Method for fractioning of pyrolysis oil

Abstract

The present invention relates to methods for fractioning pyrolysis oils into solid lignin, a concentrated sugar fraction and a light fraction containing a.o. lignin derived phenolics and cyclotene. The present invention further relates to solid lignin, a concentrated sugar fraction and a light fraction obtained by the present methods. Specifically, the present invention relates to method for fractioning of pyrolysis oil, the method comprises the steps of: separating pyrolytic sugars and liquid pyrolytic lignin comprised in the pyrolysis oil using liquid-liquid extraction in a ratio of aqueous extractant to pyrolysis oil of 0.2 : 2 to 2 : 0; b) separating the liquid pyrolytic lignin fraction from the pyrolytic sugars aqueous extractant fraction; c) subjecting the liquid pyrolytic lignin fraction to a heat treatment until solid pyrolytic lignin is obtained with an average Mw between 800 g / mole to 1600 g / mole and a melting point between 65°C to 95°C.

Description

[0001] METHOD FOR FRACTIONING OF PYROLYSIS OIL

[0002] Description

[0003] The present invention relates to methods for fractioning pyrolysis oils into solid lignin, a concentrated sugar fraction and a light fraction rich in a.o. lignin derived phenolics and cyclotene. The present invention further relates to solid lignin, a concentrated sugar fraction and a light phenolics fraction obtained by the present methods and the use of the present solid lignin in insulation foam, paint, resin systems & binders.

[0004] Biomass is a valuable, sustainable feedstock for the production of chemicals and materials, and will play an important role in the transition towards a sustainable process industry. Bio-based products, i.e., products wholly, or partly, derived from materials of biological origin, can result in a society more sustainable and lower its dependence on fossil fuels.

[0005] For the optimal utilization of bio-resources, fractionation on the basis of functionalities is often desired. Most commonly, biomass is separated into its main constituents lignin, cellulose and hemi-cellulose by steam or acid treatment. Thermo-chemical fractionation is an alternative two steps conversion process to transform different bio-resources into raw-materials for renewable chemicals and products. In this approach, a short thermal treatment at elevated temperature and in the absence of oxygen (fast pyrolysis) is followed by a low temperature fractionation of the practically mineral free, liquid product that keeps the key chemical functionalities intact in separate, liquid, depolymerized fractions. These fractions are comprised of components derived from the de-polymerization of cellulose, hemicellulose and lignin.

[0006] Fractionation of the liquid can provide a number of valuable end-products such as phenolic resins, binders, polyols, foundry resins, paints, engineered wood and natural fibre reinforced products.

[0007] Pyrolysis is the thermal decomposition of organic material in an oxygen-free environment, and it results in solid, liquid and gaseous products. Fast pyrolysis is applied when the aim is to maximize the liquid yield. In this context fast relates to the rapid heating of the organic material.

[0008] Typically, the process is carried out at ambient pressures and a reactor temperature of around 500°C. The biomass is rapidly heated, and the vapour stream is rapidly cooled to avoid further reactions, and to maximize the yield of liquids. In case of clean woody biomass (for example pine wood) the liquid yield can be up to 70 wt%; about 15 wt% of the biomass is converted into charcoal and the remaining 15 wt% to non-condensable gases (for example CO, CO2, CH4).

[0009] The liquid product is often designated Fast Pyrolysis Bio-Oil (FPBO). FPBO is polar and acidic mixture containing water. It can be seen as a very broad mixture of components derived from the depolymerisation of cellulose, hemicelluloses, and lignin components of the feedstock.

[0010] Nowadays, clean wood-based FPBO is commercially used to replace fossil heavy fuel oils and natural gas in boiler applications.

[0011] The very short heating time in the fast pyrolysis process results in a liquid product containing fragments of the original biomass. This means that the original chemical functionalities present in the biomass are largely retained. In the fractionation process the FPBO is separated into different fractions with specific functionalities like extractives, carbohydrates / sugars and lignin / phenolics. Each fraction can be used as renewable raw material for a wide variety of end products.

[0012] A thermo-chemical fractionation (TCF) process can be divided in two steps being i) production of a pyrolysis liquid, and ii) the fractionation of the liquid in fractions with specific properties or chemical functionalities. The production and separation can be decoupled in time and scale.

[0013] The fractionation process is based on liquid-liquid extraction by organic or aqueous extractants. An organic extractant is used to separate the extractives from the oil; an aqueous extractant is suitable to separate the FPBO into a pyrolytic lignin an pyrolytic sugar fraction.

[0014] It is an object of the present invention to provide a fractionation process based on liquid-liquid extraction using an aqueous extractant to provide a sustainable feedstock for the production of chemicals and materials.

[0015] This object of the present invention, amongst other objects, is met by fractioning methods as outlined in the appended claims.

[0016] Specifically, this object of the present invention, amongst other objects, is met by methods for fractioning of pyrolysis oil such as fast pyrolysis oil, the methods comprise the steps of: a) separating pyrolytic sugars and liquid pyrolytic lignin comprised in the pyrolysis oil using liquid-liquid extraction by adding an aqueous extractant, such as water, to the pyrolysis oil in a ratio of aqueous extractant to pyrolysis oil of 0.2 : 2 to 2 : 0.2; b) separating the liquid pyrolytic lignin fraction from the pyrolytic sugars aqueous extractant fraction; c) subjecting the liquid pyrolytic lignin fraction to pressures below 0.5 bar, such as below 0.1 bar obtained by continuously removing the gaseous phase, to a heat treatment wherein the temperature is increased from 50°C- 70°C to 180°C-240°C during 1 to 24 hours, preferably 1.5 to 15 hours, more preferably 2 to 10 hours, until solid pyrolytic lignin is obtained with an average Mwbetween 800 g / mole to 1600 g / mole and a melting point between 65°C to 95°C; wherein the method is performed as a continuous process or as a batch process.

[0017] Present step (c) as defined above is preferably performed in two or more separate steps of 30 minutes to 180 minutes wherein the temperature is increased from 50°C-70°C to 180°C-240°C

[0018] According to the present invention, the pyrolysis oil, or fast pyrolysis oil, before being used in step (a) can be subjected to an extraction process using an organic solvent.

[0019] The separation of the pyrolytic sugar stream (derived from cellulose and hemicellulose) and a liquid pyrolytic lignin stream (depolymerized lignin) is based on liquid-liquid extraction using an aqueous extractant. The extractant will end-up in the pyrolytic sugar stream, and depending on the specific use of this stream the extractant or part of it might be recycled within the process (for example, if lower water content is desired).

[0020] The present methods provide the advantages of:

[0021] Limited use of water extractant, for example 0.3-0.5 kg water per kg FPBO, while alternatives use large excess water (10-100x)

[0022] Separation on basis of chemical functionality by applying liquid-liquid extraction. The alternative “fractionated condensation” of FPBO provides separation on boiling point and does not provide desired product properties; No addition of chemicals; byproducts can at least be used as fuel (mix back in FPBO)

[0023] The present methods provide solid pyrolytic lignin which is:

[0024] More reactive than conventional lignin (e.g. kraft lignin or lignin from 2G EtOH plants).

[0025] Lower average molecular weight.

[0026] High reactivity required in many applications such as insulation foam and various resin applications.

[0027] According to a preferred embodiment of the present methods, the heat treatment of step (c) comprises the steps of:

[0028] 60°C to 90°C for 30 minutes to 120 minutes;

[0029] 110°C to 130°C for 30 minutes to 120 minutes;

[0030] 150°C to 170°C for 30 minutes to 150 minutes; and

[0031] 180°C to 220°C for 30 minutes to 180 minutes.

[0032] According to a more preferred embodiment of the present methods, the heat treatment of step (c) comprises the steps of: 75°C to 85°C for 30 minutes to 120 minutes;

[0033] 115°C to 125°C for 30 minutes to 120 minutes;

[0034] 155°C to 165°C for 30 minutes to 150 minutes; and

[0035] 185°C to 195°C for 30 minutes to 180 minutes.

[0036] According to an even more preferred embodiment of the present methods, the heat treatment of step (c) comprises the steps of:

[0037] 80°C for 90 minutes;

[0038] 120°C for 60 minutes;

[0039] 160°C for 120 minutes; and

[0040] 190°C for 150 minutes.

[0041] Besides solid lignin, the present methods provide light fractions rich in phenolics such as guaiacol, creosol, phenol, and 4-ethylguaiacol and also cyclotene which can be, in step (c), be isolated by condensation of the gaseous phase.

[0042] According to an especially preferred embodiment of the present methods, the ratio of aqueous extractant to pyrolysis oil in step (a) is from 0.2 to 1 : 1, preferably 0.3 to 0.6 : 1.

[0043] Besides, solid lignin and the light fractions, the present methods can also provide pyrolytic sugars which can be concentrated for further use.

[0044] According to the present invention, the present solid pyrolytic lignin obtained in step (c) preferably has an average Mwbetween 1000 g / mole to 1400 g / mole, more preferably an average Mwbetween 1100 g / mole to 1300 g / mole, most preferably an average Mwof 1200 g / mole.

[0045] According to another aspect, the present invention provides solid lignin obtainable by the present methods, the solid lignin has an average Mwbetween 800 g / mole to 1600 g / mole, preferably an average Mwbetween 1000 g / mole to 1500 g / mole, more preferably an average Mwbetween 1100 g / mole to 1500 g / mole and a melting point between 65°C to 95°C.

[0046] According to yet another aspect, the present invention provides phenolics obtainable by the present methods, wherein the condensed light fraction comprises (on dry -base) amongst others: 1 to 45 wt.% creosol, 1 to 12 wt.% phenol, 1 to 25 wt.% guaiacol, and 1 to 20 wt.% 4-ethylguaiacol and 1 to 25 wt.% cyclotene.

[0047] The present solid lignin is especially suitable to be used in insulation foam, resins paints and binders.

[0048] The present pyrolytic sugars are especially suitable to be used in wood modification, foundry resins or as a raw material to produce chemicals such as polyols.

[0049] The present invention will be further detailed in the following examples. In the example, reference is made to figures wherein:

[0050] Figure 1: is a schematic representation of the present methods; Figure 2: shows the properties of different fractions obtainable by the present methods;

[0051] Figure 3: shows the composition of different fractions obtainable by the present methods;

[0052] Figure 4: shows profiles obtained in the production of SPL. 7 runs in total T1 = Temperature heating oil, T2 = Temperature vapor, and SP = Set-point line. All experiments were performed under vacuum ~ 100 mbar;

[0053] Figure 5: shows a GPC Chromatogram of SPL produced in run 2.

[0054] Examples

[0055] Example 1

[0056] As shown in Figure 1, pyrolysis oil is extracted with water or an aqueous solution to obtain liquid pyrolytic lignin and pyrolytic sugars in an extractor. Subsequently, a dedicated heating system is used to further process the liquid pyrolytic lignin into solid pyrolytic lignin. Figure 2 and Figure 3 show the properties and composition of different fractions obtained, respectively.

[0057] Example 2

[0058] Several batches of LPL (liquid pyrolytic lignin) produced after liquid-liquid extraction of pyrolysis oil on pilot-scale were thermally treated under vacuum in 7 runs in a (1ST) RotoPlus 202, yielding about 1065 kg of SPL (solid pyrolytic lignin). The goal was to prepare a SPL with a melting point (mp) of 70-85 °C and an average molecular weight (Mw) of 1000-1600 g / mole.

[0059] The first run performed was executed by heating the LPL to 80 °C with a hold time of 1 h at this T (hold time = including heating), subsequently heating was continued to 120 °C with a 1 h hold time (including heating), then heating was continued to 160 °C with a 1 h hold time (including heating) and finally heating was continued to 190 °C with a 1 h hold time (including heating). During this first run (as starting point) it was observed that the program had to be adapted, due to insufficient final properties (insufficient solidification).

[0060] In Figure 4, the T profiles of the different runs are illustrated, inhere T1 is the heating oil temperature (line is set point) and T2 is the temperature of the vapor just before entering the condenser. From Figure 4, it can be clearly observed that the (light) yellow line is deviating from set point (SP) line, at the final set T. This (light) yellow line illustrates this first test run and clearly shows that the final T is not reached fast enough. Obviously more processing time was required at the high T’s to remove water and the light organic compounds. After changing the program (1 h extra at 160 °C and 1 h extra at 190 °C), a new batch of SPL was produced.

[0061] The sample showed good solidification (after cooling). Batches 2-5 were produced according to these last conditions; Figure 4 clearly illustrates that the temperatures profiles of these batches (2-5) are almost equal in course which is important in view of the production of a SPL with consistent properties / quality. Furthermore, two runs with an even longer processing time were performed (6-7) and illustrated in Figure 4.

[0062] Although runs 2-5 met certain required specifications, longer processing times were tested to see whether the melting point of the SPL (see table below, run 6) could be further tuned, which could be advantageous in some applications. As an example, the mp’s from the SPL’s obtained in run 2&6 are given in the Table. All SPL’s met the specification of having a mp between 80-85 °C. By changing the process times (at final T’s), the mp can indeed be steered to some extent.

[0063] GPC analysis (Figure 5) showed that the average molecular weight (Mw) of the produced SPL’s given in the table below were well within the range of 1000-1600 g / mole. The molar mass distribution of the SPL obtained in run 2, is given in the chromatogram (Figure 5). The mp and Mwdistribution are related, the longer the processing T (a final T’s), the higher the Mwbecomes.

[0064] Table: Temperatures vs. melting point

[0065] Tl: 80 °C, T2: 120 °C, T3: 160 °C, T4: 190 °C, MP = Melting point.

[0066] SUBSTITUTE SHEET (RULE 26)

Claims

CLAIMS1. Method for fractioning of pyrolysis oil, preferably fast pyrolysis oil, the method comprises the steps of: a) separating pyrolytic sugars and liquid pyrolytic lignin comprised in the pyrolysis oil using liquid-liquid extraction by adding an aqueous extractant, preferably water, to the pyrolysis oil in a ratio of aqueous extractant to pyrolysis oil of 0.2 : 2 to 2 : 0.2; b) separating the liquid pyrolytic lignin fraction from the pyrolytic sugars aqueous extractant fraction; c) subjecting the liquid pyrolytic lignin fraction to pressures below 0.5 bar, such as below 0.1 bar obtained by continuously removing the gaseous phase, to a heat treatment wherein the temperature is increased from 50°C- 70°C to 180°C-240°C during 1 to 24 hours, preferably 1.5 to 15 hours, more preferably 2 to 10 hours, until solid pyrolytic lignin is obtained with an average Mwbetween 800 g / mole to 1600 g / mole and a melting point between 65°C to 95°C; wherein the method is performed as a continuous process or as a batch process.

2. Method according to claim 1, wherein the temperature is increased from 50°C- 70°C to 180°C-240°C in two or more separate steps of 30 minutes to 180 minutes.

3. Method according to claim 1 or claim 2, wherein step (c) is performed under vacuum.

4. Method according to any one of the claims 1 to 3, wherein the heat treatment of step (c) comprises:60°C to 90°C for 30 minutes to 120 minutes;110°C to 130°C for 30 minutes to 120 minutes;150°C to 170°C for 30 minutes to 150 minutes; and 180°C to 220°C for 30 minutes to 180 minutes.

5. Method according to any one of the claims 1 to 4, wherein the heat treatment of step (c) comprises:75°C to 85°C for 30 minutes to 120 minutes;115°C to 125°C for 30 minutes to 120 minutes;155°C to 165°C for 30 minutes to 150 minutes; and 185°C to 195°C for 30 minutes to 180 minutes.

6. Method according to any one of the claims 1 to 5, wherein the heat treatment of step (c) comprises:80°C for 90 minutes;120°C for 60 minutes;160°C for 120 minutes; and190°C for 150 minutes.

7. Method according to any one of the claims 1 to 6, wherein step (c) further comprises isolating a light fraction containing lignin derived phenolics & cyclotene by condensation of the gaseous phase.

8. Method according to any one of the claims 1 to 7, wherein the ratio of aqueous extractant to pyrolysis oil in step (a) is from 0.2 to 1 : 1, preferably 0.3 to 0.6 : 1.

9. Method according to any one of the claims 1 to 8, wherein the separated pyrolytic sugars of step (a) are concentrated.

10. Method according to any one of the claims 1 to 9, wherein the solid pyrolytic lignin obtained in step (c) has an average Mwbetween 1000 g / mole to 1400 g / mole, preferably an average Mwbetween 1100 g / mole to 1300 g / mole, most preferably an average Mwof 1200 g / mole.

11. Solid lignin obtainable by a method according to any one of the claims 1 to 10, the solid lignin has an average Mwbetween 800 g / mole to 1600 g / mole, preferably an average Mwbetween 1000 g / mole to 1500 g / mole, more preferably an average Mwbetween 1100 g / mole to 1500 g / mole and a melting point between 65°C to 95°C.

12. Light fraction obtainable by a method according to any one of the claims 7 to 10, wherein the condensed fraction comprises amongst others: 1 to 45 wt.% creosol, 1 to 15 wt.% phenol, 1 to 25 wt.% guaiacol, 1 to 20 wt.% 4-ethylguaiacol and 1 to 25 wt.% cyclotene.

13. Use of solid lignin according to claim 11 in insulation foam, resins, binders, or paints.

14. Use of pyrolitic sugars obtained in step (a) of any one of the claims 1 to 10 in wood modification or foundry resins, or as a raw material to produce chemicals such as polyols.

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