ODS), or special denatured spirit (SDS). Ethanol may also be extra neutral alcohol (ENA) or neutral spirit (NS). In some preferred embodiments, the ethanol may be fuel grade ethanol also known as absolute alcohol (AA).

[0110] In some preferred embodiments, the mixture applied in step a) of the present process is obtained by distilling a fusel alcohol mixture comprising isoamyl alcohol. The term "fusel alcohol" as used herein has a well-established meaning within the art. More particularly, fusel alcohol (also known as fuselol or fusel oil) refers to mixtures of several higher alcohols (i.e., alcohols with more than 2 carbons). Fusel alcohols primarily comprise alcohols of the formula C5HuOH such as isoamyl alcohol (3-methyl-l- butanol), normal amyl alcohol (1-pentanol), and / or active amyl alcohol (2-methyl-l-butanol). For instance, before distillation the fusel alcohol may comprise from 5.0 to 10.0 wt.% of water; from 5.0 to 12.0 wt.% of ethanol; from 55.0 to 65.0 wt.% of isoamyl alcohol; from 5.0 to 10.0 wt.% of butanol and its chain isomers; from 1.0 to 2.0 wt.% of propanol and its chain isomers; and from 1.0 to 2.0 wt.% of methanol. In some preferred embodiments, the mixture applied in step a) of the present process is obtained by distilling a fusel alcohol mixture, thereby obtaining a mixture comprising at least two different chain length primary Ci.g alcohols.

[0111] Advantageously, the fusel alcohols as referred to herein may be obtained as a by-product of alcoholic fermentation, which can aid in improving the overall sustainability of the present process.

[0112] It is apparent to the skilled person that the Guerbet reaction may often be accompanied by several undesired side reactions, which may depend on processing conditions and the type of starting materials used. Possible side reactions include aldehyde overoxidation, ether formation, polymerization or resinification, and the formation of low molecular weight olefins or hydrocarbons via dehydration or decarboxylation pathways. These side reactions reduce the selectivity and purity of the desired Guerbet alcohols, requiring careful control of reaction temperature and residence time. For instance, lower temperatures may lead to higher alcohol selectivities, but may also lower reaction rates making high conversions (> 30.0 wt.% of alcohol based on the total weight of the mixture) difficult to achieve.

[0113] Another challenge with reaching high conversions and / or alcohol selectivity with Guerbet reactions disclosed in the art, is that the reaction typically produces water, which can slow reaction rates significantly and / or promote hydrolysis reactions. The present inventors have surprisingly found that the catalysts as disclosed herein can circumvent these disadvantages observed in the art and are water-tolerant. This advantageously allows to achieve high conversions and alcohol selectivity at moderate processing conditions (i.e., temperature, residence time, and / or pressure). Another advantage of reducing or avoiding unwanted by-products such as tars, acids, or resins is that this helps prevent catalyst fouling or deactivation, which can significantly extend operational uptime and lower catalyst replacement costs.

[0114] The Guerbet reaction may be catalysed to improve the efficiency and / or selectivity of the reaction. Suitable catalysts include metal catalyst comprising a transition metal element, such as Ruthenium (Ru), Iron (Fe), Osmium (Os), Iridium (Ir), Rhodium (Rh), Molybdenum (Mo), Tungsten (W), Scandium (Sc), Technetium (Tc), Palladium (Pd), Platinum (Pt), Zinc (Zn), Nickel (Ni), or a combination thereof.

[0115] The preferred amount of catalyst used may depend to some extent upon the use of the starting mixture comprising at least two different chain length primary alcohols neat or with an additional solvent so as to stay within the confines of the operating temperature, pressure, time, and other variables known to those skilled in the art. Preferably, the amount of the catalyst used is between 0.0001-20.0 wt.%, more preferably 0.01-10.0 wt.% and most preferably 1.00-5.0 wt.%, with wt.% relative to the total weight of the mixture comprising at least two different chain length primary alcohols.

[0116] In particular embodiments, the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, Ni, or a combination thereof. Preferably, the metal catalyst comprises Ru, Fe, Ir, Rh, Pd, Pt, Zn, Ni, or a combination thereof.

[0117] In particular embodiments, the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (L)nM(OH)n(H2O)mtype complex wherein, n and m are positive integers. M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and L is a ligand. Preferably, M is Ru, Fe, Ir, Rh, Pd, Pt, Zn, or Ni. The term "positive integer" as used herein refers to a whole number with a value greater than zero, such as 1, 2, 3, 4, or 5. The complex therefore comprises at least one ligand L.

[0118] The ligand L may refer to any suitable ligand capable of donating at least one pair of electrons to a central metal atom, preferably Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, Ni, to form a coordination complex. The ligand L as described herein may be neutral (e.g., indole) or charged (e.g., halide, alkoxide). The ligand L as described herein may be donate one or more electron pairs to the central metal atom. For instance, the ligand L may be monodentate (i.e., donates one pair of electrons), bidentate (i.e., donates two pairs of electrons), or polydentate (i.e., donates multiple pairs of electrons). The number of ligands L that can be coordinated around a central metal atom, depends on the type of metal atom and other variables known to those skilled in the art.

[0119] The preferred amount of the ligand used may depend to some extent upon the use of catalyst. Preferably, the amount of the ligand used is between 0.1-200 molar equivalents based on the molecular weight of the reaction mixture.

[0120] In some embodiments, the ligand L is referred to as ligand HL; wherein HL is a protic mono-, di-, or a polydentate organic ligand selected from the group comprising indole, maleimide, maltol, 5- hydroxymaltol, kojic acid, tropolone, thujaplicin, hinokitiol, stipitatic acid, 2,6-bis[4-isopropyl-2- oxazolin-2-yl]pyridine, imidazole, 2,6-bis[4-phenyl-2-oxazolin-2-yl]pyridine, 2,6-bis[(3,8)-8H- indeno[l,2-d]oxazolin-2-yl)pyridine, pyrrole, pyrazole, 4-hydroxypyrazole, pyrazole-3- carboxyladehyde, pyrazole-3-carboxylic acid, pyrazole-4-carboxylic acid, pyrazole-3,5-dicarboxylic acid, 4-alkyl / aryl pyrazole, 3-alkyl / aryl pyrazole, 5-alkyl / aryl pyrazole, 3,5-alkyl / aryl pyrazole, 1- benzylpyrazole, 3,5-di(2-pyridyl)pyrazole, 2-(lH-pyrazol-3-yl)phenol, 2-(lH-pyrazol-5-yl)aniline, 3- alkylpyrazole-5-carboxylic acid, indazole, 5-hydroxypyrazole, tris(l-pyrazolyl)methane, tris(3,5- dimethyl-l-pyrazolyl)methane, bis(pyrazolyl)methane, 4-hydroxybenzimidazole, 1-benzylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, 2-alkylimidazole, 2-arylimidazole, 4-alkylimidazole, 2- aminobenzimidazole, 2-alkylbenzimidazole, 4,5-diarylimidazole, 4,5-dialkylimidazole, 2,4,5- triarylimidazole, 2,4,5-trialkylimidazole, 4-arylimidazole, 5-alkylimidazole, 5-arylimidazole, 4- methylimidazole, 1-benzylpyrazole, 4-arylimidazole, 5-methylimidazole, 2-(lH-imidazol-2-yl)pyridine, 2-(l-hydroxyethyl)benzimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-lH- benzimidazole, lH-pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2- pyridyl)benzimidazole, 2-(lH-imidazol-2-yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)- lH-benzimidazole, 2-(2-pyridyl)benzothiophene, 2-aryl-4H-(l,2,4)triazole, 2-(4-methyl-2-pyridyl)-lH- benzimidazole, 2-arylbenzothiazole, 2, 2'-bipyridine-4, 4' -dicarboxylic acid, 2,2'-bipyridine-5,5'- dicarboxylic acid, 2, 2'-bipyridine-3, 3' -dicarboxylic acid, 4-imidazolecarboxylic acid, 4- pyrozolecarboxylic acid, pyrrole-3-carboxylic acid, 5-oxazolecarboxylic acid, 2,2'-bis(4,5- dimethylimidazole), 2,2'-bisimidazole, imidazole-4-carboxaldehyde, imidazole-4,5-dicarboxylic acid, 4,4'-bisimidazole, 4,4'-bisbenzimidazole, 2,2'-bisbenzimidazole, 4,5-bis(hydroxymethyl)imidazole, 2- (diphenylphosphino)benzenesulfonic acid, 2-[di(2-methoxyphenyl)phosphino]benzenesulfonic acid, and mixtures thereof.

[0121] In some preferred embodiments, the ligand L is referred to as ligand HL; wherein HL is selected from the group comprising indole, maleimide, maltol, 5-hydroxymaltol, kojic acid, tropolone, thujaplicin, hinokitiol, stipitatic acid, 2,6-bis[4-isopropyl-2-oxazolin-2-yl]pyridine, imidazole, 2,6-bis[4-phenyl-2- oxazolin-2-yl]pyridine, 2,6-bis[(3,8)-8H-indeno[l,2-d]oxazolin-2-yl)pyridine, pyrrole, pyrazole, 4- hydroxypyrazole, pyrazole-3-carboxyladehyde, pyrazole-3-carboxylic acid, pyrazole-4-carboxylic acid, pyrazole-3,5-dicarboxylic acid, 4-alkyl / aryl pyrazole, 3-alkyl / aryl pyrazole, 5-alkyl / aryl pyrazole, 3,5- alkyl / aryl pyrazole, 1-benzylpyrazole, 3,5-di(2-pyridyl)pyrazole, 2-(lH-pyrazol-3-yl)phenol, 2-(lH- pyrazol-5-yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5-hydroxypyrazole, tris(l- pyrazolyl)methane, tris(3,5-dimethyl-l-pyrazolyl)methane, bis(pyrazolyl)methane, 4- hydroxybenzimidazole, 1-benzylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, 2- alkylimidazole, 2-arylimidazole, 4-alkylimidazole, 2-aminobenzimidazole, 2-alkylbenzimidazole, 4,5- diarylimidazole, 4,5-dialkylimidazole, 2,4,5-triarylimidazole, 2,4,5-trialkylimidazole, 4-arylimidazole, 5-alkylimidazole, 5-arylimidazole, 4-methylimidazole, 1-benzylpyrazole, 4-arylimidazole, 5- alkylimidazole, 5-arylimidazole, 5-methylimidazole, 2-(lH-imidazol-2-yl)pyridine, 2-(l- hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)- lH-benzimidazole, lH-pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2- pyridyl)benzimidazole, 2-(lH-imidazol-2-yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)- lH-benzimidazole, 2-(2-pyridyl)benzothiophene, 2-aryl-4H-(l,2,4)triazole, 2-(4-methyl-2-pyridyl)-lH- benzimidazole, 2-arylbenzothiazole, 2,2'-bipyridine-4, 4' -dicarboxylic acid, 2,2'-bipyridine-5,5'- dicarboxylic acid, 2, 2'-bipyridine-3, 3' -dicarboxylic acid, 4-imidazolecarboxylic acid, 4- pyrozolecarboxylic acid, pyrrole-3-carboxylic acid, 5-oxazolecarboxylic acid, 2,2'-bis(4,5- dimethylimidazole), 2, 2' -bisimidazole, imidazole-4-carboxaldehyde, imidazole-4,5-dicarboxylic acid, 4,4'-bisimidazole, 4,4'-bisbenzimidazole, 2,2'-bisbenzimidazole, 4,5-bis(hydroxymethyl)imidazole, 2- (diphenylphosphino)benzenesulfonic acid, 2-[di(2-methoxyphenyl)phosphino]benzenesulfonic acid.

[0122] In some preferred embodiments, the ligand L is referred to as ligand HL; wherein HL is selected from the group comprising imidazole, 4-hydroxybenzimidazole, 1-benzylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, 2-alkylimidazole, 2-arylimidazole, 4-alkylimidazole, 2-aminobenzimidazole, 2- alkylbenzimidazole, 4,5-diarylimidazole, 4,5-dialkylimidazole, 2,4,5-triarylimidazole, 2,4,5- trialkylimidazole, 4-arylimidazole, 5-alkylimidazole, 5-arylimidazole, 4-methylimidazole, 4- arylimidazole, 5-alkylimidazole, 5-arylimidazole, 5-methylimidazole, 2-(lH-imidazol-2-yl)pyridine, 2- (l-hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)- lH-benzimidazole, 2-(2-pyridyl)benzimidazole, 2-(lH-imidazol-2-yl)pyridine, 2,6-bis(2- benzimidazolyl)pyridine, 2-(3-pyridyl)-lH-benzimidazole, 2-(4-methyl-2-pyridyl)-lH-benzimidazole, 2,2'-bis(4,5-dimethylimidazole), 2,2'-bisimidazole, imidazole-4-carboxaldehyde, imidazole-4,5- dicarboxylic acid, 4,4'-bisimidazole, 4,4'-bisbenzimidazole, 2,2'-bisbenzimidazole, 4,5- bis(hydroxymethyl)imidazole, and mixtures thereof.

[0123] Preferably, the ligand L is referred to as ligand HL; and wherein HL is imidazole.

[0124] In some embodiments, the ligand L is referred to as ligand L*; wherein L* is selected from the group comprising: a halide, a hydride, an alkoxide, an aryloxide, an amide, an acetate, an acetylacetonate, an alkyl, an aryl, CO, NO, phosphine, pyridine, an alkene, an alkyne, N-heterocyclic carbene, cyclopentadiene, a mono-dentate phosphine of formula PR1R2R3, a bidentate phosphine such as R1R2P- PR^2, a methylene linked R1R2P-CH2-PR1R2, RlR2P-(CH2)n-PR1R2, or R1R2P-(CH2)n-NR4-(CH2)n-PR1R2; wherein each R1, R2, and / or R3is independently selected from alkyl or aryl, with optional variable functionality such as sulfonate, halide, and wherein R1, R2, R3, R4can be identical or different.

[0125] In some preferred embodiments, the ligand L is referred to as ligand L*; wherein L* is selected from the group comprising a mono-dentate phosphine of formula PR1R2R3, a bidentate phosphine such as R1R2P-PR1R2, a methylene linked R1R2P-CH2-PR1R2, RlR2P-(CH2)n-PR1R2, or R1R2P-(CH2)n-NR4-(CH2)n- PR3R2; wherein each R1, R2, and / or R3is independently selected from alkyl or aryl, with optional variable functionality such as sulfonate, halide, and wherein R1, R2, R3, R4can be identical or different; preferably wherein R1, R2, R3,and R4are all phenyl.

[0126] In particular embodiments, the process comprises the steps of: a) converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg.ig alcohols by means of a Guerbet reaction; b) dehydrating the mixture comprising Cg.ig alcohols to Cg.ig olefins and water; and c) hydrogenating the Cg.ig olefins to aliphatic hydrocarbons; wherein the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (L)nM(OH)n(H2O)mtype complex wherein,

[0127] ■ n and m are positive integers;

[0128] ■ M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and

[0129] ■ L is a ligand.

[0130] In particular embodiments, the Guerbet reaction in step a) is performed in the presence of activated carbon and / or Raney® Ni.

[0131] The Guerbet reaction in step a) of the present process may be performed in the presence of a base. Any suitable base may be used, preferably a base with a pKa value (in H2O) close to that of the alpha proton of an aldehyde (i.e., around 20). For instance, a base with a pKa (in H2O) of from 5 to 30, or from 10 to 30.

[0132] In some preferred embodiments, the Guerbet reaction in step a) is performed in the presence of at least one base, preferably wherein the base is an alkoxide or hydroxide. Preferably, the amount of base used is from at least 1.0 to at most 30.0 wt.%, more preferably from at least 2.0 to at most 20.0 wt.%, and most preferably from at least 5.0 to at most 10.0 wt.%; with wt.% based on the weight of the mixture comprising at least two different chain length primary alcohols.

[0133] In some preferred embodiments, the base is selected from the group comprising potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium tert-butoxide, sodium tert- butoxide, potassium isoamylate, sodium isoamylate, and mixtures thereof.

[0134] The optimum temperature employed in the Guerbet reaction in step a) of the present process may vary with the composition of the mixture comprising at least two different chain length primary alcohols, and desired process pressure. Generally, the Guerbet reaction can be carried out at the reflux temperature of the mixture comprising at least two different chain length primary alcohols. While a temperature of as low as 100°C can be used and satisfactory results are obtained, it is preferable to employ a temperature of at least 120°C but less than 300°C. In some preferred embodiments, the Guerbet reaction of step a) comprises heating the mixture comprising at least two different chain length primary alcohols to a temperature of from at least 120°C to less than 300°C, for example at least 160°C to at most 275°C or at least 160°C to at most 250°C.

[0135] In some preferred embodiments, the Guerbet reaction of step a) is performed at a pressure of at least 0.01 bar to at most 200.0 bar, such as at least 0.5 bar to at most 200.0 bar, or at least 1.0 bar to at most 200.0 bar, or at least 5.0 bar to at most 200.0 bar, or at least 5.0 bar to at most 150.0 bar.

[0136] In some exemplary embodiments, the Guerbet reaction of step a) is performed at a temperature of between 220°C and 280°C for a reaction time of between 1 hour and 5 hours.

[0137] In some exemplary embodiments, the Guerbet reaction of step a) is performed at a temperature of between 150°C and 250°C for a reaction time of between 1 hour and 5 hours.

[0138] In some exemplary embodiments, the Guerbet reaction of step a) is performed at a temperature of between 200°C and 250°C for a reaction time of between 1 hour and 5 hours.

[0139] In some exemplary embodiments, the Guerbet reaction of step a) is performed at a temperature of between 150°C and 200°C for a reaction time of between 1 hour and 5 hours.

[0140] The specific time period over which the conversion to higher alcohols (i.e., a mixture comprising Cg.ig alcohols) may be achieved upon reaching a target temperature and pressure, i.e., the "retention time or residence time" may depend on a number different factors including, for example, the composition of the mixture comprising at least two different chain length primary alcohols, the types of catalyst(s) as defined herein, in the mixture and their various concentrations. These and other factors may be varied to optimise a given process to maximise the yield and / or reduce the processing time. Preferably, the retention time is sufficient to convert all or substantially all of the mixture comprising at least two different chain length primary alcohols used into the product mixture comprising Cg-ig alcohols. The time required for the reaction is not particularly critical and can be varied as desired, although it should preferably be sufficiently long to ensure obtaining an appreciable conversion of the mixture comprising at least two different chain length primary alcohols to the mixture comprising Cg. ig alcohols, but at the same time preferably not so long as to allow further condensation to higher oligomers. In general, a reaction time of 5 minutes to 24 hours or more is adequate although best results are obtained with a period of about 0.5-6 hours at optimum temperature, pressure, and / or catalyst concentration.

[0141] Guerbet reaction of step a) of the present process provides that the lower molecular weight alcohols of the starting mixture are converted to p-alkylated alcohols of higher molecular weight. The resulting mixture comprising Cg.ig alcohols also termed herein "Guerbet mixture" or "Guerbet alcohol mixture" preferably comprises at least a Cg alcohol, a Cg alcohol, a CM alcohol, and a CMalcohol, including all isomers thereof.

[0142] The chain length of the alcohols comprised in the Guerbet mixture depends in principle on the different chain length primary alcohols used as a starting material. Advantageously, it has been found herein that by using a larger number of diverse alcohols, a greater variety of alcohols comprised in the Guerbet mixture can be obtained. In particular, the composition of the starting alcohol mixture can be tuned to obtain a Guerbet mixture comprising a desired amount of alcohols with desired chain length.

[0143] The chemical composition of the Guerbet mixture can be distinguished by using different analytical techniques well known to the person skilled in the art. For example, mass spectrometry,1H and13C NMR, and elemental analysis may be used among other techniques. Gas chromatography-mass spectrometry (GC-MS) may be particularly suitable for determining the composition of the Guerbet mixture as described in herein in the Example section.

[0144] In an exemplary embodiment, the mixture comprising Cg.ig alcohols comprises a Cg alcohol, a CM alcohol, a C12 alcohol, and a CMalcohol; preferably in a ratio of 5.0: 15.0: 40.0: 10.0: 30.0.

[0145] In an exemplary embodiment, the mixture comprising Cg.ig alcohols comprises a Cg alcohol, a Cg alcohol, a CM alcohol, a Cn alcohol, a C12 alcohol, a C13 alcohol, a CMalcohol, and a C15 alcohol; preferably in a ratio of 2:14:28:24:15:10:5:2.

[0146] It should be noted that the mixture comprising Cg.ig alcohols may further comprise C2-7 alcohols which can be unreacted primary alcohols of the starting mixture and / or lower dimerization products. For instance, in the event that the initial mixture comprises ethanol and isoamyl alcohol, two ethanol molecules may be converted to a C4alcohol by means of the Guerbet reaction.

[0147] In exemplary embodiments, the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising ethanol and fusel alcohol, preferably isoamyl alcohol; and the resulting mixture after Guerbet reaction is a mixture comprising Cg and CM alcohol. The resulting mixture may further comprise C4, C5, Cg, and C7alcohol. In some preferred embodiments, the mixture comprising Cg-ig alcohols comprises at least 60 wt.% of Cg-ig alcohols, or at least 70 wt.% of Cg-ig alcohols, or at least 75 wt.% of Cg-ig alcohols, or at least 80 wt.% of Cg-ig alcohols, or at least 85 wt.% of Cg-ig alcohols, or at least 90 wt.% of Cg-ig alcohols, or at least 95 wt.% of Cg-ig alcohols, or at least 98 wt.% of Cg-ig alcohols, with wt.% based on the total weight of the mixture.

[0148] It has been found herein that achieving high alcohol purity significantly reduces the need for extensive downstream purification. In particular, if the starting alcohol is not cleanly and completely converted into the desired alcohol mixture, side products with similar or overlapping boiling points may form. This complicates separation and hampers further purification. As a result, the overall process may become economically unviable, potentially requiring tedious purification steps such as additional rectification columns, increasing both capital (CAPEX) and operational (OPEX) expenditures.

[0149] In some preferred embodiments, the mixture comprising Cg-ig alcohols comprises at least 60 wt.% of Cg-ig alcohols, and preferably at most 40 wt.% of C2-7 alcohols, or at least 70 wt.% of Cg-ig alcohols, and preferably at most 30 wt.% of C2-7 alcohols, or at least 75 wt.% of Cg-ig alcohols, and preferably at most 25 wt.% of C2-7 alcohols, or at least 80 wt.% of Cg-ig alcohols, and preferably at most 20 wt.% of C2-7 alcohols, or at least 85 wt.% of Cg-ig alcohols, and preferably at most 15 wt.% of C2-7 alcohols, or at least 90 wt.% of Cg-ig alcohols, and preferably at most 10 wt.% of C2-7 alcohols, or at least 95 wt.% of Cg-ig alcohols, and preferably at most 5 wt.% of C2-7 alcohols, or at least 98 wt.% of Cg-ig alcohols, and preferably at most 2 wt.% of C2-7 alcohols.

[0150] In particular embodiments, converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg-ig alcohols by means of a Guerbet reaction is characterized by a conversion of between 20% and 98% per pass, or between 20% and 90% per pass, or between 20% and 85% per pass, or between 20% and 80% per pass, or between 20% and 75% per pass, or between 20% and 70% per pass, or between 30% and 70% per pass, or between 40% and 70% per pass.

[0151] In particular embodiments, the present process further comprises the step of isolating desired Cg-ig alcohols from the mixture comprising Cg-ig alcohols. For instance, the Cg-ig alcohols may be separated from lower dimerization products (e.g., C2-7alcohols) and possible impurities comprised in the Guerbet mixture. Suitable separation techniques include distillation. The remaining C2-7 alcohols may further be converted to higher alcohols in another Guerbet reaction or by other dimerization reactions.

[0152] The separated C2-7 alcohols may further be converted to higher alcohols by other dimerization reactions. A suitable dimerization system is shown herein in FIG. 3. In some preferred embodiments, the mixture comprising Cg-ig alcohols may be purified before step b) of the present process to have at least 60 wt.% of Cg-ig alcohols, or at least 70 wt.% of Cg-ig alcohols, or at least 75 wt.% of Cg-ig alcohols, or at least 80 wt.% of Cg-ig alcohols, or at least 85 wt.% of Cg-ig alcohols, or at least 90 wt.% of Cg-ig alcohols, or at least 95 wt.% of Cg-ig alcohols, or at least 98 wt.% of C8-ig alcohols, with wt.% based on the total weight of the mixture.

[0153] A commercial process to convert a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg-ig alcohols by means of a Guerbet reaction using aspects of the present invention may be realized in many different ways, for example depending on the preferred conditions for the starting alcohol mixture to be converted. By way of example, an industrial process employing features of the present invention may include some or all of the following steps.

[0154] Any one of the different chain length primary alcohols comprised in the starting mixture may be pretreated to achieve a desired composition and / or degree of purity. Pre-treatment may include the removal of trace contaminants and / or distillation. The catalyst may be prepared when required either offsite by specialist suppliers or onsite, depending on the type of reaction system and the ease of catalyst preparation, transportation, and storage.

[0155] The process sub-steps involved in step a) of the present process such as heating / pressurization and cooling / de-pressurization may be facilitated by performing the process in a continuous flow system which may be a CSTR or tubular reactor or a microchannel reactor apparatus.

[0156] Following the pre-treatment, a feed comprising the starting alcohol mixture (i.e., comprising at least two different chain length primary alcohols) and catalyst solution may be fed to the system. Separate pumps may be used to dose the starting mixture and catalyst solution. Both streams may flow to a mixer. A reactor system, which may comprise a heating thermostat and temperature control, may be used to pre-heat the mixture, for example to 50°C.

[0157] The reactor preferably allows for control over residence time, mixing rate, temperature ramping rate as well as final reaction temperature, for example of 160-275°C. The processes of heating / pressurisation and cooling / de-pressurisation may be facilitated by performing the process of the invention in a continuous flow system which may be a CSTR or tubular reactor or a microchannel reactor.

[0158] An optimum reaction temperature for the production of Guerbet alcohols is typically in the range of 160-275°C and pressure of about 100 bar with a residence time of less than 10 hours. The reaction 1 pressure may be controlled by a pressure regulator. The pressure elevation may be realised by a feed pump (A), and / or one or more catalyst solution pumps (B).

[0159] Once the mixture has fully reacted, the product mixture comprising Cg.ig alcohols are preferably separated from the catalyst solution in a separator, for example by means of pressure, temperature, and / or velocity control. In some embodiments, the catalyst solution is recycled through a pump, and directed back to a mixer.

[0160] The alcohol products that are separated in a separator, preferably flow towards a distillation system. A cooling thermostat may be used to perform a fractionated distillation. The quantity of fractionated product streams can be modified in regard of the process conditions and requirements.

[0161] In a second step of the present process (step b)), the mixture comprising Cg.ig alcohols obtained in step a) of the present process is subjected to a dehydration reaction to obtain Cg.ig olefins and water. The terms "dehydration" or "dehydrating" as used herein as synonyms refer to a chemical reaction that can convert alcohols into their corresponding olefin. Typically, dehydration reactions of alcohols are associated with side-reactions such as the formation of corresponding ethers. Advantageously, it has been found herein that present process may suppress such side-reactions, which makes the present process more selective for the formation of desired Cg.ig olefins.

[0162] In some preferred embodiments, dehydration of the mixture comprising Cg.ig alcohols according to step b) of the process of the present invention results in the formation of less than 5 % of ether, or less than 2 % of ether; with % based on the total amount of Cg.ig alcohols.

[0163] Olefins are molecules with a well-established meaning within the state of the art. In particular, olefins also known as alkenes, are hydrocarbons that contain a carbon-carbon double bond. In the context of the present invention, the term "Cg.ig olefins" refers to olefins of the formula CnH2nof specific chain length. The chain length, denoted by n, specifies the exact number of carbon atoms in the olefin. More particularly, the Cg.ig olefins as described herein are mono-olefins (i.e., comprising a single double bond) having a fixed number of carbon atoms in its longest continuous carbon chain.

[0164] The dehydration of Cg.ig alcohols to Cg.ig olefins according to step b) of the present process can be catalysed by many different catalysts as apparent to the person skilled in the art. In general, acidic heterogeneous or homogeneous catalysts are particularly suitable, for instance when used in a reactor maintained under conditions suitable for dehydrating the alcohol. Typically, the Cg.ig alcohol is activated by the (acid) catalyst to facilitate the loss of water. The water is usually isolated from the reaction mixture. Because water may be generated in large quantities in the dehydration step, the catalysts used are generally tolerant to water and a process for removing the water from the reaction mixture and product may be part of any process that contains a dehydration step.

[0165] The amount of catalyst used will depend to some extent upon the composition of the mixture comprising Cg.ig alcohols neat or with an additional solvent so as to stay within the confines of the operating temperature, pressure, time, and other variables known to those skilled in the art. Preferably, the amount of the catalyst used is between 0.0001-10 wt.%; with wt.% relative to the total weight of the mixture comprising Cg.ig alcohols.

[0166] In particular embodiments, step b) of dehydrating the mixture comprising Cg.ig alcohols is performed in the presence of at least one solid acid catalyst. Suitable solid acid catalysts include acidic resins, alumina and aluminosilicates, heteropolyacids, W or Mo functionalized oxides. Non-limiting examples of acidic resins include Amberlyst™, Nation™, Dowex™, and Meryt™. Non-limiting examples of aluminosilicates include SiOj-AhOg and zeolites such as H-beta, H-Y, H-ZSM-5. Non-limiting examples of heteropolyacids include tungstophosphoric acid, silicotungstic acid, molybdotungstic acid, molybdophosphoric acid. Non-limiting examples of W and Mo functionalized oxides include MOx / ZrC , MOx / TiOj, MOx / ALOg, where x is 1-3 and M = Mo or W. More traditional acid catalysts may also be used where necessary such as para-toluene sulfonic acid; H2SO4, H3PO4, and triflic acid. Alternatively, ZnO, Zn / ALOg, or ZnO / ALOg may also be used as a dehydrating catalyst.

[0167] In some preferred embodiments, the solid acid catalyst is selected from the group comprising aluminosilicates, preferably H-ZSM-5, and heteropolyacids. It has been found herein that the listed solid acid catalysts provide for more selective conversion of olefins over ethers at modest processing conditions. In addition, said catalyst can advantageously be recycled several times. It is also upscalable using existing petrochemical assets.

[0168] The optimum dehydration temperature may vary depending on the composition of the mixture comprising Cg.ig alcohols and catalyst used. While a temperature of as low as 120°C can be used and satisfactory results are obtained, it is preferable to employ a temperature of at least 160°C but less than 250°C to minimize the formation of ethers in the dehydration process.

[0169] The specific time period over which the dehydration reaction may be achieved upon reaching a target temperature and pressure, i.e., the "retention time or residence time" may depend on a number different factors including, for example, the amount of Cg.ig alcohol in the mixture and their various concentrations, the type of catalyst used. These and other factors may be varied to optimise a given method to maximise the yield and / or reduce the processing time. Preferably, the retention time is sufficient to convert all or substantially all of the mixture comprising Cg.ig alcohols into the product Cg. ig olefins to avoid subsequent distillation and separation procedures. In general, a reaction time of 5 minutes to 36 hours or more is adequate although best results are obtained with a period of about 0.5-10 hours at optimum temperature, pressure, and catalyst concentration.

[0170] In a third step of the present process (step c)), the Cg-ig olefins obtained in step b) of the present process are hydrogenated to aliphatic hydrocarbons. The terms "hydrogenation" and "hydrogenated" as used herein as synonyms refer to a chemical reaction wherein molecular hydrogen (Hz) is added to an unsaturated hydrocarbon (e.g., olefin) to reduce double bonds, thereby obtaining saturated, aliphatic hydrocarbons.

[0171] Aliphatic hydrocarbons are compounds with a well-established meaning within the state of the art. More specifically, the terms "aliphatic hydrocarbons" or "alkanes" as used herein interchangeably refer to organic compounds consisting exclusively of carbon and hydrogen atoms. Aliphatic hydrocarbons are characterized by their open-chain (linear or branched) structure, distinguishing them from cyclic and aromatic hydrocarbons.

[0172] The hydrogenation of Cg-ig olefins to aliphatic hydrocarbons according to step c) of the present process can be catalysed by catalysts that facilitate the addition of hydrogen as apparent to the person skilled in the art. Suitable catalysts include metal catalysts comprising transition metals such as Pt, Pd, Rh, Ru, Ir, Ni, Fe, Cu, Co, Cr, or combinations thereof. These metal catalysts can be used in various forms, including supported on a substrate (e.g., activated carbon, alumina, silica) or as colloidal dispersions. Non-limiting examples of suitable metal catalysts include homogeneous hydrogenation catalysts such as (Rh PPhgJgCI), Ru(PPh3h(lnd)CI, Rh(cod)(acac), [lr(cod)(acac)] or heterogeneous catalysts such as Raney Ni, Co, or Cr catalysts.

[0173] The amount of the catalyst used will depend to some extent upon the composition of the Cg-ig olefins so as to stay within the confines of the operating temperature, pressure, time, and other variables known to those skilled in the art. Preferably, the amount of the hydrogenation catalyst used is between 0.0001-20 wt.%; with wt.% based on the total weight of olefins.

[0174] The optimum temperature employed in the hydrogenation reaction will vary with the composition of the C8-is olefins, catalyst used, and desired process pressure. While a temperature of as low as 50°C can be used and satisfactory results are obtained, it is preferable to employ a temperature of at least 150°C but less than 300°C.

[0175] In preferred embodiments, the aliphatic hydrocarbons comprise Cg-ig alkanes. In an exemplary embodiment, the aliphatic hydrocarbons comprise a Cg alkane, a CM alkane, a C12 alkane, and a CMalkane; preferably in a ratio of 6:5:2:2.

[0176] In an exemplary embodiment, the aliphatic hydrocarbons comprise a Cg alkane, a Cg alkane, a CM alkane, a Cn alkane, a C12 alkane, a C13 alkane, a CMalkane, and a C15 alkane; preferably in a ratio of 2:14:28:24:15:10:5:2.

[0177] As described herein, the various operations of the process of the present invention (e.g., Guerbet reaction, dehydration reaction, hydrogenation reaction, etc.) can be carried out in a suitable reactor vessel. Non-limiting examples of suitable reactors include a batch reactor, a flow reactor, a continuous flow reactor, a tubular reactor, or a microchannel reactor. Preferably, the process of the present invention is performed in a continuous stirred-tank reactor (CSTR) or batch reactor. The present invention also comprises a reactor or system of reactors configured to perform the process of the present invention, and (preferred) embodiments thereof.

[0178] In particular embodiments, step a) and / or step b) and / or step c) of the present process may be performed in the presence of a suitable solvent. The solvent used may be the same or different for each step. Suitable solvents include aromatics, poly(ethylene glycol) (PEG) monoalkyl ethers, aliphatics (straight chain or branched), aromatics with aliphatic substitutions, xylenes, cycloalkanes, substituted cycloalkanes, naphthenes, indenes, fluorene, biphenyls, Petrosolv 200-300, Petroflux ND, Petrosolv 250-450, SOLGAD 150, SOLGAD 200, SOLGAD 200 ULN, SOLGAD 150 ULN, sulfolane, dimethyl sulfoxide, dimethyl formamide, N-methyl pyrrolidone, N,N-dimethyl acetamide, 1,4-dioxane, anisole, propylene carbonate, benzyl alcohol, N-methylpyrrolidone, N-ethylpyrrolidone, N- cyclohexylpyrrolidone, N-octylpyrrolidone, ethyllactate, butyllactate, morpholine, glycerin, glycerin- mono-tert-butyl-ether, glycerin-di-tert-butyl-ether, glycerin-tri-tert-butyl-ether, acetonitrile, propionitrile, di-arylether, alkyl aryl ethers, ionic liquids, dicarboxylic / tricarboxylic ester-based plasticisers, bis(2-ethylhexyl) phthalate, diisononyl phthalate, bis(n-butyl)phthalate, butyl benzyl phthalate, diisodecyl phthalate, di-n-octyl phthalate, diisooctyl phthalate, diethyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate, trimellitates, trimethyl trimellitate, tri-(2-ethylhexyl) trimellitate, tri- (n-octyl,n-decyl) trimellitate, tri-(heptyl, nonyl) trimellitate, n-octyl trimellitate, bis(2- ethylhexyl)adipate, dimethyl adipate, monomethyl adipate, dioctyl adipate, sebacate-based plasticisers, dibutyl sebacate, maleates, dibutyl maleate, diisobutyl maleate, benzoates, epoxidised vegetable oils, sulfonamides, N-ethyl toluene sulfonamide (ortho and para isomers), N-(2- hydroxypropyl) benzene sulfonamide, N-(n-butyl) benzene sulfonamide, organophosphates, tricresyl phosphate, tributyl phosphate, glycols, polyethers, triethylene glycol dihexanoate, tetraethylene glycol diheptanoate, polybutene, acetylated monoglycerides, alkyl citrates, triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, trioctyl citrate, acetyl trioctyl citrate, trihexyl citrate, acetyl trihexyl citrate, butyryl trihexyl citrate, trihexyl o-butyryl citrate, trimethyl citrate, alkyl sulphonic acid phenyl ester, vinyl chloride copolymers, 1,2-cyclohexane dicarboxylic acid diisononyl ester, biphenyl, triphenylmethane, polyaromatic hydrocarbons, tetralin, naphthalene, tetrahydro anthracene, anthracene, hexahydro pyrene, trihydropyrene, pyrene, phenanthrene, chrysene, paraffins, paraffinic intermediates, light naphtha, mid-naphtha, light gas oil, mid gas oil, heavy gas oil, light vacuum gas oil, mid-vacuum gas oil, heavy vacuum gas oil, vacuum residue, linear alkyl benzenes, vegetable oils, fatty acid methyl esters, animal fats / tallow, a optionally substituted derivatives thereof, and combinations thereof.

[0179] In some preferred embodiments, the solvent comprises aromatics with aliphatic substitutions, such as mesitylene. In some preferred embodiments, the solvent comprises a Petrosolv solvent, which boils at 250°C. Petrosolv 200-300 is not a stand-alone molecule but a cut from a distillation and has certain uses as a solvent. It consists of over 200 molecules in different ratios from GC. In some preferred embodiments, the solvent comprises mesitylene and Petrosolv. In some preferred embodiments, the solvent comprises xylene(s). In some preferred embodiments, the solvent comprises xylene(s) and mesitylene. In some preferred embodiments, the solvent comprises xylene(s) and a Petrosolv solvent. In some preferred embodiments, the solvent comprises xylene(s), mesitylene, and a Petrosolv solvent. In some preferred embodiments, the solvent comprises 1-propanol. In some preferred embodiments, the solvent used in one or more steps of the present process may be recycled for use in subsequent reactions.

[0180] The present invention further encompasses the aliphatic hydrocarbons obtained or obtainable by means of the process according to a first aspect of the present invention.

[0181] The invention also relates to the use of the aliphatic hydrocarbons prepared with the process as described herein, and (preferred) embodiments thereof, as a jet fuel and / or as a diesel fuel. In some embodiments, the aliphatic hydrocarbons are used as jet fuel. In some embodiments, the aliphatic hydrocarbons are used as diesel fuel. The invention also relates to the use of the aliphatic hydrocarbons prepared with the process as described herein, and (preferred) embodiments thereof, as a precursor for jet fuel and / or diesel fuel. In some embodiments, the aliphatic hydrocarbons are used as a precursor for jet fuel. In some embodiments, the aliphatic hydrocarbons are used as a precursor for diesel fuel. It is clear that (preferred) embodiments of the processes for preparing aliphatic hydrocarbons as described herein are also intended to be (preferred) embodiments of the uses as described herein, and vice versa.

[0182] The invention also relates to a process for preparing jet and / or diesel fuel, comprising the steps of:

[0183] - preparing aliphatic hydrocarbons with the process as described herein, and (preferred) embodiments thereof; and,

[0184] - providing the prepared aliphatic hydrocarbons as jet and / or diesel fuel.

[0185] The invention also relates to a process for preparing a precursor for jet and / or diesel fuel, comprising the steps of:

[0186] - preparing aliphatic hydrocarbons with the process as described herein, and (preferred) embodiments thereof; and,

[0187] - providing the prepared aliphatic hydrocarbons as a precursor for jet and / or diesel fuel.

[0188] It is clear that (preferred) embodiments of the processes for preparing aliphatic hydrocarbons as described herein are also intended to be (preferred) embodiments of the processes for preparing (precursors for) jet fuels and / or diesel fuels as described herein, and vice versa.

[0189] EXAMPLES

[0190] The invention is illustrated but not limited by the following examples.

[0191] Materials

[0192] Commercially obtained reagents were used as received from appropriate commercial vendors, such as VWR or Merck, without any further purification.

[0193] Ethanol (industrial-fuel grade) with specifications listed in ASTM D4806 was purchased from VWR Chemicals. Isoamyl alcohol (technical grade) - alternatively crude fusel alcohol resulting from a bioethanol production facility may also be used - and technical grade xylenes mixture, were purchased from VWR Chemicals. KOH (>85%) was purchased from Carl Roth GmbH. Iron (II) chloride tetrahydrate was purchased from Merck. Triphenyl phosphine was purchased from Acros Organics. Celite 535 was purchased from Macherey-Nagel GmbH & Co. KG.

[0194] Analytics Gas chromatogram - flame ionization detector (GC-FID), gas chromatogram - mass spectra (GC-MS) analyses were carried out on an Agilent 8890 using a HP-5ms column, in-house. All crude solutions were prepared in diethyl ether in 2mL vials with PTFE screw caps. The conditions listed in Table 1 were used for each gas chromatography analysis of the starting materials, formed intermediates, and / or formed products as described herein. Low boiling methanol or isopropanol were used as internal standards to determine the concentration of each analysed mixture.

[0195] Table 1. Chromatographic Conditions for product analysis

[0196] GC Agilent 8890 / 5977B GC / MSD

[0197] Sampler Agilent 7650A, 5.0-pL syringe

[0198] Carrier Hydrogen 30 cm / s, constant flow

[0199] Inlet Split (15:1); 250°C, purge flow 22.5 mL / min

[0200] Inlet liner Deactivated dual taper direct connect

[0201] Column Agilent HP-5ms 30 m x 0.25 mm x 0.25 pm

[0202] Oven 42°C (6 min) to 220°C (10°C / min), 15°C / min to 310°C

[0203] Detection MSD source at 230°C, quadrupole at 150°C, scan range 30 to 300 amu

[0204] Ethanol

[0205] All experiments employed industrial grade - fuel grade ethanol as listed below. In particular, an ethanol feed complying with ASTM D4806 standard for denatured fuel ethanol for blending with gasolines for use as automotive spark ignition engine fuel with specifications as listed below in Table 2 was used.

[0206] Table 2.

[0207] Quality Parameter Limits ASTM Test Methods

[0208] Ethanol, % by volume, min 92.1 D5501

[0209] Methanol, % by volume, max 0.5 D5501

[0210] Solvent washed gum, mg / lOOmL, max 5.0 D381

[0211] Water content, % by volume, (% by mass), max 1.0 (1.26) D7923, E1064 or E203

[0212] Inorganic Chloride, mg / kg (mg / L), max 6.7 (5) D7319 or D7328

[0213] Copper, mg / kg, max 0.1 D1688

[0214] Acidity, as acetic acid, mg / kg, (% by mass) [mg / L], max 70 (0.0070) D7795 pH 6.5-9.0 D6423

[0215] Sulphur, mg / kg, max 30.00 D5453 Existent Sulphate, mg / kg, max 4 D7318, D7319 or D7328

[0216] Fusel alcohol

[0217] All experiments employed commercial grade - crude fusel alcohol as listed in Table 3 and illustrated in FIG. 4. This was distilled to separate desired amyl alcohols from higher boiling compounds prior to use in the process according to the present invention. Table 3.

[0218] Compound wt.% Boiling point (°C) acetaldehyde 0.0000 20.2 ethanol 2.5850 78.4 ethyl acetate 0.0000 77.1

[0219] 1-propanol 0.1400 97

[0220] 1,1-diethoxy ethane 0.0000 104

[0221] 2-methyl propanol 0.8970 108 isoamyl alcohol 88.9640 131

[0222] 1-pentanol 0.2800 138

[0223] 1-hexanol 1.5130 157 l-(l-ethoxyethoxy)-pentane 0.00 173 high boiling compounds 1.1210 > 200

[0224] Water 4.5000 100

[0225] Chloride ASTMD512M 3.8 mg / kg

[0226] Sulphur 62 mg / kg

[0227] Nitrogen 28 mg / kg

[0228] Total acidity (as acetic acid) EN 15491 0.324 wt%

[0229] Distillation of crude fusel alcohol was performed in a 50L PD 256 PB Continuous Pulsed-Batch Distillation System with a 2000 mm column length, a nominal diameter of DN100, and wire-mesh packing. The instrument was operated in a batch mode. A feed of fusel alcohol was loaded into the reboiler vessel of the distillation system. An initial temperature difference of 50°C between vessel and surrounding jacketed oil was applied for maximum heat / power transfer. Pressure was kept at atmospheric and reflux ratio was varied during the distillation. For each parameter set, a single cut was taken. Further details of the distillation process are shown in Table 4. First, a low reflux ratio was applied to remove most of the lower-boiling compounds. Next, the reflux ratio was gradually increased to improve the purity of this cut. Once the head temperature reached the boiling point of isoamyl alcohol, the process was repeated twice to increase the amyl alcohol content. After cut 3, the distillation rate dropped, and the pressure was lowered to 600 mbar with a 20% increase in heating power to distil out any remaining isoamyl alcohol. The distillation was then terminated and individual samples from each cut were weighed on a IFB 300K-2 weighing scale from Kern with an accuracy of 0.01 kg. GC analysis was performed on cut 1-3 and the remaining residue as shown in FIG. 5-7. Cut 3 represented 99.2% pure amyl alcohol with 87.03% of isoamyl alcohol (3-methyl-butanol) and 12.97% of active amyl alcohol (2-methyl-butanol). Summarized, the crude fusel alcohol distillation had the following mass balance:

[0230] Input: Crude fusel 25.95 kg

[0231] Output: Light ends 3.08 kg (contains 0.12 kg of water - used as feed for Guerbet); Isoamyl alcohol 16.2 kg; Heavy ends 1.04 kg (contains 0.86 kg of isoamyl alcohol - recycled); Holdup 3.88 kg (residual isoamyl alcohol); Water fractions 1.72 kg.

[0232] Table 4.

[0233] Feed Cut range, head (°C) Time (min) P (mbar) RR MB (kg)

[0234] Cut 1 < 90 20 1000 5 3.08

[0235] Cut 2 90 < x < 120 35 1000 3 5.61

[0236] Cut 3 120 < x < 140 72 1000 10 16.20

[0237] Residue - - 600 - 1.04

[0238] Wherein the following abbreviations were used RR = Reflux Ratio = reflux time / offtake time, MB = mass balance.

[0239] Catalyst for the Guerbet reaction

[0240] A catalyst for the Guerbet reaction (herein termed Catalyst A) was prepared by mixing ruthenium as a trichloride. hydrate salt, imidazole, Raney® Ni, and activated carbon in a molar ratio of 1.0: 0.76: 2.42: 43.2. The catalyst was used as such without further purification.

[0241] Example 1

[0242] In a first example, it was determined whether suitable mixtures comprising alcohols with a desirable carbon distribution could be obtained by means of a Guerbet reaction when starting from different primary alcohol mixtures.

[0243] Catalyst A (30 ppm), KOH (120 g, 4%), 2 mL water, and a mixture comprising a first primary alcohol Cxand a second primary alcohol Cyin a ratio of a:b as shown in Table 5 were premixed at ambient temperature in air. For each mixture, the resulting 3L feed was dosed with a PD 5206 Heidolph peristaltic pump to a fixed head 2L Parr reactor vessel IL at a time, equipped with heating mantle and an overhead stirrer at a controlled stirring speed set at 350 rpm. The reactor vessel was made from stainless steel 316. Each reaction mixture was then heated at 70°C (2h), then ramped at 20°C increments to a temperature T in lh, time at temperature T = 't' (see Table 5). Each resulting (Guerbet) reaction mixture was cooled to about 20°C and subsequently transferred to a separating funnel, and washed with water containing 2% acetic acid (4 times 250 mL). The crude product obtained after separation was dried over anhydrous MgSO4and filtered using a Buchner funnel. The filtered product was analysed with GC-FID and GC-MS. Selected results of the GC-FID and GC-MS analysis are shown in FIGs 8-14.

[0244] Table 5.

[0245] Run Cx:Cy a:b t T (°C) Conversion Selectivity Selectivity Selectivity Selectivity (h) 2x (%) xy (%) yx (%) 2y (%)

[0246] 1§C2:C21 6 210" 60.43 80.16 6.29a13.55b

[0247] 2§C2:C31:2 6 200" 55.30 22.40 34.00c11.50d32.10e

[0248] 3 C2:C51:5 8 195" 59.80 5.69 62.37 16.56* 15.38

[0249] 4 C3:C51:2 12 225 39.60 22.43 71.39 2.91 3.40

[0250] 5 C4:C51:1 10 235 40.90 32.00 50.78 10.98 6.04

[0251] 6 C6:C51:1 10 220 70.09 39.50 47.48 5.70 7.32

[0252] 7 C7:C51:1 10 220 51.91 36.91 51.41 5.41 6.59

[0253] 8 C8:C51.1 10 220 59.97 35.46 51.73 5.44 7.37

[0254] 9 Ci2:C51:1 10 230 63.94 30.59 52.63 6.92 9.87

[0255] 10 C5:C51 6 230 55.00 95.00

[0256] 11 C4:C41 6 210 62.40 98.00

[0257] 12 C7:C71 6 235 66.00 96.40

[0258] Reaction was performed with xylene as solvent with substrate to xylene 1:3 by volume,a2-ethylbutanol,bn- hexanol,c2-methyl butanol,dn-pentanol,e2-methylpentanol, ’sum of C7and C9, ’’reaction pressure of 100 bar.

[0259] The crude sample reaction mixture from run 9 (2.2 kg), see Table 6, was transferred to a 3L round bottom flask equipped with an oval Teflon stir bar and a fractionating column of 50cm long fitted with iron or copper wool to increase the number of theoretical plates. Cut 1-3 containing most of the feed alcohol mix was transferred back and treated again until purified fractions containing at least 97% of desired alcohol mixture was obtained.

[0260] Table 6.

[0261] Feed Cut range, head (°C) Time (min) P (mbar) RR MB (kg)

[0262] Cut la56 1000 3 0.33

[0263] Cut 2b96 < x < 110 42 1000 3 0.21

[0264] Cut 3C110 < x < 190 72 500 5 0.14 Cut 4d170 < x < 220 52 300 5 0.38

[0265] Cut 5e170 < x < 200 68 100 5 0.96

[0266] Residue - - 0.14

[0267] Concentrations of each cut were determined to beaC5 / water - 72.0 / 28.0,bC5 / C7 / C12 / C14 -33.5 / 64.7 / 1.2 / 0.7,cC7 / Cio / Ci2 / Ci4 - 81.1 / 3.2 / 10.1 / 5.7,dC7 / C10 / C12 / C14 - 7.6 / 6.8 / 52.3 / 32.9,eCi0 / Ci2 / Ci4- 1.5 / 21.8 / 76.8 and wherein the following abbreviations were used RR = Reflux Ratio = reflux time / offtake time, MB = mass balance.

[0268] The same procedure was repeated for the remaining runs (i.e., runs 1-8, and 10-12), until fractions containing at least 97% of desired alcohol mixture was obtained.

[0269] Example 2

[0270] In a second example, a mixture comprising Cg.ig alcohols was prepared by means of a Guerbet reaction according to step a) of the process as described herein.

[0271] The reactor consisted of a CSTR 2L Parr reactor. A crude feed mixture of ethanol / xylenes (1:3, 80L), KOH (1.0 kg) and catalyst solution (25g) in ethanol / xylenes (1:3, 20L) were fed to a CSTR 2L Parr reactor. In particular, a first pump was dosing ethanol / xylene solution, and a second pump was dosing a catalyst A solution. The mixing volume ratios were 1:4 for feed and catalyst mix. Both streams were directed to a mixer. A reactor system allows for control over residence time of 2.5h, reaction temperature of 250°C, pressure 100 bar. The reaction pressure (100 bar) is controlled by a pressure regulator.

[0272] Once the mixture had fully reacted, the products were separated from the catalyst solution in a separator. The separator temperature was maintained at 90°C, the separator dome pressure was kept inactive so as to collect all crude at the same time in a 30L SS barrel at a time. The crude reaction mixture consisting of ethanol, n-butanol, 1-hexanol, 2-ethyl butanol, 1-octanol (5:4:l:l:trace) and xylenes is recycled and directed back to the mixer and re-run under the same conditions as above. It is important to get more n-butanol in the mix as this results in the formation of Cg, Cg, CM due to the follow up run with isoamyl alcohol C5along with Cg, C4, Cg and C7. The goal being to achieve the first carbon numbers of 8-9-10 as shown in FIG. 15 carbon distribution of jet fuel Al. At this time, isoamyl alcohol (25L) containing (Cg, C4, Cg, and C7alcohols), KOH (200g) and catalyst A (5g) were dosed along with the crude reaction mixture into the reactor (D) with a residence time of 2.5h, reaction temperature of 250°C and pressure of 70 bar. The fusel feed consisted of Cg (0.3%), C4(0.3%), C5(99.2%), C6(0.1%), and C7(0.1%).

[0273] About 125L of the crude mixture comprising Cg.ig alcohols was collected into a small 300L IBC. Water was first added to the 30L drums containing around 25L of crude mixture. Next, the contents of the 30L drums was mixed by rolling the barrel. The goal of this wash step is to remove as much of the remaining KOH (which readily dissolves in aqueous phase) to prevent buildup during distillation. An additional aqueous solution (5% acetic acid in water, 30L) was added, for better phase separation. The mixture was left to settle into two phases overnight. Water was drained from the bottom and the crude washed mixture comprising Cg.ig alcohols was directed to a distillation system to perform a fractionated distillation and remove light ends (i.e., C2-7 alcohols). The removed light end (C2-7) alcohols were then recirculated into the present process to increase the yield of Cg.ig alcohols.

[0274] Fractionated distillation was performed in a PD 256 PB Continuous Pulsed-Batch Distillation System equipped with a 50 L flask size, 2000 mm column length, DN100, and wire-mesh packing. The instrument was operated in a batch mode with 40L feed at a time. The feed consisting of the crude washed mixture comprising Cg.ig alcohols was loaded into the reboiler vessel. An initial AT of 50°C between vessel and surrounding jacketed oil was applied for maximum heat / power transfer. The initial pressure was kept at 1000m Bar with subsequent drop to ImBar with a variable reflux ratio and offtake time during the distillation. For each parameter set, a single cut was taken. Further details are shown in Table 7. First, a low reflux ratio was applied to offtake most of the light end C2-g alcohols. The individual samples were weighed on a IFB 300K-2 weighing scale from Kern with an accuracy of 0.01 kg.

[0275] Table 7.

[0276] Feed Cut range, head (°C) Time (min) P (mbar) RR MB (kg)

[0277] Cut l 50 < x < 140 110 1000 3-5 76.10

[0278] Cut 2 130 < x < 200 46 700 5 10.21

[0279] Cut 3 160 < x < 295 84 1 10 32.13

[0280] Residue - - 1.16

[0281] Wherein the following abbreviations were used RR = Reflux Ratio = reflux time / offtake time, MB = mass balance.

[0282] Example 3

[0283] In a third example, a mixture comprising alcohol(s) was dehydrated to olefins and water. The same procedure was repeated for each alcohol mixture obtained in Example 1 described above.

[0284] 2.5L of alcohol mixture was placed into a 3.0L glass round bottom flask equipped with a Teflon stir bar. The flask was placed on an aluminium block, the round bottom flask was then connected to a Dean-Stark apparatus and a 400mm graham condenser at atmospheric pressure. Different acid catalysts (2 wt%, 25g) were added into the side arm of the Dean-Stark apparatus with 20mL of an alcohol mixture as shown in Table 8. The flask was then heated to 220°C. The resulting water formed from dehydration was collected in the side arm of the Dean-Stark apparatus. The dehydration reaction was continued until completion and followed by sampling and analysis on a gas-chromatograph, and until no more water could be recovered. After the reaction, the reaction mixture comprising olefins was cooled and subsequently transferred to a separating funnel and washed with water (3 times 300mL) and then with 10% KOH / water (lOOmL). The water was removed and the crude product dried over anhydrous MgSO4and filtered using a Buchner funnel.

[0285] Table 8.

[0286] Run Mix Cat t T (°C) Conversion Selectivity Selectivity

[0287] (h) olefin ether

[0288] 1 2PH H3PO4 5 220 63.1 62.3 37.7

[0289] 2 2PH HOTf 5 220 33.2 56.7 43.3

[0290] 3 2PH Hf(OTf)45 210 46.8 72.7 27.3

[0291] 4 2PH HZSM-5 5 200 82.0 97.7 2.3

[0292] 5 2PH Meryt 5 180 71.0 95.0 5.0

[0293] 6 1-octanol H3PO46 220 64.2 31.7 68.3

[0294] 7 1-octanol HOTf 6 220 28.7 67.3 32.7

[0295] 8 1-octanol Hf(OTf)46 210 66.8 41.8 58.2

[0296] 9 1-octanol HZSM-5 6 200 62.0 32.0 68.0

[0297] 10 1-octanol Meryt 6 180 51.9 38.0 62.0

[0298] 11 IMH HZSM-5 5 200 71.2 98.9 1.1

[0299] 12 2PN HZSM-5 5 200 73.5 96.7 3.3

[0300] 13 IMH Meryt 5 180 67.0 95.7 4.3

[0301] 14 2PN Meryt 5 180 69.1 97.2 2.7

[0302] 15 2PH: 2PN: IMH HZSM-5 5 200 77.0 97.3 2.7

[0303] 16 2PH: 2PN: IMH: 1-octanol HZSM-5 10 200 74.2 90.2 9.8

[0304] 17 1-dodecanol HZSM-5 5 200 44.2 34.1 65.9

[0305] 18 1-dodecanol HZSM-5 5 230 56.2 33.2 66.8

[0306] Wherein the following abbreviations were used 2-propyl heptanol (2PH), 2-isopropyl-5-methyl-l-hexanol (IMH), 2-pentylnonanol (2PN). HZSM-5 Meryt (ET 53) are acid catalysts purchased from Zeolyst and Meryt Chemicals, respectively.

[0307] Run 4, 11, 12, 13, 14, 15 gave the best results as it shows Guerbet alcohols dehydrate to give exclusively olefins. GC-FID and GC-MS analysis of the obtained products is shown in FIGs 16-18.

[0308] The washed, crude mixture comprising olefins was subsequently further purified by means of distillation. A PD 256 PB Continuous Pulsed-Batch Distillation System was used equipped with a 50 L flask size, 2000 mm column length, DN100, and wire-mesh packing. The instrument was operated in batch mode. 7.0 kg of the crude washed, mixture comprising olefins was loaded into the reboiler vessel. An initial AT of 50°C between vessel and surrounding jacketed oil was applied for maximum heat / power transfer. The initial pressure was kept at 1000m Bar with subsequent drop to 10m Bar with a variable reflux ratio and offtake time during the distillation. For each parameter set, a single cut was taken. Further details are shown in Table 9. First, a low reflux ratio was applied to offtake most of the light ends of Cut 1. Cut 2 contained most of the mixed olefins 95-97%. The individual samples were weighed on a IFB 300K-2 weighing scale from Kern with an accuracy of 0.01 kg.

[0309] Table 9.

[0310] Feed Cut range, head (°C) Time (min) P (mbar) RR MB (kg)

[0311] Cut l 50 < x < 160 18 1000 3 0.16

[0312] Cut 2 160 < x < 285 88 500-10 5 3.06

[0313] Cut 3 200 < x < 310 26 10-5 5 0.05

[0314] Residue - - 3.71

[0315] Wherein the following abbreviations were used RR = Reflux Ratio = reflux time / offtake time, MB = mass balance.

[0316] Example 4

[0317] In a fourth example, the mixture comprising Cg-ig alcohol(s) produced in Example 2 was dehydrated to Cg-ig olefins and water according to step b) of the process as described herein.

[0318] 0.6L of alcohol mixture consisting of 2,5-dimethylhexanol, 2-isopropyl-5-methyl-hexanol, 2-propyl- heptanol, 2-pentyl-nonanol, 2-isoamyl-heptanol in ratio 5.0: 15.0: 40.0: 10.0: 30.0 was placed into a 1.0L glass round bottom flask with 50g of H-ZSM5. The flask was placed on an aluminium block, the round bottom flask was then connected to a Dean-Stark apparatus and a 400mm Graham condenser at atmospheric pressure. The flask was then heated to 250°C for 36h. The resulting water formed from dehydration was collected in the side arm of the Dean-Stark apparatus. The dehydration reaction was continued until completion and followed by sampling and analysis on a gas-chromatograph, and until no more water could be recovered. Net water collected was 55mL corresponding to a >95% conversion. GC-FID (see FIG. 19) showed 90% of olefins with 5% high boiling products and 5% unreacted alcohols. After the completion of the reaction, the reaction mixture was cooled filtered to afford clear olefin mixture.

[0319] Example 5

[0320] In a fifth example, Cg-ig olefins obtained in Example 4 were hydrogenated to aliphatic hydrocarbons according to step c) of the process as described herein. Catalyst (5g, Pd / ALOg 5%, pellets 3 mm) was loaded in a static catalyst basket on a 2L Parr reactor. The feed consists of an olefin mixture (2.4L). This homogeneous clear solution was then dosed with a pump to a fixed head 2L Parr reactor vessel 0.8L at a time, equipped with heating mantle and an overhead stirrer at a controlled stirring speed set at 450 rpm. The reactor vessel is made from stainless steel 316. The vessel was flushed 2 times with hydrogen gas and then pressurized at 10-15 bar. The reaction mixture was then heated at 70°C (2h), then ramped at 10°C increments to temp 150°C in lh. The reaction time was 24-48h. After the completion of the reaction as judged by the gas chromatograph, the reaction mixture was cooled to room temperature a net 2.4L of crude. The catalyst Pd / ALOg 5%, pellets 3 mm can be used several times over as noted here - 3 times in consecutive runs. The crude product comprising aliphatic hydrocarbons was filtered over celite using a Buchner funnel to remove any particulates from catalyst residue. Followed by distillation.

[0321] The crude product comprising aliphatic hydrocarbons (2.4 kg) was transferred to a 3L round bottom flask equipped with an oval Teflon stir bar and a fractionating column 50cm long fitted with iron or copper wool to increase the number of theoretical plates. The distillation is preferably carried out at atmospheric pressure, with variable pressure. In general, the number of trays in the column and amount of heat transferred to the material being purified in the column are sufficient to produce a liquid stream of purified aliphatic hydrocarbons containing a purity of at least 97-99%. The purified aliphatic hydrocarbons comprised 0.05kg of light fractions consisting of residual lighter hydrocarbons <Cg. The second fraction consisted entirely of aliphatic hydrocarbons i.e., synthetic paraffinic kerosene with a bottoms residue of 0.32 kg as judged by gas chromatograph. GC-MS analysis of the obtained hydrocarbons is shown in FIG. 20. The individual samples were weighed on a IFB 300K-2 weighing scale from Kern with an accuracy of 0.01 kg as shown in Table 10.

[0322] Table 10.

[0323] Feed Cut range, head (°C) Time (min) P (mbar) RR MB (kg)

[0324] Cut 1 50 < x < 140 15 1000 3 0.05

[0325] Cut 2 150 < x < 320 58 2 10 1.98

[0326] Residue - - 0.32

[0327] Wherein the following abbreviations were used RR = Reflux Ratio = reflux time / offtake time, MB = mass balance.

[0328] Example 6

[0329] In a sixth example, a blend (Blend 1 as referred to further herein) of 10 vol.% aliphatic hydrocarbons obtained in Example 5 and 90 vol.% commercial jet Al fuel was prepared and compared to a 100 vol.% commercial jet Al fuel. The resulting properties of the fuel mixtures is shown below in Table 11. Two analysis runs were performed on Blend 1, which support that reproducible results could be obtained.

[0330] Table 11.

[0331] Properties Jet Al Jet Al Blend 1 Blend 1 required Commercial (analysis 1) (analysis 2) Electrical conductivity, ambient (pS / m) | 50 < x < 600 249 193 135

[0332] *Jet Al Specs derived from ASTM D1655 'Standard Specification for Aviation Turbine Fuels

[0333] From the data presented in Table 11, it can be concluded that blend 1 meets the criteria and specifications of a commercial jet Al fuel.

Claims

CLAIMS1. A process for preparing aliphatic hydrocarbons suitable for jet and / or diesel fuels, the process comprising the steps of: a) converting a mixture comprising at least two different chain length primary alcohols to a mixture comprising Cg-ig alcohols by means of a Guerbet reaction; b) dehydrating the mixture comprising Cg-ig alcohols to Cg-ig olefins and water; and c) hydrogenating the Cg-ig olefins to aliphatic hydrocarbons; wherein the Guerbet reaction in step a) is performed in the presence of at least one metal catalyst, wherein the metal catalyst comprises an (L)nM(OH)n(H2O)mtype complex wherein,■ n and m are positive integers;■ M is a metal selected from the group comprising Ru, Fe, Os, Ir, Rh, Mo, W, Sc, Tc, Pd, Pt, Zn, and Ni; and■ L is a ligand.

2. The process according to claim 1, wherein the mixture comprising Cg-ig alcohols comprises at least 80.0 wt.%, preferably at least 90.0 wt.%, ofCg.ig alcohols, based on the total weight of the mixture; or wherein the mixture comprising Cg-ig alcohols is purified before step b) to have at least 80.0 wt.%, preferably at least 90.0 wt.%, ofCg.ig alcohols, based on the total weight of the mixture.

3. The process according to claim 1 or 2, wherein the Guerbet reaction in step a) is performed in the presence of at least one base, wherein the base is an alkoxide or hydroxide; and is preferably selected from the group comprising potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium tert-butoxide, sodium tert-butoxide, potassium isoamylate, sodium isoamylate, and mixtures thereof.

4. The process according to any one of claims 1 to 3, wherein the different chain length primary alcohols of step a) are primary C1-30 alcohols; preferably Ci.g primary alcohols selected from the group comprising ethanol, isoamyl alcohol, methanol, n-propanol, / so-propanol, n- butanol, sec-butanol, / so-butanol, normal amyl alcohol, active amyl alcohol, neopentyl alcohol, hexan-l-ol, 2,2-dimethylbutan-l-ol, 2,3-dimethylbutan-l-ol, 3,3-dimethylbutan-l-ol,2-ethylbutan-l-ol, 2-methylpentan-l-ol, 3-methylpentan-l-ol, and 4-methylpentan-l- ol.

5. The process according to any one of claims 1 to 4, wherein the mixture comprising at least two different chain length primary alcohols of step a) is a mixture comprising: ethanol and isoamyl alcohol; or methanol and isoamyl alcohol; or ethanol, n-propanol, iso-propanol, and isoamyl alcohol; or ethanol, n-butanol, and isoamyl alcohol; or ethanol, 1-hexanol, and isoamyl alcohol; or ethanol and a primary C5-20 alcohol; or ethanol, a first primary C5-20 alcohol, and a second primary C5-20 alcohol; or ethanol, a first primary C5-20 alcohol, a second primary C5-20 alcohol, and a third primary C5. 20 alcohol.

6. The process according to any one of claims 1 to 5, wherein the Guerbet reaction of step a) comprises heating the mixture comprising at least two different chain length primary alcohols to a temperature of from at least 120°C to less than 300°C for a period of from at least 5 minutes to at most 24 hours.

7. The process according to any one of claims 1 to 6, wherein the mixture comprising at least two different chain length primary alcohols of step a) is obtained by distilling a fusel alcohol mixture comprising isoamyl alcohol.

8. The process according to any one of claims 1 to 7, wherein the mixture comprising Cg.ig alcohols of step a) is separated from the unreacted mixture comprising at least two different chain length primary alcohols.

9. The process according to any one of claims 1 to 8, wherein the ligand L is a protic mono-, di, or a polydentate organic ligand selected from the group comprising indole, maleimide, maltol, 5-hydroxymaltol, kojic acid, tropolone, thujaplicin, hinokitiol, stipitatic acid, 2,6-bis[4- isopropyl-2-oxazolin-2-yl]pyridine, imidazole, 2,6-bis[4-phenyl-2-oxazolin-2-yl]pyridine, 2,6- bis[(3,8)-8H-indeno[l,2-d]oxazolin-2-yl)pyridine, pyrrole, pyrazole, 4-hydroxypyrazole, pyrazole-3-carboxyladehyde, pyrazole-3-carboxylic acid, pyrazole-4-carboxylic acid, pyrazole-3,5-dicarboxylic acid, 4-alkyl / aryl pyrazole, 3-alkyl / aryl pyrazole, 5-alkyl / aryl pyrazole, 3,5- alkyl / aryl pyrazole, 1-benzylpyrazole, 3,5-di(2-pyridyl)pyrazole, 2-(lH-pyrazol-3-yl)phenol, 2- (lH-pyrazol-5-yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5-hydroxypyrazole, tris( 1- pyrazolyl)methane, tris(3,5-dimethyl-l-pyrazolyl)methane, bis(pyrazolyl)methane, 4- hydroxybenzimidazole, 1-benzylimidazole, 2-methylbenzimidazole, 2-phenylimidazole, 2- alkylimidazole, 2-arylimidazole, 4-alkylimidazole, 2-aminobenzimidazole, 2- alkylbenzimidazole, 4,5-diarylimidazole, 4,5-dialkylimidazole, 2,4,5-triarylimidazole, 2,4,5- trialkylimidazole, 4-arylimidazole, 5-alkylimidazole, 5-arylimidazole, 4-methylimidazole, 1- benzylpyrazole, 4-arylimidazole, 5-methylimidazole, 2-(lH-imidazol-2-yl)pyridine, 2-(l- hydroxyethyl)benzimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-lH- benzimidazole, lH-pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2- pyridyl)benzimidazole, 2-(lH-imidazol-2-yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3- pyridyl)-lH-benzimidazole, 2-(2-pyridyl)benzothiophene, 2-aryl-4H-(l,2,4)triazole, 2-(4- methyl-2-pyridyl)-lH-benzimidazole, 2-arylbenzothiazole, 2, 2'-bipyridine-4, 4' -dicarboxylic acid, 2, 2'-bipyridine-5, 5' -dicarboxylic acid, 2, 2'-bipyridine-3, 3' -dicarboxylic acid, 4- imidazolecarboxylic acid, 4-pyrozolecarboxylic acid, pyrrole-3-carboxylic acid, 5- oxazolecarboxylic acid, 2,2'-bis(4,5-dimethylimidazole), 2,2'-bisimidazole, imidazole-4- carboxaldehyde, imidazole-4,5-dicarboxylic acid, 4,4'-bisimidazole, 4,4'-bisbenzimidazole, 2,2'-bisbenzimidazole, 4,5-bis(hydroxymethyl)imidazole, 2-(diphenylphosphino)benzenesulfonic acid, 2-[di(2- methoxyphenyl)phosphino]benzenesulfonic acid, and mixtures thereof.

10. The process according to any one of claims 1 to 8, wherein the ligand L is selected from the group comprising: a halide, a hydride, an alkoxide, an aryloxide, an amide, an acetate, an acetylacetonate, an alkyl, an aryl, CO, NO, phosphine, pyridine, an alkene, an alkyne, N- heterocyclic carbene, cyclopentadiene, a mono-dentate phosphine of formula PR1R2R3, a bidentate phosphine such as R1R2P-PR1R2, a methylene linked R1R2P-CH2-PR1R2, RlR2P-(CH2)n- PR1R2, or R1R2P-(CH2)n-NR4-(CH2)n-PR1R2; wherein each R1, R2, and / or R3is independently selected from alkyl or aryl, with optional variable functionality such as sulfonate, halide, and wherein R1, R2, R3, R4can be identical or different; preferably wherein R1, R2, R3,and R4are all phenyl; and preferably wherein the ligand L is selected from the group comprising a monodentate phosphine of formula PR1R2R3, a bidentate phosphine such as R1R2P-PR1R2, a methylene linked R1R2P-CH2-PR1R2, RlR2P-(CH2)n-PR1R2, or R1R2P-(CH2)n-NR4-(CH2)n-PR1R2; wherein each R1, R2, and / or R3is independently selected from alkyl or aryl, with optionalvariable functionality such as sulfonate, halide, and wherein R1, R2, R3, R4can be identical or different; preferably wherein R1, R2, R3,and R4are all phenyl.

11. The process according to any one of claims 1 to 10, wherein step b) of dehydrating the mixture comprising Cg.ig alcohols is performed in the presence of at least one solid acid catalyst; preferably wherein the solid acid catalyst is selected from the group comprising acidic resins, alumina and aluminosilicates, heteropolyacids, W or Mo functionalized oxides, and mixtures thereof.

12. The process according to any one of claims 1 to 11, wherein step b) of dehydrating the mixture comprising Cg.ig alcohols comprises heating to a temperature of from at least 120°C to less than 250°C for a period of from at least 5 minutes to at most 24 hours.

13. The process according to any one of claims 1 to 12, wherein step c) of hydrogenating the Cg.ig olefins is performed in the presence of at least one hydrogenation catalyst and hydrogen gas, wherein the hydrogenation catalyst comprises Pt, Pd, Rh, Ru, Ir, Ni, Fe, Cu, Co, Cr, or combinations thereof; preferably wherein step c) of hydrogenating the Cg.ig olefins comprises heating to a temperature of from at least 50°C to less than 300°C for a period of from at least 5 minutes to at most 24 hours.

14. The process according to any one of claims 1 to 13, wherein the mixture comprising Cg.ig alcohols further comprises C5.g alcohols, and wherein at least some of the C5.g alcohols are isolated from the mixture and dimerized to CIO-IB alcohols.

15. Use of the aliphatic hydrocarbons prepared with the process according to any one of claims 1 to 14, as a jet fuel and / or as a diesel fuel.

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