Oligomerisation of alcohols

Abstract

The invention relates to a process for converting a C1-3 alcohol to higher alcohols, the process comprising the steps of: a. pre-mixing a C1-3 alcohol, a catalyst, and a multicomponent solvent system, to form a liquid mixture; and b. heating the liquid mixture, thereby obtaining higher alcohols; wherein the multicomponent solvent system comprises at least a basic aqueous hydrocarbon solvent phase comprising at least two different hydrocarbons; wherein the solvent comprises a base selected from the group comprising: potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium t-butoxide, sodium t- butoxide, or combinations thereof, for example a eutectic mixture of sodium and potassium hydroxide; and, wherein the catalyst comprises an (HL)M(OH)n(H2O)m type complex and activated carbon.

Description

[0001] OLIGOMERISATION OF ALCOHOLS

[0002] FIELD OF THE INVENTION

[0003] The invention relates to the technical field of catalytic oligomerisation of lower alcohols to higher alcohols, and the oligomerisation ethanol to n-butanol in particular.

[0004] BACKGROUND OF THE INVENTION

[0005] Several processes to form alcohols (C3 onwards) exist, but they all have specific shortcomings, as detailed in FIG. 1. They are usually derived from crude oil, which subsequently leads to an enormous carbon footprint.

[0006] A way to synthesise n-butanol is to use ethanol as a starting molecule and use a catalysed reaction process. Two catalysed reaction mechanisms are proposed in literature: the direct dimerisation of two molecules of ethanol, and a multi-step tandem synthetic route known as the Guerbet reaction. The prerequisite for the “direct mechanism” is a high reaction temperature (> 350°C), while the indirect route is the reaction mechanism at lower reaction temperatures. In view of the many advantages of upgrading ethanol to n-butanol (and other higher alcohols) the search for homogeneous and heterogeneous catalysts has recently received great attention in both the scientific and industrial field.

[0007] The main types of homogeneous catalysts for upgrading ethanol to n-butanol are complexes of iridium, manganese, gold, copper, niobium, platinum, palladium, vanadium, titanium, zirconium, iron, ruthenium, molybdenum, osmium, or nickel; in combination with a strong base, e.g., sodium hydroxide, potassium hydroxide, or sodium ethoxide. These reactions are believed to proceed via a Guerbet reaction mechanism. The transition metals are responsible for the dehydrogenation of the ethanol and for the aldehyde hydrogenation, while the strong base is responsible for the aldol condensation. An ethanol conversion of more than 50% in combination with a selectivity of 80% for n-butanol have been recorded in the literature, but the many problems of the homogeneous catalysts rule them out for industrial processes. These problems are: extreme sensitivity to air, poor tolerance to water, rapid decomposition of the ligands, and the fact that they are difficult to recover from the reaction products. This not only causes processing discontinuities and loss of catalyst, but most importantly, a lack of scalability of the reaction.

[0008] In view of the drawbacks of homogeneous catalysts, heterogeneous catalysts, processes, and corresponding reaction mechanisms have been extensively explored as a solution for the conversion of ethanol to n-butanol in recent years. These heterogeneous catalysts include metal oxides, zeolites, hydroxyapatite catalysts, mixed metal oxides, and supported metal catalysts. However, all reported types of heterogeneous catalysts each come with their own shortcomings. These are: low selectivity for n-butanol, low conversation rates, and harsh reaction conditions. Other problems these catalysts can suffer from are poor water tolerance and a high cost. Adequate tolerance to water is very important, since water is typically present in the reactant mixture and water is generated in the dehydration reaction of the reaction process.

[0009] Nowadays, n-butanol is industrially synthesised directly from petroleum feedstock via an energy-intensive process, or via the time-consuming fermentation process of which the yield is very low as summarised above. An alternative process is the synthesis of n-butanol from bio-ethanol via a wide variety of catalysts. This has been extensively researched and documented in both scientific papers and patents. However, limiting factors in the industrialisation of the catalysed bio-ethanol / n-butanol conversion with the catalyst synthesised up till now include: low selectivity for n-butanol, low conversion rates, harsh reaction conditions (high temperatures and / or high pressures), poor water tolerance of the catalyst(s), catalyst cost, and lack of scalability. The above explains why it is currently not economical to produce n-butanol from ethanol via a catalytic reaction.

[0010] WO 2015 / 031561 A1 discloses methods of converting a lower alcohol (e.g., ethanol) to a higher alcohol (e.g., butanol) in the presence of a water stable transition metal catalyst comprising a Group VIII transition metal and a polydentate nitrogen donor ligand.

[0011] WO 2019 / 193079 A1 discloses a process for obtaining higher aliphatic alcohols starting from aliphatic primary alcohols by condensation reactions. Specifically, the process comprises a step in which an aliphatic primary alcohol is contacted in a homogeneous phase with a catalyst mixture comprising a transition metal, a base and an additive.

[0012] Accordingly, it is an object of the present invention to provide a process that overcomes one or more of the above issues, particularly in the conversion of (bio-)ethanol to (bio-)n-butanol and higher alcohols.

[0013] SUMMARY OF THE INVENTION

[0014] The present inventors have now found that one or more of the objects above can be attained by using the process as presently claimed, and (preferred) embodiments thereof.

[0015] The present invention offers conversion of Ci, C2, C3 and, C5 alcohols that are derived from renewable feedstocks to higher (C4+) alcohols with can be further upgraded using known industrial processes.

[0016] An advantage of the present invention is that this type of catalyst is air stable and water stable. Therefore, the reaction mixture can easily be prepared in air.

[0017] A further advantage of the present invention is that a very high conversion rate of ethanol can be achieved.

[0018] A further advantage of the present invention is that little to no side products are formed, such as acetaldehyde, crotonaldehyde, or any other aldol condensation products.

[0019] A further advantage of the present invention is that no additional hydrogen feed is required. A further advantage of the present invention is that the product can be controlled by the reaction time, for example, longer reaction times afford higher alcohols as Ce and Cs homologues.

[0020] A further advantage of the present invention is that it offers an economically viable ethanol oligomerisation by providing an efficient combination of both a high-selectivity reaction step to n-butanol combined with an efficient catalyst recycling to keep catalyst leaching at its lowest. A further advantage of the present invention is that the application of specific solvent systems allows for optimal reaction conditions as well as optimal catalyst-recycling conditions.

[0021] A further advantage of the present invention is the use of just water which can be purified by simple molecular sieve distillation. Additional impurities such as fusel alcohols from fermentation process do not hinder the present process.

[0022] A further advantage of the present invention is that the complexities of the processes of the prior art are avoided.

[0023] A further advantage of the present invention is that no specific control of partial pressures is necessary as no syngas feed or hydrogen input is required.

[0024] A further advantage of the present invention is that no n-selectivity requirements exist. With the current invention only n-butanol is obtained.

[0025] A further advantage of the present invention is that mixtures may be prepared in air and have a catalyst stability of few months under ambient conditions, and no complex set ups such as those in the prior art are required.

[0026] A further advantage of the present invention is that a relatively clean single product is obtained that is simpler and leads to an overall simpler process.

[0027] A further advantage of the present invention is that in the process, C4, Ce and Cs alcohols are obtained whilst C4 product is predominant, larger conversions to Ce and Cs are formed upon prolonged heating.

[0028] A further advantage of the present invention is that it may start from bio-ethanol that is green and also operates under 200 °C making it quite simple and commercially attractive.

[0029] A further advantage of the present invention is that the process is not limited to alumina production co-location sites or pyrophoric catalysts.

[0030] A further advantage of the present invention is that the process takes about 6h in comparison to ABE fermentation and therefore provides a higher turnover.

[0031] A further advantage of the present invention is that co-location can be beneficial but is not a necessity to the success of the economics.

[0032] A further advantage of the present invention is that the conversion and selectivity to n-butanol are high enough to exclude dependence on side streams for profitability.

[0033] The present invention allows to use existing infrastructure from fossil based commercial plants and can be retrofitted. According to a first aspect, the present invention relates to a process for converting a C1.3 alcohol to higher alcohols. The process preferably comprises the steps of: a. pre-mixing a C1.3 alcohol, a catalyst, and a multicomponent solvent system, to form a liquid mixture; and b. heating the liquid mixture, thereby obtaining higher alcohols.

[0034] The multicomponent solvent system preferably comprises at least a basic aqueous hydrocarbon solvent phase comprising at least two different hydrocarbons; wherein the solvent comprises a base selected from the group comprising: potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium t-butoxide, sodium t-butoxide, or combinations thereof, for example a eutectic mixture of sodium and potassium hydroxide.

[0035] The catalyst comprises an (HL)M(OH)n(H2O)mtype complex and preferably comprises activated carbon.

[0036] M is a metal, preferably selected from the group comprising: Ru, Co, Ir, Rh, Os, Mo, W, Sc, Tc, Pt, Pd, Fe, or Ni.

[0037] HL is a protic mono-, di-, or a polydentate organic ligand, preferably 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[1 ,2- d]oxazolin-2-yl)pyridine, pyrrole, pyrazole, 4-hydroxypyrazole, pyrazole-3- carboxyladehyde, pyrazole-3-carboxylic acid, pyrazole-4-carboxylic acid, pyrazole-

[0038] 3.5-dicarboxylic acid, 4-alkyl / aryl pyrazole, 3-alkyl / aryl pyrazole, 5-alkyl / aryl pyrazole,

[0039] 3.5-alkyl / aryl pyrazole, 1-benzylpyrazole, 3,5-di(2-pyridyl)pyrazole, 2-(1 H-pyrazol-3- yl)phenol, 2-(1 H-pyrazol-5-yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5- hydroxypyrazole, tris(1-pyrazolyl)methane, tris(3,5-dimethyl-1-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-(1 H-imidazol-2-yl)pyridine, 2- (l-hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2- hydroxyphenyl)-1 H-benzimidazole, 1 H-pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl- 4-hydroxypyrazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol-2-yl)pyridine, 2,6- bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H-benzimidazole, 2-(2- pyridyl)benzothiophene, 2-aryl-4H-(1 ,2,4)triazole, 2-(4-methyl-2-pyridyl)-1 H- 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, trisodium 3,3',3"-phosphanetriyltri(benzene-1-sulfonate),2-(diphenylphosphino)benzenesulfonic acid, bis(p-sulfonatophenyl)phenylphosphine dihydrate dipotassium salt, and 4,4'- (phenylphosphinidene)bis(benzenesulfonic acid) dipotassium salt hydrate, 2-[di(2- methoxyphenyl)phosphino]benzenesulfonic acid. m and n are integers.

[0040] In some preferred embodiments, the C1.3 alcohol is ethanol, preferably bio-ethanol. In some preferred embodiments, the solvent / ethanol ratio is at least 2.0, preferably at least 3.0. In some preferred embodiments, the ethanol is fuel grade ethanol.

[0041] In some preferred embodiments, the ligand 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-(1 H-imidazol-2- yl)pyridine, 2-(1-hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-1 H-benzimidazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol-2- yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H-benzimidazole, 2-(4-methyl-2- pyridyl)-1 H-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; preferably the ligand HL is imidazole. In some preferred embodiments, the metal is Ru.

[0042] In some preferred embodiments, the catalyst further comprises a skeletal or metal sponge catalyst; preferably Raney nickel.

[0043] In some preferred embodiments, the basic aqueous solvent phase comprises an alkali hydroxide; preferably KOH.

[0044] In some preferred embodiments, step a. is performed at ambient temperature.

[0045] In some preferred embodiments, step b. comprises one or more, preferably all, of the steps of: b1 . heating the mixture to a temperature T1 in a time frame At1 ; b2. heating the mixture to a temperature T2 in a time frame At2; and, b3. maintaining the mixture at the temperature T2 during a time frame At3.

[0046] In some preferred embodiments, T2 is from at least 140°C to at most 500°C, preferably from at least 150°C to at most 400°C, preferably from at least 160°C to at most 300°C, preferably from at least 170°C to at most 260°C, preferably from at least 180°C to at most 240°C, preferably from at least 190°C to at most 220°C, preferably about 200°C.

[0047] In some preferred embodiments, the C1.3 alcohol is converted to n-butanol. In some preferred embodiments, the C1.3 alcohol is converted to Ce-s alcohols.

[0048] In some preferred embodiments, the reaction vessel acts as an intrinsic catalyst.

[0049] In some preferred embodiments, the process further comprises the step of: a. distilling the higher alcohols.

[0050] According to a second aspect, the present invention relates to use of a catalyst as described herein, in the conversion of a C1.3 alcohol to higher alcohols

[0051] The independent and dependent claims set out particular and preferred features of the invention. Features from the dependent claims may be combined with features of the independent or other dependent claims as appropriate.

[0052] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description.

[0053] BRIEF DESCRIPTION OF THE FIGURES

[0054] FIG. 1 illustrates multiple cascade reactions for the production of oxo-alcohols (underlined) from crude oil.

[0055] FIG. 2 illustrates proposed cascade reactions for the formation of n-butanol (underlined), while products from side reactions are not underlined.

[0056] FIG. 3 illustrates a conceptual diagram showing possible ligand deprotonation by bases.

[0057] FIG. 4 illustrates a schematic representation of phase separation according to an embodiment of the invention. The lower area is the water phase, while the upper area is the hydrocarbon phase.

[0058] FIG. 5 illustrates the reaction kinetics according to an embodiment of the invention.

[0059] FIG. 6 demonstrates the partition coefficient of octanol / water at 25°C of the molecules in the reaction pathway.

[0060] FIG. 7 illustrates a schematic representation of phase separation for the conversion of 1- propanol.

[0061] FIG. 8 illustrates a schematic representation of gas chromatograph of the crude phase conversion of ethanol.

[0062] FIG. 9 illustrates a schematic representation of gas chromatograph of crude phase conversion of ethanol + 1-propanol.

[0063] DETAILED DESCRIPTION OF THE INVENTION

[0064] When describing the invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise. 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.

[0065] In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects 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. 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” 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 some 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.

[0066] 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. It will be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein comprise the terms "consisting of', "consists" and "consists of".

[0067] As used in the specification and the appended claims, the singular forms "a", "an," and "the" include plural referents unless the context clearly dictates otherwise. By way of example, "a step" means one step or more than one step.

[0068] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art. All publications referenced herein are incorporated by reference thereto.

[0069] 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 sub-ranges subsumed therein. When used as an index in chemical structures, integers are typically positive non-zero integers. The term "about" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of + / -10% or less, preferably + / -5% or less, more preferably + / -1% or less, of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier "about" refers is itself also specifically, and preferably, disclosed.

[0070] When describing the present invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise.

[0071] 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, / .e., a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture.

[0072] Preferred embodiments of this invention are set herein below. Each embodiment of the invention so defined may be combined with any other embodiment 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 or statements indicated as being preferred or advantageous.

[0073] According to a first aspect, the present invention relates to a process for converting a C1.3 alcohol to higher alcohols. The process preferably comprises the steps of: a. pre-mixing a C1.3 alcohol, a catalyst, and a multicomponent solvent system, to form a liquid mixture; and b. heating the liquid mixture, thereby obtaining higher alcohols.

[0074] The catalyst comprises an (HL)M(OH)n(H2O)mtype complex, wherein m and n each independently represent an integer, for example of 1 , 2, or 3, and preferably also comprises activated carbon.

[0075] M is a metal, preferably selected from the group comprising: Ru, Co, Ir, Rh, Os, Mo, W, Sc, Tc, Pt, Pd, Fe, or Ni. In some preferred embodiments, the metal is Ru, Co, Ni or V. In some preferred embodiments, the metal is Ru or Co. In some preferred embodiments, the metal is Ru.

[0076] The choice of ligand (HL) FIG. 3 was found to be important in the present invention, since addition of a strong base such as KOH to any transition metal halide may result in the formation of insoluble, inactive, black precipitates - presumably oxides. Most importantly, the steps involved in the current invention are thermal operations such as transformation of ethanol to n-butanol, distillation, rectification, / .e., processes that normally would lead to thermal stresses on the catalyst which can cause decomposition reactions and progressive deactivation during the lifetime of the catalyst. Thermal separation processes seldom give quantitative recovery of the catalyst, which causes loss of productivity through loss of metal. The ligand provides a high polarity of the catalyst and consequent insolubility in the organic phase providing a minimum loss of metal.

[0077] In some preferred embodiments, HL is a protic mono-, di-, or a polydentate organic ligand, preferably 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[1 ,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-(1 H-pyrazol-3-yl)phenol, 2-(1 H-pyrazol-5- yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5-hydroxypyrazole, tris(1- pyrazolyl)methane, tris(3,5-dimethyl-1-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-(1 H- imidazol-2-yl)pyridine, 2-(1-hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2- pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-1 H-benzimidazole, 1 H-pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol-2- yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H-benzimidazole, 2-(2- pyridyl)benzothiophene, 2-aryl-4H-(1 ,2,4)triazole, 2-(4-methyl-2-pyridyl)-1 H-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, trisodium 3,3',3"-phosphanetriyltri(benzene-1-sulfonate), 2-(diphenylphosphino)benzenesulfonic acid, bis(p-sulfonatophenyl)phenylphosphine dihydrate dipotassium salt, and 4,4'- (phenylphosphinidene)bis(benzenesulfonic acid) dipotassium salt hydrate, 2-[di(2- methoxyphenyl)phosphino]benzenesulfonic acid.

[0078] In some preferred embodiments, the ligand 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[1 ,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-(1 H- pyrazol-3-yl)phenol, 2-(1 H-pyrazol-5-yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5- hydroxypyrazole, tris(1-pyrazolyl)methane, tris(3,5-dimethyl-1-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-(1 H-imidazol-2-yl)pyridine, 2-(1-hydroxyethyl)benzimidazole, 5- methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-1 H-benzimidazole, 1 H- pyrazol-3-ylboronic acid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol-2-yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H- benzimidazole, 2-(2-pyridyl)benzothiophene, 2-aryl-4H-(1 ,2,4)triazole, 2-(4-methyl-2-pyridyl)- 1 H-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.

[0079] In some preferred embodiments, the ligand 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-(1 H-imidazol-2- yl)pyridine, 2-(1-hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-1 H-benzimidazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol-2- yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H-benzimidazole, 2-(4-methyl-2- pyridyl)-1 H-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.

[0080] Preferably the ligand HL is imidazole. In some preferred embodiments, an aqueous hydrocarbon solvent is added under conditions of increased temperature (for example at least 40°C) in the presence of at least one “additional” catalyst.

[0081] By “additional catalyst” it will be understood that the catalyst is supplementary to the reaction components, i.e., separate to components intrinsically present in together with the reaction components such as C1.3 alcohols, the catalyst of claim 1 , aqueous solvent and / or walls of a reactor apparatus. In other words, an “additional” catalyst as contemplated herein may be considered to be an “extrinsic” catalyst in the sense that it is provided to the reaction as an individual reaction component.

[0082] An additional catalyst as contemplated herein may be selected from the following non-limiting examples of which include: base catalysts, acid catalysts, alkali metal hydroxide catalysts, transition metal hydroxide catalysts, alkali metal formate catalysts, transition metal formate / acetate catalysts, reactive carboxylic acid catalysts, transition metal catalysts, transition metal carbonyl halide catalysts, transition metal halides or carbonyls or sulphide or phosphine or imidazole or pyrazole or acetates or butrates catalysts, noble metal catalysts, water-gas-shift catalysts, and combinations thereof.

[0083] Methods of the invention may be performed using “additional” catalyst / s in combination with “intrinsic” catalyst / s.

[0084] The optimal quantity of an additional catalyst used in the methods of the invention may depend on a variety of different factors including, for example, the type or source of ethanol under treatment 1stgeneration, 2ndgeneration, CO derived and / or fossil derived, the volume of ethanol under treatment, the aqueous solvent utilised, the specific temperature and pressure employed during the reaction, the type of catalyst and the desired properties of the end product, selective to n-butanol or a mixture of higher alcohols besides the nature of the reactor apparatus.

[0085] In some preferred embodiments, an additional catalyst or combination of additional catalysts may be used in an amount of between about 0.01 % and about 50% w / v catalysts, between about 0.1 % and about 20% w / v catalysts, between about 0.1 % and about 10% w / v catalysts, between about 0.1% and about 5% w / v catalysts, between about 0.1% and about 2.5% w / v catalysts, between about 0.1% and about 1 % w / v catalysts, or between about 0.1% and about 0.5% w / v catalysts (in relation to the ethanol feed).

[0086] In certain embodiments, the hydrolysis catalysts may be base catalysts. Any suitable additional base catalyst may be used.

[0087] In some preferred embodiments, alumino-silicates including hydrated forms (e.g., zeolites) may be used to assist in dehydration (elimination) of water. Non-limiting examples of zeolites include ZSM-5, mordenite, Y, USY and beta zeolites, SAPO-1 1 , SAPO-34, molecular sieves, phosphates, zirconates, kaolinite, montmorillonite, pillared clays, hydrotalcites, and acid ionexchange resins such as Amberlyst-15®, and -35®, Nation SAC-13®, etc.

[0088] In some preferred embodiments, the removal of oxygen may be enhanced by thermal means involving decarbonylation, e.g., aldehydes (giving R3C-H and CO gas or C2H4) and decarboxylation of carboxylic acids in the material under treatment (giving R3C-H and CO2 gas) FIG. 2. The rate of these reactions may be enhanced by the addition of acid and / or transition (noble) metal catalysts. Any suitable transition or noble metal may be used including those supported on solid acids or merely as the surface of the reaction apparatus. Non-limiting examples include Pt / AI2O3 / SiO2, Pd / AI2O3 / SiO2, Ni / AI2O3 / SiO2, Ru / AI2O3 / SiO2, Os / AI2O3 / SiO2, Cr / AI2O3 / SiO2, Co / AI2O3 / SiO2, Fe / AI2O3 / SiO2, W / AI2O3 / SiO2, Mo / AI2O3 / SiO2, Re / AI2O3 / SiO2, Cu / AI2O3 / SiO2 and mixtures thereof.

[0089] In some preferred embodiments, a combined acid / base and hydrogenation catalyst may be used to enhance the removal of oxygen, for example, by hydrodeoxygenation, i.e., elimination of water via acid / base component and saturation of double bonds via metal component. Any suitable combined acid / base and hydrogenation catalyst may be used including those supported on solid acids or in conjunction with ion exchange resins. Non-limiting examples include Pt / AI2O3 / SiO2, Pd / AI2O3 / SiO2, Ni / AI2O3 / SiO2, NiO / MoOs, CoO / MoOs, Ni0 / W02, zeolites loaded with noble metals (e.g., ZSM-5, Beta, ITQ-2), and mixtures thereof.

[0090] In some preferred embodiments, a water gas shift catalyst may be used to enhance the concentration of hydrogen into the reaction, i.e., via a water-gas shift reaction. Any suitable water gas shift (WGS) catalyst may be used including, for example, transition metals, transition metal oxides, and mixtures thereof e.g., magnetite, platinum based WGS catalysts, finely divided copper and nickel, Raney® nickel, or copper and components of the reactor material and mixtures thereof.

[0091] In some preferred embodiments, catalysts which are suitable particularly advantageously for use in the process according to the invention is that of skeletal or metal sponge catalysts, which are referred to as “Raney® catalysts” may be used. These include Raney® nickel, cobalt or copper and copper-containing metal alloys in the form of a Raney® catalyst. Preferably, Raney® catalysts whose metal component consists of components contained in stainless steel to an extent of at least 70%, especially to an extent of 99%. Raney nickel may also be referred to as spongy nickel.

[0092] In some preferred embodiments, the catalyst further comprises a skeletal or metal sponge catalyst; preferably Raney nickel. Raney nickel is a Nickel-Aluminium alloy. Preferably the alloy has a Ni:AI ratio of about 1 :1.

[0093] In some embodiments, the catalyst is provided as a single-site catalyst. In some embodiments, the catalyst is supported, preferably supported on an aluminosilicate framework. In some preferred embodiments, the catalyst is provided in step a. from at least 0.01 mol% to at most 1 .00 mol%, preferably from at least 0.02 mol% to at most 0.10 mol%, preferably about 0.05 mol%.

[0094] In some embodiments, any kind of activated carbon may be used, such as activated charcoal. Preferably, the activated carbon is sourced from peat. Preferably the activated carbon is steam activated. Preferably the activated carbon is in powder form. For example, activated Charcoal Norit® greener alternative Norit® SA2, from peat, steam activated, powder from Merck may be used. Advantageously, the process as disclosed herein comprising a catalyst that comprises activated carbon, was found to reduce the amount of byproducts and impurities, while simultaneously improving the reaction rate, thereby promoting the desired coupling of alcohol compounds.

[0095] The multicomponent solvent system preferably comprises at least a basic aqueous hydrocarbon solvent phase, comprising at least two different hydrocarbons. In some embodiments, the solvent system is provided in step a. at a solvent / Ci.3 alcohol ratio of at least 1 to at most 10, preferably of at least 2 to at most 5, preferably about 3.

[0096] In some preferred embodiments, treatment with a subcritical aqueous hydrocarbon solvent (as opposed to supercritical aqueous solvent) may be advantageous in that less energy is required to perform the methods and the aqueous hydrocarbon solvent may be better preserved during reaction. When a subcritical aqueous hydrocarbon solvent is utilised, it is contemplated that the additional use of one or more catalysts may be particularly beneficial in increasing the yield and / or selectivity to n-butanol. Further, the cost benefits of reduced input energy, / .e., to maintain subcritical rather than supercritical conditions and preservation of the solvent may significantly outweigh the extra cost incurred by additionally including one or more of the catalysts described herein.

[0097] The solvent preferably comprises a base selected from the group comprising: potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium t-butoxide, sodium t-butoxide, or combinations thereof, for example a eutectic mixture of sodium and potassium hydroxide. In some preferred embodiments, the basic aqueous solvent phase comprises an alkali hydroxide, preferably KOH. In some embodiments, alkoxides of higher alcohols may be used as a base.

[0098] The solvent comprises a multicomponent solvent system, comprising at least two different hydrocarbons. In some preferred embodiments, the solvent system is a thermomorphic multicomponent solvent system, preferably comprising a high boiling hydrocarbon solvent phase.

[0099] An additional high boiling hydrocarbon solvent as understood herein may be any solvent that enhances the selectivity of n-butanol as an extractive solvent, extracting the intermediates as outlined in FIG. 2 in addition to n-butanol thereby preventing the formation of higher alcohols from ethanol using the methods of the invention whilst allowing heating of the reactor apparatus within safe operation limits and stabilizing the catalyst. Critical temperature (Tc) for ethanol is 240.95 °C, boiling point is 78.37 °C, / .e., it leads to unsafe reaction conditions if ethanol is heated alone under reaction conditions of the current invention. Addition of a higher boiling hydrocarbon solvent may also provide appropriate elevation of boiling point of ethanol. Preferably, the hydrocarbon solvent has at least two components of different polarity and have a high temperature dependent miscibility gap. Preferably, the reaction components are immiscible at low temperatures and completely miscible at elevated reaction temperatures. Higher dilutions such as the one with an aqueous hydrocarbon solvent also, dissociates the acetaldehyde hydrate CH3CH(OH)2or semi-acetals CH3CH(OH)(OEt) back to acetaldehyde water and ethanol. Thereby promoting the subsequent aldol condensation leading to n- butanol. Similar, effect on rapid n-butanal hydrate dissociation following by hydrogenation leads to the formation of n-butanol. Preferably, the hydrocarbon solvent may also act as an entrainer towards the effective distillation of azeotropes resulting in the reaction mixture such as ethanol / water, and n-butanol / water.

[0100] The area and shape of the ‘phase separation zone’ of the applied thermomorphic multicomponent solvent system would depend upon various parameters as water to alcohol ratio, temperature and the type of alcohol, ethanol, or n-butanol and so on. Ethanol is the only one with high solubility in water in contrast to butanol (73 g / L at 25 °C). At higher conversions, the solubility drops further thereby interaction with the active catalytic water phase will become low thereby increasing the selectivity to n-butanol. Of-course as the reaction proceeds the liquid phase will consist of unreacted ethanol, water, n-butanol, intermediates, and hydrocarbon solvent. An appropriate choice of water / alcohol / hydrocarbon at reaction conditions may be used to carefully control this regime thereby the selectivity to n-butanol, based on the corresponding distribution coefficients. FIG. 4 and FIG. 7.

[0101] In some preferred embodiments of the invention, the feed may contain one or more different aqueous alcohol / s such as fusel alcohols. However, it is emphasised that the inclusion of alcohols is optional rather than a requirement. For example, it may be suitable or preferable to use a higher boiling alcohol as the solvent depending on availability.

[0102] In some preferred embodiments, the solvent comprises a mixture of two or more aqueous alcohols. Suitable alcohols may comprise between C3-C2o. Non-limiting examples of suitable alcohols include linear or branched alcohols as 1-propanol, isopropyl alcohol, isobutyl alcohol, pentyl alcohol, amyl alcohols, hexanol and iso-hexanol.

[0103] In some preferred embodiments, the high boiling hydrocarbon solvent phase comprises a high boiling hydrocarbon selected from the group comprising: poly(ethylene glycol) (PEG) monoalkyl ethers, aliphatics (straight chain or branched), aromatics, 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, diarylether, 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, tri mellitates, 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.

[0104] In some preferred embodiments, the solvent comprises aromatics with aliphatic substitutions, such as mesitylene, which boils at 164°C. 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 be xylenes and mesitylene. in some preferred embodiments, the solvent comprises be xylenes and a Petrosolv solvent. In some preferred embodiments, the solvent comprises be xylenes, mesitylene, and a Petrosolv solvent. In some preferred embodiments, the solvent comprises 1-propanol. In some preferred embodiments, hydrocarbon solvents according to the invention may be recycled for use in subsequent reactions for conversion of ethanol into n-butanol. The recycled solvents may be re-used during the process of cooling / de-pressurisation followed by distillation may be facilitated by performing the methods of the invention in a continuous flow system. This may be particularly advantageous in embodiments of the invention relating to extended operation at scales at or larger than pilot plant scale. In general, it is contemplated that the recycling of solvents present in reaction components may allow for a situation where a top-up of solvent / ethanol is required during start-up operation.

[0105] In some embodiments, the high boiling hydrocarbon solvent phase comprises a high boiling hydrocarbon in a ratio from 1 :1 to 1 :1000. Preferably, the ethanol: solvent ratio is 1 :100, 1 :10, 1 :5, 1 :3, 1 :2, 1 :1. Higher solvent volumes are preferred for higher reaction temperatures (>250 °C), and lower solvent volumes are preferred for temperatures lower than 250 °C. The feed may comprise more than about 5 wt. %, 10 wt. %, 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, 40 wt. %, 45 wt. % or 50 wt. % of the hydrocarbon solvent or alcohols and combinations thereof.

[0106] In some preferred embodiments, the C1.3 alcohol is ethanol, preferably bio-ethanol. In some preferred embodiments, the solvent / ethanol ratio is at least 2.0, preferably at least 3.0. Preferably the bio-ethanol is obtained from fermentation.

[0107] By “ethanol feed”, it will be understood that it encompasses any ethanol comprising of two carbon alcohol, including both fossilised and non-fossilised or bio-forms. No limitation exists regarding the particular type of ethanol is utilised in the methods of the invention, although it is contemplated that certain forms of ethanol (e.g., bio-based ethanol) may be more suitable than others.

[0108] In some preferred embodiments, the ethanol may be rectified spirit, / .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). Impurities or fusel alcohols may be a part of the feed. Such impurities may be aldehydes, acids, esters, higher alcohols, amyl alcohols. These may be either purified of may be used as a crude feed straight from the fermentation process.

[0109] In some preferred embodiments, the ethanol may be extra neutral alcohol (ENA) or neutral spirit (NS).

[0110] In some preferred embodiments, the ethanol may be fuel grade ethanol also known as absolute alcohol (AA), comprising of a blend of fusel alcohols and / or denaturing agents.

[0111] In some preferred embodiments, the ethanol may be derived from 1st generation (food based), 2nd generation (waste based) or via CO / CO2 recycling or other. No limitation exists regarding the proportion of the different sources of ethanol. For example, ethanol may comprise more than about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90% or 95 wt. % of the feed. Preferably the ethanol is higher grade ethanol, such as fuel grade ethanol or G1 ethanol. In some preferred embodiments, the concentration of ethanol in the feed may be above about 98 wt. %, above about 95 wt. %, or above about 90 wt. %. Accordingly, the concentration of water may be above about 10 wt. %, above about 8 wt. %, above about 6 wt. %, above about 5 wt. %, above about 4 wt. %, or above about 3 wt. %.

[0112] In some preferred embodiments, the concentration of water is between about 1 wt. % and about 10 wt. %. In particularly preferred embodiments, the water is recycled from the product of the process. For example, a portion water present following completion of the reaction may be taken off as a side stream and recycled into the feed. It has been observed that if the water concentration is too high, the conversion rate drops.

[0113] In some preferred embodiments, fusel alcohols may be present in the ethanol feed. Fusel alcohols are higher boiling and volatile than ethanol, and therefore present resulting from the fermented mash. These may be a mixture of primarily alcohols, including active amyl alcohol (2-methyl-1 -butanol), isoamyl alcohol, isobutyl alcohol, 1-propanol and, n-amyl alcohol, n-butyl alcohol, and methionol. Less volatile alcohols also present in the mash that are poorly extracted by distillation, including phenethyl alcohol and tyrosol may also be present. Accordingly, the concentration of fusel alcohols may be above about 10wt.%, above about 5wt.% or above about 3 wt. %. It has been observed that the presence of fusel alcohols increases the conversion rate.

[0114] In some preferred embodiments, ethanol may be fed to the reactor as a liquid stream.

[0115] In some preferred embodiments, the ethanol stream is substantially free of external hydrogen, e.g., less than 0.5 wt.% hydrogen, less than 0.1 wt.%, or less than 0.01 wt.%. The feed stream may also comprise other molecules, such as high boiling hydrocarbon solvents. Inert gases may be in the gaseous stream and thus may include methane, argon, nitrogen, or helium. Preferably, no hydrogen is introduced with the gaseous stream, and thus the gaseous stream is substantially free of hydrogen. The hydrogen needed for the intermediate reactions may be produced in-situ for example with sodium formate, potassium formate, or ammonium formate. The present catalyst system is such that no additional hydrogen is required.

[0116] The catalyst / s may be added to ethanol, aqueous hydrocarbon solvent, before heating / pressurisation to target reaction temperature and pressure, during heating / pressurisation to target reaction temperature and pressure, and / or after reaction temperature and pressure are reached. The timing of catalyst addition may depend on the desirable output. For example, highly selective n-butanol formation may benefit from catalyst addition close to or at the target reaction temperature and pressure, whereas a mixture of higher alcohols may have a broader process window for catalyst addition, i.e., the catalysts may be added prior to reaching target reaction temperature and pressure. In some preferred embodiments, an aqueous hydrocarbon solvent is added under conditions of increased temperature and pressure in the presence of at least one “additional” catalyst. As noted above, an “additional” catalyst will be understood to indicate that the catalyst is supplied supplementary to catalysts intrinsically present in the reaction.

[0117] In some preferred embodiments, step a. is performed at ambient temperature.

[0118] In some preferred embodiments, step b. comprises one or more, preferably all, of the steps of: b1. heating the mixture to a temperature T1 in a time frame At1 ; b2. heating the mixture to a temperature T2 in a time frame At2; and, b3. maintaining the mixture at the temperature T2 during a time frame At3.

[0119] In some preferred embodiments, T2 is from at least 140°C to at most 500°C, preferably from at least 150°C to at most 400°C, preferably from at least 160°C to at most 300°C, preferably from at least 170°C to at most 260°C, preferably from at least 180°C to at most 240°C, preferably from at least 190°C to at most 220°C, preferably about 200°C.

[0120] The specific time period over which the conversion to n-butanol may be achieved upon reaching a target temperature and pressure, / .e., the “retention time or residence time” may depend on a number different factors including, for example, the type of hydrocarbon solvent used, the percentage of ethanol in the solvent, the amount of water, the types of catalyst / s as defined herein, in the mixture and their various concentration / s, and / or the type of reactor apparatus as described above in which the methods are performed. 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 the ethanol used as a feed into n-butanol.

[0121] In some preferred embodiments, T1 is from at least 60°C to at most 80°C, preferably about 70°C.

[0122] In some preferred embodiments, T2 is from at least 140°C to at most 500°C, preferably from at least 150°C to at most 400°C, preferably from at least 160°C to at most 300°C, preferably from at least 170°C to at most 260°C, preferably from at least 180°C to at most 240°C, preferably from at least 190°C to at most 220°C, preferably about 200°C.

[0123] In some embodiments, At1 is from at least 90 to 180 minutes, preferably about 120 minutes. In some embodiments, At2 is from at least 30 to 90 minutes, preferably about 60 minutes.

[0124] In some embodiments, At3 is from at least 120 to 360 minutes, preferably about 240 minutes. Reaction mixes that do not contain a significant proportion of hydrocarbon solvent may require a very fast initial conversion to generate some solvent in-situ. However, the incorporation of high boiling hydrocarbon component into the reaction mixture as described herein allows the component to act as a solvent thus alleviating the requirement for rapid heating / pressurisation. In continuous flow systems, pressure will generally change from atmospheric to target pressure during the time it takes to cross the pump, i.e., close to instantaneous, whereas in a batch system it will mirror the time that it takes to heat the mixture up.

[0125] In some preferred embodiments, the reaction mixture may be brought to a target temperature and / or pressure in a time period of between about 30 seconds and about 360 minutes.

[0126] In some preferred embodiments, the reaction mixture may be brought to a target temperature and / or pressure in a time period less than about 15 minutes, less than about 10 minutes, less than about 5 minutes, or less than about 2 minutes.

[0127] In some preferred embodiments, the reaction mixture may be brought to a target pressure substantially instantaneously and brought to a target temperature in less than about 20 minutes, less than about 10 minutes, or less than about 5 minutes. Preferably, the reaction mixture may be brought to a target pressure substantially instantaneously and brought to a target temperature in less than about two minutes. In other embodiments, the reaction mixture may be brought to a target pressure substantially instantaneously and brought to a target temperature in between about 1 and about 2 minutes.

[0128] In some preferred embodiments, At1 residence times are about 360 minutes, 240 minutes, 180minutes, 120minutes, 60 minutes, 45 minutes, 30 minutes, 25 minutes, 20 minutes, 15 minutes, 10 minutes or less than about 5 minutes. Preferably, the residence time is less than about 120 minutes, 60 minutes, 45 minutes, 30 minutes, 25 minutes, 20 minutes, 15 minutes, 10 minutes or more than about 5 minutes.

[0129] In some preferred embodiments, At2, and At3 residence time is between about 1 minute and about 360 minutes. Preferably, the residence time is between about 10 minutes and about 120 minutes, between about 20 minutes and about 140 minutes, between about 30 minutes and about 180 minutes, or between about 40 minutes and about 240 minutes. Preferably, the retention / residence time is between about 20 minutes and about 30 minutes.

[0130] Additionally or alternatively, following completion of the retention time period the reaction mixture may be cooled to between about 140° C and about 200° C, between about 150° C and about 200° C, preferably between about 160° C and about 190° C, and more preferably about 150° C, in a time period of less than about 10 minutes, preferably less than about 7 minutes, more preferably less than about 6 minutes, preferably between about 4 and about 6 minutes, and more preferably about 5 minutes. Following the initial cooling period, the temperature may further reduced to ambient temperature with concurrent de-pressurisation by fast release into a cool aqueous medium, e.g., cooled water.

[0131] It has been found that the conversion of ethanol to n-butanol takes place advantageously at temperatures of 140° to 300° C, in particular, from 170 ° to 220 °C, and most preferably from 190° to 200 °C. Pressures may range from 1 to 300 bar, particularly from 5 to 100 bar, and most preferably from 10 to 80 bar. The processes of heating / pressurisation and cooling / de-pressurisation may be facilitated by performing the methods of the invention in a continuous flow system which may be a CSTR or tubular reactor or a microchannel reactor apparatus.

[0132] The current invention utilises an alcohol feed (ethanol) which is converted to another alcohol (n-butanol).

[0133] Similarly, the retention time required will be influenced by the proportions of various components in the reaction mixture (e.g., water, solvent, alcohol catalysts etc.).

[0134] In some preferred embodiments, step b. is performed at a pressure of at least 2 bar to at most 250 bar. This allows to keep the mixture in the liquid phase rather than gas phase to ensure the selectivity. Higher pressure helps stay in the liquid phase.

[0135] The inventors have found that the present components provide a homogeneous dispersion.

[0136] In some embodiments, step b. comprises a stirring rate modulated from 0 rpm to 5000 rpm, preferably from 200 rpm to 1200 rpm.

[0137] By “dispersion” it will be understood that the reaction mixture is thoroughly mixed. The exhaustive dispersion may depend upon the nature of the reactor. Batch and flow reactors exhibit different mixing mechanisms, where tube reactors inherently have much smaller diffusion times and achieve mixing much faster (higher surface to volume ratio) than in batch. This, in combination with reaction kinetics will determine if flow conditions are beneficial, based, most of the time, on the reaction Reynolds numbers (Re). Preferably, the mixture is stirred vigorously enough to be able to benefit thermomorphic multicomponent hydrocarbon solvent system, / .e., temperature dependency of the miscibility gap is as high as possible, to switch from homogeneous to biphasic separation at low energy consumption, elimination of liquid-liquid interface to enable unification of reaction components, and only a single solvent is preferred that can homogenise catalyst, ethanol feed, and preferentially n-butanol phase upon cooling such that additional separation units for product purification and solvent recovery are dispensable.

[0138] In some preferred embodiments, a bubble column reactor type mechanism may be used to ensure good heat and mass transfer rates therefore, excellent dispersion, with no moving parts, compactness, easy operating and low maintenance and operating costs.

[0139] In some preferred embodiments, with a batch reactor, one may use an overhead stirring unit with variable speeds from 0-1200 rpm. Alternatively, a Teflon coated stir bar may be used with a hot stir plate with a suitably sized aluminium metal block equipped with a temperature probe and controlled stirring but with limited efficiency may also be used.

[0140] In some embodiments, step b. is performed in a batch reactor, a flow reactor, a continuous flow reactor, a tubular reactor, or a microchannel reactor; preferably step b. is performed in a batch reactor or a tubular reactor. For the present invention, heat transfer and mass transfer or mixing limitations, rather than the fundamental kinetics, control the reaction rate. The conversion of two equivalents of ethanol to one equivalent of n-butanol and water each at ambient conditions is -46.6 kJ / mol, / .e., such an exothermic reaction may require a couple of hours as described above to carry out in a batch reactor, not because of any kinetic constraint, but because of the time necessary to remove the heat of reaction and to operate in a safe manner.

[0141] In some preferred embodiments, the reactor may be any suitable batch reactor or combination of reactors. Preferably, the reactor comprises a fixed bed reactor or a series of such reactors. In some preferred embodiments, the reactor is a gas flow catalytic reactor or a series of such reactors.

[0142] In some preferred embodiments, the reactor is a continuous stirred tank reactor or a fluidised bed reactor or a tubular reactor.

[0143] Although the methods of the invention need not be performed under conditions of continuous flow, doing so may provide several advantageous effects. For example, continuous flow may facilitate the accelerated implementation and / or removal of heat and / or pressure applied to the mixture. This may assist in achieving the desired rates of mass and heat transfer, heating / cooling and / or pressurisation / de-pressurisation.

[0144] Continuous flow may also allow the retention time of the reaction mixture to be tightly controlled. Without limitation to a particular mode of action, it is postulated that the increased speed of heating / cooling and / or pressurisation / de-pressurisation facilitated by continuous flow conditions along with the capacity to tightly regulate retention / residence times assists in preventing the occurrence of undesirable side-reactions as cited in FIG. 2 as the reaction mixture heats / pressurises and / or cools / de-pressurises.

[0145] Continuous flow is also believed to enhance reactions responsible for conversion of ethanol to n-butanol by virtue of generating mixing and shear forces believed to aid in emulsification which may be an important mechanism involved in the transport and “storage” of the n-butanol generated away from the reactive surfaces of the catalyst as well as providing interface surface area for so-called ‘on-water catalysis’.

[0146] Accordingly, in preferred embodiments the methods of the invention are performed under conditions of continuous flow. As used herein, the term “continuous flow” refers to a process wherein ethanol mixed with a high boiling aqueous hydrocarbon solvent in the form of a mixture (with or without additional catalysts) is subjected to:

[0147] (a) heating and pressurisation to a set target operating temperature and pressure,

[0148] (b) treatment at target operating temperature(s) and pressure(s) for a defined time period ( / .e., the “retention / residence time”), and

[0149] (c) cooling and de-pressurisation followed by distillation, while the mixture is maintained in a stream of continuous movement along the length (or partial length) of a given surface. It will be understood that “continuous flow” conditions as contemplated herein are defined by a starting point of heating and pressurisation ( / .e., (a) above) and by an end point of cooling and de-pressurisation ( / .e., (c) above).

[0150] Continuous flow conditions as contemplated herein imply no particular limitation regarding flow velocity of the mixture provided that it is maintained in a stream of continuous movement.

[0151] Preferably, the minimum (volume-independent) flow velocity of the mixture along a given surface exceeds the settling velocity of solid catalyst components within the mixture, / .e., the terminal velocity at which a suspended particle having a density greater than the surrounding solution moves (by gravity) towards the bottom of the stream of mixture, allowing for uniform diffusion.

[0152] For example, the minimum flow velocity of the mixture may be above about 0.001 cm / s, above about 0.05 cm / s, preferably above about 0.5 cm / s and more preferably above about 5 cm / s. The upper flow velocity may be influenced by factors such as the volumetric flow rate and / or retention / residence time. This in turn may be influenced by the components of a particular reactor apparatus utilised to maintain conditions of continuous flow.

[0153] Continuous flow conditions may be facilitated, for example, by performing the methods of the invention in a suitable reactor apparatus. A suitable reactor apparatus will generally comprise heating / cooling, pressurizing / de-pressuring and reaction components in which a continuous stream of reaction mixture is maintained.

[0154] The use of a suitable flow velocity (under conditions of continuous flow) may be advantageous in preventing scale-formation or catalyst deposition along the length of a particular surface that the reaction mixture moves along, e.g., vessel walls of a reactor apparatus and / or generating an effective mixing regime for efficient heat transfer into and within the reaction mixture.

[0155] In a batch process, cooling only takes place at the surface of the reactor. The formation of hot spots or the accumulation of reaction heat may favour undesirable side reactions or fragmentation as described in the FIG. 2. This becomes even more evident when looking at the scaling-up of a production routine. The surface-to-volume ratio is a function of reactor size. Larger reactors have smaller surface-to-volume ratios. For example, 100mL flask has a surface / volume (cm2 / cm3) of 1 , while that for a 189 L (50-gallon) reactor is 0.08, for a 1m3reactor it is 0.06 and for a flat microchannel reactor with width approximately 100 pm is 200.

[0156] In some preferred embodiments, the continuous stirred tank reactor or a tubular reactor is favoured over a batch or a CSTR reactor.

[0157] Therefore, a synthetic procedure that works well in a small glass insert in R&D may pose huge problems when transferred directly to larger vessels in a kilo laboratory or pilot plant and subsequently to a commercial plant. In flow chemistry, a single flow reactor (e.g., a microreactor) has a larger surface-to-volume ratio. For scaling-up from gram to kilogram scale to multi-ton scale, only the operation time of the microreactor system is extended, and no further process development is necessary.

[0158] In some preferred embodiments, a continuous stirred tank reactor (CSTR) or a fixed bed reactor may be used to support continuous production. Preferably, several specialised reactors may also be used: (1) microreactors, (2) continuous tubular reactors / plug flow reactor, (3) bubble column reactor (BCR), (4) reverse flow reactors and (4) CSTRs with continuous tubular reactor in tandem. Additionally, or alternatively, reverse flow reactors heat exchange for heating the feed flow and cooling the product flow may be combined in the fixed bed reaction section, saving on heat exchanger cost. Additionally, or alternatively, the reactor may also be a high pressure reactive distillation, wherein reactive distillation (RD), benefits can be realised by using the reaction to improve separation of unreacted ethanol, and products as water, n-butanol and higher alcohols (e.g., overcoming azeotropes, reacting away contaminants, avoiding difficult separations) wherein, the catalyst components are embedded in the column packing material to improve efficiency or by using separation to improve reactions (e.g., enhancing overall rates, overcoming reaction equilibrium limitations, improving selectivity) - the maximum effect being achieved when both aspects apply.

[0159] In some preferred embodiments, flow reactors (e.g., microreactors) with their high surface-to- volume ratios may be used to absorb the heat created from the reaction much more efficiently than a batch reactor. In a large batch reactor, there is a strong temperature gradient from the cooled surface of the reactor to its centre. In a microreactor, much less heat is created, and it only takes a few millimetres of path length for the stream to cool down to the operational temperature. This results from higher heat transfer in flow reactors compared with batch reactors. For example, typical heat transfer coefficient for different reactors depending on reactor type are, for a jacketed batch reactor the volumetric heat transfer coefficient (MW / m3K) is 10-2to 10'3while for shell and tubes it is 0.2 and for plates or glass fluidic modules it is 1.3- 1.7 MW / m3K. Thus, a microreactor may offer further reduction of carbon footprint of the overall process.

[0160] To further take advantage of the properties and benefits of continuous flow reactors, miniaturised flow reactors may be designed in a variety of shapes, lengths, diameters, and construction materials. The key feature of every flow design unit is the ability to maintain a steady flow rate though the reactor over process time. Additional features may incorporate the implementation of baffles to promote mixing and / or static mixers to increase turbulent flow. Flow reactors are typically designed to have reduced reactor volumes, physical footprint, and energy requirements when compared with their batch reactor counterparts. Due to their design and size, these reactors are operated in a safer environment and offer the benefits of increasing reaction rates (e.g., at a higher temperature than batch reactors), operating solvent- less or low solvent / ethanol ratios, enhancing mixing, and effectively removing the heat produced by the exothermic reaction due to a more efficient heat transfer capacity and well- defined reaction concentration profile that enables to control the conversion of ethanol and n- butanol to Ce, Cs and Cw alcohols. The ability to control accurately the residence time in the reaction zone gives greater reproducibility of product distribution and process robustness in terms of operating conditions for flow process intensification. There are also several other specialised reactors designed for the current invention, such as the spinning disk reactor (SDR), a spinning tube-in-a-tube reactor, and tubular reactors designed for multiphase catalytic reactions. These can be used as a standalone unit or as a combination of, thereby to optimise the conversion and selectivity to n-butanol.

[0161] In some preferred embodiments, the C1.3 alcohol is converted to n-butanol. In some preferred embodiments, the C1.3 alcohol is converted to Ce-8 alcohols.

[0162] In some embodiments, the reaction achieves favourable conversion of ethanol and favourable selectivity, and productivity to n-butanol. For the purposes of the present invention, the term “conversion” refers to the amount of ethanol in the feed that is converted to a compound other than ethanol. Conversion is expressed as a percentage based on ethanol in the feed. The conversion of ethanol may be at least 20%, e.g., at least 30%, at least 40%, or at least 60%, or at least 80%.

[0163] Selectivity, as it refers to the formation of n-butanol, is expressed as the ratio of the amount of carbon in the desired products and the amount of carbon in the total products. Preferably, the selectivity to n-butanol is at least 30%, e.g., at least 40%, or at least 60%, or at least 90%. In some embodiments, the catalyst selectivity to Ce+ alcohols, is at least 5%, e.g., at least 10%, at least 20%, or at least 25%. Preferred embodiments of the process demonstrate a low selectivity to undesirable products, such as di-ethyl ether, methane, ethane and ethene as shown in FIG. 2. The selectivity to these undesirable products preferably is less than 20%, e.g., less than 5% or less than 1%. More preferably, these undesirable products are not detectable. More preferably, these undesirable products are not formed.

[0164] In some preferred embodiments, production of n-butanol from ethanol in accordance with the methods of the invention may be enhanced by the presence of “intrinsic” catalyst / s that are innately present in a given reaction component such as, for example, in ethanol, aqueous solvent, and / or vessel walls of a reactor apparatus in which the reaction mixture may be treated.

[0165] Accordingly, the methods of the invention may be performed using “additional” catalysts in combination with “intrinsic” catalysts, or, “intrinsic” catalysts as standalone depending on reactor apparatus type and material.

[0166] The optimal quantity of an intrinsic catalyst used in the methods of the invention may depend on a variety of different factors including, for example, the type of ethanol under treatment, the volume of ethanol under treatment, the aqueous hydrocarbon solvent utilised, the specific temperature and pressure employed during the reaction, the type of catalyst and the desired conversion, and selectivity to n-butanol.

[0167] In some preferred embodiments, an intrinsic catalyst or combination of intrinsic and additional catalyst may be used in an amount of between about 0.1% and about 20% w / v catalysts, between about 0.1% and about 10% w / v catalysts, between about 0.1 % and about 5% w / v catalysts, between about 0.1% and about 2.5% w / v catalysts, between about 0.1% and about 1 % w / v catalysts, or between about 0.1 % and about 0.5% w / v catalysts (in relation to the ethanol).

[0168] In some preferred embodiments, an “intrinsic” catalyst used in the reaction process may be an alkali and / or alkaline earth metal salt, e.g., potassium, calcium and / or sodium salts. For example, alkali metal hydroxides and carbonates may be effective in reducing the oxygen content of the aldol condensation products. In one embodiment, the optimum catalyst concentration (in the reaction itself) of an alkali metal hydroxide and / or alkali metal carbonate catalyst under a given set of otherwise substantially constant reaction conditions may be in the range of about 0.1 Molar to about 5 Molar. In some preferred embodiments, the concentration may be about 0.1 Molar to about 2 Molar. Preferably, the concentration of alkali metal hydroxide and / or alkali metal carbonate catalyst is less than about 25% w / w; between about 5% and about 15% w / w.

[0169] For example, bio-ethanol from distilleries may comprise a variable amounts of impurities, e.g., between 0.1% to about 2% impurities, and the impurities in turn may comprise various amounts of alkali salts, e.g., potassium, sodium salts and / or calcium salts resulting from extraction of fusel alcohols. Other metals that are present in fuel grade ethanol my comprise of manganese, iron, lead, cobalt, cadmium, zinc, copper, nickel in varying amounts. These may be catalysts for a range of reactions under the reaction conditions of the present invention including those reactions described in FIG. 2. Additionally or alternatively, an aqueous hydrocarbon solvent used in the methods of the invention may provide intrinsic catalysts to the reaction. Non-limiting examples of these catalysts include hydronium and / or hydroxide ions of water. Additionally or alternatively, “intrinsic” catalysts may be provided by the vessel walls of a reactor apparatus in which the reaction may be treated. Non-limiting examples of materials commonly used for reactor construction, i.e., including reactor vessel walls, are alloys of iron with other metals including chromium, nickel, manganese, vanadium, molybdenum, titanium and silicon.

[0170] In some preferred embodiments, “intrinsic” catalysts that may be provided by the vessel walls of a reactor apparatus are transition / noble metals.

[0171] Non-limiting examples of “intrinsic” catalysts may be provided by the vessel walls of a reactor apparatus include iron metal, hydroxides of iron, oxides of iron, carbonates of iron, hydrogen carbonates of iron, acetates of iron; nickel metal, hydroxides of nickel, oxides of nickel, carbonates of nickel, hydrogen carbonates of nickel; chromium metal, hydroxides of chromium, oxides of chromium, carbonates of chromium, hydrogen carbonates of chromium; manganese metal, hydroxides of manganese metal, oxides of manganese metal, carbonates of manganese metal, and / or hydrogen carbonates of manganese metal. Hydroxides may be present by virtue of reaction of the metals with water and alkaline “additional” catalysts. Oxides may be present by virtue of reaction of metals with oxygen-containing compounds and as passivating layers. Carbonates and hydrogen carbonates may be present by virtue of reactions of metals, metal oxides and / or metal hydroxides with carbon dioxide generated in- situ by decarboxylation reactions. Acetates of metals may be present by virtue of reactions of metals, metal oxides, metal hydroxides, metal hydrogen carbonates and metal carbonates with acetic acid generated in-situ by hydrolysis. Metals and metal compounds associated with surfaces made of steel and similar materials may catalyse various reactions including, but not limited to, one or more of the reactions described in FIG. 2.

[0172] By way of non-limiting example only, intrinsic catalysts, e.g., alkali salts such as potassium, sodium and calcium salts may be transferred to the aqueous hydrocarbon phase during the reaction. Because significant concentrations of such catalysts, e.g., alkali salts of potassium, sodium and calcium may be present in ethanol processed according to methods of the invention, in certain embodiments aqueous hydrocarbon phases containing dissolved catalysts, e.g., potassium, sodium, and / or calcium salts may be recycled.

[0173] In some preferred embodiments, intrinsic catalysts from various reaction components, e.g., from either by product water, or ethanol feed, or the aqueous hydrocarbon solvent, and / or vessel walls of a reactor apparatus may be renewed in situ alleviating or reducing the need to provide “additional” catalysts in subsequent rounds of ethanol conversion. This may be particularly advantageous in embodiments of the invention relating to extended operation at scales at or larger than pilot plant scale. In general, it is contemplated that the recycling of intrinsic catalysts present in reaction components, e.g., alkali salts may allow for a situation where “additional” catalysts are required during start-up operation only.

[0174] In some preferred embodiments, the “intrinsic” catalyst and catalyst components may be preformed and analysed or added as individual components as molar equivalents of the ethanol feed. This may be particularly advantageous in embodiments of the invention relating to extended operation on a commercial scale and related to the long-term storage of the catalysts.

[0175] In some preferred embodiments, the reaction vessel acts as an intrinsic catalyst. In some preferred embodiments, the reactor apparatus may be used to enhance the conversion of ethanol. Any reactor apparatus that is made from 316 stainless steel, an alloy of Fe, Cr (12- 20%), Ni (10-14%), Mo (2-3)%, Mn (<2%) and in some cases smaller amounts of Si (<1%), P(<0.045%), and S(<0.03%), that is generally considered to be inert and highly corrosion resistant, as it passivates itself through the build-up of a mechanically strongly adherent chromium oxide layer of <100 A thickness, for example, may be used to enhance the removal of oxygen, i.e., elimination of water from ethanol when treated with appropriate strong base or acid. Non-limiting examples of austenitic stainless steel or martensitic stainless steel or ferritic stainless steel that

[0176] In some preferred embodiments, the process further comprises the step of: c. distilling the higher alcohols.

[0177] Subsequent distillation of the reaction mixture to purify n-butanol is a preferred step of the process. Traditional set ups at steam or catalytic crackers including distillation have also key drawbacks in terms of high capital costs, due to the large equipment used, and significant operating costs due to the low energy efficiency.

[0178] The separation of multi-component mixtures preferably uses a direct or indirect sequence of at least two distillation columns. In which case, a dividing-wall column (DWC) may also be applied. DWC offers some major benefits compared with classic distillation design: high thermodynamic efficiency due to reduced remixing effects, 25-40% lower energy requirements, high purity for all product streams, reduced maintenance costs, small footprint and up to 30% lower investment costs due to the reduced number of equipment units.

[0179] Several energy demanding separation steps are required to reach the purity target of n- butanol, mainly due to the presence of the well-known binary azeotrope ethanol-water (95.63%wt ethanol) and n-butanol-water. Unlike ethanol, n-butanol and water form a heterogeneous azeotrope at 364.6 K, with a composition of 76.33 mol % water. Therefore, the first step may be carried out in a pre-concentration distillation column (PDC) that recovers ethanol up to 92.4-94%wt. The second step is ethanol dehydration up to concentrations above the azeotropic composition. This is typically carried out in an extractive distillation column (EDC) followed by a solvent recovery column (SRC). Although extractive distillation presents relatively high energy costs, it is still the option of choice in the case of large-scale production of bio-ethanol fuel - being preferred over pervaporation, adsorption, pressure- swing distillation, azeotropic distillation, or hybrid methods combining these options. This may be applied if the production of n-butanol were to be co-located to an ethanol producing facility. Extractive dividing-wall column (E-DWC) systems may be used for extractive distillation, including or not the pre-concentration distillation column (PDC).

[0180] In some preferred embodiments, a subsequent molecular sieve distillation, to further purify butanol with MFI-type zeolite membranes (e.g., silicalite-1), because of its well-defined pore structure (ca. 0.5 nm) and high hydrophobicity, may be deployed to obtain n-butanol with purity of 99.99%. According to a second aspect, the present invention relates to use of a catalyst as described herein, in the conversion of a C1.3 alcohol to higher alcohols

[0181] The independent and dependent claims set out particular and preferred features of the invention. Features from the dependent claims may be combined with features of the independent or other dependent claims as appropriate.

[0182] EXAMPLES

[0183] Materials

[0184] Commercially obtained reagents were used as received from appropriate commercial vendors such as VWR, Merck, without any further purification.

[0185] 1 -propanol (technical grade), zinc fine powder, technical grade xylenes mixture, and K2CO3 anhydrous were purchased from VWR Chemicals, Ni / AI 50 / 50%, and KOH (>85%) were purchased from Carl Roth GmbH, cobalt (II) chloride, anhydrous 97%, bromopentacarbonylmanganese(l) >98%, benzimidazole, and imidazole, 99% was purchased from Thermo Scientific. Petrosolv 200-300 was purchased from Raincarbon Inc. and dried over molecular sieves type 3 purchased from Carl Roth GmbH, iron (II) chloride tetrahydrate, sodium metal, tppts, and mesitylene were purchased from Merck, 2-(2-pyridylbenzimidazole), Ba(OH)2 94-98%, and sodium formate (98%) were purchased from Alfa Aesar, CS2CO3 >98% and pyrazole were purchased from TCI Chemicals, Triphenyl phosphine was purchased from Acros Organics, activated Charcoal Norit® greener alternative Norit® SA2, from peat, steam gactivated, powder from Merck was used. RUCI3.3H2O was purchased from Pressure Chemicals, Celite 535 was purchased from Macherey-Nagel GmbH & Co. KG.

[0186] Methods

[0187] All reactions were conducted with either a 10mL stainless steel reactor, a 100m L Parr stainless steel reactor vessel or with a 600 mL Parr stainless steel reactor vessel with or without glass inserts. The inventors would have found that the use of a glass liner may not be sufficient to prevent the reactor from playing a role in catalytic processes, as this does not limit exposure of the reaction solution to the lid, drive shaft and impeller used to stir the reaction, all of which are typically constructed from the same material as the reactor body itself. This is particularly true at high stirring speeds used when gaseous reactants must be dissolved in the reaction mixture or at high temperature, when substantial mass transport by convection and distillation takes place within the enclosed reactor space. However, this does minimise the exposure to the reagents in the present invention which occurs in the solution / liquid phase thereby providing a reasonably sound basis for the conversions with / without reactor metal influence. In addition, for 10 mL high pressure reactors without an overhead stirrer and a Teflon stir bar minimises the exposures further offering a better control of reaction parameters in general. This was also tested for 600mL Parr stainless steel reactor vessel heated on an aluminium block. All test runs were prepared in air unless stated otherwise. All components were found to be stable in air.

[0188] Analytics

[0189] Gas chromatogram - flame ionisation 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.

[0190] Table 1. Chromatographic Conditions for raw oligomerisation product analysis

[0191] “GC Agilent 8890 / 5977B GC / MSD

[0192] Sampler Agilent 7650A, 5.0-pL syringe

[0193] Carrier Hydrogen 30 cm / s, constant flow

[0194] Inlet Split (15:1); 250 °C, purge flow 22.5 mL / min

[0195] Inlet liner Deactivated dual taper direct connect

[0196] Column Agilent HP-5ms 30 m x 0.25 mm x 0.25 pm

[0197] Oven 42 °C (10 min) to 220 °C (20 °C / min), 15 °C / min to 310 °C

[0198] Detection MSD source at 230 °C, quadrupole at 150 °C, scan range 30 to 300 amu

[0199] Ethanol

[0200] All experiments employed industrial grade - fuel grade ethanol (G1) and neutral ethanol (G2) as listed below. G1 : Ethanol feed 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 Table 2.

[0201] Table 2.

[0202] Quality Parameter Limits ASTM Test Methods

[0203] Ethanol, % by volume, min 92.1 D5501

[0204] Methanol, % by volume, max 0.5 D5501

[0205] Solvent washed gum, mg / 100mL, max 5.0 D381

[0206] Water content, % by volume, (% by mass), max 1.0 (1 .26) D7923, E1064 or E203

[0207] Inorganic Chloride, mg / kg (mg / L), max 6.7 (5) D7319 or D7328

[0208] Copper, mg / kg, max 0.1 D1688

[0209] Acidity, as acetic acid, mg / kg, (% by mass) [mg / L], 70 (0.0070) D7795 max pHe 6.5-9.0 D6423

[0210] Sulphur, mg / kg, max 30.00 D5453

[0211] Existent Sulphate, mg / kg, max 4 D7318, D7319 or

[0212] D7328 G2: Ethanol specification used for tests as neutral ethanol derived by fermentation of cereals and carbohydrate containing juices of sugar beet and / or sugar cane with the specifications as listed in Table 3 and 4. Table 3.

[0213] Parameter Unit Limit Reference Method

[0214] Ethanol % vol. > 96.0 Reg. (EC) No

[0215] 2870 / 2000

[0216] Sensory properties no detectable taste / smell; clear, Organoleptic test colourless

[0217] Total acidity g / hL of 100% vol. ale. < 1.5 Reg. (EC) No expressed as acetic acid 625 / 2003

[0218] Esters g / hL of 100% vol. ale. < 1.3 Reg. (EC) No expressed as ethyl acetate 2870 / 2000

[0219] Aldehydes g / hL of 100% vol. ale. < 0.5 Reg. (EC) No expressed as acetaldehyde 2870 / 2000

[0220] Higher alcohols g / hL of 100% vol. ale. < 0.5 Reg. (EC) No expressed as methyl-2- 2870 / 2000 propanol-1

[0221] Methanol g / hL of 100% vol. ale. < 30 Reg. (EC) No

[0222] 2870 / 2000

[0223] Dry extract g / hL of 100% vol. ale. < 1.5 Reg. (EC) No

[0224] 625 / 2003

[0225] Volatile bases containing g / hL of 100% vol. ale. < 0.1 Reg. (EC) No nitrogen 625 / 2003 expressed as nitrogen

[0226] Furfural not detectable Reg. (EC) No

[0227] (<0.01 g / hL of 100% vol. ale.) 2870 / 2000

[0228] Table 4. Elemental analysis of neutral ethanol

[0229] Sodium mg / kg max. 1

[0230] Copper mg / kg max. 0.1

[0231] Iron mg / kg max. 0.1

[0232] Sulphur content mg / kg max. 1

[0233] Chlorine inorganic mg / kg max. 1

[0234] Nitrogen mg / kg max. 1 nitrogenous, alkaline parts mg / kg max. 1

[0235] Colour Saybolt > 25 electrical conductivity pS / cm < 2.5

[0236] Sulphate content mg / kg < 4.0

[0237] Water % 0.2-0.5

[0238] Comparative Example 1

[0239] G1 grade ethanol, iron as a dichloride. tetrahydrate salt, imidazole, KOH in molar ratio (681.0: 1.0: 2.9: 177.2), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1 -butanol compared with all the other components in the product other than ethanol. GC-trace showed 5% conversion, >98% selectivity.

[0240] Comparative Example 2

[0241] G1 grade ethanol, cobalt as a dichloride salt, imidazole, KOH in molar ratio (444.7: 1.0: 1.9: 115.7), and 3 mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 5% conversion, >98% selectivity.

[0242] Comparative Example 3

[0243] G1 grade ethanol, manganese as a pentacarbonyl bromide salt, KOH in molar ratio (138.5: 1 .0: 115.3), and 2mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 180°C in 1 h, time at temp T = 10h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 5% conversion, >99% selectivity. The Mn pentacarbonyl was found to be air sensitive. Adding an imidazole still resulted in an air sensitive catalyst. 4

[0244] G1 grade ethanol, manganese as a pentacarbonyl bromide salt, PPhs, KOH in molar ratio (138.5: 1.0: 1.54: 115.3), and 2mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 180°C in 1 h, time at temp T = 10h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 4% conversion, >99% selectivity. Comparative Example 5

[0245] G1 grade ethanol, manganese as a pentacarbonyl bromide salt, imidazole, KOH in molar ratio (138.5: 1.0: 2.8: 115.3), and 2mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 180°C in 1 h, time at temp T = 10h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed traces of conversion.

[0246] Comparative Example 6

[0247] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, KOH in molar ratio (710.5: 1.0: 184.8), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 10.1% conversion, 66.7% selectivity.

[0248] Comparative Example 7

[0249] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH in molar ratio (710.5: 1.0: 3.0: 184.8), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 24.6% conversion, 63.5% selectivity. 8

[0250] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, benzimidazole, KOH in molar ratio (710.5: 1.0: 1.76: 184.8), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 4% conversion, 85.8% selectivity. Comparative Example 9

[0251] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, 2-(2-pyridylbenzimidazole), KOH in molar ratio (710.5: 1.0: 1.1 : 184.8), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 5.1 % conversion, 85.1% selectivity.

[0252] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, pyrazole, KOH in molar ratio (710.5: 1.0: 3.0: 184.8), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 11.1 % conversion, 71.2% selectivity.

[0253] Comparative Example 11

[0254] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, tppts, KOH in molar ratio (710.5: 1.0: 0.74: 184.8), and 3mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 15.1 % conversion, 69.2% selectivity. 12

[0255] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Zn in molar ratio (710.5: 1.0: 12.2: 184.8: 31.7), and 1mL mesitylene and 2mL Petrosolv 200-300 solvent were premixed at ambient temperature in nitrogen, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 18.6% conversion, 79.8% selectivity.

[0256] Comparative Example 13

[0257] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Zn in molar ratio (710.5: 1.0: 12.2: 184.8: 31.7), and 2mL mesitylene and 1 mL Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 6h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 14.8% conversion, 82.3% selectivity.

[0258] Comparative Example 14

[0259] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (177.6: 1.0: 0.76: 46.2: 2.42), and 1mL mesitylene and 2mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 27.5% conversion, 75.0% selectivity.

[0260] Example 15

[0261] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (177.6: 1.0: 0.76: 46.2: 2.42: 43.2), and 1mL mesitylene and 2mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 49% conversion, 72.7% selectivity.

[0262] Comparative Example 16

[0263] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, sodium formate in molar ratio (177.6: 1.0: 0.76: 46.2: 6.2), and 1mL mesitylene and 2mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 20.8% conversion, 77.2% selectivity.

[0264] Example 17

[0265] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (1973.6: 1.0: 5.1 : 410.8: 13.4: 96.0), and 50mL mesitylene and 100 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 36.9% conversion, 82.48% selectivity.

[0266] Example 18

[0267] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (1973.6: 1.0: 5.1 : 410.8: 13.4: 96.0), and 50mL mesitylene and 100 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 170°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 44.9% conversion, 77.7% selectivity.

[0268] Example 19

[0269] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (1973.6: 1.0: 5.1 : 410.8: 13.4: 96.0), and 50mL mesitylene and 100 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 180°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 44.1% conversion, 74.47% selectivity.

[0270] Example 20

[0271] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (1973.6: 1.0: 5.1 : 410.8: 13.4: 96.0), and 50mL mesitylene and 100 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 190°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 60.4% conversion, 79.2% selectivity.

[0272] Example 21

[0273] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (1973.6: 1.0: 5.1 : 410.8: 13.4: 96.0), and 50mL mesitylene and 100 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 200°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 54.4% conversion, 79.2% selectivity.

[0274] Example 22

[0275] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (1973.6: 1.0: 5.1 : 410.8: 13.4: 96.0), and 50mL mesitylene and 100 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 210°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1- butanol compared with all the other components in the product other than ethanol. GC-trace showed 60.4% conversion, 80.2% selectivity. 23

[0276] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, in molar ratio (177.6: 1.0: 0.76: 35.1), and 3mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 7h. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1 -butanol compared with all the other components in the product other than ethanol. GC-trace showed 22.0% conversion, 77.4% selectivity.

[0277] Comparative Example 24

[0278] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, in molar ratio (177.6: 1.0: 0.76: 35.1), and 2mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 7h. The solvent / ethanol ratio was 2. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1 -butanol compared with all the other components in the product other than ethanol. GC-trace showed 13.1% conversion, 78.6% selectivity.

[0279] Comparative Example 25

[0280] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, in molar ratio (177.6: 1.0: 0.76: 35.1), and 1mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 7h. The solvent / ethanol ratio was 1. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1 -butanol compared with all the other components in the product other than ethanol. GC-trace showed 4.9% conversion, 91.0% selectivity.

[0281] Comparative Example 26

[0282] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, in molar ratio (177.6: 1.0: 0.76: 35.1), and 0.5mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 7h. The solvent / ethanol ratio was 0.5. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1 -butanol compared with all the other components in the product other than ethanol. GC-trace showed 5.2% conversion, 86.5% selectivity. 27

[0283] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, in molar ratio (177.6: 1.0: 0.76: 35.1), were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 7h. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 2.6% conversion, 81.8% selectivity.

[0284] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, Na, in molar ratio (88.8: 1.0: 1.5: 46.0), and Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (1 h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 3h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 22.4% conversion, 84.2% selectivity.

[0285] Comparative Example 29

[0286] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, K2CO3, in molar ratio (88.8: 1.0: 1.5: 46.0), and Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (1h), then ramped at 20°C increments to 150°C in 1h, time at temp T = 3h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed no conversion.

[0287] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, CS2CO3, in molar ratio (88.8: 1.0: 1.5: 46.0), and Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (1 h), then ramped at 20°C increments to 150°C in 1h, time at temp T = 3h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed trace levels of conversion. 31

[0288] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, Ba(OH)2, in molar ratio (88.8: 1.0: 1.5: 46.0), and Petrosolv 200-300 solvent were premixed at ambient temperature in air, then heated at 70°C (1 h), then ramped at 20°C increments to 150°C in 1h, time at temp T = 3h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed trace levels of conversion.

[0289] G2 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (1973.6: 1.0: 5.1 : 492.9: 13.4), 5mL tap water, 140mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 4h. The solvent / ethanol ratio was 2.8. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 16.3% conversion, 85.8% selectivity.

[0290] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (1973.6: 1.0: 6.8: 821.0: 10.8), and 100mL xylenes were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 180°C in 1 h, time at temp T = 2h. The solvent / ethanol ratio was 4. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 23.6% conversion, 81.6% selectivity.

[0291] Comparative Example 34

[0292] G1 grade ethanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (710,5: 1.0: 12.2: 184.8: 7.3), and 30mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 210°C in 1 h, time at temp T = 2h with agitated stirring. The solvent / ethanol ratio was 3. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 1-butanol compared with all the other components in the product other than ethanol. GC-trace showed 52.9% conversion, 88.7% selectivity.

[0293] Comparative Example 35

[0294] The conversion of 1-propanol was tested under similar conditions as ethanol. 1-propanol will lead to propionaldehyde. Aldol condensation of propionaldehyde will result in 2-methylpent-2- enal which will be hydrogenated subsequently to 2-methylpentan-1-ol under our reaction conditions. The partition coefficients of 1-propanol and subsequent intermediates and final product are listed in FIG. 6. Technical grade 1-propanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (2948.6: 1.0: 5.5: 786.6: 7.7), and 140mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 200°C in 1 h, time at temp T = 2h. The solvent / 1 -propanol ratio was 2.8. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 2- methylpentan-1-ol compared with all the other components in the product other than 1- propanol. GC-trace showed 46.95% conversion, >99% selectivity.

[0295] Comparative Example 36

[0296] Technical grade 1-propanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (2948.6: 1.0: 5.5: 786.6: 7.7), and 140 mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 180°C in 1 h, time at temp T = 2h. The solvent / 1 -propanol ratio was 2.8. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 2-methylpentan-1-ol compared with all the other components in the product other than 1-propanol. GC-trace showed 37.47% conversion, >99% selectivity.

[0297] Comparative Example 37

[0298] Technical grade 1-propanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (2948.6: 1.0: 5.5: 786.6: 7.7), and 140mL mesitylene were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 160°C in 1 h, time at temp T = 2h. The solvent / 1 -propanol ratio was 2.8. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 2-methylpentan-1-ol compared with all the other components in the product other than 1-propanol. GC-trace showed 33.67% conversion, >99% selectivity. Comparative Example 38

[0299] G1 grade ethanol, technical grade 1-propanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni in molar ratio (88.8: 138.6: 1.0: 1.5: 36.9: 6.1), and 2mL mesitylene solvent were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 7h. The solvent / alcohol ratio was 1.34. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. A representative GC trace is shown in FIG. 9.

[0300] Example 39

[0301] Technical grade 1-propanol, ruthenium as a trichloride. hydrate salt, imidazole, KOH, Raney® Ni, activated carbon in molar ratio (554.3: 1.0: 18.3: 184.8: 9.7; 172.8), and 1mL mesitylene and 1 mL Petrosolv 200-300 were premixed at ambient temperature in air, then heated at 70°C (2h), then ramped at 20°C increments to 150°C in 1 h, time at temp T = 2h. The solvent / 1- propanol ratio was 2. Upon completion of the reaction, the reactor was cooled in an ice-cold bath and pressure released. The reaction mixture was filtered through celite and analysed with GC-FID and GC-MS. The selectivity is determined for example by integration of GC signals for 2-methylpentan-1-ol compared with all the other components in the product other than 1- propanol. GC-trace showed 11.2% conversion, >99% selectivity.

[0302] Example 40 Distillation

[0303] A representative crude sample reaction mixture (300mL) resulting from the tests with a GC- FID such as the one shown in FIG. 8 was transferred to a 1000mL round bottom flask equipped with a 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, although it is possible to operate at sub-atmospheric or super-atmospheric pressures, if desirable under certain circumstances. 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 n-butanol containing at least about 97-99% of n-butanol.

[0304] The distillation products have the following compositions as judged by GC-FID: Fraction 1 : 78.5 °C, 12.4g (ethanol);

[0305] Fraction 2: 78.5-116.5 °C, 7.2g (mixture of 2:1 :0.1 ethanol: n-butanol: acetaldehyde diethyl acetal);

[0306] Fraction 3: 116.5-118.5 °C, 14.2g (n-butanol);

[0307] Fraction 4: Bottoms (residue) rest.

[0308] This example demonstrates that the inventors successfully distilled the sample. Example 41

[0309] Catalyst, ethanol, and solvent according to the invention were premixed at ambient temperature, then heated at 70°C (2h), then ramped at 20°C increments to temp #°C in 1 h, time at temp T = 4h. The catalyst was present at 0.0494 mol% and the solvent / ethanol ratio was 3. Results are shown in Table 5 below.

[0310] Run 1 corresponds to the details set out in Example 22. Runs 2 and 3 correspond to the details set out in Example 21. Run 4 corresponds to the details set out in Example 20. Run 5 corresponds to the details set out in Example 19. Run 6 corresponds to the details set out in Example 18. Runs 7 and 8 correspond to the details set out in Example 17. Runs 2 and 3 were identical, except for the fact that Run 3 was performed after leaving the catalyst exposed to elements for 4 months. Runs 7 and 8 were identical, except for the fact that Run 8 was performed after leaving the catalyst exposed to elements for 6 months. This illustrates the relative stability in air / water of the catalyst system.

[0311] # Temp. Conversion Selectivity C4 Selectivity C6 Selectivity C6

[0312] (°C) (%) (%) 2-ethylbutanol n-hexanol (%) (%)

[0313] 22 210 60.43 80.16 6.29 13.55

[0314] 21 200 58.15 82.37 4.93 12.7

[0315] 21 ’ 200 54.41 79.19 6.21 14.59

[0316] 20 190 60.44 79.23 5.54 15.23

[0317] 19 180 44.13 74.47 7.33 18.19

[0318] 18 170 44.98 77.75 6.85 15.4

[0319] 17 160 36.91 82.66 5.24 12.09

[0320] 17’ 160 25.95 82.48 8.95 8.57

[0321] Table 5

[0322] In the examples according to the invention, no intermediates were formed, as observed by GC. In the examples according to the invention, only n-butanol was formed, no other butanol isomers were observed. Examples that had a longer run-time, allowed for more C6 and C8 formation from n-butanol, as illustrated in FIG. 5.

Claims

CLAIMS1 . A process for converting a C1.3 alcohol to higher alcohols, the process comprising the steps of: a. pre-mixing a C1.3 alcohol, a catalyst, and a multicomponent solvent system, to form a liquid mixture; and b. heating the liquid mixture, thereby obtaining higher alcohols; wherein the multicomponent solvent system comprises at least a basic aqueous hydrocarbon solvent phase comprising at least two different hydrocarbons; wherein the solvent comprises a base selected from the group comprising: potassium hydroxide, sodium hydroxide, potassium ethoxide, sodium ethoxide, potassium t-butoxide, sodium t- butoxide, or combinations thereof, for example a eutectic mixture of sodium and potassium hydroxide; wherein the catalyst comprises an (HL)M(OH)n(H2O)m type complex and activated carbon; wherein M is a metal selected from the group comprising: Ru, Co, Ir, Rh, Os, Mo, W, Sc, Tc, Pt, Pd, Fe, or Ni; wherein HL is a protic mono-, di-, or a polydentate organic ligand and, wherein m and n are integers.

2. The process according to claim 1 , 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[1 ,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-(1 H- pyrazol-3-yl)phenol, 2-(1 H-pyrazol-5-yl)aniline, 3-alkylpyrazole-5-carboxylic acid, indazole, 5-hydroxypyrazole, tris(1-pyrazolyl)methane, tris(3,5-dimethyl-1- 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-(1 H-imidazol-2-yl)pyridine, 2-(1-hydroxyethyl)benzimidazole, 2-(2- pyridyl)benzimidazole, 2-(2-hydroxyphenyl)-1 H-benzimidazole, 1 H-pyrazol-3-ylboronicacid hydrate, 3,5-dimethyl-4-hydroxypyrazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol- 2-yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H-benzimidazole, 2-(2- pyridyl)benzothiophene, 2-aryl-4H-(1 ,2,4)triazole, 2-(4-methyl-2-pyridyl)-1 H- 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.

3. The process according to any one of claims 1 or 2, wherein the C1.3 alcohol is ethanol, preferably bio-ethanol and / or fuel grade ethanol.

4. The process according to claim 3, wherein the solvent / ethanol ratio is at least 2.0, preferably at least 3.0.

5. The process according to any one of claims 1 to 4, wherein the ligand 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-(1 H-imidazol-2-yl)pyridine, 2-(1- hydroxyethyl)benzimidazole, 5-methylimidazole, 2-(2-pyridyl)benzimidazole, 2-(2- hydroxyphenyl)-1 H-benzimidazole, 2-(2-pyridyl)benzimidazole, 2-(1 H-imidazol-2- yl)pyridine, 2,6-bis(2-benzimidazolyl)pyridine, 2-(3-pyridyl)-1 H-benzimidazole, 2-(4- methyl-2-pyridyl)-1 H-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; preferably wherein the ligand HL is imidazole.

6. The process according to any one of claims 1 to 5, wherein the metal is Ru.

7. The process according to any one of claims 1 to 6, wherein the catalyst further comprises a skeletal or metal sponge catalyst; preferably Raney nickel.The process according to any one of claims 1 to 7, wherein the basic aqueous solvent phase comprises an alkali hydroxide; preferably KOH. The process according to any one of claims 1 to 8, wherein step a. is performed at ambient temperature. The process according to any one of claims 1 to 9, wherein step b. comprises one or more, preferably all, of the steps of: b1 . heating the mixture to a temperature T1 in a time frame At1 ; b2. heating the mixture to a temperature T2 in a time frame At2; and, b3. maintaining the mixture at the temperature T2 during a time frame At3. The process according to claim 10, wherein T2 is from at least 140°C to at most 500°C, preferably from at least 150°C to at most 400°C, preferably from at least 160°C to at most 300°C, preferably from at least 170°C to at most 260°C, preferably from at least 180°C to at most 240°C, preferably from at least 190°C to at most 220°C, preferably 200°C. The process according to any one of claims 1 to 11 , wherein the C1.3 alcohol is converted to n-butanol. The process according to any one of claims 1 to 12, wherein the C1.3 alcohol is converted to Ce-8 alcohols. The process according to any one of claims 1 to 13, wherein said process is conducted in a reaction vessel, and wherein the reaction vessel acts as an intrinsic catalyst. The process according to any one of claims 1 to 14, further comprising the step of: c. distilling the higher alcohols.

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