LOW ENERGY PROCESS TO PRODUCE A HYDROPHOBIC OIL FROM BIOMASS PYROLYSIS LIQUIDS

Abstract

Described is a novel process for fractionating biomass pyrolysis oil quantitatively into energy dense hydrophobic aromatic fraction and water-soluble organics in an economical and energy efficient manner. Using the concepts of solvents and anti-solvent behaviors to separate the pyrolysis oil, which is an emulsion, a method utilizing minimal quantities of solvents and water is proposed, by comparison with the existing methods to isolate the hydrophobic aromatic fraction, there is a volume reduction of greater than 50:1. Additionally, there is a significant time saving over the 24 hours for the accepted method as a solvent, and the anti-solvent system is spontaneous.

Claims

1-18. (canceled)

19. A process comprising: fractionating pyrolysis oil to yield: an organic phase comprising hydrophobic aromatics, and an aqueous phase comprising water soluble organics; and extracting the aqueous phase with an organic solvent to yield: a fraction that is soluble in the organic solvent, and a fraction that is insoluble in the organic solvent.

20. The process according to claim 19, wherein the extracting comprises: combining the aqueous phase and the organic solvent to yield a mixture; agitating the mixture; and allowing the mixture to settle.

21. The process according to claim 19, further comprising distilling the fraction that is soluble in the organic solvent to remove the organic solvent, thereby yielding a product.

22. The process according to claim 21, wherein the product comprises phenolic monomers.

23. The process according to claim 19, further comprising: extracting the fraction that is insoluble in the organic solvent with an additional organic solvent to yield: a fraction that is soluble in the additional organic solvent, and a fraction that is insoluble in the additional organic solvent.

24. The process according to claim 23, further comprising distilling the fraction that is insoluble in the additional organic solvent to remove water, thereby yielding a product.

25. The process according to claim 23, wherein the product comprises pyrolytic sugars.

26. The process according to claim 23, further comprising removing the additional organic solvent from the fraction that is soluble in the additional organic solvent.

27. The process according to claim 23, further comprising: combining the fraction that is soluble in the organic solvent and the fraction that is soluble in the additional organic solvent to yield a mixture.

28. The process according to claim 27, further comprising distilling the mixture to remove the organic solvent and the additional organic solvent, thereby yielding a product.

29. The process according to claim 28, wherein the product comprises phenolics.

30. The process according to claim 23, further comprising: combining the fraction that is soluble in the organic solvent, the fraction that is soluble in the additional organic solvent, and the organic phase to yield a mixture.

31. The process according to claim 30, further comprising distilling the mixture to remove the organic solvent, the additional organic solvent, and water thereby yielding a product.

32. The process according to claim 31, wherein the product comprises the hydrophobic aromatics.

33. The process according to claim 23, wherein extracting the fraction that is insoluble in the organic solvent with the additional organic solvent comprises: combining the fraction that is insoluble in the organic solvent and the additional organic solvent to yield a mixture; and allowing the mixture to settle.

34. The process according to claim 19, wherein the organic solvent is diethyl ether.

35. The process according to claim 34, wherein the additional organic solvent is dichloromethane.

36. The process according to claim 19, wherein the organic solvent is butyl acetate.

37. The process according to claim 36, wherein the additional organic solvent is butyl acetate.

38. A process comprising: fractionating pyrolysis oil to yield: an organic phase comprising hydrophobic aromatics, and an aqueous phase comprising water soluble organics; extracting the aqueous phase with diethyl ether to yield: a diethyl ether-soluble fraction, and a diethyl ether-insoluble fraction; extracting the diethyl ether-insoluble fraction with dichloromethane to yield: a dichloromethane-soluble fraction, and a dichloromethane-insoluble fraction; distilling the dichloromethane-insoluble fraction to remove water, thereby yielding pyrolytic sugars; distilling the diethyl ether-soluble fraction and the dichloromethane-soluble fraction to remove the diethyl ether and the dichloromethane, thereby yielding phenolic monomers.

39. A process comprising: fractionating pyrolysis oil to yield: an organic phase comprising hydrophobic aromatics, and an aqueous phase comprising water soluble organics; extracting the aqueous phase with butyl acetate to yield: a first butyl acetate-soluble fraction, and a first butyl acetate-insoluble fraction; extracting the first butyl acetate-insoluble fraction with additional butyl acetate to yield: a second butyl acetate-soluble fraction, and a second butyl acetate-insoluble fraction; distilling the second butyl acetate-soluble fraction to remove water, thereby yielding pyrolytic sugars; combining the first butyl acetate-soluble fraction and the second butyl acetate-soluble fraction with the organic phase to yield a mixture; and distilling the mixture to remove the butyl acetate and water, thereby yielding the hydrophobic aromatics.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1. Anti-solvent/solvent behaviour with pyrolysis oil (Winson type emulsion).

[0027] FIG. 2. Process of flow diagram to produce HAF.

[0028] FIG. 3. Process of flow diagram to produce HAF with low molecular weight phenolics.

[0029] FIG. 4. FTIR spectral comparison of HAF and pyrolignin.

DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention relates to a process for converting PO obtained by pyrolysis of biomass into high-quality fuel/boiler fuel/marine fuel, chemicals and fuel blends, pyrolytic sugars, phenolic oligomers and alkyl esters. In certain embodiments, a process is disclosed for fractionating or phase separating the PO and subsequently these fractions will be used to produce specific high-value products, the process comprising steps in which, a) the organic phase of the phase separated product is further distilled to recover the solvent as well as hydrophobic aromatic polymer (HAF) as the primary product, and b) the aqueous phase of the phase separated product after a phase separation process is further processed by liquid-liquid extraction with solvents to extract and recover pyrolytic sugars and low molecular weight phenolics.

[0031] PO is a single-phase material as defined in ASTM D7544-12 Standard Specification for Pyrolysis Liquid Biofuel—Grades G and Grade D. This single-phase material has a low viscosity on the account of −25% mass fraction of water embodied in what is recognised to be an emulsion. The remainder of the material consists of water soluble small molecules—including acetic acid (HAc) as the most prominent; sugar and sugar polymers derived from the cellulose, and a hydrophobic aromatic polymer (HAF) derived from both the lignin and the cellulose breakdown. Often the HAF is described as “pyrolytic lignin”, which is a term of art that describes the substance that precipitates out of cold water when PO is slowly added.

[0032] There is an analytical procedure to quantify the “pyrolytic lignin” wherein the PO is first mixed with an equal mass of water to obtain a raw precipitate. This precipitate typically has about 50% of the initial mass. However, this is still contaminated with other materials from the PO and has to be re-dissolved in an equal mass of methanol. To this mixture, another equal mass e.g. 1 kg of water is added to precipitate a purified pyrolytic lignin from which the methanol has to be evaporated.

[0033] Alternative means of obtaining pyrolytic lignin make extensive use of organic solvents. Again, the mass ratios of PO to solvent are at least 1:1, and on separation, the solvent has to be water washed typically again with an equal or greater mass, followed by an acid-base process to extract the HAF comprised of phenols and neutrals. Both of these behaviours are very characteristic of emulsions and breaking them into separate phases.

[0034] There is direct evidence for the emulsion nature of PO that has come from small angle neutron scattering (SANS). The main phase consists of aggregates of lignin-derived molecules—while the dispersed phase is not visible in SANS and is presumed to be the water and water soluble molecules. With ageing, the aggregates tend to grow, and they are typically the equivalent volume of 4-coniferyl alcohol C-9 lignin units (typically called G-Lignin as they have the guiacyl OH and methoxy substituents in the ring). The molecular weight of 4G-lignins i.e. tetramer lignin is approximately 700-750 g/mol.

[0035] As PO ages, there are chemical reactions taking place that result in the production of water, some cross-linking of small molecules, and according to the SANS results in agglomeration of the tetramer units into larger units. This is not polymerization per se, the forces holding the tetramers together are van der Waals/Electrostatic, but the net result is that these aggregates fall out of solution.

[0036] The VTT group has recently published further insight into the emulsion nature of single phase PO (Lehto et al. 2013). The picture that has emerged is that the water insoluble (WIS) material—aka pyrolytic lignin—is held together using co-solvent molecules, in a loose network which solubilizes the water, and water solubles. The co-solvent molecules are C1-C6 type small organic molecules with a polar group e.g. —OH (alcohol and phenol), >C═O, —COOH, and a non-polar hydrocarbon or aromatic “body”. The water soluble (WS) phase holds most of the water, and the organic molecules that are highly polar e.g. sugars including anhydrosugars such as levoglucosan, and polyols e.g. sugar monomers and oligomers.

[0037] This emulsion can be destabilised by increasing the water to organic ratio so that the WIS (tetramer lignin) separates, and then adding a co-solvent back to the freshly phase separated material such that a single uniform phase is formed.

[0038] This is anti-solvent behaviour and the single-phase PO exists as a Type IV Winsor emulsion as shown in FIG. 1. In this case, the HAF (pyrolytic lignin) is behaving as a surfactant as well as an oil normally immiscible in water, while the polar organics are in an aqueous solution. On increasing the water concentration the WIS (water insoluble HAF) forms a bottom phase on account of its density, and an upper phase of mainly water and water soluble polar materials—a Winsor Type II emulsion is created, and as shown in (Oasmaa et al. 2015), adding small quantities of amphiphile molecules can reverse this and convert the Winsor Type II emulsion back to the apparent single phase Winsor Type IV emulsion.

[0039] There is, however, another Winsor emulsion—a type I which can be created by adding a lipophilic polar solvent—one which has Hansen solubility parameters in the range (Dispersion 8-10 MPa{circumflex over ( )}0.5, Polar 2-3 MPa{circumflex over ( )}0.5, and Hydrogen Bonding in the range of 2-4.5 MPa{circumflex over ( )}0.5). For a list of typical values for organic molecules see (Hansen 2007). Only a small amount of the lipophilic polar solvent is needed if the Winsor type IV emulsion is close to the critical point of converting to a Winsor type I emulsion. Then only a small amount of additional water as anti-solvent will trigger the formation of the Type I emulsion with an aqueous phase containing the majority of the sugar and water-soluble organics, and a solvent phase containing the HAF—pyrolytic lignin.

[0040] For recovery of the HAF, the very concentrated solution in the lipophilic polar solvent can be extracted from a minuscule volume of distilled water, and after drying the solvent phase, the residual heavy oil can be recovered by evaporation of the solvent. The combined water phase can be extracted with organic solvents and subsequently distilled to produce clean fractions of pyrolytic sugars and phenolic monomers. Further, these phenolic monomers can be added back to the HAF fraction for the future upgrading purposes.

[0041] Using the Winsor emulsion behaviour, the additional volumes of solvent and water are minimized. Process flow diagram of the process is shown in FIGS. 2 and 3. In FIG. 2, to the PO (10), solvent (20) is added at first and stirred vigorously for ˜30 minutes at room temperature in a batch or continuous reactor (100). Wherein the amount of solvent, depending on the water content of the PO is in the range of 1-20% mass ratio concerning PO. Wherein the preferable is range is from 5 to 10% concerning the PO.

[0042] To this mixture, solvent (30) is added and stirred vigorously for ˜60 minutes at room temperature in a batch or continuous reactor (200). The solvents are selected from C.sub.4-C.sub.8 monohydric alcohols, C.sub.2-C.sub.8 alcohol esters and diethyl ether. The preferable solvents are butyl acetate and any derivatives of butyl acetate. The amount of solvent added is, dependent on the water content of the PO, and is in the range of 1-20% mass ratio concerning PO. Wherein the preferable is range is from 5 to 10% concerning the PO.

[0043] After settling the mixture for about 10 to 90 minutes, a clear, distinct phase separation is achieved i.e. a top organic phase (300) and a bottom aqueous phase (400). Further distillation (301) of the top organic phase (300) results in HAF (700) and also anti-solvent (20R) and solvent (30R) which are recycled. The bottom aqueous phase (400) is further solvent extracted followed by distillation to produced pyrolytic sugars (500) and phenolic monomers (600).

[0044] The process shown in FIG. 3 follows the same procedure as FIG. 2 but also, the phenolic monomers (600) produced from the bottom aqueous phase (400) are added to the final HAF product (701). This addition, in turn, increases the yields of the HAF of up to 10%. Also, recycled solvent (30R1) and anti-solvent (20R1) from bottom aqueous phase are added back to the recycling lane.

[0045] In a typical example starting with 100% of PO the addition of butyl acetate (˜10%), and 5˜2% of water anti-solvent concerning PO, will produce an instant phase separation into the fractions of a top organic phase (42%) and bottom aqueous phase (58%). Assuming all the 100% butyl acetate or solvent is recycled, the overall yields from the process comprising of 36% of HAF, 30% of pyrolytic sugars, 11% phenolic monomers and the rest is residual water (˜23%). In most cases, these yields vary between the type of feedstocks and processing conditions used to produce the corresponding PO. In another scenario, the 11% phenolic monomers are added back to the HAF fraction, and this will increase the overall yield of HAF to 47%. The fractionation step is typically carried out at a temperature of from 0° C.-75° C. However, a range of from 15-75° C. is preferred and especially from 15-25° C. Although temperatures in the range of 0-15° C. produce faster fractionation, the shortened time period is offset in cost and energy terms by the increased cost in cooling the system.

[0046] The HAF produced from the above steps, and then evaporation of the solvent produces a viscous black liquid with the same properties as the pyrolytic lignin isolated using water washing methods. This is also confirmed by the FTIR spectral comparing of the HAF and pyrolignin as shown in FIG. 4.

[0047] Eligible solvents are required to have Hansen parameters in the above range, and simultaneously must have low solubility in water, and depending on the downstream process requirements, there will be a need for appropriate stability, environment, health and safety characteristics to enable its recovery.

Analytical Methods

[0048] Viscosity

[0049] Viscometric measurements were performed at 40° C. with a Brookfield DV-11+ Pro viscometer with small sample adapter and spindle SC4-18.

[0050] Heating Value Measurements

[0051] To determine the higher heating value (HHV) of the biofuels and different phases, approximately 1 g of samples were burned in an IKA C5003 type bomb calorimeter under 3 MPa oxygen pressure and in the dynamic method of operation. Standardisation and thermochemical corrections followed the ASTM D 240 test method. Samples with high water content were combusted with paraffin strips as spiking material (45.78 MJ/kg).

[0052] TAN and Water Analyses

[0053] The total acid number (TAN) and water content of the fuel samples were determined by Aqumax TAN and Aquamax KF Volumetric titrators (GRScientific) according to ASTM D 664 and ASTM E 203 standards.

[0054] CHN

[0055] The elemental composition analysis of the samples (C, H and N) was carried out at 900° C. by a Flash 2000 analyser, and the oxygen content (O) was calculated by difference.

[0056] GC-MS Analysis

[0057] Sugar compounds were analysed by gas chromatography-mass spectrometry (Agilent 7890A GC-MS) after a standard trimethylsilylation with HMDS. The injection unit temperature of the GC was 300° C., and it was coupled to an HP-VOC column (60 m×0.2 mm, 1.12 μm). The GC oven was heated from 45° C. to 280° C. at a rate of 3 K/min while the system was purged with helium carrier gas with a split ratio of 25. Separated compounds were recorded with the Agilent 5975C mass selective detector with ionisation energy of 70 eV and a scanning range of m/z 30-550 in the full scan mode.

EXAMPLES

Example 1

[0058] 100 grams of PO was placed into a 500 cm3 autoclave equipped with a magnetic stirrer. To this approximately 2-10% mass ratio of anti-solvent (for ex. distilled water) was added with stirring (˜1000 rpm) at room temperature for the duration of 10-60 minutes. To the resultant product, 1-30% mass ratio of solvent (for ex. butyl acetate) was added and stirred vigorously (˜1000 rpm) for the duration of 10-60 minutes. After leaving the mixture at ambient temperature, the liquid product consisted of two phases: a dark organic phase at the top and an aqueous phase at the bottom. These phase-separated products were centrifuged to obtain a clean separation of the organic and aqueous phases. The organic phase was subsequently distilled. Distillation yields a two-phase liquid product, a top light yellow organic phase (solvent) and a minor amount of colourless aqueous phase. The HAF will remain in the distillation flask. Similarly, the aqueous phase from an earlier phase separation process was put in a separatory funnel, and an equal amount of diethyl ether was slowly added, and the funnel was shaken vigorously for several minutes and then allowed to rest for approximately 30 min. The resultant solution separated into two distinct layers. The upper layer and bottom layer were designated as ether-soluble (ES) fraction and the ethers insoluble (EIS) fraction, respectively. Subsequently, from the ES fraction, ether was removed under reduced pressure with a rotary evaporator resulting in a low molecular weight phenolics. For the second liquid-liquid extraction, an equal quantity of dichloromethane was added to the EIS fraction, and the mixture was shaken for several minutes before being allowed to sit for approximately 30 min. The mixture gradually separated into two layers. The bottom layer was designated as the dichloromethane-soluble fraction of EIS (DCMS), and the upper layer was the dichloromethane-insoluble fraction of the EIS (DCMIS). The layers were separated, and the dichloromethane was removed under the vacuum with a rotary evaporator. Subsequent distillation of the DCMIS fraction yields a high amount of pyrolytic sugars and water as a by-product. Also, a subsequent distillation of both the ES fraction and DCMS fraction yields a high amount of low molecular weight phenolics and solvent as a by-product, and it will be further recycled to use for extraction purposes.

[0059] The typical product yields from this process are HAF (35-50% mass ratio), pyrolytic sugars (20-30% mass ratio), phenolics (8-12% mass ratio) and the remainder is the water content. These yields mostly depend on the type of biomass feed used to produce the PO and vary between feed to feed. Table 1 shows the comparison of properties of crude PO and HAF such as viscosity, HHV, Total acid number (TAN), water content and elemental analysis.

TABLE-US-00001 TABLE 1 Comparison of physical and chemical properties of crude PO, pyrolignin, HAF and HAF with phenolics Pyrolysis HAF with Property oil Pyrolignin HAF phenolics Units Total acid 111.85 73 88.15 103 mgKOH/g number Water mass 23 3 1.60 2.7 % fraction Density 1.12 na 1.15 na g/cm.sup.3 C mass fraction 41.68 55.95 62.61 60.42 % H mass fraction 7.61 7.26 7.40 6.98 % O mass fraction 50.70 36.80 29.99 32.60 % (by difference) Viscosity 22.60 na 268 na mPa .Math. s at 40° High heating 18.3 24.37 28.00 26.03 MJ/kg value, dry basis

Example 2

[0060] 100 grams of PO was placed into a 500 cm.sup.3 autoclave equipped with a magnetic stirrer. To this approximately 2-10% mass ratio of anti-solvent (for example distilled water) was added with stirring (˜1000 rpm) at room temperature for the duration of 10-60 minutes. To the resultant product, 1-30% mass ratio of solvent (for example butyl acetate) was added and stirred vigorously (˜1000 rpm) for 10-60 minutes. After leaving the mixture at ambient temperature, the liquid product consisted of two phases: a dark organic phase at the top and an aqueous phase at the bottom. These phases separated products were centrifuged to obtain a clean separation of the organic and aqueous phases. It has been found that a preferred range for the centrifugation step is at an applied force of 8000 g-12000 g.

[0061] The aqueous phase from the above phase separation process was put in a separatory funnel, and an equal amount of butyl acetate was slowly added, and the funnel was shaken vigorously for several minutes before being allowed to rest for approximately 30 min. The resultant solution separated into two distinct layers. The upper layer and bottom layer were designated as a butyl acetate-soluble (BS-1) fraction and the butyl acetate-insoluble (BIS-1) fraction, respectively. Subsequently, an equal quantity of butyl acetate was slowly added to the BS-1 fraction, and the funnel shaken vigorously for several minutes and then allowed to rest for approximately 30 min. The resultant solution separated into two distinct layers. The upper layer and bottom layer were designated as a butyl acetate-soluble (BS-2) fraction and the butyl acetate-insoluble (BIS-2) fraction, respectively. The fractions BS-1 and BS-2 were combined and added to the dark organic phase obtained from the first phase separation of PO. Finally, the resultant mixture (a dark organic phase+BS-1 &2) was subjected to distillation under vacuum or atmospheric conditions to remove or evaporate the butyl acetate and water. The HAF remained in the distillation flask. Similarly, a subsequent distillation of the BIS-2 fraction yielded a high amount of pyrolytic sugars and water as a by-product.

[0062] The typical product yields from this process are HAF (35-50% mass ratio), pyrolytic sugars (20-30% mass ratio), with the remainder is being water content. These yields mostly depend on the type of biomass feed used to produce the PO and vary from feed to feed. Table 2 shows the comparison of properties of crude PO and HAF such as viscosity, HHV, Total acid s number (TAN), water content and elemental analysis.

TABLE-US-00002 TABLE 2 Comparison of physical and chemical properties of crude PO, pyrolignin, and HAF with phenolics Pyrolysis HAF with Property oil Pyrolignin phenolics Units Total acid 111.85 73 85 mgKOH/g number Water mass 23 3 0 % fraction Density 1.12 na 1.18 g/cm.sup.3 C mass fraction 41.68 55.95 64.0 % H mass fraction 7.61 7.26 6.80 % O mass fraction 50.70 36.80 29.20 % (by difference) Viscosity 22.60 na na mPa .Math. s at 40° High heating 18.3 24.37 27.4 MJ/kg value, dry basis