An alcohol conversion process

Abstract

The present invention relates to an alcohol conversion process. A base and a catalyst are provided, which are mixed with the primary alcohol(s). The resulting mixture is heated to a process temperature below the boiling point of water under reaction conditions and the water resulting from the thus obtained condensation and dehydration of the primary alcohols is then removed.

Description

[0001] An alcohol conversion process

[0002] The present invention relates to an alcohol conversion process, and a system for such process.

[0003] A commonly used industrial production of alcohols is mainly based on an oxo process. Said process comprises the reaction of an alkene with oxo gas, which is a mixture of hydrogen and carbon monoxide in a 1 :1 molar ratio. The reaction is followed by hydrogenation of the aldehyde into the desired alcohol.

[0004] An alternative process for the synthesis of alcohols is based on the Guerbet reaction, which is known for many decades (M. Guerbet, C. R. Hebd. Seances Acad. Sci. 1899, 128, p. 511-513). It is generally accepted that the mechanism leading to Guerbet alcohols comprises the following three steps: (i) dehydrogenation of a primary alcohol to the respective aldehyde; (ii) aldol condensation of two aldehyde molecules to an a,p-unsaturated aldehyde with elimination of water; and (iii) hydrogenation of the unsaturated aldehyde to the dimer alcohol. An alkaline catalyst, e.g. sodium or potassium hydroxide or sodium or potassium alkoxides, is required for the Guerbet reaction. Often homogeneous or hetereogeneous metal catalysts are added to accelerate the dehydrogenation and hydrogenation steps. However, the Guerbet reaction generally suffers from harsh conditions, poor selectivity, separation issues and low yield.

[0005] In the chemical industry, 1 -butanol is an important intermediate product and solvent for a broad variety of products, including paints and various plastics. Up to now, 1 -butanol is produced from a petro-based feedstock, leading to a significant product carbon footprint for 1 -butanol and the resulting products. Therefore, it is important for the chemical industry to find and open an economical and sustainable process route to butanol with a lower product carbon footprint.

[0006] Y.Xie et aL, “Highly efficient Process for Production of Biofuel from ethanol Catalyzed by Ruthenium Pincer Complexes”, Journal of the American Society, vol. 138, no. 29, 2016-07-18, pages 9077 to 9080, relates to a ruthenium pincer-catalyzed Guerbet-type process for the production of biofuel from ethanol.

[0007] US 2014 / 235901 A1 relates to a reactive distillation method which comprises introducing a feed stream to a reactive distillation column, contacting the feed stream with one or more catalysts in the reactive distillation column during a distillation, and removing one or more higher alcohols during the distillation from the reactive distillation column as a bottoms stream. The feed stream comprises one or more alpha hydrogen alcohols, and the feed stream reacts in the presence of the one or more catalysts to produce a reaction product comprising the one or more higher alcohols.

[0008] WO 2013 / 156399 A1 relates to a method for producing branched alcohols using at least one alcohol of formula R1-CH2-CH2-OH, the groups R1being different or the same and being selected from C2-C3 alkyl, linear or branched, in a homogeneous phase in the presence of at least one base, characterized in that at least one complex compound containing Ru(ll) is used, in which the Ru(ll) has at least one ligand L1, which is at least bidentate, at least one coordination site of L1being a nitrogen atom.

[0009] Ethanol may be a sustainable feedstock to produce chemicals. Using ethanol in the Guerbet reaction may be a profitable and sustainable approach to produce 1 -butanol. Whereas the Guerbet reaction is used up to date to produce higher alcohols from higher boiling alcohol feedstocks than ethanol, there is so far no industrial usage for the Guerbet reaction for ethanol as the feedstock to produce 1 -butanol. While the Guerbet reaction itself may seem a simple chemical reaction, employing ethanol as the feedstock causes inherent problems particularly concerning selectivity. Because the product, 1 -butanol, can itself also undergo dehydrogenation, higher alcohols often result as side products in the process, making the reaction so far not profitable on an industrial scale.

[0010] Therefore, it was an object of the present invention to provide an alcohol conversion process suitable for a large scale production that allows for an improved control of the final distribution of obtained alcohols with respect to carbon number and branching type and number.

[0011] The present invention thus relates to an alcohol conversion process based on the Guerbet reaction, and more specifically to an alcohol conversion process, comprising

[0012] (i) providing a component C which is at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor;

[0013] (ii) preparing a liquid mixture ME comprising at least one alcohol R-CH2-CH2-OH, a base, and the component C provided according to (i), R being selected from the group consisting of H and Ci-C4-alkyl;

[0014] (iii) subjecting the liquid mixture ME prepared according to (ii) to alcohol conversion conditions in a reaction space SG and obtaining in said reaction space a reaction mixture MG comprising at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH, x being an integer in the range of from 1 to 4, wherein the alcohol conversion conditions comprise a temperature of the reaction mixture MG in the range of from 100 to 250 °C and a pressure in the reaction space SG in the range of from 1 x 105to 4 x 106Pa; wherein the temperature of the reaction mixture in the reaction space SG is below the boiling point of water under alcohol conversion conditions, and wherein water resulting from the alcohol conversion is removed;

[0015] (iv) separating the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the reaction mixture MG obtained according to (iii), obtaining the at least one alcohol R-CH2-CH2-(CHR-CH2)X- OH and a mixture Mos;

[0016] (v) recycling at least a part of the mixture Mos obtained according to (iv) to (ii); wherein

[0017] (a) the base is selected from the group consisting of ammonium hydroxide, alkali hydroxides, alkaline earth hydroxides, ammonium carbonate, ammonium hydrogen carbonate, alkali carbonates, alkali hydrogen carbonates, alkaline earth carbonates, alkaline hydrogen carbonates, alkali alkoxides, alkaline earth alkoxides, alkali metal amides, alkaline earth metal amides, alkali metal-2,2,6,6-tetramethylpiperidines, alkaline earth metal-2, 2,6, 6-tet- ramethylpiperidines, secondary amino acids, heterogeneous bases, which may optionally be doped, and a mixture of two or more thereof; (b) the catalyst comprises at least one selected from the group consisting of Pd(OAc)2, Pd / C, Pt / C, Cu-Zn-O, Cu-Cr-O, hydrotalcites and hydroxylapatites doped with metals, Raney Ni, Ni-MgO / SiO2, and a compound of formula (A); wherein

[0018] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0019] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, Cs-C -het- eroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:

[0020] L3is selected from the group consisting of CO, PRaRbRc, AsRaRbRc, SbRaRbRc, SRaRb, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0021] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0022] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRd2, NH3, NRd3, and Rd2NSO2Rd;

[0023] Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -het- erocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and Ci-Cio-alkyl; and X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl;

[0024] (c) the precursor of the catalyst comprising a compound of formula (A) comprises 1 ) a mixture comprising a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2-Ci2-alkenyl, Cs-Cis-cycloalkenyl, C5-C20- aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)

[0025] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0026] L1and L2, are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, Cs-C -het- eroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:

[0027] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0028] Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -het- erocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and Ci-Cio-alkyl; and X is optional is and selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyL

[0029] The present invention further relates to a system for the above alcohol conversion process, the system comprising:

[0030] - a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;

[0031] - a water separation unit connected to the reactor to receive from the reactor vapor evolving in the alcohol condensation process, and to remove water from the vapor; and

[0032] - an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the removed part of the reaction mixture MG to obtain a mixture Mos, and returning at least a part of the mixture Mos to the reactor.

[0033] The present invention also relates to a use of a system for the above alcohol conversion process, the system comprising:

[0034] - a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;

[0035] - a water separation unit connected to the reactor to receive from the reactor vapor evolving in alcohol condensation process, and to remove water from the vapor; and

[0036] - an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the removed part of the reaction mixture MG, and returning at least a part of the removed part of the reaction mixture to the reactor.

[0037] Advantageously, the present invention enables a large scale production of alcohols where the final distribution of alcohols can be controlled by separating the desired reaction products and optionally returning parts of the obtained reaction mixture into the reaction chamber for further reaction processing. The alcohols obtained by the conversion process may advantageously be used as additives for fuels like diesel or jet fuels, where they increase the electric conductivity and thus decrease the probability of ignition by static electricity. The alcohols may also be used as precursors of esters such as acrylates, methacrylates, or phthalates. The alcohols may moreover be hydrodeoxygenated and possibly further refined for obtaining gasoline, diesel fuel or aviation gasoline and jet fuel constituents. The alcohols may alternatively be dehydrated to alpha-olefins, which can then be polymerized or oligomerized, and be used for producing surfactants that are e.g. suited for utilization in petroleum industry operations.

[0038] The process in accordance with the present invention is preferably a continuous process. Alternatively, the process is preferably a semi-batch process or a batch process. Preferably, from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base, and the component C.

[0039] The alcohol conversion conditions according to (iii) preferably comprise the presence of at least one inert gas in the reaction space SG, wherein the at least one inert gas is preferably selected from the group consisting of nitrogen, argon, and a mixture thereof.

[0040] Also preferred is the alcohol conversion conditions according to (iii) comprising a pressure in the reaction space SG in the range of from 1 x 105to 3.5 x 106Pa, preferably in the range of from 1 x 105to 3.1 x 106Pa, more preferably in the range in the range of from 1 x 105to 2 x 106Pa, more preferably in the range in the range from 1 x 105to 1 .5 x 106Pa.

[0041] Furthermore, preferably, the alcohol conversion conditions according to (iii) comprise a temperature of the reaction mixture MG in the range of from 100 to 200 °C, more preferably in the range of from 120 to 180 °C, and more preferably in the range of from 130 to 160 °C.

[0042] The alcohol conversion conditions according to (iii) may also preferably comprise an amount of the base in the reaction mixture MG in the range of from 0.1 to 10 weight-%, more preferably in the range of from 0.5 to 8 weight-%, and more preferably in the range of from 1 to 5 weight-%, based on the total weight of the reaction mixture MG.

[0043] The process temperature in the reaction space SG is preferably at least 3 °C, more preferably at least 5 °C, more preferably at least 10 °C, more preferably at least 15 °C, more preferably at least 20 °C, more preferably at least 25 °C, below the boiling point of water under alcohol conversion conditions.

[0044] The boiling point of water under alcohol conversion conditions can be determined, for example on the basis of a vapor pressure curve for water in a temperature / pressure graph or diagram. The boiling point of water in the sense of the present invention refers to the boiling point of pure water under given alcohol conversion conditions, including the temperature and pressure under alcohol conversion conditions.

[0045] Preferably, the alcohol conversion conditions according to (iii) comprise an amount of the catalyst in the reaction mixture MG in the range of from 0.001 to 2 weight-%, more preferably in the range of from 0.001 to 1 weight-%, more preferably in the range of from 0.001 to 0.5 weight-%, based on the total weight of the reaction mixture MG.

[0046] The reaction space in step (iii) preferably comprises a the reaction mixture MG and a gas phase, wherein the gas phase comprises H2, and wherein the alcohol conversion conditions according to (iii) comprise maintaining the H2 partial pressure of the gas phase in the range of from 2 x 104 to 3.1 x 106Pa, preferably in the range of from 2 x 104to 1 .1 x 106Pa, more preferably in the range of from 2 x 104to 6 x 105Pa.

[0047] The H2 partial pressure of the gas phase is preferably maintained by introducing H2 into the gas phase. The H2 partial pressure of the gas phase is also preferably maintained by relaxation of the gas phase.

[0048] “Maintaining” the H2 partial pressure of the gas phase in the sense of the present invention includes ensuring that the H2 partial pressure is within the desired range during the reaction. In case the H2 partial pressure is within the desired range, no active steps have to be carried out mandatorily, but the pressure may still be adjusted to a different part of the range if desired. However, in order to ensure that the H2 partial pressure is neither too high nor too low, the H2 partial pressure may preferably be adjusted, or must be adjusted in case of ensuring that the H2 partial pressure is maintained within the desired range, for example by relaxation of the gas phase, in which case the H2 partial pressure may be reduced, or, alternatively, by introducing H2 into the gas phase, in which case the H2 partial pressure may be increased. Depending upon the H2 partial pressure during the reaction, one or even both of said alternatives may be carried out if desired to adjust the H2 partial pressure and to maintain the H2 partial pressure within the desired pressure range at all times during the reaction.

[0049] The pressure during can be monitored by, for example, determination of the overall pressure and comparison to the starting pressure. As hydrogen tends to build up during the reaction, the H2 partial pressure changes, e.g. increases, resulting in the pressure to increase over time. For example, by actively measuring and controlling the overall pressure during the reaction, it may be ensured that the H2 partial pressure is within the claimed range. If the overall pressure built up is too high, this tends to be at least in part the result of the H2 partial pressure increasing. By relaxation of the gas phase, hydrogen can be removed from the gas phase and the H2 partial pressure can be maintained in the desired range. Thus, in one preferred embodiment, the H2 partial pressure of the gas phase is preferably maintained in the respective range by monitoring the overall pressure of the reaction and adjusting the overall pressure if required, preferably by relaxation of the gas phase, in which case the H2 partial pressure may be reduced, or, alternatively, by introducing H2 into the gas phase, in which case the H2 partial pressure may be increased.

[0050] Alternatively, the hydrogen partial pressure can be determined by other means, such as taking samples of the gas phase during the reaction and analyzing same. As another alternative, the pressure may be monitored via online measurement, and adjusted accordingly as outlined above.

[0051] The at least one alcohol R-CH2-CH2-OH and the component C provided according to (i) is preferably pretreated with respect to removing acidic components and / or ester components and / or water prior to preparing a liquid mixture ME. Preferably, the component C is provided in a fixed bed, or a slurry fluidized bed, or a mobile bed. Also preferred is the component C being selected from the group consisting of Cu-Zn-ox- ide, Cu-chromite, Raney Ni, Ni-MgO / SiC>2, Pd / C, Pt / C, a metal selected from the group consisting of Ni, Pd, Cu, doped heterogeneous bases, Pd(OAc)2, and a mixture of two or more thereof.

[0052] In a preferred embodiment, the component C comprises a mixture comprising 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cy- cloalkyl, C2-Ci2-alkenyl, Cs-Cis-cycloalkenyl, Cs-C2o-aryl, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H’) wherein M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru; L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0053] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0054] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst comprising a compound of formula (A) an acridinyl unit; n is 0 or 1 , and if R1, R2, R3and R4are hydrogen, n is 0;

[0055] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-C -heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0056] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0057] Preferably, the component C comprises a compound comprising a metal M selected from the group consisting of lrCI3x H2O, [lr(COD)CI]2, [lr(COE)2CI]2, [lr(C2H4)2CI]2, [lr(COD)OH]2, [lr(COD)MeO]2, [lrCp*CI2], [lrCpCI2], lr4(CO)i2, [lr(PPh3)2(CO)CI], [lr(acetylacetonate)3], and [lr(acetylacetonate)(COD)], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadi- enyl, COD is 1 ,5-cyclooctadienyl, COE is cyclooctenyl, and methylallyl is 2-methylallyl. Alternatively, preferably, the component C comprises a compound comprising a metal M selected from the group consisting of, Ru(p-cymene)Cl2]2, [Ru(benzene)Cl2]y, [Ru(CO)2Cl2]y, where y is in each case in the range from 1 to 1000, [Ru(CO)3Ch]2, [Ru(COD)(allyl)], RuCh x H2O, [Ru(acety- lacetonate)3], [Ru(DMSO)4Ch], [Ru(cyclopentadienyl)(CO)2CI], [Ru(cyclopentadienyl)(CO)2H], [Ru(cyclopentadienyl)(CO)2]2, [Ru(Cp)(CO)2CI], [Ru(Cp*)(CO)2H], [Ru(Cp*)(CO)2]2, [Ru(in- denyl)(CO)2CI], [Ru(indenyl)(CO)2H], [Ru(indenyl)(CO)2]2, ruthenocene, [Ru(COD)CI2]2, [Ru(Cp*)(COD)CI], [RU3(CO)I2], [Ru(PPh3)4(H)2], [Ru(PPh3)3(CI)2], [Ru(PPh3)3(CO)(CI)2], [Ru(PPh3)3(CO)(CI)(H)], [Ru(PPh3)3(CO)(H)2], and [Ru(cyclooctadienyl)(methylallyl)2], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 , 5-cyclooctadienyl, and methylallyl is 2-methylallyl.

[0058] Preferably, the reduced form of the precursor comprises a compound of formula (P-l) or (P-ll): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroquinoline unit, a decahydroquinoline unit, a tetrahydroacridine unit, or a tetradecahydroacridine unit; and wherein L1and L2are, independently of each other, as defined above; -ll) wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above.

[0059] More preferred is that the reduced form of the precursor comprises a compound of formula (P-l): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroacridine unit, or a tetradecahydroacridine unit.

[0060] In another more preferred embodiment, the reduced form of the precursor comprises a compound of formula (P-ll): wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above.

[0061] Preferably, the component C comprises a compound of formula (A’) wherein M, R1, R2, R3and R4, L1, L2, , L3, Y and n are as defined above.

[0062] Preferably, the component C comprises a compound of formula (B) wherein

[0063] M is selected from the group consisting of Ir, Ru, and Mn;

[0064] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0065] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0066] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-C -cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0067] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH. In another preferred embodiment, the component C comprises a compound of formula (C) wherein

[0068] M is selected from the group consisting of Ir, Ru, and Mn;

[0069] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0070] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0071] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-Cw-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-Cw-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0072] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0073] Preferably, M is selected from the group consisting of Ir and Ru, wherein M is preferably Ru. Also preferred is L3being CO.

[0074] It is also preferred that L1and L2are each (PRaRb), and wherein Raand Rbare Ci-Cw-alkyl, more preferably wherein Raand Rbare each isopropyl or tert-butyl.

[0075] Preferably, L1and L2are each (PRaRb), and wherein Raand Rbare Cs-Cw-cycloalkyl, preferably wherein Raand Rbare each cyclohexyl.

[0076] It is also preferred that L1and L2are each (PRaRb), and wherein Raand Rbare Cs-C -aryl.

[0077] In another preferred embodiment, Y is selected from the group consisting of F, Cl, Br, and I, more preferably wherein Y is selected from the group consisting of Cl or Br, more preferably wherein Y is Cl.

[0078] In yet another preferred embodiment, Y is CO.

[0079] Preferably, the component C comprises a compound of formula (D) wherein Cy is cyclohexyl.

[0080] Also preferred is that the component C comprises a reduced form of the catalyst of formula (D’) wherein Cy is cyclohexyl.

[0081] In a further preferred embodiment, the component C comprises a compound of formula (E) wherein iPr is isopropyl.

[0082] In a further preferred embodiment, the component C comprises a reduced form of the catalyst of formula (E’) wherein iPr is isopropyl.

[0083] It is also preferred that the component C comprises a compound of formula (F) wherein tBu is tert-butyl.

[0084] Preferably, the component C comprises a reduced form of the catalyst of formula (F’) wherein tBu is tert-butyl.

[0085] In a preferred embodiment, x is 1 or 2, preferably wherein x is 1 .

[0086] Preferably, R is selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl, more preferably from the group consisting of H, methyl, ethyl, propyl, and isopropyl, more preferably selected from the group consisting of H, ethyl, and propyl, wherein more preferably R is H.

[0087] In a further preferred embodiment, the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G) or a reduced form thereof wherein R1, R2, R3and R4, L1, L2, and n are as defined above. Preferably, R1, R2, R3and R4, L1, L2, and n of the compound of formula (G) or a reduced form thereof are identical to R1, R2, R3and R4, L1, L2, and n of the at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor of the component C.

[0088] More preferred is that in the liquid mixture ME prepared according to (ii) and subjected to alcohol conversion conditions according to (iii), the molar ratio of the compound of formula (G) or a reduced form thereof relative to the compound of formula (A) is in a range of from 1 :1 to 10:1 , preferably in the range of from 1.02:1 to 8:1 , more preferably in the range from 1 :05:1 to 5:1. Also preferred is that the compound of formula (G) or a reduced form thereof is selected from the group consisting of dicyclohexyl-[[5-(dicyclohexylphosphanylmethyl)acridin-4-yl]me- thyl]phosphane, diisopropyl-[[5-(diisopropylphosphanylmethyl)acridin-4-yl]methyl]phosphane, dicyclohexyl-[[5-(dicyclohexylphosphanylmethyl)pyridin-4-yl]methyl]phosphane and diisopropyl- [[5-(diisopropylphosphanylmethyl)pyridin-4-yl]methyl]phosphane, more preferably wherein the compound of formula (G) or a reduced form thereof is cyclohexyl-[[5-(dicyclohexylphosphanyl- methyl)acridin-4-yl]methyl]phosphane or diisopropyl-[[5-(diisopropylphosphanylmethyl)acridin-4- yl]methyl]phosphane.

[0089] Preferably, the base is selected from the group consisting of alkali hydroxides, alkali alkoxides, and a mixture thereof. More preferably, the alkali hydroxide is selected from the group consisting of NaOH, KOH, and a mixture thereof, preferably wherein the alkali hydroxide is KOH. It is also preferred that the alkali alkoxide is selected from the group consisting of sodium alkoxides, potassium alkoxides, and a mixture thereof, preferably from the group consisting of sodium ethoxide, potassium ethoxide, and a mixture thereof.

[0090] In a further preferred embodiment, the at least one alcohol R-CH2-CH2-OH is a bio-based alcohol, preferably obtainable or obtained from sugar-containing crops, preferably from one or more of sugar cane and corn.

[0091] Preferably, the base is a heterogeneous base, which may optionally be doped with metals selected from the group consisting of Ni, Pd, Cu, and a mixture of two or more thereof. More preferably, the heterogeneous base is selected from the group consisting of hydrotalcites, hydroxyapatite, alkali and alkaline earth doped mixed oxides, and oxinitrides, wherein the oxinitrides preferably are vanadium-aluminium-phosphorous-oxinitride VAIPON or aluminium-phospho- rous-oxi nitride Al PON.

[0092] The liquid mixture ME further preferably comprises a solvent component which comprises one or more solvents. The one or more solvents of the solvent component preferably has a boiling point at 1 atm (101325 Pa) of 140 °C or more, more preferably a boiling point of 160 °C or more, more preferably a boiling point of 180 °C or more, more preferably a boiling point of 190 °C or more. It is also preferred that the solvent component has a solubility in water at 25 °C of from 0 to 0.5 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.1 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.05 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.01 weight-%, based on 100 weight-% water. It is furthermore preferred that the distribution coefficient of the catalyst in a system of the solvent component and water is from 0 to 0.01 , more preferably from 0 to 0.005, more preferably from 0 to 0.005, based on 1 kg catalyst.

[0093] Preferably, the solvent component comprises at least two solvents with a boiling point at 1 atm (101325 Pa) of 180 °C or more. In another preferred embodiment, the solvent component comprises at least one solvent selected from the group consisting of biphenyl, diphenyl ether, 1-tert- butyl-3,5-dimethyl-benzene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n-butylbutyrate, n-hexylhexyrate, n-octyloctyrate, texanole, di-n-butylether, di-iso-butylether, di-sec-butylether, and a mixture of two or more thereof, more preferably from the group consisting of biphenyl, diphenyl ether, and a mixture thereof, wherein more preferably, the solvent component comprises a mixture of biphenyl and diphenyl ether. More preferred is the solvent component comprising a mixture of biphenyl and diphenyl ether, preferably wherein the solvent component comprises a mixture of biphenyl and diphenyl ether at a molar ratio of biphenyl relative to diphenyl ether in the range of from 1 :2 to 1 :6, preferably in the range of from 1 :2.5 to 1 :4.

[0094] In a preferred embodiment, the solvent does not include any one of benzene, toluene, xylene or mesitylene.

[0095] Preferably, the solvent does not form an azeotrope with water. An azeotrope or a constant heating point mixture is a mixture of two or more components in fluidic states whose proportions cannot be altered or changed by simple distillation. This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture. Each azeotrope has a characteristic boiling point. It is not possible to separate the components by fractional distillation.

[0096] In a further preferred embodiment, the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2-OH, the process further comprising separating at least a part of said unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG. More preferably, separating at least a part of the unreacted alcohol R-CH2-CH2-OH from MG is carried out by distillation, extraction, flashing, or by employing a membrane. In another preferred embodiment, at least a part of the at least one unreacted alcohol R-CH2-CH2-OH separated from MG is recycled to (ii) or (iii).

[0097] Preferably, the reaction space SR is comprised a reactor vessel, wherein the reactor vessel is preferably a complete-mixing reactor vessel.

[0098] It is also preferred that from 90 to 100 weight-%, more preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base, the solvent component and the component C.

[0099] In a further preferred embodiment, the mixture Me obtained according to (iv) comprises the catalyst and further comprises the solvent component.

[0100] Preferably, the alcohol conversion conditions according to (iii) comprise an amount of the solvent component in the reaction mixture MG in the range of from 5 to 50 weight-%, more preferably in the range of from 5 to 30 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the total weight of the reaction mixture MG. The process preferably further comprises recycling at least a part of the solvent component comprised in the mixture Me obtained according to (iv) to (i) or (ii).

[0101] Preferably, the reactor is selected from the group consisting of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor. The present invention also relates to the use of a system for the afore-mentioned alcohol conversion process, the system comprising:

[0102] - a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;

[0103] - a water separation unit connected to the reactor to receive from the reactor vapor evolving in alcohol condensation process, and to remove water from the vapor; and

[0104] - an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the removed part of the reaction mixture MG, and returning at least a part of the removed part of the reaction mixture to the reactor.

[0105] Preferably, the reactor is one of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0106] Preferably, the after-treatment system comprises a first after-treatment system to separate a catalytic component and an alkaline component from the part of the reaction mixture MG received from the reactor, and a second after-treatment system connected to the first after-treatment system to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the part of the reaction mixture treated by the first after-treatment system and to return at least a residual part of the reaction mixture after separation of separate the at least one alcohol R-CH2-CH2- (CHR-CH2)X-OH to the reactor. More preferably, the second after-treatment system comprises a liquid-liquid mixer-settler configuration to receive the reaction mixture treated by the first after- treatment system and to provide a phase separation of the components present in the mixture, an alcohols column to receive a primarily alcohol components containing phase from the liquidliquid mixer-settler configuration and to dry the alcohol components, and an alcohols splitter column connected to the alcohols column and the reactor, to separate the at least one alcohol R- CH2-CH2-(CHR-CH2)X-OH from the dried alcohol components and to return the remaining dried alcohols to the reactor.

[0107] Preferably, the second after-treatment system further comprises a water column to receive the primarily water containing phase from the liquid-liquid mixer-settler configuration, separate water from that phase, and return alcohols containing water to the liquid-liquid mixer-settler configuration.

[0108] It is also preferred that the water separation unit is further adapted to return the vapor components different to the separated water to the reactor, and to provide the still alcohols containing separated water to the liquid-liquid mixer-settler configuration.

[0109] Preferably, the system further comprises a pretreatment facility to remove acidic components and / or ester components and / or water from the starting material prior to supplying the starting material to the reactor. The present invention further provides a system for the aforementioned alcohol conversion process, the system comprising:

[0110] - a reactor comprising a reaction space for receiving the liquid mixture and for heating the reaction mixture to a temperature below the boiling point of water under alcohol conversion conditions;

[0111] - a water separation unit connected to the reactor to receive from the reactor vapor evolving in the alcohol condensation process, and to remove water from the vapor; and

[0112] - an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture separating at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the removed part of the reaction mixture to obtain a mixture Mos, and returning at least a part of the mixture Mos to the reactor.

[0113] Preferably, the after-treatment system comprises a first after-treatment system to separate a catalytic component and an alkaline component from the part of the reaction mixture received from the reactor, and a second after-treatment system connected to the first after-treatment system to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the part of the reaction mixture treated by the first after-treatment system and to return at least a residual part of the reaction mixture after separation of separate the at least one alcohol R-CH2-CH2- the reactor.

[0114] The reactor is preferably one of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0115] In another preferred embodiment, the second after-treatment system comprises a liquid-liquid mixer-settler configuration to receive the reaction mixture treated by the first after-treatment system and to provide a phase separation of the components present in the mixture, an alcohols column to receive a primarily alcohol components containing phase from the liquid-liquid mixersettler configuration and to dry the alcohol components, and an alcohols splitter column connected to the alcohols column and the reactor, to separate the at least one alcohol R-CH2-CH2- from the dried alcohol components and to return the remaining dried alcohols to the reactor.

[0116] The second after-treatment system preferably further comprises a water column to receive the primarily water containing phase from the liquid-liquid mixer-settler configuration, separate water from that phase, and return alcohols containing water to the liquid-liquid mixer-settler configuration.

[0117] Preferably, the water separation unit is further adapted to return the vapor components different to the separated water to the reactor, and to provide the still alcohols containing separated water to the liquid-liquid mixer-settler configuration.

[0118] The system furthermore preferably comprises a pretreatment facility to remove acidic components and / or ester components and / or water from the starting material prior to supplying the starting material to the reactor. Water formed during the reaction is preferably continuously removed from the reactor. To this end, vapors including steam, such as water vapor, evolving during the reaction process may be removed from the reactor through a vapor outlet port and fed into the water separation unit via the unit's vapor inlet port. The water separation unit removes the water contained in the vapor received from the reactor. The water separation unit is further preferably configured to recycle part of the alcohols present in the vapor received and to return these via the unit's alcohol outlet port and the reactor's reflux inlet port back into the reaction mixture located inside the reactor.

[0119] In a preferred setup, the separated water, usually still containing some of the light alcohols or other products originating from the reaction mixture, is discharged from the water separation unit through the water outlet port. Examples for water separation units are water separation columns, Dean-Stark traps, molecular sieves, and membranes. Preferred are distillation separation columns, including rotating packed bed units (HiGee), heat integrated distillation units (HiDic) and any alternative technology suited for the separation of close boiling point compounds.

[0120] Between the reactor and the water separation unit, or integrated in the water separation unit, a separator, such as flash, column or purge / splitter, can be optionally provided for removing some light components, to facilitate the operation of the water separation unit.

[0121] In a preferred embodiment, a stirrer may be disposed within the reactor for stirring the reaction mixture and facilitating a separation between the liquid and the vapor phases in the reactor. The heating of the reaction can be accomplished using internal coils, a heating jacket, an external heat-exchanger with external recirculation, or any other suitable means.

[0122] For separating the obtained alcohols, at least part of the reaction mixture MG may be discharged from the reactor via a discharge port. When applying a more continuous processing, part of the reaction mixture is removed from a certain stage of the reaction, and supplied to a separation system where the desired alcohols are separated, and the additional alcohols are preferably returned to the reactor. Once started, the removal of part of the reaction mixture can be effected on a continuous or discontinuous basis.

[0123] Prior to a separation of the desired alcohols from the reaction mixture, the discharged reaction mixture is preferably processed in a first after-treatment system to remove the catalyst, the base and possibly degradation products of the former, such as salts formed by neutralization of the base, and optionally any employed solvent. The separation of the catalyst from the discharged reaction mixture depends on the respective catalyst's properties. When using palladium(ll)-ace- tate (Pd(OAc)2) as is preferred in some embodiments, the catalyst may be washed out with water allowing it to precipitate. The catalyst can then be filtered out, optionally dried, and returned to the reactor using a catalyst inlet port, or can be eliminated from the process loop and regenerated into fresh catalyst. The homogeneous base may be removed using an acid, which may for example include an ion exchange resin or electro dialysis, and separating the resulting salt from the mixture. The resin may be regenerated by an acid wash. The first after-treatment system may further also be configured to remove other solids from the discharged reaction mixture. Optionally, an additional hydrogenation reactor may be provided downstream of the reactor, e.g. downstream of the first after-treatment system. The aim of this reactor is to complete the dehydration-hydrogenation of the reaction intermediates and to enrich the stream in alcohols. Any conventional catalyst can be used for this step and preferably catalysts containing Ni, or a noble metal. A supplement of hydrogen (H2) may also be fed to this reactor if desired.

[0124] For the separation of the desired alcohols and the recovery of the alcohols to be returned to the reaction chamber, a second after-treatment system may preferably be used which comprises a liquid-liquid mixer-settler (or decanter) configuration, a water column, an alcohols column, and an alcohols splitter column.

[0125] The liquid-liquid mixer-settler configuration receives the output from the first after-treatment system as well as the output from the water outlet port of the water separation unit. The composition from the water outlet port of the water separation unit and the output from the first after- treatment system are initially introduced into the mixer where a phase separation is expected to occur.

[0126] The organic fraction from the settler is preferably fed into to the alcohols column, e.g. a stripping column, where the dried alcohols are obtained at the bottom while an alcohol / water mixture is taken from the top, condensed, cooled and finally returned to the mixer. The operation of the alcohols column is preferably effected under vacuum conditions (e.g. lower than 0.4 bar) enabling a lowering of the working temperature of the reboilers.

[0127] Optionally, between the liquid-liquid mixer-settler and the alcohols column, there is an additional separation unit, as e.g. flash, column or purge / splitter, to avoid building-up of some light components.

[0128] The aqueous fraction from the settler is preferably fed into the water column, e.g. a stripping column, where it is split into a water bottom stream representing the systems waste water and an alcohol / water mixture on the top that is returned to the mixer after having been condensed and cooled. Also, the water column is preferably operated under vacuum conditions (e.g. lower than 0.4 bar).

[0129] In the return loops described above, one or several systems can be provided to remove certain components which have the tendency to show ever increasing concentrations in this loop because they have no outlet and because they are not converted in the reactor, which have undesirable effects in the reactor or elsewhere in the loop, or which, through reaction, give rise to the formation of components having such undesirable effects. Such removal systems can be selective, e.g. distillation columns, or non-selective, i.e. , simple purge streams.

[0130] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In par- ticular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The process of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The process of any one of embodiments 1 , 2, 3 and 4". Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.

[0131] 1 . An alcohol conversion process, comprising

[0132] (i) providing a component C which is at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor;

[0133] (ii) preparing a liquid mixture ME comprising at least one alcohol R-CH2-CH2-OH, a base, and the component C according to (i), R being selected from the group consisting of H and Ci-C4-alkyl;

[0134] (iii) subjecting the liquid mixture ME prepared according to (ii) to alcohol conversion conditions in a reaction space SG and obtaining in said reaction space a reaction mixture MG comprising at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH, x being an integer in the range of from 1 to 4, wherein the alcohol conversion conditions comprise a temperature of the reaction mixture MG in the range of from 100 to 250 °C and a pressure in the reaction space SG in the range of from 1 x 105to 4 x 106Pa; wherein the temperature of the reaction mixture in the reaction space SG is below the boiling point of water under alcohol conversion conditions, and wherein water resulting from the alcohol conversion is removed;

[0135] (iv) separating the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the reaction mixture MG obtained according to (iii), obtaining the at least one alcohol R-CH2-CH2- (CH R-CH2)X-OH and a mixture Mos;

[0136] (v) recycling at least a part of the mixture Mos obtained according to (iv) to (ii); wherein

[0137] (a) the base is selected from the group consisting of ammonium hydroxide, alkali hydroxides, alkaline earth hydroxides, ammonium carbonate, ammonium hydrogen carbonate, alkali carbonates, alkali hydrogen carbonates, alkaline earth carbonates, alkaline hydrogen carbonates, alkali alkoxides, alkaline earth alkoxides, alkali metal amides, alkaline earth metal amides, alkali metal-2,2,6,6-tetramethylpiperidines, alkaline earth metal-2,2,6,6-tetramethylpiperidines, secondary amino acids, heterogeneous bases, which may optionally be doped, and a mixture of two or more thereof;

[0138] (b) the catalyst comprises at least one selected from the group consisting of Pd(OAc)2, Pd / C, Pt / C, Cu-Zn-O, Cu-Cr-O, hydrotalcites and hydroxylapatites doped with metals, Raney Ni, Ni-MgO / SiC>2, and a compound of formula (A); wherein

[0139] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0140] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:

[0141] L3is selected from the group consisting of CO, PRaRbRc, AsRaRbRc, SbRaRbRc, SRaRb, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0142] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0143] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRd2, NH3, NRd3, and Rd2NSO2Rd;

[0144] Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C1-C10- alkyl; unsubstituted or substituted Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; and unsubstituted or substituted Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and C C -alkyl; and

[0145] X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl;

[0146] (c) the precursor of the catalyst comprising a compound of formula (A) comprises a mixture comprising 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2-Ci2-alkenyl, C3-C15- cycloalkenyl, Cs-C2o-aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)

[0147] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0148] L1and L2, are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:

[0149] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0150] Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C1-C10- alkyl; unsubstituted or substituted Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; and unsubstituted or substituted Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and C C -alkyl; and

[0151] X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyL

[0152] 2. The process of embodiment 1 , wherein the process is a continuous process.

[0153] 3. The process of embodiment 1 , wherein the process is a semi-batch process or a batch process.

[0154] 4. The process of any one of embodiments 1 to 3, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base, and the component C.

[0155] 5. The process of any one of embodiments 1 to 4, wherein the alcohol conversion conditions according to (iii) comprise the presence of at least one inert gas in the reaction space SG, wherein the at least one inert gas is preferably selected from the group consisting of nitrogen, argon, and a mixture thereof.

[0156] 6. The process of any one of embodiments 1 to 5, wherein the alcohol conversion conditions according to (iii) comprise a pressure in the reaction space SG in the range of from 1 x 105to 3.5 x 106Pa, preferably in the range of from 1 x 105to 3.1 x 106Pa, more preferably in the range in the range of from 1 x 105to 2 x 106Pa, more preferably in the range in the range from 1 x 105to 1 .5 x 106Pa.

[0157] 7. The process of any one of embodiments 1 to 6, wherein the alcohol conversion conditions according to (iii) comprise a temperature of the reaction mixture MG in the range of from 100 to 200 °C, preferably in the range of from 120 to 180 °C, more preferably in the range of from 130 to 160 °C.

[0158] 8. The process of any one of embodiments 1 to 7, wherein the alcohol conversion conditions according to (iii) comprise an amount of the base in the reaction mixture MG in the range of from 0.1 to 10 weight-%, preferably in the range of from 0.5 to 8 weight-%, more preferably in the range of from 1 to 5 weight-%, based on the total weight of the reaction mixture MG.

[0159] 9. The process of any one of embodiments 1 to 8, wherein the process temperature in the reaction space SG is at least 3 °C, preferably at least 5 °C, more preferably at least 10 °C, more preferably at least 15 °C, more preferably at least 20 °C, more preferably at least 25 °C, below the boiling point of water under reaction conditions.

[0160] 10. The process of any one of embodiments 1 to 9, wherein the alcohol conversion conditions according to (iii) comprise an amount of the catalyst in the reaction mixture MG in the range of from 0.001 to 2 weight-%, preferably in the range of from 0.001 to 1 weight-%, more preferably in the range of from 0.001 to 0.5 weight-%, based on the total weight of the reaction mixture MG.

[0161] 11 . The process of any one of embodiments 1 to 10, wherein the reaction space in step (iii) comprises a the reaction mixture MG and a gas phase, wherein the gas phase comprises H2, and wherein the alcohol conversion conditions according to (iii) comprise maintaining the H2 partial pressure of the gas phase in the range of from 2 x 104to 3.1 x 106Pa, preferably in the range of from 2 x 104to 1 .1 x 106Pa, more preferably in the range of from 2 x 104to 6 x 105Pa.

[0162] 12. The process of embodiment 11 , wherein the H2 partial pressure of the gas phase is maintained by introducing H2 into the gas phase.

[0163] 13. The process of embodiment 11 , wherein the H2 partial pressure of the gas phase is maintained by relaxation of the gas phase, preferably by removing at least a part of H2 from the gas phase.

[0164] 14. The process of any one of embodiments 11 to 13, wherein the H2 partial pressure of the gas phase is maintained by monitoring the overall pressure during the reaction, preferably by monitoring and, if required, adjusting the overall pressure of the gas phase, more preferably by adjusting the overall pressure of the gas phase by relaxation of the gas phase and / or by introducing H2 into the gas phase.

[0165] 15. The process of any one of embodiments 11 to 13, wherein the H2 partial pressure of the gas phase is maintained by taking samples of the gas phase during the reaction and analyzing same, and, if required, by preferably adjusting the overall pressure of the gas phase, more preferably by adjusting the overall pressure of the gas phase by relaxation of the gas phase and / or by introducing H2 into the gas phase.

[0166] 16. The process of any one of embodiments 1 to 15, wherein the least one alcohol R-CH2- CH2-OH and the component C provided according to (i) is pretreated with respect to removing acidic components and / or ester components and / or water prior to preparing a liquid mixture ME.

[0167] 17. The process of any one of embodiments 1 to 16, wherein the component C is a solid heterogeneous catalyst, a precursor thereof, a reduced form of the catalyst and reduced form of the precursor provided in a fixed bed, or a slurry fluidized bed, or a mobile bed.

[0168] 18. The process of any one of embodiments 1 to 16, wherein the component C is selected from the group consisting of Cu-Zn-oxide, Cu-chromite, Raney Ni, Ni-MgO / SiC>2, Pd / C, Pt / C, a metal selected from the group consisting of Ni, Pd, Cu, doped heterogeneous bases, Pd(OAc)2, and a mixture of two or more thereof. 19. The process of any one of embodiments 1 to 16, wherein the component C comprises a mixture comprising 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2-Ci2-alkenyl, Cs-Cis-cycloalkenyl, Cs-C2o-aryl, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H’) wherein M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru; L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd; L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0169] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst comprising a compound of formula (A) an acridinyl unit; n is 0 or 1 , and if R1, R2, R3and R4are hydrogen, n is 0;

[0170] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-C -heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0171] 20. The process of any one of embodiments 1 to 16, wherein the component C comprises a compound comprising a metal M selected from the group consisting of I rCh x H2O, [lr(COD)CI]2, [lr(COE)2CI]2, [lr(C2H4)2CI]2, [lr(COD)OH]2, [lr(COD)MeO]2, [lrCp*CI2], [IrCpCh], lr4(CO)i2, [lr(PPh3)2(CO)CI], [lr(acetylacetonate)3], and [lr(acety- lacetonate)(COD)], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 ,5-cyclooctadienyl, COE is cyclooctenyl, and methylallyl is 2-methylallyl.

[0172] 21 . The process of any one of embodiments 1 to 16, wherein the component C comprises a compound comprising a metal M selected from the group consisting of, Ru(p-cy- mene)Cl2]2, [Ru(benzene)Cl2]y, [Ru(CO)2Cl2]y, where y is in each case in the range from 1 to 1000, [Ru(CO)3Ch]2, [Ru(COD)(allyl)], RuCh x H2O, [Ru(acetylacetonate)3], [Ru(DMSO)4Ch], [Ru(cyclopentadienyl)(CO)2CI], [Ru(cyclopentadienyl)(CO)2H], [Ru(cyclo- pentadienyl)(CO)2]2, [Ru(Cp)(CO)2CI], [Ru(Cp*)(CO)2H], [Ru(Cp*)(CO)2]2, [Ru(in- denyl)(CO)2CI], [Ru(indenyl)(CO)2H], [Ru(indenyl)(CO)2]2, ruthenocene, [Ru(COD)Ch]2, [Ru(Cp*)(COD)CI], [RU3(CO)I2], [Ru(PPh3)4(H)2], [Ru(PPh3)3(CI)2], [Ru(PPh3)3(CO)(CI)2], [Ru(PPh3)3(CO)(CI)(H)], [Ru(PPh3)3(CO)(H)2], and [Ru(cyclooctadienyl)(methylallyl)2], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 , 5-cyclooc- tadienyl, and methylallyl is 2-methylallyL The process of any one of embodiments 1 to 16, wherein the component C comprises a compound of formula (B) wherein

[0173] M is selected from the group consisting of Ir, Ru, and Mn;

[0174] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0175] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0176] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; Cs-C -heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0177] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH. The process of any one of embodiments 1 to 16, wherein the component C comprises a compound of formula (C) wherein

[0178] M is selected from the group consisting of Ir, Ru, and Mn;

[0179] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0180] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0181] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of

[0182] H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-Cw-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0183] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0184] 24. The process of any one of embodiments 1 to 16, 22 and 23, wherein M is selected from the group consisting of Ir and Ru, wherein M is preferably Ru.

[0185] 25. The process of any one of embodiments 1 to 16, 22 and 23, wherein L3is CO.

[0186] 26. The process of any one of embodiments 1 to 26, and 22 to 25, wherein L1and L2are each (PRaRh),anc|werein Raand Rbare Ci-Cw-alkyl, preferably wherein Raand Rbare each isopropyl or tert-butyl.

[0187] 27. The process of any one of embodiments 1 to 16, and 22 to 25, wherein L1and L2are each (PRaRb), and wherein Raand Rbare Cs-Cw-cycloalkyl, preferably wherein Raand Rbare each cyclohexyl.

[0188] 28. The process of any one of embodiments 1 to 16, and 22 to 25, wherein L1and L2are each (PRaRb), and wherein Raand Rbare Cs-C -aryl.

[0189] 29. The process of any one of embodiments 1 to 16, and 22 to 28, wherein Y is selected from the group consisting of F, Cl, Br, and I, preferably wherein Y is selected from the group consisting of Cl or Br, more preferably wherein Y is Cl.

[0190] 30. The process of any one of embodiments 1 to 16, and 22 to 28, wherein Y is CO.

[0191] 31 . The process of any one of embodiments 1 to 16, wherein the component C comprises a compound of formula (D) wherein Cy is cyclohexyl.

[0192] 32. The process of any one of embodiments 1 to 16, wherein the reduced form of the catalyst comprises a compound of formula (D’) wherein Cy is cyclohexyl. The process of any one of embodiments 1 to 16, wherein the component C comprises a compound of formula (E) wherein iPr is isopropyl. The process of any one of embodiments 1 to 16, wherein the reduced form of the catalyst comprises a compound of formula (E’) wherein iPr is isopropyl. The process of any one of embodiments 1 to 16, wherein the component C comprises a compound of formula (F) wherein tBu is tert-butyl. The process of any one of embodiments 1 to 16, wherein the reduced form of the catalyst comprises a compound of formula (F’) wherein tBu is tert-butyl.

[0193] 37. The process of any one of embodiments 1 to 36, wherein the reduced form of the precursor comprises a compound of formula (P-l) or (P-ll): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroquinoline unit, a decahydroquinoline unit, a tetrahydroacridine unit, or a tetradecahydroacridine unit; and wherein L1and L2are, independently of each other, as defined above; wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above.

[0194] 38. The process of any one of embodiments 1 to 36, wherein the reduced form of the precursor comprises a compound of formula (P-l): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroacridine unit, or a tetradecahydroacridine unit.

[0195] 39. The process of any one of embodiments 1 to 36, wherein the reduced form of the precursor comprises a compound of formula (P-ll): wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above.

[0196] 40. The process of any one of embodiments 1 to 39, wherein integer x is 1 or 2, preferably wherein integer x is 1 .

[0197] 41 . The process of any one of embodiments 1 to 40, wherein R is selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl, preferably from the group consisting of H, methyl, ethyl, propyl, and isopropyl, more preferably selected from the group consisting of H, ethyl, and propyl, wherein more preferably R is H.

[0198] 42. The process of any one of embodiments 1 to 16 and 19 to 41 , wherein the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G) or a reduced form thereof wherein R1, R2, R3and R4, L1, L2, and n are as defined above.

[0199] 43. The process of embodiment 42, wherein R1, R2, R3and R4, L1, L2, and n of the compound of formula (G) or a reduced form thereof are identical to R1, R2, R3and R4, L1, L2, and n of the at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor of the component C.

[0200] 44. The process of embodiment 42 or 43, wherein in the liquid mixture ME prepared according to (ii) and subjected to alcohol conversion conditions according to (iii), the molar ratio of the compound of formula (G) or a reduced form thereof relative to the compound of formula (A) is in a range of from 1 :1 to 10:1 , preferably in the range of from 1.02:1 to 8:1 , more preferably in the range from 1 .05:1 to 5:1 .

[0201] 45. The process of any one of embodiments 42 to 44, wherein the compound of formula (G) or a reduced form thereof is selected from the group consisting of dicyclohexyl-[[5-(dicy- clohexylphosphanylmethyl)acridin-4-yl]methyl]phosphane, diisopropyl-[[5-(diiso- propylphosphanylmethyl)acridin-4-yl]methyl]phosphane, dicyclohexyl-[[5-(dicyclohex- ylphosphanylmethyl)pyridin-4-yl]methyl]phosphane and diisopropyl-[[5-(diiso- propylphosphanylmethyl)pyridin-4-yl]methyl]phosphane, preferably wherein the compound of formula (G) or a reduced form thereof is cyclohexyl-[[5-(dicyclohexylphosphanylme- thyl)acridin-4-yl]methyl]phosphane or diisopropyl-[[5-(diisopropylphosphanylmethyl)acri- din-4-yl]methyl]phosphane.

[0202] 46. The process of any one of embodiments 1 to 45, wherein the base is selected from the group consisting of alkali hydroxides, alkali alkoxides, and a mixture thereof.

[0203] 47. The process of embodiment 46, wherein the alkali hydroxide is selected from the group consisting of NaOH, KOH, and a mixture thereof, preferably wherein the alkali hydroxide is KOH.

[0204] 48. The process of embodiment 46, wherein the alkali alkoxide is selected from the group consisting of sodium alkoxides, potassium alkoxides, and a mixture thereof, preferably from the group consisting of sodium ethoxide, potassium ethoxide, and a mixture thereof.

[0205] 49. The process of any one of embodiments 1 to 48, wherein the at least one alcohol R-CH2- CH2-OH is a bio-based alcohol, preferably obtainable or obtained from sugar-containing crops, preferably from one or more of sugar cane and corn.

[0206] 50. The process of any one of embodiments 1 to 45, wherein the base is a heterogeneous base, which may optionally be doped with metals selected from the group consisting of Ni, Pd, Cu, and a mixture of two or more thereof.

[0207] 51 . The process of embodiment 50, wherein the heterogeneous base is selected from the group consisting of hydrotalcites, hydroxyapatite, alkali and alkaline earth doped mixed oxides, and oxinitrides, wherein the oxinitrides preferably are vanadium-aluminium-phos- phorous-oxinitride VAIPON or aluminium-phosphorous-oxinitride AIPON.

[0208] 52. The process of any one of embodiments 1 to 51 , wherein the liquid mixture ME further comprises a solvent component which comprises one or more solvents.

[0209] 53. The process of embodiment 52, wherein the one or more solvents of the solvent component have a boiling point at 1 atm (101325 Pa) of 140 °C or more, preferably a boiling point of 160 °C or more, more preferably a boiling point of 180 °C or more, more preferably a boiling point of 190 °C or more.

[0210] 54. The process of embodiment 52 or 53, wherein the solvent component has a solubility in water at 25 °C of from 0 to 0.5 weight-%, preferably a solubility in water at 25 °C of from 0 to 0.1 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.05 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.01 weight-%, based on 100 weight-% water. 55. The process of any one of embodiments 52 to 54, wherein the distribution coefficient of the catalyst in a system of the solvent component and water is from 0 to 0.01 , preferably from 0 to 0.005, more preferably from 0 to 0.005, based on 1 kg catalyst.

[0211] 56. The process of any one of embodiments 52 to 55, wherein the solvent component comprises at least two solvents with a boiling point at 1 atm (101325 Pa) of 180 °C or more.

[0212] 57. The process of any one of embodiments 52 to 56, wherein the solvent component comprises at least one solvent selected from the group consisting of biphenyl, diphenyl ether, 1-tert-butyl-3,5-dimethyl-benzene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n-butylbutyrate, n-hexylhexyrate, n-octyloctyrate, texanole, di-n-butylether, di-iso-butylether, di-sec-butylether, and a mixture of two or more thereof, preferably from the group consisting of biphenyl, diphenyl ether, and a mixture thereof, wherein more preferably, the solvent component comprises a mixture of biphenyl and diphenyl ether.

[0213] 58. The process of any one of embodiments 52 to 57, wherein the solvent component comprises a mixture of biphenyl and diphenyl ether, preferably wherein the solvent component comprises or is a mixture of biphenyl and diphenyl ether at a molar ratio of biphenyl relative to diphenyl ether in the range of from 1 :2 to 1 :6, preferably in the range of from 1 :2.5 to 1 :4.

[0214] 59. The process of any one of embodiments 52 to 58, wherein the solvent does not form an azeotrope with water.

[0215] 60. The process of any one of embodiments 1 to 59, wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2- OH, the process preferably further comprising separating at least a part of said unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG.

[0216] 61 . The process of embodiment 60, wherein separating at least a part of the unreacted alcohol R-CH2-CH2-OH from MG is carried out by distillation, extraction, flashing, or by employing a membrane.

[0217] 62. The process of embodiment 60 or 61 , wherein at least a part of the at least one unreacted alcohol R-CH2-CH2-OH separated from MG is recycled to (ii) or (iii).

[0218] 63. The process of any one of embodiments 1 to 62, wherein the reaction space SR is comprised a reactor vessel, wherein the reactor vessel is preferably a complete-mixing reactor vessel.

[0219] 64. The process of any one of embodiments 52 to 63, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base, the solvent component and the component C.

[0220] 65. The process of any one of embodiments 52 to 64, wherein the mixture Me obtained according to (iv) comprises the catalyst and further comprises the solvent component.

[0221] 66. The process of any one of embodiments 52 to 65, wherein the alcohol conversion conditions according to (iii) comprise an amount of the solvent component in the reaction mixture MG in the range of from 5 to 50 weight-%, preferably in the range of from 5 to 30 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the total weight of the reaction mixture MG.

[0222] 67. The process of embodiment 65, further comprising recycling at least a part of the solvent component comprised in the mixture Mcs obtained according to (iv) to (i) or (ii).

[0223] 68. The process of any one of embodiments 1 to 67, wherein the reactor is selected from the group consisting of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0224] 69. Use of a system for an alcohol conversion process according to any one of embodiments 1 to 68, the system comprising:

[0225] - a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;

[0226] - a water separation unit connected to the reactor to receive from the reactor vapor evolving in alcohol condensation process, and to remove water from the vapor; and

[0227] - an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x- OH from the removed part of the reaction mixture MG, and returning at least a part of the removed part of the reaction mixture to the reactor.

[0228] 70. The use according to embodiment 69, wherein the reactor is one of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0229] 71 . The use according to embodiments 69 or 70, wherein the after-treatment system comprises a first after-treatment system to separate a catalytic component and an alkaline component from the part of the reaction mixture MG received from the reactor, and a second after-treatment system connected to the first after-treatment system to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the part of the reaction mixture treated by the first after-treatment system and to return at least a residual part of the reaction mixture after separation of separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH to the reactor. 72. The use according to embodiments 71 , wherein the second after-treatment system comprises a liquid-liquid mixer-settler configuration to receive the reaction mixture treated by the first after-treatment system and to provide a phase separation of the components present in the mixture, an alcohols column to receive a primarily alcohol components containing phase from the liquid-liquid mixer-settler configuration and to dry the alcohol components, and an alcohols splitter column connected to the alcohols column and the reactor, to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the dried alcohol components and to return the remaining dried alcohols to the reactor.

[0230] 73. The use according to embodiments 71 or 72, wherein the second after-treatment system further comprises a water column to receive the primarily water containing phase from the liquid-liquid mixer-settler configuration, separate water from that phase, and return alcohols containing water to the liquid-liquid mixer-settler configuration.

[0231] 74. The use according to embodiment 69, wherein the water separation unit is further adapted to return the vapor components different to the separated water to the reactor, and to provide the still alcohols containing separated water to the liquid-liquid mixer-settler configuration.

[0232] 75. The use according to any of embodiments 69 to 74, further comprising a pretreatment facility to remove acidic components and / or ester components and / or water from the starting material prior to supplying the starting material to the reactor.

[0233] 76. A system for an alcohol conversion process according to any one of embodiments 1 to 68, the system comprising:

[0234] - a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;

[0235] - a water separation unit connected to the reactor to receive from the reactor vapor evolving in the alcohol condensation process, and to remove water from the vapor; and

[0236] - an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x- OH from the removed part of the reaction mixture MG to obtain a mixture Mos, and returning at least a part of the mixture Mos to the reactor.

[0237] 77. The system according to embodiment 76, wherein the after-treatment system comprises a first after-treatment system to separate a catalytic component and an alkaline component from the part of the reaction mixture MG received from the reactor, and a second after- treatment system connected to the first after-treatment system to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)X-OH from the part of the reaction mixture treated by the first after-treatment system and to return at least a residual part of the reaction mixture after separation of separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH to the reactor. 78. The system according to embodiment 76 or 77, wherein the reactor is one of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0238] 79. The system according to embodiment 77, wherein the second after-treatment system comprises a liquid-liquid mixer-settler configuration to receive the reaction mixture treated by the first after-treatment system and to provide a phase separation of the components present in the mixture, an alcohols column to receive a primarily alcohol components containing phase from the liquid-liquid mixer-settler configuration and to dry the alcohol components, and an alcohols splitter column connected to the alcohols column and the reactor to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the dried alcohol components and to return the remaining dried alcohols to the reactor.

[0239] 80. The system according to any one of embodiments 77 to 79, wherein the second after- treatment system further comprises a water column to receive the primarily water containing phase from the liquid-liquid mixer-settler configuration, separate water from that phase, and return alcohols containing water to the liquid-liquid mixer-settler configuration.

[0240] 81 . The system according to embodiment 76, wherein the water separation unit is further adapted to return the vapor components different to the separated water to the reactor, and to provide the still alcohols containing separated water to the liquid-liquid mixer-settler configuration.

[0241] 82. The system according to any of embodiments 76 to 781 further comprising a pretreatment facility to remove acidic components and / or ester components and / or water from the starting material prior to supplying the starting material to the reactor.

[0242] The determination of the distribution coefficient of the solvent component in water comprises the following steps:

[0243] 1 . combining the two components, e.g. feed and solvent component, in a predefined solvent ratio;

[0244] 2. turbulent mixing of the combined components over a longer period of time (> 10 min) at a defined extraction temperature;

[0245] 3. allowing for phase separation;

[0246] 4. taking samples of each phase at the extraction temperature;

[0247] 5. centrifuging the samples and withdrawing clear samples at the extraction temperature;

[0248] 6. analyzing the samples; and

[0249] 7. comparing the results of extract- and raffinate - calculation of the partition equilibrium / parti- tion coefficient at the selected temperature.

[0250] The boiling point of water under alcohol conversion conditions can be determined, for example on the basis of a vapor pressure curve for water in a temperature / pressure graph or diagram. The vapor pressure curve of a given liquid, such as water, may be measured using a pressure gauge. There are different methods to determine the vapor pressure, depending on the specific conditions and the type of vapor.

[0251] One commonly used method is to measure the saturated vapor pressure with a pressure gauge such as a manometer or pressure sensor. This involves measuring the pressure of the vapor at different temperatures to create the vapor pressure curve.

[0252] Another method is to measure the vapor pressure curve by evaporating a liquid in a closed system, such as a Dewar vessel. This involves gradually increasing the temperature of the system and measuring the pressure of the vapor.

[0253] There are also more advanced methods such as vapor pressure osmometry, which measures the osmosis of vapor through a semipermeable membrane. This method requires special equipment and is mainly used in research.

[0254] The vapor pressure curve of a liquid may be measured by evaporating the liquid in a closed system. In this process, the temperature of the system is gradually increased while the pressure of the vapor is measured.

[0255] Initially, the liquid is placed in a container connected to a pressure gauge or pressure sensor. The container is sealed to ensure that no vapor escapes or enters from the outside.

[0256] The temperature in the system is then slowly increased, for example by heating the vessel or applying an external heat source. As the temperature increases, the energy in the liquid increases, resulting in an increased evaporation rate. This increases the pressure of the vapor in the vessel.

[0257] During the temperature increase, measurements of the pressure are taken periodically. These measurements are usually taken at specific temperature intervals to create the vapor pressure curve in the form of a graph.

[0258] The vapor pressure curve shows the relationship between the temperature and the pressure of the vapor of a liquid. It represents how the pressure changes when the temperature is increased and provides information about the vapor pressure characteristics of the liquid.

[0259] By determining a temperature / pressure curve for water using a suitable one of the determination methods as outlined above, the reaction can be carried out by selecting the alcohol conversion conditions such that the temperature of the reaction mixture in the reaction space SG is below the boiling point of water under alcohol conversion conditions for the given conditions, including the pressure in the reaction space SG.

[0260] Cited literature:

[0261] M. Guerbet, C. R. Hebd. Seances Acad. Sci. 1899, 128, p. 511-513 - Y.Xie et aL, “Highly efficient Process for Production of Biofuel from Ethanol Catalyzed by Ruthenium Pincer Complexes”, Journal of the American Society, vol. 138, no. 29, 2016- 07-18, pages 9077 to 9080

[0262] - US 2014 / 235901 A1 - WO 2013 / 156399 A1

Claims

Claims1 . An alcohol conversion process, comprising(i) providing a component C which is at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor;(ii) preparing a liquid mixture ME comprising at least one alcohol R-CH2-CH2-OH, a base, and the component C provided according to (i), R being selected from the group consisting of H and Ci-C4-alkyl;(iii) subjecting the liquid mixture ME prepared according to (ii) to alcohol conversion conditions in a reaction space SG and obtaining in said reaction space a reaction mixture MG comprising at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH, x being an integer in the range of from 1 to 4, wherein the alcohol conversion conditions comprise a temperature of the reaction mixture MG in the range of from 100 to 250 °C and a pressure in the reaction space SG in the range of from 1 x 105to 4 x 106Pa; wherein the temperature of the reaction mixture in the reaction space SG is below the boiling point of water under alcohol conversion conditions, and wherein water resulting from the alcohol conversion is removed;(iv) separating the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the reaction mixture MG obtained according to (iii), obtaining the at least one alcohol R-CH2-CH2- (CH R-CH2)X-OH and a mixture Mos;(v) recycling at least a part of the mixture Mos obtained according to (iv) to (ii); wherein(a) the base is selected from the group consisting of ammonium hydroxide, alkali hydroxides, alkaline earth hydroxides, ammonium carbonate, ammonium hydrogen carbonate, alkali carbonates, alkali hydrogen carbonates, alkaline earth carbonates, alkaline hydrogen carbonates, alkali alkoxides, alkaline earth alkoxides, alkali metal amides, alkaline earth metal amides, alkali metal-2,2,6,6-tetramethylpiperidines, alkaline earth metal-2,2,6,6-tetramethylpiperidines, secondary amino acids, heterogeneous bases, which may optionally be doped, and a mixture of two or more thereof;(b) the catalyst comprises at least one selected from the group consisting of Pd(OAc)2, Pd / C, Pt / C, Cu-Zn-O, Cu-Cr-O, hydrotalcites and hydroxylapatites doped with metals, Raney Ni, Ni-MgO / SiC>2, and a compound of formula (A);whereinM is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:L3is selected from the group consisting of CO, PRaRbRc, AsRaRbRc, SbRaRbRc, SRaRb, RdCN, RdNC, N2, PF3, pyridine, and thiophene;R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRd2, NH3, NRd3, and Rd2NSO2Rd;Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C1-C10- alkyl; unsubstituted or substituted Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; and unsubstituted or substituted Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and C C -alkyl; andX is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl;(c) the precursor of the catalyst comprising a compound of formula (A) comprises a mixture comprising a compound comprising a metal M and at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2-Ci2-alkenyl, Cs-Cis-cy- cloalkenyl, Cs-C2o-aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and a compound of formula (H)M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;L1and L2, are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C1-C10- alkyl; unsubstituted or substituted Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; and unsubstituted or substituted Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and C C -alkyl; andX is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-G -alkyl.

2. The process of claim 1 , wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base and the component C.

3. The process of claim 1 or 2, wherein the process temperature in the reaction space SG is at least 3 °C, preferably at least 5 °C, more preferably at least 10 °C, and more preferably at least 20 °C below the boiling point of water under reaction conditions.

4. The process of any one of claims 1 to 3, wherein the catalyst is selected from the group consisting of Cu-Zn-oxide, Cu-chromite, Raney Ni, Ni-MgO / SiC>2, Pd / C, Pt / C, a metal selected from the group consisting of Ni, Pd, Cu, doped heterogeneous bases, Pd(OAc)2 and a mixture of two or more thereof.

5. The process of any one of claims 1 to 3, wherein the component C is part of a mixture further comprising a compound comprising 1 ) a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2-Ci2-alkenyl, Cs-Cis-cycloalkenyl, C5-C20- aryl, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H’)wherein M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru; L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd; L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst comprising a compound of formula (A) an acridinyl unit; n is 0 or 1 , and if R1, R2, R3and R4are hydrogen, n is 0;Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C C -alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-C -heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

6. The process of any one of claims 1 to 3, wherein the component C comprises a compound of formula (D)wherein the component C comprises a compound of formula (E)wherein iPr is isopropyl; or wherein the component C comprises a compound of formula (F)wherein tBu is tert-butyl.

7. The process of any one of claims 1 to 6, wherein x is 1 or 2, preferably wherein x is 1 .

8. The process of any one of claims 1 to 7, wherein R is selected from the group consisting of H, ethyl, and propyl.

9. The process of any one of claims 1 to 3 and 5 to 8, wherein the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G) or a reduced form thereofwherein R1, R2, R3and R4, L1, L2, and n are as defined above.

10. The process of claim 9, wherein in the liquid mixture ME prepared according to (ii) and subjected to alcohol conversion conditions according to (iii), the molar ratio of the compound of formula (G) or a reduced form thereof relative to the compound of formula (A) is in a range of from 1 :1 to 10:1.11 . The process of any one of claims 1 to 10, wherein the liquid mixture ME further comprises a solvent component, preferably wherein the solvent component comprises at least one solvent selected from the group consisting of biphenyl, diphenyl ether, 1 -tert-butyl-3,5-di- methyl-benzene, xylene, mesitylene, toluene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n-butylbutyrate, n-hexylhexyrate, n-octy- loctyrate, texanole, di-n-butylether, di-iso-butylether, di-sec-butylether, and a mixture of two or more thereof, more preferably from the group consisting of biphenyl, diphenyl ether, and a mixture thereof.

12. A system for an alcohol conversion process according to any one of claims 1 to 11 , the system comprising:- a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;- a water separation unit connected to the reactor to receive from the reactor vapor evolving in the alcohol condensation process, and to remove water from the vapor; and- an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x- OH from the removed part of the reaction mixture MG to obtain a mixture Mos, and returning at least a part of the mixture Mos to the reactor.

13. The system according to claim 12, wherein the after-treatment system comprises a first after-treatment system to separate a catalytic component and an alkaline component from the part of the reaction mixture MG received from the reactor, and a second after-treatment system connected to the first after-treatment system to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)X-OH from the part of the reaction mixture treated by the first after-treatment system and to return at least a residual part of the reaction mixture after separation of separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH to the reactor.

14. Use of a system for an alcohol conversion process according to any one of claims 1 to 13, the system comprising:- a reactor comprising a reaction space SG for receiving the liquid mixture ME, and for heating the reaction mixture MG to a temperature below the boiling point of water under alcohol conversion conditions;- a water separation unit connected to the reactor to receive from the reactor vapor evolving in alcohol condensation process, and to remove water from the vapor; and- an after-treatment system connected to the reactor to receive from the reactor at least part of the reaction mixture MG, separating at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH from the removed part of the reaction mixture MG, and returning at least a part of the removed part of the reaction mixture to the reactor.

15. The use according to claim 14, wherein the after-treatment system comprises a first after- treatment system to separate a catalytic component and an alkaline component from the part of the reaction mixture MG received from the reactor, and a second after-treatment system connected to the first after-treatment system to separate the at least one alcohol R-CH2-CH2-(CHR-CH2)X-OH from the part of the reaction mixture treated by the first after- treatment system and to return at least a residual part of the reaction mixture after separa- tion of separate the at least one alcohol R-CH2-CH2-(CHR-CH2)x-OH to the reactor.

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