NL2019066B1 - Process for obtaining cellulose from plant material - Google Patents

Abstract

The invention relates to a process for obtaining cellulose or a cellulosecontaining substance from plant material, the process comprising - providing mashed plant material having a water content of at least 10 wt.%; then - subjecting the plant material, when having a temperature of at least 40 °C, to a reduction in pressure by at least 0.1 bar by means of vacuum extrusion; then - fermenting the plant material to yield a fermentation broth comprising cellulose; then - isolating the cellulose or the cellulose-containing substance from the fermentation broth by one or more separation methods selected from the group of distillation, decantation, centrifugation, filtration, evaporation and washing with a fluid.

Description

Netherlands Patent Office © 2019066 © Application number: 2019066 © Application filed: June 14, 2017 © BI PATENT © Int. Cl .:

C12P 19/04 (2017.01) C12P 7/06 (2017.01) C08B

1/00 (2017.01) D21C 5/00 (2017.01) © Application registered:

December 2018 © Request published:

© Patent granted:

December 2018 © Patent issued:

April 2019 ® Patent Holder (s):

Innovative Sustainable Technologies B.V. in Wemeldinge.

© Inventor (s):

Cornells Adrianus Maria van Loon in Goes. Eduard Jan van Antwerpen in Ovezande. Johannes Izaak van Klink in Wemeldinge. Ulrich Dreier in Estavayer-le-Lac (CH). Manfred Steiner in Mont-Sur-Rolle (CH).

© Authorized representative:

Dr. T. Hubregtse in Beek-Ubbergen.

© Process for receiving cellulose from plant material © The invention relates to a process for obtaining cellulose or a cellulose-containing substance from plant material, the process including

- providing mashed plant material with water content or at least 10 wt.%; then

- subjecting the plant material, when having a temperature of at least 40 ° C, a reduction in pressure by at least 0.1 bar by means of vacuum extrusion; then

- fermenting the plant material to yield a fermentation broth including cellulose; then

- isolating the cellulose or the cellulose-containing substance from the fermentation broth by one or more separation methods selected from the group of distillation, decantation, centrifugation, filtration, evaporation and washing with a fluid.

NL Bl 2019066

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

Process for obtaining cellulose from plant material

The invention relates to a process for obtaining cellulose from plant material and to cellulose obtainable by such a process.

Fueled by growing concerns about the environment and energy demands, there is an increasing interest to produce low-cost, biodegradable and environmentally friendly materials derived from renewable resources, such as agricultural waste or agro-industrial by-products.

Cellulose is one of the world's most useful and abundant natural materials. Essentially, they are chains of linked sugar molecules (monosaccharides) that form the main component of cell walls in plant material. Since they are non-toxic, biodegradable and come from a renewable source, cellulose, and especially cellulose fibers, are an excellent component for the manufacture of a variety of consumer goods, such as textiles, paper and diapers, but also as a dietary fiber . In addition, due to their strength and durability, fibers or cellulose are increasingly being used as reinforcing materials in thermoset and thermoplastic polymeric matrices. Composite products reinforced by natural fibers can be used to replace those that are reinforced by synthetic fibers, for example in the automotive, packaging, and furniture manufacturing. Cellulose may also be used as an effective thermal insulator, for example as an airgel in walls.

For many applications of cellulose (fibers), it is important that the cellulose is free of the other components that are naturally present in the plant from which the fibers are obtained, or at least that they are present in an amount that does not have a negative influence in the application of the cellulose. This concerns for example the presence of starch, hemi-cellulose, lignin, (oligo) saccharides (such as sugar), proteins and salts. The incorporation of one or more or such components may lead to decreased product properties. For example, the presence of sugar or protein in paper or cardboard often causes an unpleasant odor. Also, the use of cellulose as a reinforcement fiber does not benefit from the presence of additional components such as lignin or hemicelluloselt is this thus very important that other plant materials are partly or completely stripped from the cellulose during the isolation process.

Isolating cellulose from plant material usually requires the destruction of the plant's cellular structure, including the disruption of the cells themselves. In conventional methods, this is often performed with extensive mechanical, chemical, and / or thermal treatments for disrupting the cell walls. Mechanical treatments to specifically break open the cellular structure include milling, shearing, grinding, crushing or squeezing. Other methods for disrupting cell walls include mechanical agitation, ultrasonic treatment, and electroporation. Typical chemical treatments are alkali treatments, bleaching treatments, acid treatments and oxidative treatments such as ozonolysis. Processes that rely on high temperature and / or high pressure are, for example, torrefaction, hot water treatments, steam explosion, CO2 explosion and the like.

Drawbacks of these conventional processes are that they generate high amounts of chemical waste and / or are energy intensive, which makes them unattractive to use from an environmental point of view. Moreover, they require high capital expenditures.

It is therefore an object of the present invention to provide a clean and effective process for obtaining cellulose (or cellulose fibers) from plant material. It is also an object to provide cellulose fibers that can replace conventional fibers in the reinforcement of materials.

It has now been found that this can be achieved by making use of a particular sequence of treatments or the source plant material.

The present invention relates to a process for obtaining cellulose or a cellulose-containing substance from plant material, the process including providing mashed plant material having a water content or at least 10 wt.%; subjecting the plant material, when having a temperature of at least 40 ° C, to a reduction in pressure by at least 0.1 bar by means of vacuum extrusion, to yield vacuum extruded plant material;

fermenting the vacuum extruded plant material to yield a fermentation broth including the cellulose or the cellulose-containing substance;

isolating the cellulose or cellulose-containing substance from the fermentation broth mixture by one or more separation methods selected from the group of distillation, decanting, centrifuging, filtering, evaporating, and washing with a fluid (e.g. with water.)

For the purpose of the invention, by a polysaccharide is meant a polymer comprising two or more saccharide monomers joined by glycosidic bond. Polysaccharides that comprise up to saccharide monomers are usually termed oligosaccharides. Sugars include monosaccharides and oligosaccharides, in particular oligosaccharides or two, three or four saccharide monomers, for example sucrose, fructose, glucose, galactose, maltose, lactose, and mannose.

Figure 1 displays a schematic representation of the process of the invention.

The application of vacuum extrusion on plant material followed by a fermentation appears to be a mild and effective method to destroy the plant's cellular structure and at the same time to provide a first product stream or cellulose (or a cellulose-containing substance) and a second product stream or fermentation product (s), ie products resulting from the fermentation of mono- or oligosaccharides, for example sugar.

The vacuum extrusion as well as the fermentation are performed under relatively mild conditions and can easily be integrated into one process. It was found that the obtained cellulose is substantially free of sugar, and has a reduced content of hemicellulose, pectin and lignin as compared to the cellulose originally present and also as compared to the cellulose obtained through conventional processes. The particular properties of the obtained cellulose make it suitable for use as e.g. a reinforcement material or an isolation material.

In the process of the invention, the vacuum extrusion to disrupt the cells is in fact an extrusion of the plant material into a decompression chamber. This comprises feeding the plant material from an inlet into a vacuum chamber that is at a pressure below atmospheric pressure. Typically, prior to feeding into the chamber, the plant material is at atmospheric pressure or at a pressure in the range of 1.0-2.5 bar. The vacuum chamber is a dynamic vacuum during operation, and is therefore connected to a vacuum pump. Since the inlet is typically at atmospheric pressure or above atmospheric pressure, there is a pressure difference between both sides of the opening. The entrance into the chamber occurs through a relatively small opening, so that the pressure difference is maintained and the flow of plant material into the vacuum chamber is not too high. In this way, an explosion-like evaporation of water occurs, as a result of which the cellular structure is disrupted. It is understood that the capacity of the vacuum pump and an eventual condenser associated thereto, as well as the dimensions of the vacuum chamber also play a role in here, since a strong pump and a large vacuum chamber may allow for a bigger opening without compromising the result of the vacuum extrusion (the size of the opening can usually be set, for example by means of a pump). Moreover, the size of the vacuum chamber is important for its capacity for separating water from cellulose-preserving plant material.

The temperature of the stream or mashed plant material at the entrance of the vacuum chamber is at least 40 ° C. It is typically in the range of 40-80 ° C, for example in the range of 45-70 ° C or in the range or 50-60 ° C. In particular, when sugar bite is used as a plant material, a temperature in the range or 60-70 ° C is preferred.

In general, the higher the temperature of the plant material just before the entrance of the vacuum chamber, the more efficient the vacuum extrusion step is (more plant cells are broken open in less time and / or larger sized pieces of plant material can be used ). Further, heating of the plant material prior to the vacuum extrusion also helps to reduce the number of micro-organism contaminants. In some others, the plant material can be heated to a temperature as high as about 120 ° C. In most cases, however, a lower temperature is sufficient for an efficient vacuum extrusion. Generally, temperature is less than 100 ° C.

Part of the water that is present in the stream of mashed plant material evaporates upon entry into the vacuum chamber, which is therefore often provided with a condenser. As a result, the temperature of the plant material drops and the water vapor condenses in the vacuum chamber. The water may be collected from the bottom of the vacuum chamber and fed upstream to the mashed plant material. In general, the higher the initial temperature of the mashed plant is prior to the decompression, the higher the temperature of the vacuum is extruded material after the decompression. In the event that mashed plant material or sugar bite is used at a temperature in the range of 70-90 ° C before the decompression, it drops to a temperature in the range or 30-50 ° C in the vacuum chamber, which is a suitable temperature for the fermentation of the vacuum extruded product. Further heating or fermentation broth is then usually not necessary. When an active condenser is present, then the capacity influences the drop in temperature. For example, with a high capacity, more water is condensed, which results in a lower temperature of the vacuum extruded product.

It has been found that the vacuum extrusion not only destroys the plant material's cellular structure, but also other living cells present, such as micro-organisms originating from the soil in which the plant was grown or that became associated with the plant material during storage . Thus, the vacuum extrusion also has the effect of reducing the number of micro-organisms present in the plant material feedstock. Usually, this effect plays a significant role when the temperature of the mashed plant material at the entrance of the vacuum chamber is at least 85 ° C. This is especially advantageous in view of the subsequent fermentation, because micro-organisms often disturb the fermentation, especially when present in high amounts. It is therefore an advantage of the process of the invention with the disruption of the plant material's cellular structure, also the number of micro-organisms is reduced. This may reduce the need for extensive cleaning or the raw plant material.

Without wishing to be bound to any theory, the rapid decompression during vacuum extrusion is believed to result in an explosion of the cell wall of the plant material, resulting in the destruction of the cell. Any microorganisms present on the plant material (e.g. from the soil in which the plant was grown or that became associated with the plant material during storage), will probably also be killed during the vacuum extruding process.

By the term vacuum chamber is meant a chamber (e.g., a container or vessel) that is at a reduced pressure, i.e., a pressure lower than atmospheric pressure. The pressure in the vacuum chamber during operation of the process may in principle be at any value between 0 and 1 bar. Since the vacuum chamber receives a continuous feed of wet plant material, the pressure in the vacuum chamber during operation of the process of the invention is not actually a high vacuum, so that in practice it is typically at least 0.005 bar. For example, it is in the range or 0.01-0.9 bar, in the range or 0.05-0.5 bar, or in the range or 0.1-0.25 bar. The reduction in pressure is usually a reduction in the range of 0.2-5 bar, in particular in the range or 0.25-2.5 bar, more in particular in the range or 0.3-1.3 bar, even more in particular in the range or 0.5- 0.9 bar. For, the pressure before entrance into the vacuum chamber may be 4 bar or less, 3 bar or less, 2 bar or less, 1.5 bar or less or 1.2 bar or less. In principle, the pressure is one bar or higher. Preferably, the pressure before entering the vacuum chamber is in the range or 1-2 bar, more preferably in the range or 1.0-1.5 bar.

In particular, when sugar bite is used as a plant material, the pressure before entrance into the vacuum chamber is in the range or 1.0-2.0 bar and drops to a pressure in the range or 0.05-0.25 bar in the vacuum chamber. The temperature in the vacuum chamber may then be in the range of 25-45 ° C, in particular in the range or 30-40 ° C.

In many conventional processes for the extraction of valuable products from plant material, the plant material is sliced or cut into smaller pieces (such as cossettes) and then boiled to form an aqueous extract with the desired components. This is for example the treatment on which the isolation of sucrose from sugar beets conventionally relies. The residue that remains after the separation of the extract contains cellular material, which is for a large part cellulose. However, the cellulose obtained in this way is usually not suitable for use in consumer products, such as card board or on the high-end, for use as a reinforcement fiber. It is therefore commonly used as a fertilizer or fed to a fermenter for the production of biogas.

The plant material in a process of the invention, on the other hand, needs to be mashed or crushed prior to the vacuum extruding and have a water content or at least 10 wt.% So that an effective disruption occurs during the vacuum extrusion. Usually, it is at least 25%, preferably it is at least 50%. It may be in the range or 10-90 wt.%, In particular in the range or 50-80 wt.%. The mashing ensures that the original shape and structure of the plant material as formed during its growth are essentially lost, so that the mashed plant material has essentially become a fluid. This is important because the transport of the plant material through the opening to the vacuum chamber should not be discontinued due to the presence of lumps of material that may only pass a whole. In addition, it is important that the plant material is not too viscous and can easily flow through the pipes in the system in which the process has been performed (e.g., through the heat exchanger and through the pipes that feed the inlet or the vacuum chamber). The skilled person will be able to find the appropriate process conditions for a specific plant material, such as the water content (and thus the viscosity) or the mashed plant material, the temperature at the entrance of the vacuum chamber and the pressure at which the vacuum chamber is operated by routine experimentation and without exerting an inventive effort.

Preferably, the flow of plant material to the vacuum chamber in such a system is accomplished without exerting high pressures, because this would put additional requirements for the equipment and is not energy-efficient. In case the mashed plant material as such does not easily flow in the system, extra water may be added. For example, a sugar beet has a water content of approximately 75 wt.%. For a good processability of the mashed bite, the flow properties may be improved by the addition of water. For example, water is added to yield a total water content or up to 80 wt.%, Up to 85 wt.% Or up to 90 wt.%.

Apart from these considerations with respect to processability, it is preferred, however, that the water content in a process of the invention is as low as possible. This is because in subsequent process steps any water that is present also has been removed from the cellulose fibers. When this is performed by evaporation (or distillation), this requires undesired amounts of energy, and when this is performed by a filtration or decanting, there is a stream of aqueous waste that is relatively diluted, which is also undesired. Therefore, the water content is usually 90 wt.% Or less, preferably it is 80 wt.% Or less, more preferably it is 70 wt.% Or less.

Harvested plant material often comprises the dirt that is typically present in an agricultural field, such as sand, soil, organic material not belonging to the harvested crop, micro-organisms, fertilizer or manure. Such contaminations may interfere with the process, and negatively affect it. Yeasts and bacteria present on the plant material may be particularly disturbing during the fermentation and can then give undesired products. Therefore, the plant material in a process or the invention is usually cleaned before it is used in the process. This may be performed by washing it with water, preferably by making use of a high speed water spray.

Generally, the term "plant material" refers to a relatively unprocessed plant material, having intact plant cells. The plant material may be any plant material. Usually, it is derived from a plant selected from the group consisting of a grain, a root, a vegetable, a fruit, a legume, and a grass. When mashed, a stream or such plant material may be obtained that is suitable for being processed in a process of the invention.

More in particular, the plant material may be derived from a plant selected from the group consisting of sorghum, sweet sorghum, oats, barley, wheat, rye, millet, berry, grape, rye, maize, rice, potato, sweet potato, cassava, sugar bite, sugar cane, pineapple, grasses, and vegetables and parts, such as stamps and leaves.

The process of the invention works particularly effectively with plant material there is a moderate degree of lignification of the cellulose. Lignification of a material is known as the result of the deposition of lignin in the extracellular polysaccharidic matrix (cellulose), making that material hard, like wood. A softer plant material usually has a lower degree of lignification and is more prone to delignification by a process of the invention. A plant material that is particularly suitable as a feed in the process of the invention is a plant material that is derived from sugar beet crop (Beta vulgaris subsp. Vulgaris), in particular the root of this crop.

This species appeared to be a particularly suitable substrate plant material to feed to the process of the invention and so let it undergo the vacuum extrusion to destruct the cell walls and convert these into cellulose or a high grade substance. It seems that the stripping of lignin, pectin and hemicellulose from the cellulose is performed particularly well with this species.

Another advantage of using sugar bite is that it yields a first product stream or fermented sugar products and a second product stream or cellulose (or a cellulose-containing substance). Without wishing to be bound to theory, it is contemplated that the advantages obtained with the use of sugar are based on the features of the cellulose fibers (appropriate dimensions, not too long, not too much lignified) in combination with the presence of an appropriate amount sugar. There appears to be a synergy between the two in the consumption of sugar leads to an improved disengagement of the cellulose.

On the other hand, it is preferred not to use plant material derived from wood, because this material is usually too much lignified (i.e., too hard and too solid) for vacuum extrusion.

Usually, the plant material is plant material that has been mashed after its harvesting and which has not yet undergone any treatments of some of its contents were removed (such as extraction). However, it is possible that the plant material that has been used in a process of the invention has indeed already been subjected to such treatments, for example to a sugar extraction treatment in the case of sugar beets. The cellulose waste product produced by the conventional processing of sugar beets may act as the source plant material in a process of the invention. This waste material usually consists of slices and / or chunks or sugar bite that still have their original shape, but which are well suited to transform into cellulose fibers through a process of the invention.

By fermentation is meant the process of transforming an organic molecule into another molecule using a micro-organism. Refer to the aerobic transformation of sugars or other molecules from extruded plant material to produce one or more products selected from the group of alcohols (eg ethanol, methanol, butanol), organic acids (eg, citric acid, acetic acid, itaconic acid, lactic acid, gluconic acid), ketones (eg, acetone), amino acids (eg glutamic acid), gases (eg H ₂ and CO2), antibiotics (eg penicillin and tetracycline), enzymes, vitamins (eg riboflavin, B ₁₂ , beta-carotene), and hormones. Fermentation can include fermentations used in the consumable alcohol industry (eg beer and wine), dairy industry (eg, fermented dairy products), leather industry, and tobacco industry. Thus, fermentation includes alcohol fermentation. Fermentation also includes anaerobic fermentations, for example, for the production of biogas.

The fermentation serves two main purposes. First, it converts part of the plant's constituents, in particular sugars, into valuable products such as fuels or starting materials for various chemical processes. Second, many plant constituents that naturally surround the cellulose in the plant material, are removed from the cellulose during the fermentation (lignin, pectin, hemicellulose). In this way, cellulose can be obtained that is substantially free of such constituents, or contains substantially smaller amounts of them. In this way, the invention accomplished that the plant material is converted into two valuable product streams by applying one single, integrated, process, viz. a first stream of cellulose (or a cellulose-containing substance) and a second stream of fermentation product (s). Moreover, this process is robust and straightforward.

The fermenting step usually comprises the preparation of the fermentation mixture. This may be performed by mixing the extruded plant material with water and yeast. It may be advantageous to add water to the vacuum extrusion product is preferred prior to the fermentation, to lower the viscosity and facilitate the transport in the pipes that feed the vacuum chamber, circumventing for example the use of high pressure to achieve the transport.

In some, the preparation of the fermentation mixture comprises the addition of an enzyme, which converts the polysaccharides into the fermentation mixture into fermentable sugars and / or further breaks down plant cell walls. The amount of enzyme may be in the range or 1-200 g or enzyme per hectolitre or fermentation mixture, in particular in the range or 100-150 g. It may also be in the range or 5-50 g or in the range or 10-20 g or enzyme per hectolitre or fermentation mixture. The fermentation mixture may also be prepared without the addition of an enzyme. A stabilizer may be added to order to create better conditions for fermentation, for example one or more compounds selected from the group of SO2, antibiotics and potassium metabisulfite (K2S2O5).

The fermentation is usually carried out by incubating the fermentation mixture to a temperature in the range of 10-80 ° C. Depending on the type of yeast, a particular temperature may be applied. For example, the temperature may be in the range of 15-50 ° C, in the range or 20-40 ° C, or in the range or 30-35 ° C. It may also be in the range of 30-75 ° C, in the range or 40-60 ° C or in the range or 45-55 ° C. Fermentations to yield ethanol are usually carried out at a temperature in the range of 10-40 ° C, for example at a temperature in the range of 32-34 ° C.

In case sugar beet crop is used in the process of the invention, the process is usually performed 1) with mashed sugar beet crop that comprises an additional amount of water in the range or 0-25%; 2) at a temperature that is in the range of 25-40 ° C; 3) with a pH that is in the range of 1.0-10.0, in particular in the range or 2.0-9.0, more in particular in the range or 2.5 to 8.0. In such a process, it is preferred that 1) the mashed plant material comprises an additional amount of water in the range or 0-20%; 2) the temperature is in the range of 28-32 ° C;

and 3) the pH is in the range of 3.0-7.0, more preferably in the range of 3.5-6.0. It is further preferred that the fermentation mixture is stirred at regular intervals.

The fermentation may be performed batch-wise or in a continuous manner. When batch-wise, the period during which the fermentation takes place is usually in the range of 4-200 hours, in particular in the range or 5-120 hours, more in particular in the range or 10-72 hours and even more in particular in the range of 35-48 hours.

For the purpose of the present invention, the mixture of products that is formed during the fermentation of the plant material is named the fermentation broth. This mixture contains the cellulose and / or the cellulose-containing substance as well as the products into which polysaccharide materials (in particular the sugars) or the plant material are converted.

In an embodiment, the fermentation comprises adding water and yeast to the vacuum extruded plant material to form a fermentation mixture;

maintaining the fermentation mixture at a temperature in the range of 3035 ° C during a time period in the range of 5-120 hours.

The fermentation is usually performed by a fungal organism (e.g., yeast or filamentous fungi). The yeast may in principle be any yeast that is capable of converting constituents of the plant material into the desired product. Usually, the yeast is capable of producing ethanol. The yeast can include strains from a Pichia or Saccharomyces species. The yeast species may be Saccharomyces cerevisiae.

It is also possible that the fermentation is performed by bacteria. For example by Clostridium acetobutylicum (which produces butanol) and Corynebacterium glutamicum (which produces monosodium glutamate (MSG)).

The microorganism used in the fermentation (e.g., yeast or bacteria) can be a genetically modified microorganism.

The pH of the mixture during fermentation also depends on the type of yeast. Usually, however, the pH is in the range of 3.0-6.6, in particular in the range or 5-6, more in particular in the range or 5.0-6.0.

The fermentation results in the formation of the fermentation product mixture, the fermentation broth. This is an aqueous mixture comprising the products produced by the yeasts and the products resulting from the further destruction of the cellular materials, such as cellulose or a cellulose-containing substance, the latter being a composite or cellulose with eg hemicellulose, pectin and / or lignin.

The cellulose product (and / or the cellulose-containing product) needs to be isolated from the fermentation broth. This comprises a purification method, which is typically a solid-liquid separation, since the cellulose is not dissolved. This purification or separation may be performed by techniques known in the art, in particular by a method selected from the group of distillation, decanting, centrifuging, and filtering. In particular, a solid-solid separation may be required to remove solid residues of the fermentation broth (e.g., remnants of the yeasts) from the cellulose. In case the products produced by the yeasts have a suitable boiling point, for example ethanol, then these can be removed by distillation. In such a case, a further solid-solid separation may be particularly necessary because residues from the fermentation broth are still present after distillation. The (residual) fermentation product containing the cellulose may then be washed to remove dissolved byproducts such as salts and other water-soluble components that originate from the treated plant material or are formed during the process of the invention. Use may e.g. be made of filtration and / or sedimentation followed by decantation. Techniques for solid-solid separation that are known in the art may also be applied, in particular to remove non-cellulosic material that is not dissolved, from the cellulose or the cellulose-containing substance.

In an embodiment, the isolation of the cellulose or cellulose-containing substance comprises heating the fermentation broth to remove ethanol, followed by washing the cellulose with water, or a water-containing fluid.

Usually, the purification method comprises, or is followed by, the removal of water so that a substantially dry product is obtained. This may be performed by centrifugation or by evaporation of water, in particular by drying under reduced pressure (usually at a pressure lower than atmospheric pressure). For example, the water content in the isolated cellulose or the cellulose-containing substance is 5 wt.% Or less, 4 wt.% Or less, 3 wt.% Or less, 2 wt.% Or less, 1 wt.% Or less, 0.5 wt.% or less, 0.2 wt.% or less, 0.1 wt.% or less or 0.05 wt.% or less.

Figure 1 displays an embodiment of process (1) or the invention, in which the subsequent process steps are identified. First, mashed plant material (11) is provided, which undergoes the vacuum extrusion to yield the vacuum extruded plant material (12). Thereafter, this is fermented to yield fermentation broth (13). The fermentation broth is then separated into different components (14). The cellulose or the cellulose containing substance is separated as the first product stream (14a), which is typically a substantially dry product. The product (s) resulting from the fermentation of sugar (typically ethanol obtained by distillation) form (s) the second product stream (14b). The matter that remains after the separation of (14a) and (14b) from the fermentation broth is residue (14c).

The cellulose product produced by the process of the invention may be cellulose or a cellulose-containing substance. Depending on the purity, it is obtained as a dry powder or a more tight or stiff solid substance. It may be a white, off-white, yellow or even brownish substance. In an embodiment, the cellulose or cellulose-containing substance was isolated as cellulose fibers.

The cellulose product may also be modified, for example into an airgel. The obtained cellulose may also be converted into other products, such as levulinic acid.

The cellulose-containing substance formed in the process of the invention usually contains at least 50 wt.% Of cellulose. It may also be 60 wt.% Or more, 75 wt.% Or more, 80 wt.% Or more, 85 wt.% Or more, 90 wt.% Or more, 95 wt.% Or more, 97 wt.% or more, 98 wt.% or more, 99 wt.% or more or 99.5 wt.% or more. Usually, it is in the range or 65-99.8 wt.%, Or in the range or 80-98.5 wt.%.

The invention further relates to cellulose or a cellulose-containing substance available by the process of the invention.

The invention further relates to an object, in particular a plastic object, that is reinforced with cellulose or a cellulose-containing substance available by the process of the invention, in particular with cellulose fibers available by the process of the invention.

In a process of the invention, there is in principle no need to add a further chemical such as liquid ammonia or potassium hydroxide for treating the plant material prior to the vacuum extrusion, or at any later stage of the process.

Since the vacuum extrusion has been performed under relatively mild conditions, such as low temperatures (eg 40-60 ° C) and pressures around atmospheric pressure (eg 0.1-1.1 bar), the process is energy-efficient and saves energy as compared to conventional processes . The mildness also manifests in that vacuum extrusion does not produce toxic derivatives which can inhibit the subsequent fermentation step, such as furaldehyde, 5-hydroxymethyl-2furaldehyde, and phenolic compounds resulting from lignin depolymerization. The formation of such inhibitors often occurs with harsh methods such as steam explosion - this then requires a washing step with e.g. water to remove the inhibitors prior to the fermentation.

The use of sugar as a plant material proved to be particularly advantageous, since a high quality cellulose can be isolated, or at least a cellulose-containing material with beneficial properties, by the process of the invention. The stripping of lignin, pectin and hemicellulose from the cellulose in this species occurs particularly effective with a method of the invention. In parallel to this, the process of the invention also yields a useful fermentation product. Further, considering that sugar beets provide a very high yield of sugar / hectare per harvest over a cropping period of 6-9 months, that improves the soil structure and soil fertility, leading to better crop results or the other crop in the rotation cycle .

An advantage of the process of the invention is that no further chemicals (for example ammonia or potassium / sodium hydroxide) are needed for the treatment of the plant material. In addition, no high pressures need to be applied, which results in a simple and cost-effective process as compared to those known in the art.

The invention further relates to the use of vacuum extrusion and fermentation for the isolation of cellulose or a cellulose containing substance from plant material, in particular isolation in a dry form, in which the vacuum extrusion comprises subjecting the plant material, when having a temperature of at at least 40 ° C, to a reduction in pressure by at least 0.1 bars, and the vacuum extrusion is followed by the fermentation.

Claims (5)

Conclusions A method for obtaining cellulose or a cellulose-containing substance from vegetable material, the method comprising - providing vegetable vegetable material with a water content of at least 10% by weight; afterwards - exposing the vegetable material, when it is at a temperature of at least 40 ° C, to a reduction in pressure of at least 0.1 bar by means of vacuum extrusion; afterwards - fermenting the vegetable material to obtain a fermentation slurry comprising cellulose; afterwards - isolating the cellulose or cellulose-containing substance from the fermentation slurry by one or more separation methods selected from the group of distilling, decanting, centrifuging, filtering, evaporating and washing with a fluid. The method of claim 1, wherein the plant material is derived from a plant selected from the group consisting of a grain, a root, a vegetable, a fruit, a legume, and a grass. A method according to claim 1 or 2, wherein the plant material is derived from a plant selected from the group of sorghum (milo), sweet sorghum, oats, barley, wheat, rye, millet, berry, grape, corn, rice, potato , sweet potato, cassava, sugar beet, sugar cane, pineapple, grasses, and vegetables and portions thereof such as stems and leaves. A method according to any one of claims 1-3, wherein the vegetable material is derived from sugar beet {Beta vulgaris subsp. vulgaris). A method according to any one of claims 1-4, wherein the water content of the vegetable vegetable material is in the range of 10-90% by weight, in particular in the range of 50-80% by weight. The method of any one of claims 1-5, wherein the vacuum extrusion is carried out at a pressure in the range of 0.05 and 0.5 bar. A method according to any one of claims 1-6, wherein the reduction in pressure is a reduction in the range of 0.2 - 1.1 bar, in particular in the range of 0.3 - 1.0 bar, more in particular in the range of 0.5 - 0.9 bar. A method according to any one of claims 1-7, wherein the vegetable material is at a temperature in the range of 45-70 ° C when it is exposed to the reduction in pressure in the vaccine extrusion, in particular at a temperature in the range from 50-60 ° C. The method of any one of claims 1-8, wherein the fermentation comprises - adding water and yeast to the vacuum-extruded vegetable material to form a fermentation slurry; - keeping the fermentation slurry at a temperature in the range of 30-35 ° C for a period of at least 5 hours, in particular in the range of 5-120 hours. A method according to any of claims 1-9, wherein the isolation of the cellulose or the cellulose-containing substance comprises heating the fermentation slurry to remove ethanol, followed by washing the cellulose or the cellulose-containing substance with a fluid, in particular water. The method of any one of claims 1-10, wherein the cellulose-containing substance contains at least 85% by weight of cellulose. The method of any one of claims 1 to 11, wherein the cellulose-containing substance is isolated as fibers. A method according to any one of claims 1-12, wherein water is removed during the isolation, so that the cellulose or cellulose-containing substance is isolated as a substantially dry product, preferably with a water content of 1% by weight or less. A method according to any one of claims 1-13, followed by converting the obtained cellulose to levulinic acid. 15. Cellulose or cellulose-containing substance obtainable by the process of any one of claims 1-13. Figure 1