Field of the invention This invention relates to a process of splitting cellulosic material using an electromagnetic radiation and a process of producing ethanol from cellulosic material.

Background The increasing industrialization and motorization of the world has led to a steep rise for the demand of petroleum-based fuels. Today fossil fuels take up 80 % of the primary energy consumed in the world, of which 58 % alone is consumed by the transport sector. The sources of these fossil fuels are becoming exhausted. Major contribution in greenhouse gas (GHG) emissions is resulting from con- sumption of fossil fuels to fulfill the energy demand, which leads to many negative effects including climate change, receding of glaciers, rise in sea level, loss of biodiversity, etc. Thus there are attempts to gradually increase the share of fuels derived from renewable sources.

So called, first generation biofuels include liquid fuels produced from sugars, grains or seeds and require a relatively simple process to produce the finished fuel product. A well-known example is ethanol fermented using sugar extracted from crop plants and other starchy crops. The viability of the first-generation biofuels production is, however, questionable because of the conflict with food supply. Cellulose is a long chain polymer molecule consisting of repetitive gly- coside residues linked together by 1→4- -glycosidic bonds. It is also the most prevalent natural polymer. Industrial sources include e.g. wood as well as agricultural lignocellulosic biomass, which are either nonedible residues of food crop production or non-edible whole plant biomass (e.g. grasses or trees specifically grown for production of energy). Cellulose has an excellent energy balance in biofuel production. When energy balances of corn ethanol and cellulosic ethanol are compared there is 1 .5 to 27 fold difference in favor of cellulosic raw material depending on the production method. These facts favor using cellulosic raw material as a source of sugars / saccharides instead of edible sugar sources.

The drawback in using cellulosic material for manufacturing biofuels, like bio- ethanol, is poor efficiency and high cost of cellulose chain cleavage (splitting) to separate glucose units. Several processes of hydrolyzing or splitting cellulose molecule into glucose units are known, e.g. hydrolysis with acid, enzymatic hydrolysis and ionic liquids treatment. However, these methods are expensive, need hazardous chemicals in processing and large processing facilities, are energy consuming itself and have problems with recovery of chemicals.

There is a continuing need for environmentally and economically acceptable sources of saccharides for biofuel production. There is also a continuing need sugar units usable for production for bio-based monomers instead of monomers from fossil fuel. Cellulose derived saccharides can be used as a raw material for monomer and biofuel production. However, the prior art methods of splitting or hydrolyzing cellulosic materials have several drawbacks. Thus there is a need for alternative and improved method for splitting cellulosic material.

Summary It is an object of the invention to provide an alternative process for splitting cellulosic material. This and other objects together with the advantages thereof over known methods are achieved by the present invention as hereinafter described and claimed.

The invention is based on the use of electromagnetic radiation for splitting of cellulosic material to saccharides.

An aspect of the invention is process of splitting cellulosic material. According to the invention said process comprises the steps of exposing said cellulosic material to an electromagnetic radiation having fluence of 0.0001 J/mm ² to 10 000 000 J/mm ² . The second aspect of the invention is a process of producing ethanol from cellulosic material. According to the invention said process comprises the steps of exposing said cellulosic material to an electromagnetic radiation having fluence of 0.0001 J/mm ² to 10 000 000 J/mm ² , recovering the exposed material and fermenting said material into ethanol.

The present invention provides a cost effective and environmentally acceptable process for producing saccharides from cellulosic material, especially cellulose, for e.g. biofuel applications and for use as a starting material in industrial applications. In the following, the invention will be discussed more closely with the aid of a detailed description and with references to working examples.

Brief description of the figures

Figure 1 is a graphical view of one embodiment of the invention where exposure is performed on material on conveyor belt. Figure 2 is a graphical view of one embodiment of the invention where the sheet formed cellulosic material is exposed between steel plates.

Detailed description of the invention

The present invention relates to a process of splitting cellulosic material com- prising exposing said cellulosic material to an electromagnetic radiation having fluence of 0.0001 J/mm ² to 10 000 000 J/mm ² . Cellulosic material is split to saccharides. In one embodiment of the invention the fluence is at least 100 J/mm ² . In one embodiment of the invention the fluence is a 100 to 250 J/mm ² . In one embodiment of the invention the fluence is at least 300 to 3000 J/mm ² . These fluences allow splitting cellulosic material essentially to di- and monosaccharides without remarkable pyrolysis. Exposed and split material can be recovered using any method.

The finding is surprising as it has been understood that when cellulosic material is subjected to electromagnetic radiation such as laser beam it is evident to use high temperatures resulting to gaseous evaporation product (as pyrolysis above 350 °C e.g. in cutting applications). Also melting of cellulose on 260 to 270 °C is known. However, splitting of cellulosic material into saccharides using electromagnetic radiation has not been proposed.

In one embodiment of the invention the radiation has a wavelength of 120 nm to 12000 nm.

In one embodiment of the invention the cellulosic material is subjected to a laser radiation which means such electromagnetic radiation that it is monochromatic, has certain wavelength band, and is all in one phase. In one embodiment of the invention the wavelength is 10.6 μιτι corresponding to CO ₂ laser energy density range 10 W/mm ² to 100 W/mm ² . In another embodiment of the invention the wavelength is about 200 nm what corresponds to excimer lasers. Most suitable wavelengths are dependent on type of the laser and the material to be treated.

Laser splitting of cellulosic material has several advantages over the prior art methods such as acid or enzymatic hydrolysis. Laser treatment can be per- formed without high investments to equipment using mainly existing equipment. Number of laser units, power used and splitting used makes laser processes easily scalable from industrial processes to domestic use.

Laser treatment is typically robust and reliable process providing repeatable result. Laser splitting is not very sensitive to process temperature, moisture or pressure (when compared to prior art methods of splitting cellulosic material). The maintenance of laser equipment is easy. In addition use of chemicals can be almost completely avoided which is an important cost and environmental factor and provides relatively pure hydrolysate suitable for use even without any purification for e.g. certain fermentation applications. In one embodiment the radiation has an energy density of 100 W/mm ² to 10000000 W/mm ² . In one embodiment the radiation has an energy density of 100 W/mm ² to 10000000 W/mm ² . In one embodiment the radiation has an energy density of 10 W/mm ² to 100 W/mm ² . In one embodiment the radiation has an energy density of 10 W/mm ² to 1000000 W/mm ² . In one embodiment the cellulosic material comprising exposing said cellulosic material to laser beam having energy density of 100 W/mm ² to 10000000 W/mm ² and wavelength of 120 nm to 12000 nm. As a result the cellulose fraction is split into smaller glucose oligomers, trimers, dimers and monomers.

Electromagnetic beam or laser beam can have a fixed position and only the cellulosic raw material is moved. Alternatively the laser unit or the unit producing the electromagnetic radiation can be moved in relation to the cellulosic material. It is also possible that both the beam and the cellulosic material are moved. Naturally also the number of the units can vary.

In this connection expression "cellulosic material" means any cellulose containing material including wood crops (soft wood, hard wood, etc), forest and agri- cultural residues (e.g. saw dust, thinnings, mill waste, corn stover and sugarcane bagasse), portions of solid municipal waste (e.g. waste paper) and herbaceous corps (e.g. switch-grass). Delignified or partially delignified cellulosic material comprising mainly cellulose and optionally hemicellulose is preferred as providing more pure mixture of saccharides. Cellulosic material having only mi- nor amount of impurities such as plant extracts, resin, printing ink, caolin, adhe- sives and respective is preferred especially when the aimed field of use of the saccharides requires high purity. Essentially pure cellulose is the most preferred as consisting of easily usable glucose units.

The cellulosic material can be in any form; solid (such as saw dust, nanocellu- lose, powder, crystal or any other similar to these or any combination of these), dissolved solids (such as pulp residues or pretreated woody or agricultural material) or liquid.

In one embodiment of the invention said cellulosic material is side-stream of pulp and paper industry, cellulosic agricultural side-stream, side stream of forest and wood industry, cellulosic municipal waste or recycled cellulosic fibre.

When side streams of forestry and wood industry are used as a raw material it may be beneficial to pretreat the material by e.g. milling, grinding, steaming, cooking or e.g. partial acid hydrolysis. It is believed that also particulate material can be split, e.g. saw dust having particle size up to 90 μιτι. Moisture content of the cellulosic material to be split with a laser is typically 0.0001 % to 100 %. The cellulosic material has dry fibre content of 2 to 50 wt-% (dry matter). Dry pulp (2 to 10 wt-% moisture) can be used as well as mechanically dewatered pulp (20 wt-% to 50 wt-% moisture) as well as pulp slurry with high fibre content (5 to10% dry matter).

Suitable grammage of the cellulosic material is 0.0001 g/m ² - 100000 g/m ² . As understood by a person skilled in the art laser parameters are adjusted to raw material parameters (mainly grammage and thickness), It is, however, also possible to select the material for the best laser parameters if there is some equipment limitations.

During the exposure the cellulose molecules are split (cleaved) to glucose or its di, tri or oligomers (glucose polysaccharides, trisaccharides, disaccharides and monosaccharides). Possible hemicellulose fractions within the cellulosic material are split to polysaccharides, tri-saccharides, disaccharides and monosaccharides comprised to the hemicellulose.

In this connection expression "saccharides" includes polysaccharides, tri- saccharides, di-saccharides and mono-saccharides (such as glucose from cellulose and galactose or xylose from hemicellulose). Di- and monosaccharides are preferred. Monosaccharides being readily usable in e.g. fermentation applications and chemical synthesis are most preferred.

The electromagnetic beam with wavelength of for example 120 nm to 12000 nm should be distributed evenly and peaking intensities should be avoided. A person skilled in the art knows that the electromagnetic beam can be modified using conventional methods such as mirrors, lenses kaleidoscopes, prisms and other similar optical components. Opposite to well-known cutting application the aim in this invention is to expand the beam. Mode of beam can be continuous wave (CW) or pulsed. It can be Gaussian, TEMOO, TEM10, TEM20, top hat or any other related to these. There are two different modes, when you talk about laser beam. First one is the mode of power i.e. pulsing or CW. The second mode means the power distribution in laser beam cross section which is Gaussian (e.g. TEMOO, TEM10, TEM20) The temperature for electromagnetic exposure may be: 0.0001 °C to 100 000 °C but typically a regular room temperature such as 15 to 30 °C is suitable. Humidity may also vary from 0.001 % up to 100 % but usually there is no need to modify the humidity.

Splitting can be done in any atmosphere (including inert and vacuum atmosphere) or even without it. Inert gas enhances purity of resulting saccharides which may be of importance in certain sensitive applications. In one embodiment compressed air is used. However, for different setups it can be essential to use other processing gases or to carry out the process in, for example, inert gas atmosphere.

For the exposure the gas pressure is 0.0001 bar to 1000 bar can be used. Typi- cally a small over-pressure such as 3 bar is used. In one embodiment the exposure pressure is 1 .5 to 10 bar, preferably 2 to 4 bar.

Processing speed (speed of the cellulosic material) maybe 0.0001 mm/s - 10 000 000 mm/s. In one embodiment the processing speed is 1 to 1000 mm/s, or 50 to 150 m/s. E.g. processing speed of about 100 mm/s has been shown to provide easier handling and precision. Processing speed and laser power have to be chosen respectively. Generally higher speed requires more laser power with almost linear dependence.

Interaction time basically depends on power and speed used. It effects on the time the process is on and probably it can partly compensate the power density i.e. the fluence (J/mm ² ) plays a role. Interaction time may be 0.0001 ms to 1 000 000 ms

It is believed that pulsing may help to maintain better interaction of laser beam and cellulosic material. Pulse lengths may vary between 0.0001 ms and 10 000 000 ms and pulsing may vary depending on the material to be split and/or other parameters.

Focal plane position may be -100 mm to 100 mm. The exact numerical value depends on equipment used and set up. Focal plane position has to be taken into account in relation to material thickness to maintain proper interaction of laser beam and paper material. 3. Focal length can be 0.0001 mm to 10 000 000 mm. 125 mm was used in the experimental part. Without binding the theory, higher focal lengths are better for processability but not necessarily for the process itself.

This invention relates also to a process of producing ethanol from cellulosic ma- terial comprising the steps of exposing said cellulosic material to an electromagnetic radiation having fluence of 0.0001 J/mm ² to 10 000 000 J/mm ² , recovering the exposed material and fermenting said material into ethanol. Conventional methods can be used for the fermentation.

In one embodiment solar energy is used as a power source for laser. This al- lows turning cellulosic material, including e.g. house hold and agricultural waste, into saccharides, which can optionally be further fermented to alcohol. In this case the solar energy would indirectly be turned into saccharides and alcohol having high energy density and being easy to store for later use.

Description of an embodiment with references to drawings

Reference is now made to Figures which show two illustrative embodiments of the possible arrangements for using the process of the invention. In the figures is shown a

Figure 1 shows on embodiment where the cellulosic raw material is in a form of dried pulp (1 ). The material is provided on a moving conveyor belt (4) and the stabile laser unit (2) produced a beam that exposed the whole breath of the cellulosic material. The exposure area is shown as (3). Cellulose material depoly- merized to glucose and other saccharides (9) is accumulated on the conveyor belt (4). Recovery of the saccharides can be enhanced using water spraying (5) and/or scrappers (6). Saccharides can be collected to a collecting bath (7) from where they were taken for further processing. When the conveyor belt would be very wide, there could be a number of parallel laser units or the laser unit could be movable perpendicularly to the conveyor belt.

In Figure 2 the cellulosic material (1 ) is introduced in form of a sheet between two rolls (8) of industrial steel. The laser beam will be scattered between the rolls and the material is exposed between said rolls. It should also be understood that the process of the present invention can be used with various types of cellulosic raw-material and arrangements for electromagnetic exposure. Where ever the splitting of lignocellulosic material is required, the process of the present invention may be used. It is also to be under- stood that the terminology employed herein is for the purpose of description and should not be regarded as limiting.

The features of the invention described here as separate embodiments may be provided in combination in a single embodiment. Also various features of the invention described here in the context of a single embodiment, may be provid- ed separately or in any suitable sub-combination. It should be understood, that the embodiments given in the description above are for illustrative purposes only, and that various changes and modifications are possible within the scope of the disclosure.

Below the invention is illustrated by non-limiting examples. It should be under- stood that the embodiments given in the description above and the examples are for illustrative purposes only, and that various changes and modifications are possible within the scope of the invention.

Examples Example 1 : Process using beam and a conveyor belt for transferring the raw material

Raw material in a form of dried pulp (1 ) was treated with laser (2). This laser was selected on those of lasers having appropriate power on the basis to have optimum energy (i.e. distribution of laser energy to beam area which is in con- tact with top side of cellulose material) for success of process. In this experiment easily available CO2-laser was used. Due to this treatment cellulose material was depolymerized to glucose and other saccharides (9) which were accumulated on the supporting conveyor belt (4). In order to collect the saccharides, water spraying (5) and scrappers (6) were used. Saccharides were dissolved in water and flowed down to collecting bath (7) from where they were taken for further processing. Principle of this method is shown in figure 1 . Example 2: Use of steel plates

Raw material in a form of sheet of dried pulp (1 ) was fed to the gap in between of steel rolls (8) where laser treatment of cellulosic material takes place with a laser (2). This laser (CO ₂ -laser) was selected on the basis to have optimum en- ergy density (i.e. distribution of laser energy to beam area which is in contact with top side of cellulose material) for success of process. Due to this treatment cellulose material was depolymerized to glucose and other saccharides which were accumulated on roll's (8) surface. In order to collect the saccharides, water spraying (5) and scrappers (6) were used or in the first experiment the split cel- lulosic material was manually collected from the surfaces of the rolls. Saccharides were dissolved in water and flowed down to collecting bath (7) from where they were taken for further processing. Principle of this method is shown in figure 2.

Example 3: Fermentation test using a sheet form raw material

Cellulosic material (dried pulp) split as explained in Example 2 was manually collected to minigrip plastic bags without adding water. The sugar content was estimated using a measuring kit for diabetic patients obtained from a local pharmacy. Yeast for baking by "Suomen hiiva" was added to the exposed sus- pension (9). The fermentation time was 30 hours and final alcohol content was 3%. The alcohol content was followed using alcohol meter for domestic users.

For a comparison the dried pulp was fermented but no alcohol production could be observed.

It was shown that the laser treated cellulose from a preliminary experiment can be fermented to ethanol without need of any kind of purification. This shows that the cellulose derived saccharides obtained using laser treatment as described here has very low amount of residual impurities and may be usable as such for further production steps, such as alcohol fermentation and also that laser treated cellulose is usable as a sole carbon source for alcohol fermentation. Example 4: Analysis of saccharides

Laser treated cellulose sample of 10 g obtained according to Example 2 was analyzed using Gas Chromatography with Flame Ionization Detector (GCFID) for obtained saccharides. Test results can be seen from Table 1 (only carbohydrates content is shown).

Table 1 . Test results.

Results of chemical analysis reveal that tested sample consisted of 40.6 % of glucose. This means that 4.06 g of glucose was produces by laser treatment of cellulose when 10 g sample was produced. Glucose constitutes also the biggest fraction or 90.9 % of all carbohydrates such as arabinose, xylose, mannose and galactose. Very small amounts of oxalic and acetic acids were found as well . Other components found in sample were water and inorganic substances; how- ever, they were at trace amounts at best.