Method for catalytic conversion of ketoacids via ketoacid dimer intermediate and hydrotreatment to hydrocarbons

Abstract

The present invention relates to catalytic conversion of ketoacids, including methods for increasing the molecular weight of ketoacids. The method can include providing in a reactor a raw material having at least one ketoacid. The raw material is then subjected to one or more CC-coupling reaction(s) in the presence of an ion exchange resin catalyst to produce at least one ketocid dimer. The method can include providing in a reactor a feedstock having the at least one ketoacid dimer and subjecting the feedstock to one or more CC-coupling reaction(s) at a temperature of at least 200 C.

Claims

1. A method for increasing the molecular weight of a ketoacid, the method comprising: providing in a reactor a raw material having at least one ketoacid, wherein the ketoacid is an organic molecule that has a keto or aldehyde function and a carboxylic acid or carboxylate function; subjecting the raw material to first CC-coupling reaction(s) in a presence of an ion exchange resin catalyst so as to produce at least one ketoacid dimer; providing in a reactor a feedstock having the at least one ketoacid dimer; and subjecting the feedstock to second CC-coupling reaction(s) at a temperature of at least 200 C.

2. The method according to claim 1, wherein the at least one ketoacid dimer is a dimer of a -ketoacid; and/or wherein the content of the at least one ketoacid dimer in the feedstock is at least 30 wt-%.

3. The method according to claim 1, wherein the first and second CC-coupling reaction(s) are conducted in first and second reactors, respectively.

4. The method according to claim 1, wherein the content of water in the feedstock is less than 15.0 wt-%.

5. The method according to claim 1, wherein the at least one ketoacid in the raw material is -ketoacid; and/or wherein an average pore diameter of the ion exchange resin catalyst is in the range of 150-300 ; and/or wherein the first CC-coupling reaction(s) are conducted at a temperature in the range of 100-190 C.

6. The method according to claim 1, wherein the raw material is subjected to the first CC-coupling reaction(s) in the presence of hydrogen, wherein the ion exchange resin catalyst includes at least one hydrogenating metal selected from Group VIII of the Periodic Table of Elements.

7. The method according to claim 1, wherein the feedstock is subjected to the second CC-coupling reactions in the absence of a catalyst.

8. The method according to claim 1, wherein the feedstock is subjected to the second CC-coupling reaction(s) in the presence of a solid metal oxide catalyst system having a first metal oxide and a second metal oxide.

9. The method according to claim 8, wherein the catalyst system has a specific surface area of from 10 to 500 m.sup.2/g; and/or wherein the solid catalyst system includes a mixture in which the first metal oxide is supported on the second metal oxide; and/or wherein the surface density of metal atoms of the first metal oxide supported on the second metal oxide is from 0.5 to 20 metal atoms/nm.sup.2; and/or wherein the first metal oxide includes an oxide of one of K, Li, Be, B, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th and the second metal oxide includes one of K, Li, Be B, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th, or a combination of these, the first metal oxide not being same as second metal oxide; and/or wherein the first metal oxide includes an oxide of potassium and the second metal oxide includes an oxide of titanium, or the first metal oxide includes an oxide of tungsten or cerium and the second metal oxide includes an oxide of zirconium, titanium, silicon, vanadium, or chromium, or includes an oxide of zirconium or titanium; and/or wherein the content of the first metal oxide in the catalyst system is 1.0 to 40.0 wt %, calculated by weight of metal oxide relative to the total mass of the catalyst.

10. The method according to claim 1, wherein the feedstock comprises: at least one ketoacid.

11. The method according to claim 10, wherein the content of the at least one ketoacid in the feedstock is at least 1.0 wt-%; and/or wherein the weight ratio of the at least one ketoacid content to the at least one ketoacid dimer content in the feedstock [ketoacid:ketoacid dimer] is in the range of 1:5 to 10:1.

12. The method according to claim 1, wherein the feedstock is introduced into the reactor in liquid phase; and/or wherein the second CC-coupling reaction(s) are conducted at a temperature in the range of 200-400 C.; and/or wherein the second CC-coupling reaction(s) are conducted at a pressure in the range of 0.5-150 bar; and/or wherein the second CC-coupling reaction(s) are conducted at a weight hourly space velocity (kg feedstock/kg catalyst*h) in the range of 0.05 h.sup.1 to 2.0 h.sup.1; and/or wherein the feedstock includes at least one of 4-hydroxy-4-methyl-6-oxononanedioic acid, 3-acetyl-4-hydroxy-4-methylheptanedioic acid, 5-(2-methyl-5-oxotetrahydrofuran-2-yl)-4-oxopentanoic acid, (E)-4-methyl-6-oxonon-4-enedioic acid, 4-hydroxy-6-methylnonanedioic acid, (E)-6-hydroxy-4-methylnon-4-enedioic acid, (Z)-3-acetyl-4-methylhept-3-enedioic acid, 3-(3-acetyl-2-methyl-5-oxotetrahydrofuran-2-yl)propanoic acid, (Z)-3-1(1-hydroxyethyl)-4-methylhept-3-enedioic acid, and 3-(1-hydroxyethyl)-4-methylheptanedioic acid.

13. A reaction product of the second CC-coupling reaction(s) obtained by the method according to claim 1.

14. A method for producing hydrocarbons, the method comprising: increasing the molecular weight of a ketoacid using the method according to claim 1 to obtain a reaction product, and subjecting the reaction product to a hydrodeoxygenation step and optionally to an isomerization step.

15. A hydrocarbon composition obtained by the method according to claim 14, wherein the reaction product comprises a compound selected from the group consisting of a trimer of the ketoacid, a tetramer of the ketoacid, a pentamer of the ketoacid, a hexamer of the ketoacid, and a heptamer of the ketoacid.

16. The method according to claim 1, wherein the at least one ketoacid dimer is a dimer of levulinic acid; and/or wherein the content of the at least one ketoacid dimer in the feedstock is at least 60 wt-%.

17. The method according to claim 2, wherein the first and second CC-coupling reaction(s) are conducted in first and second reactors, respectively.

18. The method according to claim 1, wherein the content of water in the feedstock is less than 5.0 wt-%.

19. The method according to claim 17, wherein the at least one ketoacid in the raw material is levulinic acid; and/or wherein the average pore diameter of the ion exchange resin catalyst in the range of 200-250 ; and/or wherein the first CC-coupling reaction(s) are conducted at a temperature in the range of 120-140 C.

20. The method according to claim 18, wherein the raw material is subjected to the first CC-coupling reaction(s) in the presence of hydrogen, wherein the ion exchange resin catalyst includes at least one hydrogenating metal selected from Group VIII of the Periodic Table of Elements: Co, Ni, Ru, Rh, Pd, and Pt.

21. The method according to claim 8, wherein the catalyst system has a specific surface area of from 10 to 500 m.sup.2/g; and/or wherein the solid catalyst system includes a mixture in which the first metal oxide is supported on the second metal oxide; and/or wherein the surface density of metal atoms of the first metal oxide supported on the second metal oxide is from 0.5 to 20 metal atoms/nm.sup.2; and/or wherein the first metal oxide includes an oxide of one of K, Li, Be, B, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th and the second metal oxide includes one of K, Li, Be B, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th, or a combination of these, the first metal oxide not being same as the second metal oxide; and/or wherein the first metal oxide includes an oxide of potassium and the second metal oxide includes an oxide of titanium, or the first metal oxide includes an oxide of tungsten or cerium and the second metal oxide includes an oxide of zirconium, titanium, silicon, vanadium, or chromium, or includes an oxide of zirconium or titanium; and/or wherein the content of the first metal oxide in the catalyst system is 13.0 to 30.0 wt-% calculated by weight of metal oxide relative to the total mass of the catalyst.

22. The method according to claim 10, wherein the content of the at least one ketoacid in the feedstock is at least 30.0 wt-%; and/or wherein the weight ratio of the at least one ketoacid content to the at least one ketoacid dimer content in the feedstock [ketoacid:ketoacid dimer] is in the range of 1:3 to 5:1.

23. The method according to claim 1, wherein the feedstock is introduced into the reactor in liquid phase; and/or wherein the second CC-coupling reaction(s) are conducted at a temperature in the range of 220-260 C.; and/or wherein the second CC-coupling reaction(s) are conducted at a pressure in the range of 1.0-20 bar; and/or wherein the second CC-coupling reaction(s) are conducted at a weight hourly space velocity (kg feedstock/kg catalyst*h) in the range of 0.25 h.sup.1 to 1.25 h.sup.1; and/or wherein the feedstock includes at least one of 4-hydroxy-4-methyl-6-oxononanedioic acid, 3-acetyl-4-hydroxy-4-methylheptanedioic acid, 5-(2-methyl-5-oxotetrahydrofuran-2-yl)-4-oxopentanoic acid, (E)-4-methyl-6-oxonon-4-enedioic acid, 4-hydroxy-6-methylnonanedioic acid, (E)-6-hydroxy-4-methylnon-4-enedioic acid, (Z)-3-acetyl-4-methylhept-3-enedioic acid, 3-(3-acetyl-2-methyl-5-oxotetrahydrofuran-2-yl)propanoic acid, (Z)-3-1(1-hydroxyethyl)-4-methylhept-3-enedioic acid, and 3-(1-hydroxyethyl)-4-methylheptanedioic acid.

24. The method according to claim 12, wherein the second CC-coupling reaction(s) are conducted at a temperature in the range of 210-300 C.

25. The method according to claim 1, wherein the ketoacid comprises pyruvic acid, oxaloacetic acid, alpha-ketoglutaric acid, acetoacetic acid, or levulinic acid.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a scheme illustrating conversion of lignocellulosic material to levulinic acid.

(2) FIG. 2 shows a scheme illustrating some reaction products of some levulinic acid dimers. The figure is not intended to cover all reaction products of levulinic acid dimers, nor is it intended to show all types of levulinic acid dimers. FIG. 2 illustrates possible CC-coupling reactions of levulinic acid dimers through ketonisation and aldol condensation reaction.

(3) FIG. 3 shows an overview of a possible process scheme for further upgrading the products from the CC-coupling reactions.

(4) FIG. 4 shows an overview of a possible process scheme for preparing and upgrading the products from the CC-coupling reactions.

DETAILED DESCRIPTION OF THE INVENTION

(5) One of the challenges in increasing the molecular weight of ketoacids by CC-coupling reactions is the high reactivity of the product intermediates, which results in too high a degree of oligomerization of the starting components.

(6) The inventors have found that the oligomerization of a ketoacid, specifically of levulinic acid, in the presence of a solid base catalyst such as K.sub.2O/TiO.sub.2 results in high formation of coke and tar, which poison the catalyst by blocking the reactive sites on the surface of the catalyst and eventually result in plugging of the reactor. Without being bound to any theory this is suggested to occur due to reactions of levulinic acid to more reactive precursors such as angelica lactones, which are known to have a high tendency to polymerise at temperatures of over 200 C.

(7) The inventors also found that oligomerization of levulinic acid in the presence of an ion exchange resin catalyst such as Amberlyst 70 results in formation of levulinic acid dimers but the yield of higher molecular weight products such as trimers, tetramers and pentamers of levulinic acid remains very small. One of the reasons for the poor performance of the Amberlyst catalyst in formation of higher molecular weight compounds is the requirement of relative low reaction temperatures since the ion exchange catalyst tends to degrade at temperatures of above 200 C.

(8) It was first attempted to reduce the undesired polymerization reactions and to control the oligomerization reactions of levulinic acid by conducting the K2O/TiO2 catalysed reactions in dilute aqueous solutions. The addition of water to suppress coking reactions was, however, found also to decrease the performance of the catalyst system resulting in low yields of the desired oligomerization products.

(9) The invention is based on a surprising finding that the molecular weight of ketoacids can be increased by selective production of ketoacid dimers in the presence of an ion exchange resin catalyst and subsequent oligomerization of the ketoacid dimers to higher molecular weight compounds at a temperature of at least 200 C. Without being bound to any theory, it is suggested that ketoacid dimers are less prone to formation of reactive intermediates at temperatures of above 200 C. and this enables increasing the molecular weight of ketoacid dimers through CC-coupling reactions while significantly reducing the formation of coke and tar and other undesired polymerization products.

(10) The inventors have also found that the ion exchange resin catalyst is especially suitable for production of certain types of ketoacid dimers, which can be converted to ketoacid trimers, tetramers, hexamers and heptamers at a temperature of at least 200 C.

(11) Accordingly, one aspect the present invention is a method for increasing the molecular weight of a ketoacid as defined in claim 1.

(12) The present invention also relates to a method for increasing the molecular weight of ketoacids.

(13) Ketoacids are organic molecules that have both a keto function (>CO) as well as a carboxylic acid (COOH) or carboxylate (COO.sup.) function. In the present specification special forms of ketoacids include embodiments where the keto function is an aldehyde (CHO).

(14) The ketoacid may be an alpha-ketoacid (such as pyruvic acid, oxaloacetic acid and alpha-ketoglutaric acid), beta-ketoacid (such as acetoacetic acid), gamma-ketoacid (such as levulinic acid), or delta-ketoacid. The ketoacid may have more than one keto functionality, and more than one carboxylic acid function. Preferably the ketoacid only has one keto functionality and one carboxylic acid functionality.

(15) ##STR00003##

(16) Scheme 1 illustrates exemplary ketoacids according to the present invention, for example where n and m are integers each selected independently of each other from the list consisting of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 The ketoacid is preferably a gamma ketoacid, more preferably levulinic acid (m=2, n=0).

(17) A ketoacid dimer refers here to a product of a dimerization reaction, in which two ketoacid molecules are coupled together by a CC-coupling reaction.

(18) Preferably more than 15 wt % of the reaction product may be determined to belong to the group containing trimerisation, tetramerisation, pentamerisation, and hexamerisation products of ketoacid. By trimerisation, tetramerisation, pentamerisation and hexamerisation products is meant reaction products relating to three, four, five and six molecules of one or more of ketoacid units being coupled together, respectively. The reactions may occur between ketoacid dimers or between ketoacids and ketoacid dimers as shown in FIG. 2. Usually the majority of the remainder of the reaction product (i.e. excluding the trimerisation, tetramerisation, pentamerisation, and hexamerisation products of ketoacid) corresponds to non-reacted material.

(19) In the case of a feedstock comprising ketoacid derivatives in addition to ketoacid dimers and ketoacids, the trimerisation, tetramerisation, pentamerisation, and hexamerisation products may additionally contain mixed CC-coupling products comprising one or more ketoacids units and/or derivatives thereof.

(20) In the present invention the molecular weight of the keto acids and ketoacid dimers are increased through one or more types of CC-coupling reaction(s). Many types of CC-coupling reactions are known in the art, and the skilled person would be able to identify such CC-coupling reactions based on the reaction conditions provided. In particular the CC-coupling reactions may be ketonisation reactions or reactions proceeding through an enol or enolate intermediate. Preferably, the CC-coupling reactions are selected from the list comprising: aldol-type reactions and condensations, ketonisations, reactions where the CC-coupling involves an alkene, as well as other oligomerization reactions. The CC-coupling reactions may proceed with two identical molecules or may be a crossed reaction between two different molecules.

(21) The at least one ketoacid dimer preferably contains a -ketoacid dimer, most preferably levulinic acid dimer. In addition, one or more further ketoacid dimers may be employed.

(22) Preferably, the first and second CC-coupling reaction(s) are conducted in a first and in a second reactor, respectively.

(23) Preferably the feedstock comprises as the major component one or more ketoacid dimers, for example in some embodiments the content of the at least one ketoacid dimer in the feedstock is at least 30 wt-% such as at least 40 wt-%, at least 50 wt-%, at least 55 wt-%, or at least 60 wt-%.

(24) Preferably the content of water in the feedstock is less than 5.0 wt-%, preferably less than 2.0 wt-%, more preferably less than 1.0 wt-%. In some embodiments no water is present in the feedstock, but internal water may be produced in some condensation reactions.

(25) The conversion of ketoacid dimers to desired CC-coupling reaction products was found to increase as the content of ketoacid dimer in the feedstock increased. Presence of water was found to decrease the reactions of ketocids to coke precursors but addition of water also decreased catalyst activity and the yield of desired CC-coupling reaction products was lowered. The yield of CC-coupling products has to be high enough to enable an economically feasible process for production of fuel components and chemicals from ketoacids.

(26) In addition to ketoacid dimers, the feedstock may also contain aldehydes, such as furfural or hydroxymethylfurfural.

(27) In the step of subjecting the raw material to first CC-coupling reaction(s), the at least one ketoacid undergoes at least one CC-coupling reaction with another ketoacid or ketoacid derivative present in the raw material so as to produce a ketoacid dimer.

(28) The ion exchange catalyst has been found particularly suitable for obtaining high degree of ketoacid dimers, which can be upgraded to higher molecular weight components in the presence of a solid base catalyst system.

(29) Preferably the at least one ketoacid in the raw material is a -ketoacid, preferably levulinic acid.

(30) The reactivity of an IER catalyst with a particular reactant is determined by the average pore diameter of the catalyst. Preferably the average pore diameter of the ion exchange resin catalyst is in the range of 150-300 , preferably 200-250 .

(31) Preferably the raw material is subjected to the first CC-coupling reaction(s) at a temperature of 100-190 C., preferably 120-160 C., more preferably 120-140 C. This temperature range was found to be particularly suitable for obtaining a high yield of ketoacid dimers suitable to be used as the at least one ketoacid dimer in the second CC-coupling reactions.

(32) It has also been found that the stability of the ion exchange catalyst and the yield of dimers can be improved if the raw material is subjected to CC-coupling reactions in the presence of hydrogen and if the ion exchange resin catalyst comprises a hydrogenating metal. Preferably the ion exchange resin catalyst comprises a hydrogenating metal selected from a group of Ni, Mo, Co, Ru, Rh, Pd, Pt, or a combination of these.

(33) A solid metal oxide catalyst system comprising a first and a second metal oxide has been found to catalyze multiple types of CC-coupling reactions between ketoacid dimers and monomers of ketoacids and to simultaneously to suppress the coking tendency of the reaction intermediates.

(34) The reactivity of a catalyst depends on the number the active sites on the surface of the catalyst and on the specific surface are of the catalyst. According to one embodiment, the solid base catalyst has a specific surface area of from 10 to 500 m.sup.2/g. The catalyst system having a specific surface area in these ranges have shown to provide enough reactivity with ketoacid dimers to obtain high yield of desired CC-coupling reaction products such as trimers, tetramers, pentamers, hexamers and heptamers of a ketoacid but at the same time to minimize the reactions of ketoacids to coke precursors.

(35) Preferably the first metal oxide comprises an oxide of one of K, Li, Be B, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th, and the second metal oxide comprises an oxide of one of K, Li, Be B, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th or a combination of these, the first metal oxide not being same as second metal oxide. Combinations of metal oxides include mixtures of individual metal oxides (solid solutions), mixed metal oxides and supported metal oxides.

(36) Preferably the first metal oxide comprises an oxide of one of K, W, Li, Be B, Na, Mg, Al, Si, Ca, Sr, and Ba and the second metal oxide comprises an oxide of one of Ti, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Sr, Y, Zr, Nb, Mo, Ba, W, Pb, Bi, La, Ce, Th, or a combination of these.

(37) These oxides have shown to provide good reaction properties in catalysing the second CC-coupling reactions. Furthermore, the carriers mentioned above have shown to provide good carrier properties without affecting the function of the more active part, including a synergistic interaction. Moreover, the combinations mentioned above allow using the catalyst for a long period of time without deterioration and/or dissolution in the acidic reaction medium and thus allow for reduced overall catalyst consumption.

(38) Preferably, the first metal oxide comprises potassium oxide and the second metal oxide comprises titanium oxide, preferably the potassium oxide being supported on a titanium oxide carrier.

(39) Preferably, the catalyst system comprises tungsten oxide or ceria supported on a metal oxide carrier, wherein the carrier is preferably selected from the group consisting of zirconia, titania, silica, vanadium oxide, chromium oxide, preferably zirconia or titania.

(40) The second CC-coupling reactions in the presence of K.sub.2O/TiO.sub.2 catalyst are suggested to proceed by ketonization reactions, in which reactions the molecular weight of ketoacid dimer is increased and simultaneously a significant amount of oxygen is removed. The loss of oxygen in the second CC-coupling reactions is favourable in the production of hydrocarbons from ketoacids since removal of oxygen in a hydrodeoxygenation step consumes a lot of hydrogen, which increases the process costs and also decreases the CO.sub.2 emission reductions in case hydrogen produced from fossil raw material is used in the hydrodeoxygenation step. In addition, the keto groups formed in the second CC-coupling reactions have been found to be easily hydrotreated, which enables use of lower reaction temperatures in the hydrodeoxygenation step. Use of lower hydrodeoxygenation temperatures also decreases the cyclisation tendency of the CC-coupling products.

(41) Preferably the content of the first metal oxide in the catalyst system is 1.0 to 40.0 wt-%, preferably 2.0 to 30.0 wt-%, further preferably 13.0 to 30.0 wt-%, calculated by weight of the metal oxide in relation to the total mass of the catalyst.

(42) Preferably the feedstock further comprises at least one ketoacid, preferably a -ketoacid, more preferably levulinic acid.

(43) Preferably the content of the at least one ketoacid in the feedstock is at least 1.0 wt-%, preferably at least 5.0 wt-%, more preferably at least 10.0 wt-%, or at least 30.0 wt-%.

(44) Preferably the weight ratio of the content of the at least one ketoacid to the content of the at least one ketoacid dimer in the feedstock is in the range of 1:5 to 10:1, preferably 1:3 to 5:1.

(45) Preferably the feedstock comprises a mixture of a ketoacid dimer in combination with ketoacid dimer derivatives, such as at least 30 wt-% of ketoacid dimer and at least 10 wt-% of ketoacid dimer derivative(s) based on the total mass of feedstock.

(46) Preferably the feedstock is fed into in a single reactor, or into single reactor bed. The reactor should be able to be pressurised, and to accommodate the feedstock and the catalyst system, if present. The reactor should have means, such as one or more inlets and/or outlets, for supplying gases and adding/withdrawing feedstock. In addition, means for controlling the temperature or the pressure and the temperature are preferably present.

(47) The reaction temperature has been found to have a significant effect on the product distribution. At temperatures below 200 C. the yield of CC-coupling products of ketoacid dimers in the second CC-coupling reaction(s) is too low and at temperatures above 400 C. the yield may be decreased due to formation coke in other non-desired polymerization products. The second CC-coupling reaction(s) are preferably conducted at a temperature in the range of 200-400 C., more preferably 210-300 C., even more preferably 220-280 C. and still more preferably 220-260 C. The above cited temperature ranges were found to be particularly suitable for obtaining a high degree of reaction products comprising more than two ketoacid units (C13-C30) while avoiding excessive polymerization and coking of the catalyst.

(48) Since most of the second CC-coupling reactions take place in liquid phase the pressure and temperature are suitably selected to keep the reactants in liquid phase. According to one embodiment the CC-coupling reaction(s) are conducted at a pressure of 0.5-100.0 bar, preferably 1.0-50 bar, more preferably 1.0-20 bar.

(49) Preferably the second CC-coupling reactions are conducted at a weight hourly space velocity (kg feedstock/kg catalyst*hour) of 0.05 h.sup.1 to 2.0 h.sup.1, preferably 0.1 I.sup.1 to 1.8 h.sup.1, more preferably 0.2 h.sup.1 to 1.5 h.sup.1, most preferably 0.25 h.sup.1 to 1.25 h.sup.1. The WHSV has an influence on the composition of the resulting material, since it determines the effective contact time of reagent and catalyst. The above-mentioned ranges have shown to provide a high degree of favourable products.

(50) The second CC coupling reaction(s) may proceed in the presence of hydrogen. The hydrogen may be mixed with one or more other gases, preferably an inert gas such as nitrogen, argon, helium or another of the noble gases, or gas behaving inertly to the reaction conditions of the present invention. By behaving inertly it is considered that the gas should not to a major extent participate as a reaction member, and preferably the inert gas should participate as little as possible, such as not participate at all. The hydrogen addition will usually not introduce hydrogenation activity unless the solid metal oxide catalyst system comprises a hydrogenation metal but it is proposed to modify the surface properties of the reducible metal oxide which is part of the catalyst system.

(51) Preferably, the second CC-coupling reactions are conducted at a flow ratio (H2/feedstock) of 100-3000 NI/I, preferably 200-2000 NI/I, more preferably 500-1800 NI/I and most preferably 500-1500 NI/I.

(52) Preferably, the feed ratio of nitrogen (N2/liquid feedstock) is 100-3000 NI/I, preferably 200-2000 NI/I, more preferably 500-1800 NI/I and most preferably 500-1500 NI/I. The combined use of hydrogen and nitrogen showed particularly favourable results.

(53) Preferably, the solid metal oxide catalyst system comprises a hydrogenation metal in addition to the first and second metal oxides. The hydrogenation metal is preferably selected from Ru, Rh, Pd, and Pt or a combination of these. A catalyst system comprising a hydrogenation metal was found to further increase the stability of the catalyst and to suppress the oligomerization reactions of ketoacid dimers to components not suitable for use as fuel components or chemicals.)

(54) Preferably the at least one ketoacid dimer is selected from a group of 4-hydroxy-4-methyl-6-oxononanedioic acid, 3-acetyl-4-hydroxy-4-methylheptanedioic acid, 5-(2-methyl-5-oxotetrahydrofuran-2-yl)-4-oxopentanoic acid, (E)-4-methyl-6-oxonon-4-enedioic acid, 4-hydroxy-6-methylnonanedioic acid, (E)-6-hydroxy-4-methylnon-4-enedioic acid, (Z)-3-acetyl-4-methylhept-3-enedioic acid, 3-(3-acetyl-2-methyl-5-oxotetrahydrofuran-2-yl)propanoic acid, (Z)-3-1(1-hydroxyethyl)-4-methylhept-3-enedioic acid, 3-(1-hydroxyethyl)-4-methylheptanedioic acid, or a combination thereof.

(55) The raw material may be obtained from processing of lignocellulosic material, and such processed material may be used directly, or purified to varying degrees before being used as a raw material in the method of the present invention. The levulinic acid may be produced e.g. with the Biofine method disclosed in U.S. Pat. No. 5,608,105.

(56) In another aspect of the present invention, reaction product obtainable by the method according to the present invention is provided. This product may be directly used as fuel or base oil components or chemicals or as intermediate components in production of fuel or base oil components or chemicals.

(57) The reaction product obtainable by the method of the present invention mayif desiredbe further subjected to a hydrodeoxygenation (HDO) step to remove oxygen, which in some embodiments produces completely deoxygenated material (i.e. hydrocarbon compounds having no oxygen atoms). The produced hydrocarbons may be used as fuel or base oil components or chemicals or as starting components in the production of fuel or base oil components or chemicals. The hydrodeoxygenated products may also be further isomerized to e.g. isoparaff ins.

(58) One of the advantages of the present invention is that ketoacids produced from renewable materials can be upgraded to higher molecular weight hydrocarbons and/or hydrocarbon derivatives, which may be used as fuel or base oil components or chemicals or as starting components in the production of fuel or base oil components or chemicals.

(59) The reaction products from the first and/or second CC-coupling reactions may be fractionated to remove potential unreacted ketoacid monomers and other light components such as water and CO.sub.2 formed in the first and second CC-coupling reactions from the reaction products as illustrated in FIG. 3. The fractionation can be conducted by any conventional means such as distillation. The unreacted ketoacid monomer may optionally be recycled and combined with the feed of the first reactor.

(60) Another aspect of the present invention involves a method for production of hydrocarbons, the method comprising steps of increasing the molecular weight of a ketoacid using the method of the present invention to obtain reaction product and subjecting the reaction product to a hydrodeoxygenation step and optionally to an isomerization step.

(61) Preferably, the HDO catalyst employed in the hydrodeoxygenation step comprises a hydrogenation metal on a support, such as for example a HDO catalyst selected from a group consisting of Pd, Pt, Ni, Co, Mo, Ru, Rh, W or any combination of these. The hydrodeoxygenation step may for example be conducted at a temperature of 100-500 C. and at a pressure of 10-150 bar.

(62) Water and light gases may be separated from the HDO product with any conventional means such as distillation. After the removal of water and light gases the HDO product may be fractionated to one or more fractions suitable for use as gasoline, aviation fuel, diesel or base oil components. The fractionation may be conducted by any conventional means, such as distillation. Optionally part of the product of the HDO step may be recycled and combined to the feed of the HDO reactor.

(63) Another aspect of the present invention involves a hydrocarbon composition obtainable by the method according to the present invention. This product may be used as fuel or base oil components or chemicals or as intermediate components in production of fuel or base oil components or chemicals.

(64) The product of the hydrodeoxygenation step may also be subjected to an isomerization step in the presence of hydrogen and an isomerization catalyst. Both the hydrodeoxygenation step and isomerisation step may be conducted in the same reactor. In some embodiments the isomerisation catalyst is a noble metal bifunctional catalyst, for example Pt-SAPO or Pt-ZSM-catalyst. The isomerization step may for example be conducted at a temperature of 200-400 C. and at a pressure of 20-150 bar.

(65) It is preferred that only a part of the HDO product is subjected to an isomerization step, in particular the part of HDO product which is subjected to isomerization may be the heavy fraction boiling at or above a temperature of 300 C.

(66) The hydrocarbon product obtainable from the hydrodeoxygenation and/or the isomerisation step may be used as fuel or base oil components or chemicals or as intermediate components in production of fuel or base oil components or chemicals.

(67) Generally the choice of subjecting HDO product to isomeration is highly dependable of the desired properties of the end products. In case the HDO product contains a high amount of n-paraffins, the HDO product may be subjected to isomerization step to convert at least part of the n-paraffins to isoparaffins to improve the cold properties of the end product.

EXAMPLES

Materials

(68) As example catalysts, Amberlyst CH 28-catalyst, K.sub.2O/TiO.sub.2-catalyst and WO.sub.3/ZrO.sub.2-catalyst were used in first and second CC-coupling reactions of levulinic acid and levulinic acid dimers, respectively. The K.sub.2O/TiO.sub.2-catalyst is available from BASF and the WO.sub.3/ZrO.sub.2-catalyst is available from Saint-Gobain NORPRO. The composition of the K.sub.2O/TiO.sub.2-catalyst is shown in Table 1.

(69) TABLE-US-00001 TABLE 1 Composition of the K.sub.2O/TiO.sub.2-catalyst K.sub.2O/TiO.sub.2 Type KEC25 TiO.sub.2, wt-% 96.7 K.sub.2O, wt-% 2.4 Nb.sub.2O, wt-% 0.1 Ce.sub.2O.sub.3, wt-% 0.3 Others, wt-% 0.5

(70) The WO.sub.3/ZrO.sub.2-catalyst (type SZ 6*143) had a surface area of 130 m.sup.2/g and a WO.sub.3 content of 18 wt-% calculated by total mass of the catalyst. The Amberlyst CH 28-catalyst was a Pd-doped ion exchange resin catalyst with an average pore diameter of 260 and Pd content of 0.7 wt-%.

(71) The specific surface area and tungsten oxide content of the WO3/ZrO.sub.2-catalyst and the average pore diameter of the Amberlyst CH 28 IER-catalyst have been provided by the catalyst manufacturers.

Example 1

Increasing the Molecular Weight of Levulinic Acid Dimers by Second CC Coupling Reactions with K2O/TiO2-Catalyst System

(72) The performance of K.sub.2O/TiO.sub.2-catalyst was evaluated in a reactor test run with a feedstock comprising 43 wt-parts of levulinic acid, and 55 wt-parts of levulinic acid dimers and 2 wt-parts of levulinic acid oligomers.

(73) The feedstock was obtained by reacting commercial grade levulinic acid (97 wt-%) in the presence of Amberlyst CH 28 catalyst (trade name; Pd doped ion exchange resin) at a temperature of 130 C., pressure of 20 bar, WHSV of 0.2 h.sup.1 and hydrogen to liquid raw material ratio of 1350 NI/I. The feedstock was prepared in a tubular reactor. Also 2 wt-% of H.sub.2O was continuously added to stabilize catalyst activity. WHSV and hydrogen to organic material ratio is calculated from the amount of liquid raw material fed into the reactor.

(74) The second CC coupling reactions for the feedstock were conducted in a continuous tubular fixed bed type reactor at temperatures ranging from about 220 C. to about 250 C. and under a pressure of about 1 bar, using a weight hourly space velocity (WHSV) of 0.7 h.sup.1. The reactions were conducted in nitrogen flow (10 I/h) to study the effect of hydrogen added to the feedstock. WHSV was calculated from the amount of monomers, dimers and oligomers (=liquid feedstock) fed into the reaction vessel.

(75) For reactions at various conditions the amount of gas formed was determined from the liquid yield (gas=100liquid product). The liquid product consists of the organic phase including water formed in the reaction.

(76) The quantitative amount of LA in liquid product was determined by HPLC analysis. The relative amount of dimers and oligomers in the organic phase was obtained from GPC chromatograms. The composition of the organic phase, including unreacted LA, was calculated relative to the liquid product.

(77) The product yields and compositions of the liquid phase for conversion of levulinic acid on K.sub.2O/TiO.sub.2 catalyst system in nitrogen flow are presented in Tables 2 and 3.

(78) TABLE-US-00002 TABLE 2 Process conditions and product yields with K.sub.2O/TiO.sub.2-catalyst. Process conditions Product yield Pressure Gas Liquid Temperature range flow WHSV Gas yield C. bar l/h h-1 wt-% wt-% Experiment 220 1-3 10 0.7 3 97 EX 1 240 1-3 10 0.7 6 94 EX 2 250 1-3 10 0.7 9 91 EX 3

(79) TABLE-US-00003 TABLE 3 Product distribution in the organic phase with K.sub.2O/TiO.sub.2-catalyst determined by GPC peak areas. Composition of organic phase Lactone Diacid LA dimers dimers Oligomers area-% area-% area-% area-% Experiment 28 17 52 3 FEED 27 32 26 15 EX 1 28 29 17 26 EX 2 26 27 13 35 EX 3

Example 2

Increasing the Molecular Weight of Levulinic Acid Dimers by Second CC Coupling Reactions with WO3/ZrO2 Metal Oxide Catalyst

(80) The performance of WO.sub.3/ZrO.sub.2 catalyst was evaluated in a reactor test run with a feedstock comprising 43 wt-parts of levulinic acid, and 53 wt-parts of levulinic acid dimers and 2 wt-parts of levulinic acid oligomers.

(81) The feedstock was obtained in the same manner as in Example 1.

(82) The second CC coupling reactions for the feedstock were conducted in a continuous tubular fixed bed type micro reactor at temperatures ranging from about 200 C. to about 270 C. and under a pressure of about 20 bar, using a weight hourly space velocity (WHSV) of 0.5 h.sup.1. The reactions were conducted in nitrogen flow (3 I/h) at temperatures of 240 C. and below and in hydrogen flow (3 I/h) at temperatures of above 240 C. WHSV was calculated from the amount of monomers, dimers and oligomers (=liquid feedstock) fed into the reaction vessel.

(83) For reactions at various conditions the amount of gas formed was determined from the liquid yield (gas=100liquid product). The liquid product consists of the organic phase including water formed in the reaction.

(84) The quantitative amount of LA (levulinic acid) in liquid product was determined by HPLC analysis. The relative amount of dimers and oligomers in the organic phase was obtained from GPC chromatograms. The composition of the organic phase, including unreacted LA, was calculated relative to the liquid product.

(85) The composition of the organic phase was determined by GPC (area-%).

(86) The product yields and compositions of the liquid phase for conversion of levulinic acid dimers on WO.sub.3/ZrO.sub.2 catalyst system in nitrogen and hydrogen flow are presented in Tables 4 and 5.

(87) TABLE-US-00004 TABLE 4 Process conditions and product yields with WO.sub.3/ZrO.sub.2-catalyst. Gas and liquid Yields Process conditions Gas Liquid Temperature Pressure Gas WHSV phase phase C. bar flow h.sup.1 wt-% wt-% Experiment 200 20 N.sub.2 0.5 100 EX 4 220 20 N.sub.2 0.5 100 EX 5 240 20 N.sub.2 0.5 5 95 EX 6 250 20 H.sub.2 0.5 5 95 EX 7 260 20 H.sub.2 0.5 10 90 EX 8 270 20 H.sub.2 0.5 10 90 EX 9

(88) The liquid phase contains organic oxygenates (=organic phase) and water. The amount of water in liquid phase was not determined.

(89) TABLE-US-00005 TABLE 5 Product distribution in the liquid phase with WO.sub.3/ZrO.sub.2-catalyst determined by GPC peak areas. Composition of organic phase Lactone LA dimers Diacid dimers Oligomers area-% area-% area-% area-% Experiment 28 17 52 3 FEED 26 30 38 6 EX 4 24 33 33 10 EX 5 22 33 21 24 EX 6 26 35 20 19 EX 7 24 33 16 27 EX 8 23 29 15 34 EX 9

Example 3

Increasing the Molecular Weight of Levulinic Acid Dimers by Thermal CC Coupling Reactions

(90) Oligomers of levulinic acid were produced by subjecting the same feedstock as used in Examples 1 and 2 to thermal CC-coupling reactions at temperatures of above 200 C. and in the absence of catalyst.

(91) The thermal CC coupling reactions for the feedstock were conducted in a continuous tubular reactor at temperatures ranging from about 220 C. to about 250 C. and under a pressure of about 2 bar. The reactions were conducted in 10 I/h of helium, nitrogen or hydrogen flow and also without any gas flow.

(92) For reactions at various conditions the amount of gas formed was determined from the liquid yield (gas=100liquid product). The liquid product consists of the organic phase including water formed in the reaction.

(93) The quantitative amount of LA (levulinic acid) in liquid product was determined by HPLC analysis. The relative amount of dimers and oligomers in the organic phase was obtained from GPC chromatograms. The composition of the organic phase, including unreacted LA, was calculated relative to the liquid product.

(94) The product yields and compositions of the liquid phase for conversion of levulinic acid dimers with thermal CC-coupling reactions are presented in Tables 6 and 7.

(95) TABLE-US-00006 TABLE 6 Process conditions and product yields with thermal C-C-coupling reactions. Product yield Process conditions Liquid Temperature Pressure Gas yield C bar Gas flow wt-% wt-% Experiment 220 2 He 6.4 93.6 EX 10 240 2 He 7.8 92.2 EX 11 250 2 He 9.1 90.9 EX 12 220 2 N.sub.2 2.5 97.5 EX 13 240 2 N.sub.2 6.1 93.9 EX 14 250 2 N.sub.2 4.8 95.2 EX 15 220 2 H.sub.2 2.5 97.5 EX 16 240 2 H.sub.2 2.7 97.3 EX 17 250 2 H.sub.2 9.6 90.4 EX 18 220 2 None 0.0 100.0 EX 19 240 2 None 1.4 98.6 EX 20 250 2 None 5.0 95.0 EX 21

(96) TABLE-US-00007 TABLE 7 Product distribution in the liquid phase with thermal C-C-coupling reactions determined by GPC peak areas. Composition of organic phase Lactone Diacid LA dimers dimers Oligomers area-% area-% area-% area-% Experiment 28 17 52 3 FEED 25 33 26 16 EX 10 22 26 13 39 EX 11 19 19 10 52 EX 12 31 31 28 16 EX 13 27 27 14 34 EX 14 22 22 11 45 EX 15 28 32 33 8 EX 16 29 33 23 15 EX 17 29 30 18 24 EX 18 27 28 41 5 EX 19 27 33 34 7 EX 20 29 34 29 8 EX 21

(97) In none of the Experiments of Examples 1 to 3, a significant degree of coke or tar formation was recognized after 40 days of continuous reaction. Furthermore, it can be confirmed from the above results, that oligomerization of ketoacid dimers produced at low temperature from ketoacid monomers proceeds at temperatures at and above 200 C. The resulting products had a molecular weight distribution suitable for further conversion to fuel or baseoil components and/or chemicals.