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Title:
PYROLYSIS OF LIGNIN
Document Type and Number:
WIPO Patent Application WO/2011/159154
Kind Code:
A1
Abstract:
The invention provides a process for the pyrolysis of lignin. The lignin- containing material is intimately mixed with a phyllosilicate clay and optionally pelletised. The pelletised starting material is fed into a pyrolysis reactor and pyrolysed to provide a pelletised carbonaceous product and a bio-oil containing lignin monomers.

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Inventors:
WILBERINK, Ruud (Westerduinweg 3, LE Petten, NL-1755, NL)
VAN DER LAAN, Ron (Westerduinweg 3, LE Petten, NL-1755, NL)
DE WILD, Paulus, Johannes (Westerduinweg 3, LE Petten, NL-1755, NL)
Application Number:
NL2011/050429
Publication Date:
December 22, 2011
Filing Date:
June 14, 2011
Export Citation:
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Assignee:
STICHTING ENERGIEONDERZOEK CENTRUM NEDERLAND (Westerduinweg 3, LE Petten, NL-1755, NL)
WILBERINK, Ruud (Westerduinweg 3, LE Petten, NL-1755, NL)
VAN DER LAAN, Ron (Westerduinweg 3, LE Petten, NL-1755, NL)
DE WILD, Paulus, Johannes (Westerduinweg 3, LE Petten, NL-1755, NL)
International Classes:
C10B49/10; B01J21/16; C01B31/08; C09K17/04; C10B53/02; C10G11/04; C10L5/44
Domestic Patent References:
WO2008147711A12008-12-04
WO2009138757A22009-11-19
WO2010011675A12010-01-28
WO1988000935A11988-02-11
WO2000006671A12000-02-10
Foreign References:
JPS63285110A1988-11-22
JPH1161141A1999-03-05
US4073872A1978-02-14
Other References:
DE WILD P ET AL: "Lignin valorisation for chemicals and (transportation) fuels via (catalytic) pyrolysis and hydrodeoxygenation", ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, JOHN WILEY & SONS, INC, US, vol. 28, no. 3, 1 October 2009 (2009-10-01), pages 461 - 467, XP008127447, ISSN: 1944-7442, Retrieved from the Internet [retrieved on 20090821], DOI: DOI:10.1002/EP.10391
KHAN A A ET AL: "Biomass combustion in fluidized bed boilers: Potential problems and remedies", FUEL PROCESSING TECHNOLOGY, ELSEVIER BV, NL, vol. 90, no. 1, 1 January 2009 (2009-01-01), pages 21 - 50, XP025713272, ISSN: 0378-3820, [retrieved on 20080921], DOI: DOI:10.1016/J.FUPROC.2008.07.012
LAIRD D A: "The charcoal vision: A win-win-win scenario for simultaneously producing bioenergy, permanently sequestering carbon, while improving soil and water quality", AGRONOMY JOURNAL JANUARY/FEBRUARY 2008 AMERICAN SOCIETY OF AGRONOMY US, vol. 100, no. 1, January 2008 (2008-01-01), pages 178 - 181, XP002616016, DOI: DOI:10.2134/AGRONJ2007.0161
CARROTT P J M ET AL: "Reactivity and porosity development during pyrolysis and physical activation in CO2 or steam of kraft and hydrolytic lignins", JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS, ELSEVIER BV, NL, vol. 82, no. 2, 1 July 2008 (2008-07-01), pages 264 - 271, XP022851379, ISSN: 0165-2370, [retrieved on 20080418], DOI: DOI:10.1016/J.JAAP.2008.04.004
ITO K ET AL: "Tar capture effect of porous particles for biomass fuel under pyrolysis conditions", vol. 36, no. 7, 1 July 2003 (2003-07-01), pages 840 - 845, XP008131102, ISSN: 0021-9592, Retrieved from the Internet [retrieved on 20110105]
SHIRAHAMA N: "Experiences of carbonizing furnace of paper waste sludge", KAMI PA GIKYOSHI - JAPAN TAPPI JOURNAL, KAMI PAUPU GIJUTSU KYOKAI, TOKYO, JP, vol. 59, no. 2, 1 February 2005 (2005-02-01), pages 69 - 74, XP008141786, ISSN: 0022-815X
DE WILD ET AL., ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, vol. 28, 2009, pages 461 - 469
GALAN, CLAY MINERALS, vol. 31, 1996, pages 443 - 453
Attorney, Agent or Firm:
KETELAARS, Maarten (J.W. Frisolaan 13, JS The Hague, NL-2517, NL)
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Claims:
Claims

1. A process for the thermolysis of biomass containing lignin, comprising:

mixing the biomass with a clay; and

pyrolysing the mixture.

2. The process according to claim 1, wherein the biomass and the clay are mixed with 30-70 wt.% of water on the basis the total of biomass, clay and water.

3. The process according to claim 1 or 2, wherein the mixture of biomass and clay is solidified prior to the pyrolysis.

4. The process according to any one of claims 1-3, wherein the process comprises: a. mixing the biomass containing lignin, and the clay and pre-treating the mixture by pelletising the mixture to provide a pelletised starting material;

b. introducing the pelletised starting material to a reactor;

c. pyrolysing the pelletised starting material in the reactor.

5. The process according to any one of claims 1-4, wherein the biomass comprises at least 80 wt.% of lignin on a dry weight basis.

6. The process according to any one of the preceding claims, wherein the clay comprises a hormite clay, preferably a sepiolite clay or an attapulgite clay.

7. The process according to any one of the preceding claims, wherein the clay comprises a bentonite clay.

8. The process according to any one of the preceding claims, further comprising the steps of recovering a particulate carbonaceous product and a liquid product containing lignin monomers.

9. The process according to any one of the preceding claims, wherein the biomass and the clay are mixed in a weight ratio of 90: 10 to 10:90, based on the dry weight of the materials.

10. The process according to any one of the preceding claims, wherein the pre- treatment comprises (al) providing a paste of biomass, clay and water, (a2) extruding the paste, (a3) providing particulate material, and (a4) drying the particulate material to provide the pelletised starting material.

11. The process according to any one of the preceding claims, wherein the pelletised starting material comprises pellets having mean dimensions in the range of 0.25- 10 mm.

12. The process according to any one of the preceding claims, wherein the pyrolysis is performed in a fluidised bed reactor.

13. The process according to any one of the preceding claims, wherein the pyrolysis is performed at a temperature in the range of 300-700 °C, especially in the range of 350-550 °C.

14. A pelletised product obtainable by the processes according to any one of the preceding claims.

15. A pelletised carbonaceous product comprising pellets having mean dimensions in the range of 0.25-10 mm, wherein the pellets comprise carbon in an amount of 5-60 wt.%, and oxides of magnesium and silicon in an amount of 30-95 wt.%, relative to the total dry weight of the pellets.

16. Use of the pelletised carbonaceous product according to any one of claims 14-15, as a soil improver, as a precursor for activated carbon, as a cracking catalyst, or as a C02-neutral fuel.

Description:
Pyrolysis of lignin

Field of the invention

The invention relates to the thermolysis of bio mass, such as lignin. The invention further relates to the product obtained thereby, as well as to the use of such product.

Background of the invention

The thermal treatment of biomass may be used to generate valuable materials such as char, activated charcoal, bio-oil, combustible gasses, etc.

De Wild et al, Environmental Progress & Sustainable Energy, 28 (2009) 461-

469, describes valorisation of lignin by pyrolysis and focuses on low molecular products as potential fuels, chemicals and performance products.

WO2008/147711 describes a system and method for preparing a pelletised carbon black product. The system includes a source of a carbon black product from a pyrolysis process. A mixer is in communication with the source of the carbon black product. A binder oil storage tank is in fluid communication with the mixer. The binder oil storage tank is configured to inject a desired amount of a binder oil into the mixer to form the pelletised carbon black product.

WO2009/138757 describes a biomass pyrolysis process in which biomass feed- stock is mixed with a heat carrier. The heat carrier at least partly comprises char. The ratio by weight of biomass to char is in the range 1 : 1 to 1 :20. The process may be carried out by in a screw/auger pyrolysis reactor in which the solid feedstock components are conveyed along the reactor by a first screw. A second screw conveys at least a portion of the solid products of the biomass pyrolysis back to a heat transfer medium input port. The heat transfer medium includes char from the biomass pyrolysis.

WO2010/011675 describes a method for producing activated charcoal from lignocellulose-containing material residual solids, wherein the method comprises: i) pre-treating lignocellulose-containing material; ii) hydrolyzing pre-treated lignocellulose-containing material; iii) recovering residual solids; iv) producing activated charcoal from the residual solids. The activated charcoal may be produced from charcoal made by carbonisation or pyrolysis.

WO 88/00935 describes a process for the pyrolysis of biomass to produce a high yield of a liquid bio-oil in a reactor that is capable of rapid heat exchange and short gas residence times. The pyrolysis liquid typically contains 10 % - 30 % (wt%) water and can be further processed to divide it into a water-rich fraction and a water-poor fraction. These fractions can be used as feed stocks from which valuable chemicals can be extracted. The pyrolysis process also can be used to produce a pyrolysis liquid that is suitable as a fuel oil. Finally, in another embodiment, the process can be used to produce a pyrolysis liquid that is suitable for use as liquid smoke which can be used to flavour food, particularly meat.

WO2000/06671 describes a method and device for forming synthesis gas from biomass. In a pyrolysis zone, the biomass is converted into a solid carbonisation product (char) and into gaseous pyrolysis products. The gaseous pyrolysis products are burnt in a burner zone and supply the heat for the endothermic pyrolysis process and for an endothermic gasification process for forming synthesis gas. The carbonisation products are fed to the gasification zone, in order to be converted, for example by means of steam, into H 2 and CO. The fact that the gaseous pyrolysis products and the off-gases from the combustion zone are separate from the gasification zone results in a product gas with a high calorific value which is virtually free of nitrogen. The fact that the solid carbonisation products from the pyrolysis process are fed to the gasifier results in a very pure product gas which is free of contaminants which are usually formed when gaseous pyrolysis products are converted into synthesis gas. The device according to WO2000/06671 can therefore be operated without using complex purification installations.

Summary of the invention

A disadvantage of prior art solutions is that biomass containing high levels of lignin is not easily thermally treated, such as for instance by pyrolysis. Hence, it is an aspect of the invention to provide an alternative process, which preferably obviates (prior art) problems as mentioned herein. Especially, it is an object to provide a process for the production of an upgraded lignin materials such as bio-oil and bio-char, without problems of clogging of apparatus due to the melting behaviour of the lignin. It is also an aspect of the invention to provide a process for the production of bio-char and bio- oil from a lignin, while minimising problems of clogging of equipment.

In an embodiment, the invention provides a process for the thermolysis of lignin- containing biomass comprising:

intimately mixing the biomass and a clay, and thermolysing the solidified mixture in a suitable reactor to provide a solid end product and a liquid bio-oil.

The mixing is preferably performed in the presence of water and can be followed by drying and solidification to result in a particulate material for example by pelletisation.

With the new and claimed concept for an efficient thermochemical conversion of lignin into value-added products, up to 80 wt.% of the dry lignin can be transformed into useful products such as bio-char and phenolic bio-oil. The phenolic oil is an interesting feedstock for e.g. bio-bitumen, phenol substitutes in wood-resins and for several high- value phenolic compounds like guaiacols, syringols and alkylated phenols for pharmaceutical, food, and/or transportation fuel applications. Further, continuous pyrolysis of lignin using conventional screw feeders is now possible. Further, advantageously, the shape and composition of the solid (pelletised) end product may be tuneable, which allows a tuning to the desired later application of the pelletised end product.

The amount of carbon that originates from the pyrolysis of the lignin can be adjusted by the ratio lignin : clay in the pelletised feedstock material. For soil improvement, the solid end product ('biochar') will contain varying levels of carbon, depending on the soil characteristics. In case of a sandy soil, it may be preferable to have a relative high content of clay in the solid end product to enhance the water retention in the soil. On the other hand, the application of the solid end product as gas and/or liquid filtration material for organic substances probably requires a higher amount of pyrolytic carbon because of its hydrophobic (apolar) character when compared to the clay constituent. Here, the clay may act as a porous support that gets coated with lignin-derived carbon during the pyrolysis process.

After the thermolysis, a solid end product and a liquid oil are obtained. The solid is typically a pelletised product, and is referred to below as such, even though other solid forms wherein the lignin-containing biomass and the clay are intimately mixed are covered as well. This product may herein also be indicated as "pelletised carbonaceous product". The term "pelletised end product" is used to distinguish from the pelletised starting material. The term does not exclude a later use or processing of the "pelletised end product", but refers to the product obtained by the process of the invention. Hence, the invention also provides a pelletised end product obtainable by the process of the invention. Especially, a pelletised carbonaceous product is provided comprising pellets having mean dimensions in the range of 0.25-10 mm, such as 0.25-5 mm, like 0.5-5 mm, especially 1-3 mm, wherein the pellets comprise thermolysed biomass, and wherein the pellets preferably comprise carbon in an amount of 5-75 wt.%, preferably 5-60 wt.%, oxides of magnesium and silicon preferably in an amount of 20-95 wt.%, preferably 30-95 wt.%, and 0-25 wt.%, preferably 0-10 wt.% other materials, e.g. aluminium, alkali metals like sodium and potassium, alkaline earth metals like calcium and transition metals like iron, typically in their oxide form, relative to the total weight of the pellets and on dry weight basis.

As mentioned above, the thermolysed biomass especially comprises thermolysed cellulosic material, even more especially, the thermolysed biomass comprises thermolysed lignin, which preferably consists for at least 75%, especially more than 90% by weight of carbon, predominantly in elemental form. Preferably at least 50 wt.%), even more preferably at least 80 wt.%> of the pelletised end product particles has a particle size in the indicated ranges, respectively. The term "dimensions" is used to refer to length, width and diameter. As will be clear to the person skilled in the art, diameter may especially be applicable for particles having a spherically or elliptically cross-section. The term "mean dimension" refers to an average over a plurality of particles.

The pelletised carbonaceous material (pelletised end product) can be used as a soil improver, for instance to enable or enhance the growth of feed and food crops on barren soils. The pelletised carbonaceous product may also be used as a precursor for activated carbon, for instance for the production of gas and liquid filtration media. The pelletised carbonaceous material may also be used as a (low-cost) lignin-based cracking catalyst, for instance in pyrolysis processes like the one that is described in this patent. Further, the pelletised carbonaceous product may also be used as a C0 2 -neutral fuel, for instance in waste incinerators or as internal fuel for lignin-pyrolysis processes, whereby the combustion of the carbonaceous fuel pellets ensures that the endothermic pyrolysis process is self-sufficient with respect to its heat demand.

The bio-oil contains lignin monomers, oligomers and decomposition products such as high-value phenolic compounds like guaiacols, syringols and alkylated phenols, and may also be used in all kinds of applications. Examples of uses for the bio-oil include feedstock for e.g. bio-bitumen, phenol substitutes in wood resins or phenol resins for use in adhesives and the like, for pharmaceutical, food, and/or transportation fuel applications, as well as for producing carbon fibres.

Brief description of the drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Figure 1 schematically depicts the process of the invention. References A1-A4 indicate the components of the mixture for the pre-treatment, comprising lignin (Al), clay (A2), water (A3) and optional one or more other components (A4), like catalysts for cracking, demethoxylation, decarbonylation, decarboxylation, hydrolysis, and/or dehydration, etc. Examples are commercial FCC catalysts, ZSM-5 catalysts, supported transition metals (e.g. Ni), and natural tar cracking catalysts like dolomite, olivine and iron ore.

The mixture is then subjected to a pre-treatment (B), which at least involves a pelletisation to provide a pelletised starting material. Thereafter, the pelletised starting material is subject to thermolysis (C) to provide the pelletised end product. The pelletised end product may be used in all kinds of applications (D).

Figure 2 schematically depicts an arrangement 1 of apparatus that may be used for the process of the invention. Reference numbers 2, 3 and 4 schematically depict the feeds for water (A3), lignin (Al), and clay (A2), respectively. Optionally, also other components may be added (not indicated in the drawing). Reference 10 indicates a mixer, wherein the starting materials are mixed into a paste. The paste may be extruded in an extruder, reference 20. This may for instance be followed by strand cutting and rotary drying, indicated with reference 30. Then, the pelletised starting material thus obtained is fed to a reactor. In an embodiment, this is done via a two stage process, via a metered pellet feeding screw 40 and a (water) cooled reactor feeding screw 50. The feeder is cooled so as to prevent the lignin feed from melting prior to entering the reactor. Between the feeding screw 40 and the rotary drying, a feed downer pipe 31 may be arranged, but other constructions may also be possible. Between the metered pellet feeding screw 40 and the reactor feeding screw 50 a feed bunker 41 may be arranged, but other constructions are also possible.

Preferably, the pelletised starting material is provided to a lower part of the reactor. The reactor is indicated with reference 60. Here, schematically, a pyro lysis reactor (fluid-bed based) is depicted. Reference 61 indicates the fluid bed, and reference 62 indicates a char overflow pipe, leading to a char bin 63. Fluidisation gas 64 may amongst others be introduced at the bottom 65 of the reactor 60. Particulate product may for instance be recovered via a cyclone 70. An ash bin 71 may be used to collect solid material that is entrained in the fluidisation gas, e.g. fine sand, clay and char particles. Via a hot gas particle filter 80, the particulate product, here indicate with reference 90, may be obtained. Reference 100 indicates a compressor.

Figure 3 shows the Phenolic yields from the pyrolysis of promoted Alcell lignin (A) at 400°C; X = sepiolite, Y = attapulgite, Z = bentonite, AMI and AM2 = magnesium oxide, AS = silica (sand). The y-axis in this figure indicates the product yield in wt.% dry basis (d.b.); MP indicates monomeric phenols, OP, indicates oligomeric phenols and TP indicates total phenolic fraction.

Description of preferred embodiments

At present, utilisation of lignin is growing due to an increasing interest in renewable raw materials. Large amounts of lignin and lignin containing residues originate from the pulp- and paper industry. The expected growth of the production capacity of second generation bio-fuels from ligno-cellulosic biomass will lead to another source of lignin and lignin containing residues.

Despite its large potential as a significant and valuable petrochemical substitution option for fuel, performance products (polymers) and individual low molecular weight chemicals, the main practised option to date is the use as a low-cost solid fuel for generating heat. To exploit the potential of lignin as a renewable feedstock for (transportation) fuels, chemicals and performance products, new conversion technologies are needed.

Economic and technological considerations still preclude a large-scale mass production of low molecular weight chemicals from lignin in competition with petrochemicals. This is inherent to the specific nature of the complex and stable lignin polymer that makes it difficult to convert it into valuable monomeric chemicals.

Conventional fluidised-bed pyrolysis to convert lignin into valuable products

(like biochar and bio oil) may be problematic due to the physico-chemical characteristics of lignin as a heterogeneous powder-like material that is sticky, thermoplastic but simultaneously thermally stable. The valorisation of lignin by pyrolysis processes may especially be hampered by feeding difficulties and by the recalcitrant nature of the lignin polymer towards thermal degradation.

Continuous pyrolysis of lignin using conventional screw feeders may be very difficult because the easily melting lignin powder will block the feeding tube in no time. Other feeding methods, like fast pneumatic injection of the fine lignin powder, may be problematic too because of the stickiness of the fine lignin powder and its tendency to become electrostatically charged. When the fine lignin powder eventually enters the reactor, sudden melting and blowing-up of the reacting particles may cause agglomeration and subsequent defluidisation of the hot sand bed in the reactor. As a consequence the thermal degradation of the lignin may rapidly shift to charring, causing a much decreased yield of valuable organics.

The use of the "promoted" lignin, as suggested herein, in a new and innovative pyrolysis concept offers an unexpected solution for the abovementioned problems. Hence, it is an aspect of the invention to provide an alternative process, which at least partly obviates the above-described drawbacks.

The products of thermal treatment of state of the art processes may be used in for example agricultural applications of construction applications (for instance solidification of dykes, etc.). However, the composition of such products of thermal treatment of state of the art process may not easily be varied. Hence, it is a further aspect of the invention to provide a process, wherein the composition of the product obtained thereby, is preferably variable.

With the new and claimed concept for an efficient thermochemical conversion of lignin into value-added products up to 80 wt.% (weight percentage) of the dry lignin can be transformed into useful products such as bio-char (30-50 wt.%) and phenolic bio-oil (30-50 wt.%). The phenolic oil is an interesting feedstock for e.g. bio-bitumen, phenol substitutes in wood-resins and for several high-value phenolic compounds like guaiacols, syringols and alkylated phenols for pharmaceutical, food, and/or transportation fuel applications.

The pyrolysis concept of the invention may include a combination of pre- treatment, feeding and pyrolysis conditions to convert lignin into valuable products. The pre-treatment is the main technical innovation and involves mixing of the lignin with a low-cost clay additive that - in intimate contact with the lignin - improves its feeding and pyrolysis behaviour, preferably in the presence of water. The mixing of the lignin with the additive can be achieved by state of the art pelletising methods such as extrusion and subsequent drying of an aqueous slurry of the lignin. Feeding of the (lignin-additive) pellets into the reactor may be accomplished by using an adapted continuous screw feeder. A combination of feed-rate, reactor temperature and fluidisation gas velocity may ensure an efficient pyrolysis of the pelletised starting material in such a way that a maximum yield of valuable products is obtained.

The application of the additive, in the form of lignin clay, may surprisingly prevent defluidisation of the reactor sand bed and enables an efficient separation of char, sand and condensable pyrolysis products.

In a specific embodiment, the invention provides a process for the thermolysis of bio mass containing lignin comprising:

a. pre-treating a mixture comprising the biomass and a clay, wherein the pre- treatment comprises pelletising the mixture, to provide a pelletised starting material;

b. introducing the pelletised starting material obtained at a) to a reactor; and c. thermolysing the pelletised starting material in the reactor (especially to provide a pelletised end product and a bio-oil).

The composition of the pelletised end product may be tuneable, which allows a tuning to the desired later application of the pelletised end product. The amount of carbon that originates from the pyrolysis of the lignin can be adjusted by the ratio ligninxlay in the pelletised feedstock material. For soil improvement, the pelletised end product ('biochar') should contain more or less carbon, depending on the soil characteristics. In case of a sandy soil, it might be preferable to have a relatively high content of clay in the pelletised end product to enhance the water retention in the soil. On the other hand, the application of the pelletised end product as gas and/or liquid filtration material for organic substances probably requires a higher amount of pyrolytic carbon because of its hydrophobic (apolar) character when compared to the clay constituent. Here, the clay acts as a porous support that gets coated with lignin-derived carbon during the pyrolysis process.

Preferably, the thermolysis of the pelletised starting material in the reactor comprises pyrolysing the pelletised starting material. Pyrolysis is the chemical decomposition of condensed substances by heating that occurs spontaneously at high enough temperatures without combustion. Pyrolysis is a special case of thermolysis, and is most commonly used for organic materials, being then one of the processes involved in charring. This chemical process is widely used in the chemical industry, for example, to produce charcoal, activated carbon, methanol and other chemicals from wood, to convert ethylene dichloride into vinyl chloride to make PVC, to produce coke from coal, to convert biomass into syn-gas, to turn waste into safely disposable substances, and for transforming medium-weight hydrocarbons from oil into lighter ones like gasoline. These specialised uses of pyrolysis may be called various names, such as dry distillation, destructive distillation, or cracking. Herein, pyrolysis especially refers to the process of heating materials without introduction of oxygen or air at a temperature in the range of about 300-700 °C, like 300-600 °C, such as 350-550 °C or even 400-600°C.

As used herein, "biomass" means any solid, liquid or intermediate material containing organic matter at least partly derived from biological processes, in particular plant-derived material. Preferably, the biomass comprises cellulosic material, even more preferably, the biomass comprises lignin. The content of lignin in the (dry) biomass is preferably more than 50 wt.%, more preferably more than 65 wt.%, most preferably more than 80 wt.%. For instance, in an embodiment the biomass comprises technical lignin (i.e. especially a material that contains typically > 90 wt% pure lignin). In a further embodiment, the biomass comprises a lignin from the pulp and paper industry, e.g. in the form of black liquor derived lignin (e.g. from organosolv, soda, sulfite or Kraft pulping), or a lignin from the production of second generation bio fuels (like bio-ethanol). The processes and the products of the invention are especially suitable for relatively pure lignins (> 80 wt.% lignin (dry base)) that are prepared from biomass such as wood, straw, hulls and grass by techniques such as organosolv (a mixture of water and an appropriate organic solvent such as methanol, ethanol, organic acids, etc.), delignification and soda pulping. Examples are Alcell organosolv lignin (prepared from organosolv fractionation of a mixture of hardwoods), Granit soda pulping lignin (prepared from a mixture of wheat straw and Sarkanda grass) and organosolv wheat straw lignin (OWSL). The physical appearance of these lignins is a light (Granit) to dark brown (Alcell) powder (particle size < 0.1 mm) that easily melts at low temperatures (< 200°C). The lignins are virtually immiscible with water. In general, technical lignins from e.g. organosolv fractionation or from soda pulping are not easily miscible with water due to their hydrophobic character.

The term "lignin" may refer to a natural lignin, but may also refer to chemical derivatives thereof. In one embodiment, the term "lignin" may also refer to "lignin sulfonate". In another embodiment, ammonium lignosulfonate is used as lignin compound. Lignin compounds are found in cell walls as a cement layer between cellulose strands. They are copolymers, i.e. macromolecules of which the monomers are of a different nature. Three phenyl-propane (C6-C3) derivates are considered as being monomers of lignin: e.g. coniferyl alcohol, sinapyl alcohol and coumaryl or p- hydroxy cinnamyl alcohol. They are coupled via C-C bonds of the propane chains and via ether bonds between alcoholic groups. In an embodiment, the lignin compound used in the invention comprises one or more of lignin and lignosulfonate. Lignins can be obtained from wood, like e.g. softwood (conifers) or hardwood. The molecular weight varies between about 5,000 and 10,000.

It surprisingly appears that whereas lignin alone or in combination with water, is not easily processable, clay as additive provides a mixture that is relatively easily pelletisable and later thermolysable in a reactor, without substantial clogging of equipment. For instance, mixing the lignin powder with some specific powdered (particle size < 0.1 mm) clays such as sepiolite, attapulgite and/or bentonite greatly enhances the miscibility with water and enables the preparation of an homogeneous aqueous lignin-clay slurry, e.g. using conventional homogenising equipment. The thickness of the slurry can be adjusted by the amount of water, preferably using a total amount of water of 30-70 wt.% of the total of lignin biomass, clay, water and other components.

The lignin-clay slurry can easily be pelletised by well-known techniques such as extrusion. The homogeneity of the lignin-clay slurry may ensure an even distribution of clay and lignin in the resulting pellets or extrudates. To increase the mechanical strength of the pellets, a mild temperature treatment (preferably < 150°C in air or vacuum) can be applied to sinter the lignin-clay mixture. It is assumed that the clay acts as a sort of binder for the lignin. Other clays that possess a high level of porosity and water uptake capacity might be suitable as well. In addition from a binding effect , the clay may have a catalytic effect in the pyro lysis of lignin.

The clay is preferably a porous clay, especially a phyllo silicate clay, such as magnesium and/or aluminium phyllosilicates. Suitable clays include a hormite clay (such as a sepiolite or attapulgite clay), and a smectite clay (such as a montmorrilonite clay or another bentonite clay). Especially preferred are bentonite and/or sepiolite. In an embodiment, the clay comprises hydrotalcite clay. The term "clay" may in an embodiment refer to a combination of clays, such as a combination of bentonite and sepiolite. The clay may especially be a clay from the hormite group. Clays from the hormite group are, for example, attapulgite (Mgi. 6 Al 0 . 6 Si 4 0io(OH).4H 2 0 (= paly- gorskite), sepiolite (Mg 4 Si 6 0i 5 (OH) 2 .6H 2 0), falcondoite, kaolinite, paramont- morillonite etc. Preferably, the clay used is sepiolite. The clays from the hormite group are known from the literature. Sepiolite and palygorskite are, for example, described by Galan (Clay Minerals (1996), 31, 443-453). Sepiolite is widely found in Spain.

Alternatively, the clay may also be from the smectite group. Bentonite is an absorbent aluminium phyllosilicate, generally impure clay from the smectite group, consisting mostly of montmorillonite (Na,Ca) 2 (MgAl) 2 Si 4 0io.nH 2 0). There are different types of bentonites and their names depend on the dominant elements, such as potassium (K), sodium (Na), calcium (Ca), and aluminium (Al). Bentonite usually forms from weathering of volcanic ash, most often in the presence of water. However, the term bentonite, as well as a similar clay called tonstein, have been used for clay beds of uncertain origin. For industrial purposes, two main classes of bentonite exist: sodium and calcium bentonite. Other smectites, such as saponite, beidellite, aliettite, hectorite, etc. (see www.mindata.org) can also be used.

In the pre-treatment, the lignin and the clay are mixed, in general together with water, to provide a paste or slurry, preferably a paste. The paste can be transformed to pellets following methods known in the art. Dependent upon the method chosen, the pre-treatment may include a heating before and/or after the pelletisation. Alternatively, the paste as such is subjected to thermolysis.

The biomass (typically containing 0 - 10 wt.% of moisture) and the clay (typically containing 0 - 10 wt.% of moisture) are preferably mixed in a weight ratio of 90: 10 to 10:90, preferably in a weight ratio of 80:20 to 20:80, based on the dry weight of the materials. Further, the amount of water of the mixture (before pelletisation and heating) is preferably in the range of about 30-70 wt.%, preferably in the range 40 - 60 wt% relative to the total weight of the mixture of lignin, clay and water (and optional other components).

In a specific embodiment, the pre-treatment comprises (al) providing a paste of biomass, clay and water (and optional other components), (a2) extruding the paste, (a3) providing particulate material, and (a4) drying the particulate material to provide the pelletised starting material. Instead of extruding using an extruder, the paste may also be pressed through a sieve with appropriate meshes. The pre-treatment advantageously provides a particulate material ("pelletised starting material"), that may be used for the thermolysis, especially pyrolysis. The pelletised starting material preferably comprises pellets having mean dimensions in the range of 0.25-10 mm, preferably 1-3 mm. Especially, at least 70 wt.%, more preferably at least 80 wt.%, even more preferably, at least 90 wt.% of the pelletised material consists of pellets having mean dimensions in the range of 0.25-10 mm or 1-3 mm, respectively. Optionally, too large and/or too small particles may be separated from the pelletised material, for instance by sieving or using a cyclone separator, or other methods known in the art.

The pelletised starting material may then be used in a thermal process, to provide bio-oil and a carbonaceous material, such as charcoal (herein also indicated as "bio char" since it originates from biological material). The thermal process is preferably applied in a fluidised bed reactor.

Hence, the invention also provides a process (for the thermolysis as described herein), wherein the reactor is a fluidised bed reactor. The pelletised starting material is introduced in the fluidised bed reactor and fluidised. In this fluidised "state" the lignin is thermolysed (especially pyrolysed), by which a pelletised end product is obtained and by which bio oil is obtained. The pelletised starting material is surprisingly stable, leading to a pelletised end product having substantially the same dimensions as the pelletised starting material, but now substantially consisting of thermolysed lignin (carbon) and clay. The latter may not substantially be affected by the thermolysis, whereas the former may be transformed into char and bio-oils (and gasses).

The char particles can be retrieved from the reactor. The carbonaceous product (char) will float on the fluidised bed and can conveniently be collected by providing a collecting means just above the bed surface in the form of an overflow pipe or the like, connect to a receiving bin. The oil originating from the lignin pyrolysis products in the form of condensable organic vapours, water and aerosols that contain water and organics. This product mixture can be collected downstream the reactor by means of appropriate collecting equipment, including condensers for the condensable vapours and an electrostatic precipitator for the aerosols. Hence, the invention especially provides a process for the thermolysis of bio mass as described above, to provide bio char and bio oil from a lignin. In an embodiment, the process of the invention may be a continuous process (for the production of the pelletised end product and/or bio oil). Preferably, thermolysis is performed at a temperature in the range of 300-700 °C, especially in the range of 400-600 °C.

The term "substantially" herein will be understood by the person skilled in the art. The term "substantially" may also include embodiments with "entirely", "completely", "all", etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term "substantially" may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term "comprise" includes also embodiments wherein the term "comprises" means "consists of.

The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods (or processes) of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

Experimental

Pelletising experiments with pure lignin

Pure lignin pellets can be prepared by (partially) dissolving the lignin in an organic solvent such as ethanol, methanol or acetone and subsequent evaporation of the solvent. The resulting cake can be crushed and sieved into an appropriate size fraction. However, the mechanical strength is poor, a lot of material is lost due to the sieving procedure and it is not certain if chemical changes have occurred due to the solvent treatment. Alcell lignin also can be pelletised by evaporation and subsequent crushing or extruding an aqueous slurry that is prepared by vigorously shaking the lignin powder with water. The resulting particles are weak and easily fall apart. The mechanical strength of these particles can be increased somewhat by a fusion treatment below 200°C and subsequent solidifying. This procedure also can be applied to the pure lignin powder.

(pelletising) experiment with silica sand

Lignin - sand particles were prepared by crushing and sieving of a lignin-sand cake that was made by fusion at 170°C and subsequent solidifying of a 1 : 1 (wt/wt) mixture of Alcell lignin powder with silica sand (particle size -0.25 mm). (pettetising) experiments with natural MgO mineral

Natural magnesium oxide mineral was mixed 1 : 1 with Alcell lignin and water and converted into a slurry. It proved to be extremely difficult to extrude this slurry due to phase separation during the extrusion process. However, the slurry could be dried at 200°C under air without melting.

(pelletising) experiments with clay

Powdered clay was mixed 1 : 1 with lignin and water and converted into an aqueous paste that was extruded into 3-5 mm (length) x 3 mm (diameter) extrudates. The extrudates were dried at 50 - 100°C and subsequently sintered at 100 - 200°C, (pelletising) experiments with an organic binder material

Methyl cellulose wall paper glue powder was mixed 1 : 1 with lignin and water and converted into a sticky aqueous paste that could not be extruded. Instead, the paste was dried at 50-100°C and the resulting stone-hard cake was crushed with difficulty into particles of 2-3 mm in diameter.

Sample preparation by pelletising

Five batches of 1 - 3 mm Alcell organosolv lignin particles were prepared according to the following procedures:

1. Slurrying the lignin with water under vigorous agitation, applying the resulting paste on a perforated plate (2 mm cylindrical holes), drying and sintering at 140°C under air, pressing / sieving out particles 1 - 3 mm, this sample is coded Alcell-Pure,

2. Mixing the lignin with an equal amount (weight) of 0.25 mm silica sand, melting it at 170°C in an oven under air for approx. 1 hr, cooling down / solidifying overnight till room temperature, crushing the resulting lignin - sand cake, sieving out particles of 1 - 3 mm, this sample is coded Alcell- Sand,

3. Slurrying equal amounts of lignin and sepiolite clay with water, extruding the resulting paste into 3-5 mm (length) x 3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded Alcell- Sep,

4. Slurrying equal amounts of lignin and attapulgite clay with water, extruding the resulting paste into 3-5 mm (length) x 3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded Alcell-Atta, 5. Slurrying equal amounts of lignin and bentonite clay with water, extruding the resulting paste into 3-5 mm (length) x 3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded Alcell-Ben.

To study the effect of reactor temperature, load and type of additive and type of lignin on the pyro lysis behaviour, another nine batches of 1-3 mm lignin-additive particles were prepared according to the following procedure:

1. Slurrying Alcell lignin and sepiolite clay in a weight ratio of 80:20 with water, extruding the resulting paste into 3-5 mm (length) x 2-3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded AX,

2. Slurrying Alcell lignin and attapulgite clay in a weight ratio of 80:20 with water, extruding the resulting paste into 3-5 mm (length) x 2-3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded AY,

3. Slurrying Alcell lignin and bentonite clay in a weight ratio of 80:20 with water, extruding the resulting paste into 3-5 mm (length) x 2-3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded AZ,

4. Slurrying the Alcell lignin with natural magnesium oxide mineral in a weight ratio of 80:20 with water, extruding the resulting paste into ill-defined extrudates that were sintered at 140-170°C. The resulting extrudates could not be handled without falling apart, so it was decided to crush the soft extrudates and use the Alcell- lignin powder instead., this sample is coded AMI,

5. Slurrying the Alcell lignin with natural magnesium oxide mineral in a weight ratio of 50:50 with water, preparing sintered lignin-MgO powder as described under 4. this sample is coded AM2,

6. Mixing the Alcell lignin with an equal amount (weight) of 0.25 mm silica sand, melting it at 170°C in an oven under air for approx. 1 hr, cooling down / solidifying overnight till room temperature, crushing the resulting lignin - sand cake, sieving out particles of 1 - 3 mm, this sample is coded AS,

7. Slurrying Granit lignin and sepiolite clay in a weight ratio of 80:20 with water, extruding the resulting paste into 3-5 mm (length) x 2-3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded GX,

8. Slurrying Granit lignin and attapulgite clay in a weight ratio of 80:20 with water, extruding the resulting paste into 3-5 mm (length) x 2-3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded GY, 9. Slurrying Granit lignin and bentonite clay in a weight ratio of 80:20 with water, extruding the resulting paste into 3-5 mm (length) x 2-3 mm (diameter) extrudates, drying/sintering at 140°C, this sample is coded GZ.

It should be noted that the organosolv Alcell lignin is prepared from a mixture of hardwoods (deciduous wood) while the Granit lignin is a purified lignin from the pulp- and paper industry in India, where it is produced by soda pulping of a mixture of wheat straw and Sarkanda grass. It is a representative herbaceous-derived lignin (trade-name Protobind-1000) that is produced by ALM (Asean Lignin Manufacturing) and marketed by GreenValue SA, Switzerland.

Pyrolysis experiments

Batch pyrolysis experiments were conducted with 30 - 50 g of the lignin- additive particles, using an atmospheric pressure, 1 kg/hr bubbling fluidised bed test facility at 400-500°C. Single batches of -30-50 g of the lignin-additive particles were quickly fed into the pre-heated reactor using a cooled screw-feeder. Pre-heated argon (20 ml/min) was used as fluidisation gas and mixed with an additional 1 ml/min of nitrogen from the feedstock bunker and screw. The reactor bed consisted of 600-1000 g silica sand (0.25 mm). Sampling of approximately 20% of the total product gas flow rate was conducted using liquid quenches with isopropanol (IP A) filled washing bottles.

Sampling was started prior to feeding and continued well after the moment that the permanent gases that originated from the decomposing lignin, ceased to evolve. It is assumed that the main production of reaction water and organic condensables takes place in parallel with the liberation of CO, C0 2 and CH 4 . After the experiment, trapped pyrolysis products were analysed off-line using gas chromatography with mass spectrometric and flame ionisation detection (GC/MS/FID) for the organic components in the IPA-samples.

Pyrolysis results

Batch experiments

Table 1 compares the yields of a set of GC-detected representative phenolic pyrolysis products that were obtained from the five experiments with lignin-sand 1 : 1 (m/m) and lignin-clay 1 : 1 (m/m). The yields are presented in weight percentages that are based on the dry input weight of the Alcell lignin. It should be noted that only a well characterised set of GC-detectable phenolics are presented for comparison. These compounds typically represent 40% of all GC- detected phenolics. The remaining 60% is of unknown origin. Based on their gas chromatographic behaviour (retention time in the chromatogram) it is assumed that they are of phenolic nature. Next to the GC detectables, a large fraction of undetected species originate from the pyrolysis process. This fraction consists of large oligomeric lignin-derived fragments that are not easy to identify. However, by means of a gravimetric method, its yield is estimated as roughly equal or more than the yield of all the GC detectable phenolics combined.

Table 1: Phenolic product yields from the pyrolysis of Alcell lignin at 400°C. Yields are presented in wt. % of the dry input weight of the lignin.

The use of the clays ensured a smooth feeding procedure without clogging of the feed-tube by molten lignin. Apparently, the porous clays absorb the liquefied lignin and prevent it from sticking to the tube-wall. In case of the pure lignin and the lignin-sand mixture, severe agglomeration was observed in the feed-tube and in the reactor bed, causing fluidisation problems in the reactor bed.

Actually, it appeared that with using pure lignin or using lignin in combination with sand, no process for the production of pyrolysed lignin was feasible. Especially a continuous process was not feasible, since the apparatus got clogged. Further, using an extruder, feeding screw, and/or using a fluid-bed reactor appeared to lead to an early stop of the process due to clogging, with concomitant undesired cleaning activities. However, with the clays, the process of the invention could be performed in a continuous way. Further, use of a feeding screw (preferably cooled) and/or a fluid-bed reactor was possible, without clogging, and providing particulate carbonaceous material that can be used in other processes and/or applications.

From Table 1 it follows that in the cases where the lignin had been pre-treated with an additive, phenolic yields are 30-70% higher when compared with the untreated sample. The effect is greatest for the samples that were treated with the clays sepiolite, attapulgite and especially bentonite. When compared with the sand containing sample it shows that the clay-treated lignin produces 6-30%> more phenolic compounds.

In addition, the results in Table 1 show higher yields of phenol, cresol and catechols from the pyrolysis of the clay-treated lignins when compared with the pure and sand-treated samples. This may indicate a catalytic cracking effect of the clays. Apparently the cracking effect leads to demethoxylation, demethylation and re- arrangements of the main degradation fragments syringols and guaiacols.

For comparison purposes the abovementioned results were obtained from batch tests that were conducted under the same experimental conditions. For practical reasons, these conditions were not optimised for obtaining maximum yields of phenolics. Table 2 compares the results from the pyrolysis of Alcell-Sep (1 : 1 weight ratio) under optimised conditions with the results for Alcell-Sep from Table 1. The higher yields are probably due to a different sampling procedure, involving a significantly shorter residence time of the hot pyrolysis vapours in the reactor when compared to the residence time that was used for obtaining the results in Table 1.

Taking into account the yields of the unknown GC-detected species (5.9 wt.%) and the yield of the gravimetric substance (13.2 wt.%) and assuming that they are of phenolic nature, a total yield of phenolic material of 23.2 wt.% (d.b. (dry base)) was obtained. Table 2: Optimisation of the phenolic product yields from the pyrolysis of Alcell lignin at 400°C. Yields are presented in wt. % of the dry input weight of the lignin.

Table 3 presents the results of the pyrolysis experiments in which the effects of reactor temperature, load and type of additive and type of lignin on the pyrolysis behaviour were investigated.

Table 3: Results of pyrolysis experiments at 400°C and 500°C with Alcell and Granit lignin, promoted with sepiolite clay, attapulgite clay, bentonite clay, natural magnesium oxide and silica sand. X = sepiolite, Y = atapulgite, Z = bentonite, M = magnesium oxide and S = silica sand. Weight percentages ion dry basis

AX AY AZ AMI AM2 AS AX AY AZ

Temperature [°C] 400 400 400 400 400 400 500 500 500

Additive [wt%] 20 20 20 20 50 50 20 20 20

Gases [wt%] 8 11 4 4 14 6 21 17 14

C02 [wt%] 3.8 7.0 2.8 2.7 10.0 3.8 10.2 7.1 4.5

C02 [wt%] 2.9 2.9 0.9 0.6 3.7 1.9 8.1 8.0 7.5

CH4 [wt%] 0.9 1.1 0.5 0.6 0.5 0.6 2.5 2.3 2.3

Oil [wt%] 43 41 45 33 26 21 39 49 44

Water [wt%] 15 15 13 13 13 9 15 22 14

Methanol [wt%] 1.2 1.5 1.4 1.4 0.9 0.7 1.4 1.2 1.2

Acetic acid [wt%] 0.4 0.3 0.5 0.3 0.2 0.2 0.4 0.3 0.5

Syringols [wt%] 3.2 3.0 3.3 1.4 1.1 1.5 2.6 2.1 2.6 AX AY AZ AMI AM2 AS AX AY AZ

Guaiacols [wt%] 1.7 1.6 1.8 0.9 0.6 0.7 1.5 1.3 1.6

Alkylphenols [wt%] 0.1 0.1 0.1 0.1 0.0 0.0 0.3 0.3 0.3

Catechols [wt%] 0.8 0.5 0.9 0.3 0.2 0.1 0.5 0.5 1.0

Unknowns [wt%] 2.9 2.4 3.0 1.8 0.8 1.3 3.6 2.7 3.5

Oligomerics [wt%] 18 17 20 14 8 6 14 18 19

Phenolics [wt%] 27 24 29 18 11 9 23 25 28

Char [wt%] 55 54 55 54 39 39 43 45 38

Mass balance [%] 106 106 104 91 79 66 103 111 97

Table 3 continued

From Table 3 the following conclusions can be deduced:

Effect of temperature: At 500°C more gas, less char, less pyrolysis oil for Alcell, more pyrolysis oil for Granit (due to increased amount of water and oligomers) is produced. In general, at 500 °C more alkylphenols and catechols and less syringols and guaiacols are formed.

Effect of additive: Promotion with sepiolite, attapulgite and bentonite clay increases the formation of phenolic bio-oil when compared to the promotion with natural magnesium oxide and silica sand. Application of the bentonite clay Z in general leads to the highest yields of phenolics, although the difference with sepiolite X and attapulgite Y are small. The beneficial effect of promoting lignin with clay is illustrated further in Figure 3 for the pyrolysis of Alcell lignin. Effect of lignin type: The herbaceous-derived Granit lignin clearly yields more pyrolysis oil, due to increased levels of (reaction) water and oligomeric fragments. Compared with the deciduous- derived Alcell lignin the Granit-oil contains more alkylphenols and catechols. The pyrolysis oil from Granit contains more guaiacols than syringols, the oil from Alcell lignin is higher in syringiols than in guaiacols.

Effect of clay load: In general the yields of phenolic compounds from the pyrolysis experiments with the 20 wt% loaded lignins do not seem to differ much from the yields that are obtained with a higher load of clay (50 wt%). Apparently, the main effect of the clay is to facilitate the feeding of the lignin in the reactor.

On a normalised base, pyrolysis of clay-promoted Alcell lignin yields - on the average- 53 wt% char, 39 wt% oil and 8 wt% gas at 400°C and 43% char, 41 wt% oil and 16 wt% gas. Pyrolysis of clay-promoted Granit lignin yields 47 wt% char, 43 wt% oil and 10 wt% gas at 400°C and 34 wt% char, 49 wt% oil and 16 wt% gas at 500°C. The results for the magnesium oxide and sand promoted Alcell lignin indicate a less effective pyrolysis of the Alcell lignin. Indeed it was observed that the application of magnesium oxide and sand did not prevent bed-agglomeration problems that were absent when using the clay-promoted lignin. Thus, a pyrolysis process with such additives is less feasible, due to problems in the reactor (see also below).

In general, the clay promoted lignins can be pyrolysed without operational problems due to melting and bed agglomeration. The bio-oil product typically contains up to 10 wt% (d.b. of the original lignin feed) of monomeric phenols, predominantly methoxyphenols (syringols and guaiacols). Total yield of phenolic substances (monomeric and oligomeric) varies from 23 to 38 wt%. These yields imply that the bio- oil is an interesting feedstock for a variety of applications.

Continuous experiments to study the effect of the additive

Three continuous pyrolysis experiments were conducted with 60 - 500 g of organosolv wheat straw lignin (OWSL1 : 250 g), the organosolv wheat straw lignin - organic methyl cellulose binder material (OWSL2: 60 g) and organosolv wheat straw lignin - sepiolite clay material (OWSL3: 250 g), using atmospheric pressure, 1 kg/hr bubbling fluidised bed test facility at 500°C. The continuous experiments were conducted to study the feeding behaviour of the lignin and the lignin additive materials, the possible agglomeration of the bubbling fluidised reactor bed, the production of the solid char and the production of the liquid lignin pyrolysis oil A detailed chemical analysis of the pyrolysis-oil was not carried out.

The lignin-containing feedstock was continuously fed into the pre-heated reactor using a cooled screw-feeder. Pre-heated argon (20 ml/min) was used as fiuidisation gas and mixed with an additional 1 ml/min of nitrogen from the feedstock bunker and screw. The reactor bed consisted of 600-1000 g silica sand (0.25 mm). Sampling of approximately 50-75% of the total product gas flow rate was conducted using state of the art collection equipment consisting of a heated particle filter (400°C), an ice-cooled (0°C) condenser ("knock-out pot"), an electrostatic precipitator (to trap aerosols) and a freeze-cooled condenser (-30°C, to trap low-boiling pyrolysis products), placed in series. Table 4 presents the main experimental conditions and the results obtained for the continuous lignin pyrolysis trials. Table 4: Continuous pyrolysis of pure and pre-treated organosolv wheat straw lignin at 500°C in an atmospheric bubbling fluidised bed reactor

Table 4 shows the beneficial effect of the sepiolite clay additive. No feeding problems, no agglomeration and defluidisation in the reactor bed, a well defined biochar and a free flowing lignin pyrolysis oil that can be easily recovered from the gaseous pyrolysis product that exits the reactor. In contrast, both the pure lignin and the lignin treated with the organic binder do not pyrolyse very well. In addition, the use of organic binders is not preferred because the organic constituents will be degraded as well, causing undesirable components that end up in the final liquid product. Also, from an economic perspective, the organic binders are expensive in comparison with both the lignin cost and the clay.