Method for producing ketones for fuel and oil applications

Abstract

A method and system for producing ketones, suitable for manufacture of base oil or diesel fuel components, from a feedstock of biological origin containing fatty acids and/or fatty acid derivatives, and being at least partly in liquid form, by subjecting the feedstock to a catalytic ketonisation reaction, wherein the ketonisation reaction is carried out in a system having one or more ketonisation reactor(s) (A, B) each with at least one ketonisation catalyst bed (G). The method and system for producing ketones use a gas containing CO.sub.2 produced in the ketonisation reactors as a carrier gas.

Claims

1. A method for producing ketones, suitable for manufacture of base oil or diesel fuel components, from a feedstock of biological origin containing fatty acids or fatty acid derivatives, wherein the feedstock is at least partly in liquid phase, the method comprising: introducing the feedstock into a ketonisation reactor together with a carrier gas stream containing CO.sub.2; subjecting the feedstock to a catalytic ketonisation reaction, wherein the ketonisation reaction is carried out in a system having one or more ketonisation reactor(s) each with at least one ketonisation catalyst bed; separating gas containing CO.sub.2 from an effluent exiting a ketonisation reactor whereby the effluent containing ketones is used either as a feedstock for a further ketonisation reactor or for recovery of ketones from the effluent; and recycling the separated gas containing CO.sub.2 for use in the carrier gas stream in a ketonisation reactor.

2. Method according to claim 1, wherein the feedstock is at least 60 wt-% in liquid phase.

3. Method according to claim 1, wherein the feedstock of biological origin comprises: at least one of saturated free fatty acids, saturated fatty acid esters, esters, amides, aldehydes, alcohols, anhydrides, metal salts, or mixture thereof, or fatty acid glycerols.

4. Method according to claim 1, wherein the feedstock of biological origin comprises: at least one of saturated free fatty acids, saturated fatty acid esters having an average carbon chain length of from C.sub.4 to C.sub.24, or saturated fatty acid esters having an average carbon chain length of from C.sub.6 to C.sub.24.

5. Method according to claim 1, wherein the catalyst bed comprises: a ketonisation catalyst which is a metal oxide catalyst selected from a list consisting of one or more of: Ti, Mn, Mg, Ca, and Zr containing metal oxide catalyst.

6. Method according to claim 1, wherein a temperature in the feedstock is at least 330 C.

7. Method according claim 6, wherein the temperature is 365 C. or less.

8. Method according to claim 7, wherein a pressure in a ketonisation reactor is as least 1000 kPa.

9. Method according to claim 1, wherein the liquid feed flow rate, WHSV, is from 0.1 to 10.sup.1.

10. A method according to claim 1, wherein the ketonisation reaction is carried out in a system having two or more ketonisation reactors in series each with a ketonisation catalyst bed, the method comprising: introducing the feedstock into the first ketonisation reactor together with a first carrier gas stream containing CO.sub.2; and separating the gas containing CO.sub.2 from the effluent exiting the first ketonisation reactor whereby the effluent is introduced into the second ketonisation reactor together with a second carrier gas stream containing CO.sub.2; and if the system includes more than two ketonisation reactors: separating the gas containing CO.sub.2 from the effluent exiting each ketonisation reactor leaving a degassed effluent which is subsequently introduced into a next ketonisation reactor together with a further carrier gas stream containing CO.sub.2; separating gas containing CO.sub.2 from effluent exiting a final ketonisation reactor whereby the effluent containing ketones is used for recovery; and recycling the separated gas streams containing CO.sub.2 for use as the carrier gas stream in one or more of the ketonisation reactor(s).

11. Method according to claim 10, wherein a pressure in each ketonisation reactor in series following the first ketonisation reactor is lower than a pressure in a preceding ketonisation reactor.

12. Method according to claim 10, wherein a catalyst loading in the catalyst bed in each ketonisation reactor in series following the first ketonisation reactor is higher than a catalyst loading in a first ketonisation reactor by at least 10% higher in the second reactor or at least 50% higher in a third reactor.

13. Method according to claim 1, wherein the system includes at least two ketonisation reactors.

14. Method according to claim 13, comprising: heating the effluent exiting a ketonisation reactor and separated from gas containing CO.sub.2 before introduction into a subsequent ketonisation reactor.

15. Method according to claim 1, comprising: purifying the separated gas streams containing CO.sub.2 before recycling; and recovering the separated gas steams in a separation process by: separating CO.sub.2 and H.sub.2O vapour from unreacted fatty acids and volatile organic compounds or separating substantially pure CO.sub.2, which is at least 98% pure, from the waste water; and optionally recycling unreacted fatty acids or fatty acid derivatives to a ketonisation reactor.

16. Method according to claim 15, comprising: purifying the separated gas containing CO.sub.2 by cooling, and optionally further purification drying recovered purified gas before recycling to a ketonisation reactor.

17. Method according to claim 15, comprising: recovering and compressing substantially pure CO.sub.2, optionally under heating, before being recycled to a ketonisation reactor.

18. Method according to claim 16, wherein heat generated by the cooling is used for compression under heating of the substantially pure CO.sub.2.

19. Method according to claim 1, comprising: a hydrodeoxygenation, optional isomerization, and optional hydrofinishing.

20. A system for producing ketones, suitable for manufacture of base oil components, from a feedstock of biological origin containing fatty acids or fatty acid derivatives by subjecting the feedstock to a catalytic ketonisation reaction, wherein the system comprises: one or more ketonisation reactors (A, B) each having a ketonisation catalyst bed (G), means for heating, inlet means for the feedstock, and outlet means for the effluent exiting a ketonisation reactor, wherein the one or more ketonisation reactors each includes: inlet means for carrier gas streams, and outlet means for separated gas streams containing CO.sub.2; and wherein the system comprises: one or more gas-liquid separators (D, E) for separating CO.sub.2 in separated gas streams from H.sub.2O vapour, unreacted fatty acids or fatty acid derivatives, or volatile organic compounds, and means (F) for recirculating and optionally compressing the separated CO.sub.2; and optionally recycling means for liquid containing unreacted fatty acids or fatty acid derivatives, and outlet means for separated CO.sub.2.

21. System according to claim 20, comprising: means for purifying separated CO.sub.2 to a substantially pure CO.sub.2 gas, which is at least 98% pure.

22. System according to claim 20, comprising: two, three or four ketonisation reactors, in series.

23. System according to claim 20, comprising: three ketonisation reactors (A, B, C), in series, each having a ketonisation catalyst bed (G), means for heating, inlet means for the feedstock, and outlet means for effluent exiting a ketonisation reactor; wherein the three ketonisation reactors each include: inlet means for a carrier gas stream, and outlet means for separated gas streams containing CO.sub.2; and wherein the system includes: one or more gas-liquid separators (D, E) for separating CO.sub.2 in separated gas streams from H.sub.2O vapour, unreacted fatty acids or fatty acid derivatives, or volatile organic compounds, and means (F) for recirculating and optionally compressing the separated CO.sub.2; and optionally recycling means for liquid containing unreacted fatty acids or fatty avid derivatives, and outlet means for separated CO.sub.2.

24. System according to claim 20, wherein the one or more ketonisation reactors is a trickle bed reactor.

25. System according to claim 20, comprising: means for purification of gas containing CO.sub.2, including means for separating CO.sub.2 and/H.sub.2O vapour from volatile organic compounds.

26. Method for supplying a gas containing CO.sub.2 as a carrier gas stream in a ketonisation reaction, the method comprising: producing the gas containing CO.sub.2 in a catalytic ketonisation reaction producing ketones, suitable for manufacture of base oil components, from a feedstock of biological origin containing fatty acids or fatty acid derivatives, wherein the feedstock is at least partly in liquid phase, in one or more ketonisation reactors each having a ketonisation catalyst bed; and separating the gas from effluent exiting a ketonisation reactor and recycling the gas.

27. Method according to claim 26 for enhancing the gas flow within a ketonisation reactor having a ketonisation catalyst bed, comprising: subjecting a feedstock of biological origin containing fatty acids or fatty acid derivatives to a ketonisation reaction.

28. Method according to claim 26, comprising: purifying and recovering the separated gas containing CO.sub.2 before recycling in a separation process by separating CO.sub.2 from H.sub.2O vapour or volatile organic compounds; and optionally separating the CO.sub.2 as substantially pure CO.sub.2 from the waste water.

29. Method according to claim 28, comprising: cooling the separated gas containing CO.sub.2 before purification; or drying the recovered purified gas before recycling to a ketonisation reactor.

30. Method according to claim 26, comprising: purifying and recovering substantially pure CO.sub.2, optionally under heating, before being recycled to a ketonisation reactor.

31. Method for the manufacture of base oil or base oil components, the method comprising: producing ketones according to claim 1; and manufacturing a base oil or base oil components with the ketones.

32. Method according to claim 1, wherein the feedstock is selected to be at least one of 65 wt-%, at least 70 wt-%, at least 75 wt-%, at least 80 wt-%, or at least 90 wt-% in liquid phase, or 100 wt-% in liquid phase.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a block diagram for a system for producing ketones according to the invention comprising three ketonisation reactors, two gas-liquid separators and a compressor.

(2) FIG. 2 shows a block diagram for a system for producing ketones according to the invention comprising two ketonisation reactors, two gas-liquid separators and a compressor.

DETAILED DESCRIPTION OF THE INVENTION

(3) In describing the embodiments of the invention specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

(4) When describing the embodiments of the present invention, the combinations and permutations of all possible embodiments have not been explicitly described. Nevertheless, the mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage. The present invention envisages all possible combinations and permutations of the described embodiments.

(5) The terms comprising, comprise and comprises herein are intended by the inventors to be optionally substitutable with the terms consisting of, consist of and consists of, respectively, in every instance.

(6) By the expression ketones suitable for manufacture of base oil or diesel fuel components are meant ketones produced from fatty acid containing feed wherein the fatty acid carbon chain length is 4 or more C atoms, preferably at least 6 C atoms, resulting in a ketone comprising at least 7 C atoms, preferably at least 11 C atoms, in length when ketonised. These hydrocarbons are suitable for the manufacture of diesel fuel components having the lower carbon number range, typically from C7 to C20; and base oil components having the higher carbon number range, such as from C11 upwards.

(7) The First Aspect of the Invention

(8) The feedstock used according to the invention is of biological origin and comprises fatty acids and/or fatty acid derivatives, such as esters, amides, aldehydes, alcohols, anhydrides, metal salts, or mixture thereof. The fatty acid may be saturated or unsaturated, and the derivatives may for example be fatty acid esters, including glycerols selected from mono-, di-, and triglycerides, fatty acid amides and fatty alcohols.

(9) The feedstock of biological origin may e.g. be selected from

(10) i) any kind of fats, any kind of waxes, plant fats, plant oils, plant waxes; animal fats, animal oils, animal waxes, fish fats, fish oils, fish waxes, and

(11) ii) fatty acids or free fatty acids obtained from plant fats, plant oils, plant waxes; animal fats, animal oils, animal waxes; fish fats, fish oils, fish waxes, and mixtures thereof by hydrolysis, transesterification, or pyrolysis, and

(12) iii) esters obtained from plant fats, plant oils, plant waxes; animal fats, animal oils, animal waxes; fish fats, fish oils, fish waxes, and mixtures thereof by transesterification, and

(13) iv) metal salts of fatty acids obtained from plant fats, plant oils, plant waxes; animal fats, animal oils, animal waxes; fish fats, fish oils, fish waxes, and mixtures thereof by saponification, and

(14) v) anhydrides of fatty acids from plant fats, plant oils, plant waxes; animal fats, animal oils, animal waxes; fish fats, fish oils, fish waxes, and mixtures thereof, and

(15) vi) esters obtained by esterification of free fatty acids of plant, animal, and fish origin with alcohols, and

(16) vii) fatty alcohols or aldehydes obtained as reduction products of fatty acids from plant fats, plant oils, plant waxes; animal fats, animal oils, animal waxes; fish fats, fish oils, fish waxes, and mixtures thereof, and

(17) viii) recycled food grade fats and oils, and fats, oils and waxes obtained by genetic engineering,

(18) ix) dicarboxylic acids or polyols including diols, hydroxyketones, hydroxyaldehydes, hydroxycarboxylic acids, and corresponding di- or multifunctional sulphur compounds, corresponding di- or multifunctional nitrogen compounds,

(19) x) compounds derived from algae,

(20) xi) mixtures of said feeds of biological origin.

(21) In a first embodiment of this aspect of the invention the feedstock is at least partly in liquid phase. Preferably, the feedstock is at least 60 wt-% in liquid phase, preferably at least 65 wt-%, more preferably at least 70 wt-%, at least 75 wt-%, at least 80 wt-%, or at least 90 wt-% in liquid phase, and most preferred 100 wt-% in liquid phase.

(22) In a second embodiment the feedstock of biological origin may comprise saturated free fatty acids and/or saturated fatty acid derivatives, such as esters, amides, aldehydes, alcohols, anhydrides, metal salts, or mixture thereof, preferably fatty acid glycerols.

(23) In any of the above embodiments the feedstock of biological origin may comprise saturated free fatty acids and/or saturated fatty acid esters having an average carbon chain length of from C.sub.4 to C.sub.24, preferably having an average carbon chain length of from C.sub.6 to C.sub.24.

(24) In any of the above embodiments in the ketonisation reaction the ketonisation catalyst bed may comprise a ketonisation catalyst which is a metal oxide catalyst. Typical metals include Na, Mg, K, Ca, Sc, Cr, Mn, Fe, Co, Ni, Cu, Ti, Sr, Y, Zr, Mo, Rh, Cd, Sn, La, Pb, Bi and rare earth metals. Preferably, the metals are selected from the list consisting of one or more of: Ti, Mn, Mg, Ca, and Zr containing metal oxide catalyst, most preferably the ketonisation catalyst is a Ti containing metal oxide catalyst. The metal oxides may be on a support. Typical supports are laterite, bauxite, titanium dioxide, silica and/or aluminium oxide.

(25) In designing and controlling the ketonisation performance at the catalyst beds inside the ketonisation reactors, the most important parameters to control are the WHSV, viz. catalyst loading, and the feedstock temperature.

(26) Thus, in any of the above embodiments the temperature in the feedstock may be selected as at least 330 C., preferably at least 340 C., more preferably at least 350 C., most preferably at least 355 C., and most preferred 360-365 C., in particular if the carbon number of the feed is 6 or more.

(27) In any of the above embodiments the liquid feed flow rate, WHSV, may be selected from 0.1 to 10 h.sup.1, preferably from 0.2 to 5 h.sup.1, more preferably from 0.3 to 3 h.sup.1, most preferably from 0.5 to 1 h.sup.1.

(28) In any of the above embodiments the pressure in a ketonisation reactor may be selected as at least 1000 kPa, preferably at least 1200 kPa, more preferably at least 1300 kPa, even more preferably at least 1500 kPa, most preferably at least 2000 kPa, or most preferred at least 2500 kPa. When the pressure is from 500 to 5000 kPa, major part of the acid is in liquid form. For enhancing the base oil formation the pressure is preferably from 1500-2000 bar, whereas for the diesel fuel component a pressure from 1000 to 5000 kPa is applicable.

(29) In a particular embodiment of any of the above embodiments the ketonisation reaction is carried out in a system comprising two or more ketonisation reactors in series each comprising a ketonisation catalyst bed; further comprising that the feedstock is introduced into the first ketonisation reactor together with a first carrier gas stream comprising CO.sub.2; and the gas comprising CO.sub.2 is separated from the effluent exiting the first ketonisation reactor whereby the effluent is introduced into the second ketonisation reactor together with a second carrier gas stream comprising CO.sub.2; and if the system comprises more than two ketonisation reactors, the gas comprising CO.sub.2 is separated from the effluent exiting each ketonisation reactor leaving a degassed effluent which is subsequently introduced into the next ketonisation reactor together with a further carrier gas stream comprising CO.sub.2; gas comprising CO.sub.2 is separated from the effluent exiting the final ketonisation reactor whereby the effluent comprising ketones is used for recovery; and the separated gas streams comprising CO.sub.2 are recycled and used as the carrier gas stream in one or more of the ketonisation reactor(s).

(30) In this embodiment, wherein the ketonisation reactors are arranged in series, the pressure in each ketonisation reactor following the first ketonisation reactor may be adjusted to be lower than the pressure in the preceding ketonisation reactor. By selecting the pressures in a decreasing series, the pressure difference drives the liquid stream without pumping.

(31) In this embodiment, wherein the ketonisation reactors are arranged in series, the catalyst loading in the catalyst bed in each ketonisation reactor following the first ketonisation reactor is higher than the catalyst loading in the first ketonisation reactor, preferably at least 50% higher. This measurement helps to control the adiabatic temperature decrease in ketonisation and makes operation more cost efficient. The catalyst loading is e.g. preferably at least 10% higher in the second reactor, and/or preferably at least 50% higher in the third reactor, if three reactors are included in the series.

(32) In any of the above embodiments the ketonisation system may comprise at least two ketonisation reactors, and the effluent exiting a ketonisation reactor and separated from gas comprising CO.sub.2 may be heated before introduction into a subsequent ketonisation reactor.

(33) In any of the above embodiments separated gas streams comprising CO.sub.2 may be purified before recycling and recovered in a separation process comprising steps of separating CO.sub.2 and H.sub.2O vapour from unreacted fatty acids, fatty acids derivatives and volatile organic compounds, and/or separating substantially pure CO.sub.2, such as at least 98% pure, preferably 99% pure CO.sub.2, more preferably 99.5%, most preferably 99.9% pure CO.sub.2, from the waste water, and the unreacted fatty acids and fatty acids derivatives are optionally recycled to a ketonisation reactor.

(34) The purification of the CO.sub.2 before re-feeding it to the reactor makes the gas dry and enhances ketonisation reaction rate and also assists in avoiding enrichment of other light products in the recycle loop.

(35) In any of the above embodiments separated gas comprising CO.sub.2 may be subjected to purification, such as by cooling, and optionally further purification, and/or the recovered purified gas may dried before recycling it to a ketonisation reactor.

(36) In any of the above embodiments substantially pure CO.sub.2 may be recovered and subjected to compression, optionally under heating, before recycling it to a ketonisation reactor.

(37) In any of the above embodiments the heat generated by the cooling may be used for compression under heating of the substantially pure CO.sub.2

(38) In any of the above embodiments the method may further comprise a hydrodeoxygenation step, an optional isomerisation step, and optional hydrofinishing steps. The hydrodeoxygenation step is required if base oil components are to be produced.

(39) The Hydrodeoxygenation and Isomerisation

(40) The hydrodeoxygenation step, and isomerisation step, if applied, may either be done simultaneously or in sequence. The product is a deoxygenated and optionally isomerised base oil stream comprising renewable base oil.

(41) The hydrodeoxygenation reaction is done in the presence of hydrogen gas and may be performed in the presence of a hydrodeoxygenation catalyst, such as CoMo, NiMo, NiW, CoNiMo on a support, for example an alumina support, zeolite support, or a mixed support. The hydrodeoxygenation step may for example be conducted at a temperature in the range from 250 to 400 C., and at a pressure in the range from 20 to 80 barg, a WHSV in the range from 0.5 to 3 h1, and a H.sub.2/oil ratio of 350-900 nl/l, using a catalyst, such as NiMo, optionally on a alumina support.

(42) The product of the hydrodeoxygenation step may be subjected to an isomerization step in the presence of hydrogen and an isomerization catalyst. The isomerisation catalyst may be a noble metal bifunctional catalyst such as a for example Pt-SAPO or Pt-ZSM-catalyst or NiW. The isomerization step may for example be conducted at a temperature of 250-400 C. and at a pressure of 10-60 barg. The isomerisation step may for example be conducted at a temperature of 250-400 C., at a pressure of between 10 and 60 barg, a WHSV of 0.5-3 h1, and a H2/oil ratio of 100-800 nl/l.

(43) The hydrodeoxygenation and hydroisomerisation steps may be done in a single step on the same catalyst bed using a single catalyst for this combined step, e.g. NiW, or a Pt catalyst, such as Pt/SAPO in mixture with a Mo catalyst on a support, e.g. NiMo on alumina.

(44) Hydrofinishing

(45) In the hydrofinishing step, if applied, the product is stabilised by a further hydrogenation step. The hydrofinishing step may be applied to stabilise the product and involves e.g. hydrogenation of double bonds or aromatic compounds that are present after the ketonisation reaction and the following, optional, hydrodeoxygenation and isomerisation steps. The hydrofinishing step may be conducted at a temperature below 300 C., and a pressure between 100 and 200 barg. The WHSV may for example be 0.5-3.0 h1, and the H.sub.2/oil ratio may for example be 100-500 nl/l.

(46) The Second Aspect of the Invention

(47) In a first embodiment of this aspect of the invention it may further comprise means for purifying the separated CO.sub.2 to a substantially pure CO.sub.2 gas, preferably at least 98% pure, more preferably 99% pure, even more preferably 99.5% pure, most preferably 99.9% pure CO.sub.2.

(48) In a second embodiment the system according to the present invention may comprise two, three or four ketonisation reactors, preferably in series.

(49) In any of these embodiments the system may comprise three ketonisation reactors (A, B, C), preferably in series, each comprising one or more ketonisation catalyst bed(s) (G), means for heating, inlet means for the feedstock (1) and outlet means for the effluent (2, 3, 4) exiting a ketonisation reactor; wherein the three ketonisation reactors each further comprises inlet means for a carrier gas stream (5, 6, 7), outlet means for separated gas streams comprising CO.sub.2 (8, 9, 10); and wherein the system further comprises one or more gas-liquid separators (D, E) for separating CO.sub.2 in the separated gas streams (8, 9, 10) from H.sub.2O vapour, unreacted fatty acids and/or fatty acid derivatives, and/or volatile organic compounds, and means (F) for recirculating and optionally compressing the separated CO.sub.2; and optionally recycling means for liquid comprising unreacted fatty acids and/or fatty avid derivatives (11) and outlet means for separated CO.sub.2 (12).

(50) In any of these embodiments one or more ketonisation reactor(s) is a trickle bed reactor.

(51) In any of these embodiments the system may further comprise means for purification of gas comprising CO.sub.2, such as means for separation CO.sub.2 and/H.sub.2O vapour from volatile organic compounds.

(52) The Third Aspect of the Invention

(53) In a first embodiment of this aspect the use of a gas comprising CO.sub.2 as a carrier gas stream have the effect of enhancing the gas flow within a ketonisation reactor comprising a ketonisation catalyst bed wherein a feedstock of biological origin comprising fatty acids and/or fatty acid derivatives is subjected to a ketonisation reaction. By enhancing is meant that a more uniform gas flow pattern is allowed throughout the reaction zone. As the reactor has both CO.sub.2 recycle gas and a liquid feedstock phase present in the reactor inlet, there will be a continuous gas flow through the reactor. This will prevent maldistribution of concentration gradients typically due in single phase reactor with gas evolution during reaction.

(54) In a second embodiment of this aspect, and before recycling, the separated gas comprising CO.sub.2 has been purified and recovered in a separation process comprising steps of separating CO.sub.2 from H.sub.2O vapour and/or volatile organic compounds and optionally separated as substantially pure CO.sub.2 from the waste water. Part of CO.sub.2 may be retrieved as a product before recycling. This CO.sub.2 is quite pure.

(55) In any of the above embodiments separated gas comprising CO.sub.2 has been subject to purification, e.g. by cooling, an optionally further purification, and/or the recovered purified gas has been dried before recycling to a ketonisation reactor.

(56) In any of the above embodiments substantially pure CO.sub.2 has been recovered and subjected to compression, optionally under heating, before recycled to a ketonisation reactor.

(57) The Fourth Aspect of the Invention

(58) In its fourth aspect of the invention, it relates to the use of ketones obtainable by a method of the invention for the manufacture of base oil components or for intermediate material for production of base oil components.

(59) Base oils may further be used to manufacture products including lubricants, motor oil and metal processing fluids.

(60) The base oil affects many parameters of their endproducts or application such as the viscosity, oxidation stability, volatility, cold flow properties such as pour point, and viscosity index.

(61) Base oils which can be manufactured from ketones obtained according to the present invention fulfil the requirement of Group III of The American Petroleum Institute (API) which divides base oils into five main groups. Groups I to III are petroleum base oil of varying qualities.

(62) TABLE-US-00001 TABLE 1 API base stock categories Group Sulfur, wt-% Saturates, % Viscosity Index (VI) I >0.03 and/or <90 80-119 II 0.03 And 90 80-119 III 0.03 And 90 120 IV Synthetic poly-alpha-olefins (PAOs) V Any other type of base oil than group I-IV

(63) Exemplary embodiments of the invention are now described with reference to the drawings.

(64) FIG. 1 shows a block diagram for a system for producing ketones according to the invention comprising three ketonisation reactors, two gas-liquid separators and a compressor.

(65) FIG. 2 shows a block diagram for a system for producing ketones according to the invention comprising two ketonisation reactors, two gas-liquid separators and a compressor.

(66) FIG. 1

(67) Equipment: A Reactor B Reactor C Reactor D Gas-liquid separator E Gas-liquid separator F Compressor G Ketonisation catalyst bed

(68) Streams: 1 Fatty acid feedstock to Reactor A 2 Liquid from Reactor A 3 Liquid from Reactor B 4 Liquid from Reactor C 5 CO2 to Reactor A 6 CO2 to Reactor B 7 CO2 to Reactor C 8 Gas from Reactor A 9 Gas from Reactor B 10 Gas from Reactor C 11 Liquid from Gas-liquid separator D 12 Product CO2

(69) A fatty acid feedstock (1), which is at least partly in liquid form, and comprising fatty acids and/or fatty acid derivatives having an average chain length of C.sub.n (n=4 or more) is processed in a ketonisation system wherein the ketonisation reaction is conducted in a catalyst bed system comprising three reactors (A, B, C) in series. The ketonisation catalyst beds (G) include a suitable ketonisation catalyst, such as a Ti containing metal oxide catalyst. The first reactor (A) is loaded with a certain amount of the catalyst, the second reactor (B) is loaded with a higher amount of the catalyst than reactor A, and the third reactor (C) is loaded with a higher amount of catalyst than reactor B.

(70) The reaction temperature is the same, e.g. from 330-365 C., in all reactors (A, B, C). Heating of feedstock 1 and intermediate liquid streams (2, 3) is effectuated with e.g. an oil heater. The inlet pressure in the three reactors (A, B, C) declines as the feed passes the three reactors, so that the pressure in reactor A is higher than the inlet pressure in reactor B, which pressure is again higher than the inlet pressure of reactor C; the inlet pressures are e.g. at least 1000 kPa in the reactors.

(71) The target products of the ketonisation are ketones having an average chain length of C.sub.2n-1.

(72) The feedstock 1 is led to reactor A by the inlet means and with a suitable liquid feed flow rate. At the same time a flow (5) of CO.sub.2 is led as carrier gas to reactor A.

(73) The effluent (2) leaving reactor A comprises ketones produced by the ketonisation reaction and CO.sub.2. CO.sub.2 is separated from the effluent (2), is recovered and lead as a gas stream (8) to a first gas-liquid separator (D).

(74) The remaining part of effluent 2, free of CO.sub.2, is lead to reactor B, and at the same time a flow (6) of CO.sub.2 is led as carrier gas to reactor B. The effluent (3) leaving reactor B also comprises ketones produced by the ketonisation reaction and CO.sub.2. CO.sub.2 is separated from effluent 3 as described for liquid 2, is recovered and lead as a gas stream (9) to the first gas-liquid separator (D).

(75) Finally, the effluent (4) leaving reactor C comprising ketones produced by the ketonisation reaction and CO.sub.2 is obtained. CO.sub.2 is separated from effluent 4 as described for effluent 2, is recovered and lead as a gas stream (10) to the gas-liquid separator D. Separation of the gas stream 10 from the effluent 4 leaves the target ketones for recover and further treatment.

(76) Each gas stream (8, 9, 10) recovered from the reactors effluents (2, 3, 4) is subjected to cooling and lead to the gas-liquid separator D. The separation in the gas-liquid separator D leaves a gas flow comprising CO.sub.2 and H.sub.2O vapor which is lead to a second separator (E). CO.sub.2 is recovered in separator E and purified to a substantially pure CO.sub.2 stream (12). Thereafter CO.sub.2 stream 12 is compressed in a compressor (F) before it is used as carrier gas stream to be used in one of the reactors (A, B, C). Liquid streams from separator E comprised water and a separate minor stream of organic compounds suitable for diesel.

(77) Heat released by cooling of the gas streams (8, 9, 10) is partly utilised for re-heating of compressed CO.sub.2.

(78) FIG. 2

(79) Equipment: A Reactor B Reactor D Gas-liquid separator E Gas-liquid separator F Compressor G Catalyst bed

(80) Streams: 1 Fatty acid feedstock to Reactor A 2 Liquid from Reactor A 4 Liquid from Reactor B 5 CO2 to Reactor A 6 CO2 to Reactor B 8 Gas from Reactor A 10 Gas from Reactor 611 Liquid from Gas-liquid separator D 12 Product CO2

(81) A fatty acid feedstock (1), which is at least partly in liquid form, and comprising fatty acids and/or fatty acid derivatives having an average chain length of C.sub.n (n=4 or more) is processed in a ketonisation system wherein the ketonisation reaction is conducted in a catalyst bed system comprising two reactors (A, B) in series. The ketonisation catalyst beds (G) include a suitable ketonisation catalyst. The first reactor (A) is loaded with a certain amount of catalyst, and the second reactor (B) is loaded with a higher amount of catalyst than reactor A.

(82) The reaction temperature is the same, e.g. from 330-365 C., in both reactors (A, B). Heating of the feedstock 1 and the intermediate liquid stream (2) is effectuated with e.g. an oil heater. The inlet pressure in the reactors (A, B) declines as the feed passes the two reactors, so that the pressure in reactor A is higher than the inlet pressure in reactor B; the inlet pressures are e.g. at least 1000 kPa in the reactors.

(83) The target products of the ketonisation are ketones having an average chain length of C.sub.2n-1.

(84) The fatty acid feedstock 1 is led to reactor A by the inlet means and with a suitable liquid feed flow rate. At the same time a flow (4) of CO.sub.2 is led as carrier gas to reactor A.

(85) The effluent (2) leaving reactor A comprises ketones produced by the ketonisation reaction and CO.sub.2. CO.sub.2 is separated from effluent 2, is recovered and lead as a gas stream (8) to a first gas-liquid separator (D).

(86) The remaining part of effluent 2, free of CO.sub.2, is lead to reactor B, and at the same time a flow (6) of CO.sub.2 is led as carrier gas to reactor B. The effluent (4) leaving reactor B also comprises ketones produced by the ketonisation reaction and CO.sub.2. CO.sub.2 is separated from effluent 4 as described for liquid 2, is recovered and lead as a gas stream (10) to gas-liquid separator D. Separation of the gas stream (10) from effluent 4 leaves the target ketones for recover and further treatment.

(87) Each gas stream (8, 10) recovered from the reactor effluents (2, 4) are subjected to cooling and lead to the gas-liquid separator D. The separation in gas-liquid separator D leaves a gas flow comprising CO.sub.2 and H.sub.2O which is lead to a second separator (E). CO.sub.2 is recovered in separator E and purified to a substantially pure CO.sub.2 stream (12). Thereafter the CO.sub.2 stream 12 is compressed in the compressor (F) before it is used as carrier gas stream to be used in one of the reactors (A, B).

(88) Heat released by cooling of the gas streams (8, 10) is partly utilised for re-heating of compressed CO.sub.2.

EXAMPLES

Example 1 (FIG. 1)

(89) Pure C.sub.16 fraction of palmitic acid was used as feedstock in a design wherein the reaction was conducted in a trickle bed system comprising three reactors (A, B, C) in series. The ketonisation catalyst beds (G) included a K.sub.2O/TiO.sub.2 catalyst; loaded as 13,000 kg in the first reactor, 14,000 kg in the second reactor, and 22,000 kg in the third reactor.

(90) The target product of the ketonisation of C.sub.16 acids is C.sub.31-ketones.

(91) The feed temperature was 350 C. in all reactors (A, B, C). The inlet pressure in the three reactors was 1700 kPa in the first reactor (A), 1500 kPa in the second reactor (B), and 1300 kPa in the third reactor (C).

(92) The palmitic acid feedstock (1) was led to the first reactor (A) by the inlet means.

(93) The liquid feed flow rate was 20,000 kg/h. The CO.sub.2 flow (5, 6, 7) was 15,000 kg/h.

(94) The normal boiling point of palmitic acid is around 351 C., and 1000 kPa was considered as the minimum process pressure.

(95) CO.sub.2 was used as carrier gas and was led to each of the reactors (A, B, C) as the inlet carrier gas streams (5, 6, 7). The CO.sub.2 produced by the ketonisation reaction in each reactor was separated from the effluents from each reactor (2, 3, 4) and recovered and led as the gas streams (8, 9, 10) to the gas-liquid separators (D, E). In the first separator (D) CO.sub.2 and H.sub.2O vapors were separated from liquid organics carried over, mainly unreacted feedstock, and the liquid separated in this separator (11) was recycled to the third reactor (C). The gas stream from separator D was led to a second separator (E) wherein CO.sub.2 was recovered and purified to a substantially pure CO.sub.2 stream and compressed in the compressor (F) before it was used as carrier gas stream to be used in each of the reactors (A, B, C). Liquid streams from separator E comprised water and a separate minor stream of organic compounds suitable for diesel. The major part of pure CO.sub.2 exiting separator E was lead to a compressor, whereas a part of CO.sub.2 (equal to the amount produced as side product of ketonisation) is cleaved to a substantially pure CO.sub.2 product.

(96) The feedstock (1) and intermediate liquid streams (2, 3) were heated to the operating temperature of 350 C. with an oil heater. The gas streams (8, 9, 10) were subjected to cooling to 272 C. prior to the separation in the first separator (D), and the released heat is partly utilised for re-heating of the compressed CO.sub.2. Additional heating and cooling was also required for these streams, implemented as an air cooler operating at 200 C. for additional cooling of the gas streams. For the further cooling between the two separators (D, E), a water cooler operating at 40 C. was used.

Example 2

(97) Yield and Mass Flow

(98) The ketonisation reaction provided C.sub.31 in a high yield and with high selectivity. Results are shown in Table 2.

(99) TABLE-US-00002 TABLE 2 Yield and mass flow Liquid product Molar conversion of feedstock fatty acids 99% Molar selectivity to C31 ketone 93% Weight based yield of C31 ketone from palmitic acid 82% (93% out of (theor. 87.9%) theoretical yield) Weight based yield of base oil precursors 85% (C31 ketone, other ketones, heavies) Weight based yield of diesel precursors from palmitic 2% acid Mass fraction of heavies in base oil precursors 3.8% Total mass flow of base oil precursors kg/h 17,040 CO.sub.2 product, split from the recycling Mass flow kg/h (12) 1,710 Purity of CO.sub.2 99.99% Organic side stream from the second separator (E) Mass flow kg/h 190 Weight fraction of diesel precursors 92% Waste water from the second separator (E) Mass flow kg/h 690 Purity of water 100%

(100) The results show that the ketonisation process can be implemented with a high yield of the target ketone. The present example includes three trickle-bed-reactors in series, the stripping of water and the re-heating of the liquid intermediate product stream after reactors A and B. The total base oil precursor yield is 85 weight % out of the theoretical 87.9%. The only side products are a minor amount of diesel precursors, water and CO.sub.2. The base case assumes 20,000 kg/h feedstock when operating with the temperature of 350 C. and feedstock pressure of 1800 kPa. CO.sub.2 is used as a carrier gas in the process, recycled, and the amount generated by ketonisation can be recovered in 99.99% purity and considered as another product (1710 kg/h). The total amount of CO.sub.2 flow rate is 15,000 kg/h.

(101) Energy Consumption:

(102) Table 3 provides data for the heat exchangers, the pumps and the compressor. The cooling of the reactor gas effluent (686 kW) provides a part of the heat required for the CO.sub.2 reheating (686 kW) in an integrated exchanger.

(103) TABLE-US-00003 TABLE 3 Heat exchangers Fatty acid feed heater (to heat the feedstock 4257 kW from 100 C. to 350 C.) Heater for liquid product from Reactor A 130 kW Heater for liquid product from Reactor B 522 kW Exchanger for reactor gas phase effluent (5, 6, 7) 686 kW Exchanger for heating of recycled CO.sub.2 (12) 686 kW Air cooler for additional cooling of reactor gas 692 kW stream (5, 6, 7) Electric heater for additional heating of recycled 838 kW CO.sub.2 stream Water cooler for gas effluent of gas-liquid 1222 kW separator (D, E) Pumps Liquid product pump (discharge pressure 4500 kPa 25.3 kW for HDO) Pump for returning un-reacted feedstock to 1.3 kW Reactor C (11) Compressor For re-pressurizing CO.sub.2 (F) 154 kW

Example 3

(104) Table 4 shows the ranges of other key ketonisation parameters

(105) TABLE-US-00004 TABLE 4 Process variable Min. Max. CO.sub.2 flow (kg/h) as low as still effective 15,000 Temperature ( C.) 330 360 Pressure (kPa) 1000 2500 WHSV (1/h) 0.2 as high as possible

Example 4

(106) The inventors also tested appropriate catalyst loadings for a fresh catalyst for the feed temperatures 340, 345 and 350 C. for reaching an acceptable base case performance. The conditions tested are indicated in table 5. The feed temperature/catalyst loading combinations leading to a high, viz. >83 wt.-% out of theoretical 87.9 wt.-%, base oil precursor yield is indicated.

(107) TABLE-US-00005 TABLE 5 Loading of Loading of Loading of Effective WHSV T.sub.feedstock reactor A reactor B reactor C (1/h) 340 C. 20,000 kg 22,000 kg 33,000 kg 0.27 345 C. 16,000 kg 17,000 kg 25,000 kg 0.34 350 C. 13,000 kg 14,000 kg 22,000 kg 0.41 355 C. 11,000 kg 12,000 kg 18,000 kg 0.49 360 C. 8,000 kg 9,000 kg 15,000 kg 0.63

(108) If the system works at 340 C. or below, it may be advantageous to use four reactors instead of three.

Example 5 (FIG. 2)

(109) The number of required reactors depends on the production capacity and the target yields. For the base case operation, 3-reactor-process configuration is optimal. For smaller production capacities a 2-reactor-process configuration, displayed in FIG. 2, is sufficient for providing a good ketone yield. The adiabatic temperature drop in the reactors is limited to ten degrees of centigrade, which determines the reactor sizing i.e. catalyst loadings. Qualitatively the operations are equivalent to those described in example 1.