• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a method of producing lignin with reduced amount of odorous substances comprising the steps of:i) providing a lignin containing starting material to be contacted with a water solution comprising alcohol;ii) dissolving at least guaiacol and etylguaiacol content from the lignin into the water solution, andiii) draining off the water solution with its content of guaiacol and etylguaiacol; iv) obtaining a lignin material with a reduced content guaiacol and etylguaiacol.The alcohol is preferably a C1-C4 alcohol, preferably ethanol.The invention also relates to a lignin product with reduced odour obtained and/or obtainable by the method and to the use of the obtained lignin as a component in polymer blends, an additive or filler in building materials, as binding agent in adhesives, and/or for the production of a carbon fibre, especially in indoor applications.
    公开号:SE1650898A1
    申请号:SE1650898
    申请日:2016-06-22
    公开日:2017-12-23
    发明作者:Tomani Per；Alvarado Fernando；Sedin Maria
    申请人:Valmet Oy；
    IPC主号:
    专利说明:

    Method of producing lignin with reduced amount of odorous substances TECHNICAL FIELD The present invention relates to a method of producing or treating lignin in order to reduce its amount of odorous substances, to a lignin product obtained and to a use ofthe lignin product.BACKGROUND ART Lignin is a complex polymer occurring in certain plant walls making the plant rigid. Bonds linkinglignin to cellulose are broken during a chemical pulping process. Lignin isolation from blackliquor has been used during past years to provide lignin for commercial use, for example for useas a solid biofuel and dispersant. This lignin is also a valuable material for production of "greenchemicals" and as a fuel for the production of chemicals. The production process of lignin ofthat kind is described for example in WO2006 /031 175. According to the process, lignin isseparated from black liquor. The separation method may include steps to acidify the blackliquor so that the lignin is precipitated. The solid phase is then separated from the liquor and can thereafter be cleaned or modified.
    However, there is a desire to use lignin products also in other applications than fuelapplications. The lignin product obtained by the isolation process is a renewable, non-poisonous environmentally friendly product which could be used for example as a raw materialfor building materials. However, the obtained lignin product suffers from a drawback of being malodorous, whereby the use ofthe product has been limited to few applications.There is thus a great desire to reduce or eliminate the problems with odour in lignin products.ln the prior art, there have been attempts to reduce odour levels in lignin products.
    WO 2012 /161 865 discloses a method in which pressurized black liquor may be reacted withan oxidizing agent, such as oxygen, peroxide or the like, in an amount sufficient to reduce oreliminate the odour level in the black liquor so that there will be little or no odour in the finallignin product. This step removes the odours by oxidating mercaptans (methyl, ethyl), anddimethyl, diethyl sulphides etc. However, with this process there is a risk that also lignin is oxidized and thus deteriorated or chemically modified.
    Even though there are prior art solutions for the reduction of odour levels, especially in respectof mercaptans, there is still a need for a process that removes other organic odorouscompounds effectively. There is also a need for a process in which lignin is treated carefullysuch that its chemical structure and bondings remain to a large extent and in which lignin is notessentially fractionated by the odour reduction process. There is also need for anenvironmentally friendly process with a reduced risk for hazards in the production process. lt isfurther an advantage if the dour reduction process can be integrated with lignin separation processes in a simple way.SUMMARY OF THE INVENTION The object of the present invention is to provide a method for reducing the amount of odoroussubstances in lignin products. lt is also desired to provide a method for the production of aproduct in which lignin is treated carefully such that its chemical structure and bondings remainto a large extent and in which lignin is not severely fractionated due to odour reduction. lt isalso desired to provide a method for producing less odorous lignin products with a method thatcan result in high yield. lt is also desired to provide a method which is environmentally friendly.Preferably could the method be used in connection with and/or integrated with availableprocesses for separating lignin, i.e. the production of lignin products, as well as being able to beused for treatment of lignin in various forms after it has been separated and o purified, e.g. in a pulping process.
    The present method aims to address the above object and desires of producing or modifyinglignin wherein lignin with reduced amount of odorous substances is obtained. The method isbased on the idea of using an alcohol in a solution in order to be in contact with the lignin to beproduced or treated. This treatment may be performed during a pulping process when lignin is isolated or may be used for refined lignin.Hence, the method may be simply described to comprise the steps of. 0 providing a lignin containing starting material to be contacted with a watersolution comprising alcohol; 0 dissolving at least guaiacol and etylguaiacol content from the lignin into thewater solution, and 0 draining off the water solution with its content of guaiacol and etylguaiacol; 0 obtaining a lignin material with a reduced content guaiacol and etylguaiacol.
    One advantage by using treatment with alcohol is that it is not necessary to dissolve the lignin ifit is present in solid phase, e.g. precipitated lignin isolated from black liquor in an alkalinechemical pulping process. Hence, the process works for solid lignin, e.g. particulate ligninforming a slurry with an alcohol containing solution, as well as when lignin is dissolved in thealcohol containing solution. To be noted, by solid state is meant that the lignin itself is in solidstate but it may be in a liquid solution, e.g. particulate lignin in a solution together forming aslurry. According to a preferred embodiment ofthe invention has the lignin containing startingmaterial a dry matter content above 50 percent, and a lignin content of this dry matter content exceeding 50%. lt is thus in particular advantageous to be able to use this method when lignin in solid state ispresent and still have a need for odour treatment since there is no need to dissolve the ligninonce again. For example, if solid lignin from a lignin filter cake is used could the filter cake bedisintegrated into smaller particles and located in an alcohol containing water solution andthereafter dried once again. This could be easily done for a wet filter cake which may easily bedisintegrated if placed in a solution, it may even be possible to merely stir the solution in a tankto make the filter cake be divided to rather small particles forming a slurry. Alternatively, thefilter cake could be washed with an alcohol containing solution when still on the filter. As stillan alternative, a dry lignin filter cake could be immersed in an alcohol solution, either as onepiece or integrated into smaller blocks, or even mechanically treated to form smaller particles,so as to form a slurry with the alcohol containing solution. Hence, there are many ways in whichthe method may be advantageously used and it may be avoided to completely dissolve the lignin and thus avoiding suspending and re-precipitating of solid lignin.
    The solid state material to be used have preferably been prepared and purified to mainlycomprise lignin such that the solid phase material have a lignin content above 80 %, morepreferably above 90 % and most preferably above 95 %. The method will work even if therelative amount of lignin is below 80 % but there is less risk for negative interference by undesired solid components if there is high purity of lignin in the solid phase.
    The solid starting material comprising lignin may for example be a filter cake which may beclassified as dry or wet as described above. What is considered to be dry or wet may of coursediffer. However, herein will the definitions as follows be used and a wet filter cake is defined ashaving a dry content of below 35 %, a semi-wet filter cake having a dry content from 35 % to 50%, a semi-dry filter cake having a dry content of above 50 % to 65 % and a dry filter cake havinga dry content above 65 %. The lignin must of course not be from a filter cake even though it iscommon. The same dry contents will be used also for classifying water content of lignin generally even if it's not in the shape of, or originates from, a filter cake.
    The use of lignin as a semi-dry or dry filter cake as starting material is in particular suitable if thelignin is needed to be stored or transported in order to reduce the weight and/or volume ofthelignin containing mass. The lignin may thereafter be mechanically treated and for example be inthe shape of small particles and/or larger blocks which are immersed in a solution, e.g. to forma slurry, or may be used as a continuous solid mass which is subjected to a through flow, e.g. a filter cake.
    The use of a wet filter cake as a starting material is in particular suitable if the odour reducingstep is a part of the pulping process or performed in association with the pulping process, e.g.in or in close vicinity to the pulping process plant. As is obvious, a wet filter cake will be easierto disintegrate, e.g. into small particles forming a slurry with the liquid solution, than a dry filtercake and it will thus be needed less work, or less time in the alcohol containing solution, inorder to extract or leach the undesired components comprised in the solid lignin, e.g. particles forming part of a slurry.
    The lignin may be mixed with the alcohol containing liquid solution in a reaction tank. The tankmay be provided with some arrangement for stirring or for circulating the solution in order toimprove the leaching or extraction process. ln a non-limiting example, the residence time mayfor example be from 10 minutes up to 2 hours. The residence time needed to achieve a desiredeffect is dependent on for example the size of the particles, the stirring, the purity of the ligninand concentration of alcohol in the solution/proportions of alcohol and lignin. The temperaturemay also affect the desired retention time. However, the process works perfectly well atnormal room temperature (18-25 degrees Celsius) but other temperatures could also be used.
    The process could for example include a heating of the slurry/solution up to a temperature between 50 and 90 degrees Celsius. Concerning the size ofthe solid lignin in the process tankmay it be between one extreme where one or several complete filter cakes are leached to the other extreme wherein the lignin is present as microscopic particles.
    After the alcohol treatment, the solution with solid particles, e.g. a slurry, is normallydewatered and filtrated such that there is a new filter cake built up, possibly followed by one or several drying steps.
    The alcohol treatment could also, in addition to or as an alternative, be used on a filter cakeand by forcing a alcohol containing liquid solution through the filter cake, e.g. in connection with washing or dewatering of the filter cake.
    The amount of alcohol to be used may be defined either as the concentration of alcohol in thesolution or the weight percentage of alcohol to lignin. ln general, rather small amounts ofalcohol is needed and a solution having 1% (w/w) ofalcohol may be enough. However, a higherconcentration may decrease the time needed for removing the undesired components and ifthere are other components present as solid particles or in the solution, these impurities mayinterfere with the process and higher concentrations may be desired. Hence, it may be desiredto use concentrations above 5 % (w/w) and even up to 30 %. Even though higherconcentrations also function very well and even better from the aspect of removing theundesired components, are such concentrations often disregarded due to cost aspects and alsoa possible lowered yield of lignin after the treatment due to the high alcohol concentration.However, there is no essential upper limit ofthe alcohol concentration from the aspect ofmaking the solution work in removing undesired substances from lignin. ln the other end of therange, very low concentrations also shows an effect and undesired components are removedeven if as low concentrations as 0,1 % (w/w) or lower is used. From 0,2 % there is a significantincrease in the efficiency and already above 0,5 % is the system working very efficient. Hence,concentrations of alcohol of at least 0,1 % (w/w) in the solution is applicable, more preferredare concentrations from 0,2 preferred and for industrial use are appropriate concentrations inthe interval of 0,1 to 30 % (w/w), preferably between 0,2 to 20 % (w/w) and in most cases is 0,5 - 10 % (w/w) desired.
    The amount of alcohol could also be defined in relation to the amount of lignin to be treated.Low concentrations ofthe alcohol containing solution may not be appropriate to use if the totalamount of lignin is comparatively high to the amount of solution used, in particular if the solidphase lignin is of low purity and the process may be disturbed by contaminants. ln general, it isdesired to have a proportion of alcoholzlignin in which the amount of alcohol is more than11200, in general more than 1:10O and in most cases more than 1:50. A suitable proportionwhich is used with adequate results is 1:10. There may of course be even higher concentrationsand a proportion of 1:3 or even 1:1 may work efficiently but in general is it desired to keep therelations lower in order to reduce the amount of alcohol used in order to reduce costs andunnecessary additional processing time in regaining the acid. By using a proportion ofalcoholzlignin in which the amount of alcohol is less than 1:3 will in general provide for anextraction ofthe odorous substances while lignin in itself is not affected too much. Thus, ligninis substantially not fractionated due to alcohol addition and a high yield of lignin can still be obtained.
    The alcohol is preferably a C1-C4 alcohol, e.g. methanol, ethanol, propanol or butanol. Highercarbon chain alcohols may also be used but are generally considered to be less common to usedue to the reason they are in general less common and more expensive. However, they wouldalso work in the same way if used in the process and reduce the amount of undesired substances.
    To provide a product useful in different applications, the method can further comprise the steps of: 0 dewatering and/or filtrating the solid lignin;0 washing the solid lignin; and0 drying the solid lignin.The dried lignin from can thus be used as such for different applications such as filler for building and construction materials, also aimed for in-house applications due to the reduced or eliminated odour.
    The lignin containing starting material to be treated can be lignin isolated from black liquor in an alkaline chemical pulping process. The black liquor can be soda or kraft black liquor.
    The lignin containing starting material can be obtained from a process comprising the steps of: a) precipitating lignin by acidifying black liquor obtained from the alkaline chemical pulping process; b) dewatering and/or filtrating the obtained lignin to provide a filter cake; c) re-suspending the lignin; d) adjusting the pH of the obtained suspension in step c) to a pH lower than 6; e) dewatering and/or filtrating the acidic suspension from step d) to provide a filter cake;and f) washing and dewatering the filter cake.
    Preferably, pH in step d) is adjusted to be lower than 4, such as equal with or lower than 3.5,e.g. 2-2.5, so that as much lignin as possible is re-suspended and thus a high yield and good filtration properties in the following filtration operations e) and f) can be obtained.
    Prior to the step a), the process may comprise a pre-step in which black liquor is fractionated byfiltration by for example membrane filtration such as micro- and ultra-filtration. By themechanical separation it is possible to separate for example particulate material,hemicelluloses and/or it is possible to mechanically fractionate lignin and to obtain a specificfraction of lignin. ln this way it is possible to obtain at least partially purified starting materialand/or lignin fraction while high yield can be obtained since lignin is not substantiallychemically affected. Another way to achieve fractions of lignin is a fractionation by means of different pH levels and select lignins from a certain pH-window for further processing.
    Herein, by a filter cake is meant a filter cake comprising or consisting of lignin. The washed filtercake can be directly used in step i) above, and the method of producing lignin with reducedodour, i.e. the odour-treatment, can be integrated into the process for obtaining lignin fromblack liquor. ln this way energy savings are possible, since lignin needs not to be dried beforethe odour treatment. However, it is also possible to dry the lignin as a last step in the process for obtaining lignin, wherein the process further comprises the step of:g) drying the filter cake By dewatering and drying the filter cake it will be easy to transport and thus for example the odour treatment can be made in another factory.
    To further increase odour reduction the process for obtaining lignin, also called for ligninseparation or isolation process, can also comprise the step of adding a alcohol prior to, duringor after precipitation in step a), and/or adding a alcohol prior to, during or after at least one ofthe dewatering and/or washing steps b), e) and f) to reduce the amount of odorous substances.lt is in particular adequate to add alcohol at some time after the pH-adjusting step, either in anyof the steps e or f in the lignin obtaining process or in an additional step or process after thesesteps. The alcohol may suitably be used together with acids such as sulfuric acid in steps e) andf). By the addition of alcohol during the lignin separation, the odour reduction may be furtherimproved. lt could also be possible to use a carboxylic acid in this step, e.g. methanoic acid or ethanoic acid, which could improve the removal of undesired, odorous substances in the lignin.
    The alcohol can be added in the process in an amount as previously disclosed. From the point ofview of desiring a high yield of lignin, whereby lignin not is severely affected, and essentially nofractionation of lignin is occurred may the higher ranges ofthe intervals for the alcoholconcentration be avoided while from the point of view of extracting undesired content in thelignin may it be desired to avoid the lower ranges of the alcohol concentrations disclosed.Hence, depending on the desired yield and purifying efficiency could a suitable alcohol concentration be selected. ln step i) may suitably be used lignin obtained from kraft pulping process. Kraft pulping processhas been found to be especially suitable for lignin separation, as disclosed e.g. by "Tomani, Per; The Lignoboost Process; Cellulose Chem Technol., 44(1.-3), 53-58 (2010).
    The present method of producing lignin with reduced amount of odorous substance have beentested to result in yield which is over 80%by weight, based on the weight of the isolated ligninbefore the treatment, and even over 85%. Thus, the method leads only to minor material losses.
    The odorous substances that are extracted with the present method comprise at least guaiacolor etylguaiacol, but preferably also any residual content of at least one of dimethylsulphide,dimethyldisulphide, dimethyltrisulphide, dimethyltetrasulphide, and other phenoliccompounds. ln tests has the content of guaiacol or etylguaiacol been used to verify the functionality of the cleaning process These substances cause very bad odour which has made lignin products difficult to use inindoor applications. Also other odorous substances, e.g. organic substances having lowconcentrations, can be extracted by means of the present method. The concentration oftheodorous substances has been proved to be reduced by at least 50%, the concentration beingcalculated from a peak area of a respective peak in a chromatogram. Preferably, the concentration of the odorous substances is reduced by at least 70%.
    The method also preferably comprises at least partially recirculating the alcohol back intoprocess and thus cost savings can be obtained while the process can be made more environmentally friendly. ln an advantageous embodiment is the alcohol used ethanol. A water solution with ethanoleffectively dissolves organic malodorous substances, and especially guaiacol dissolves better in ethanol than in other alcohols whereby the use of ethanol is especially advantageous.
    The present invention also relates to a lignin product with reduced odour obtained and/orobtainable by the above-defined method. The method enables a yield of the obtained ligninwhich is more than 80% by weight, based on the weight ofthe lignin containing startingmaterial. Also, the concentration ofthe odorous substances in the obtained lignin product is atleast 50% less and preferably less than 70% than in a corresponding untreated lignin, theconcentration being calculated from a peak area of a respective peak in a chromatogram. Thus, the odour problems in connection with lignin products have been reduced substantially.
    The present invention also relates to a use of the lignin product as defined above as acomponent in polymer blends, additive or filler in building materials; as binding agent inadhesives, and/or for the production of a carbon fibre. The lignin product can also be used inbuilding and construction materials that are intended for use indoors. Further application areasare for example manufacturing of fibre boards, car panels, as a cross-linking agent in vehicletyres, as antioxidants and as UV-protectors. The application areas are not limited to the above- mentioned areas, other application areas are possible.
    Further objects, features and advantages of the present invention will be described with reference to the detailed description below and to the appended drawings.
    BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a flow chart illustration ofthe method according to the invention; Fig.2 shows a flow chart illustration of an example method according to the presentinvention; and Fig. 3 shows a flow chart illustration of a process for lignin isolation; Fig.4 shows how the inventive addition of alcohol, here in form of EtOH, may be added already into the LignoboostW' process.
    DETAILED DESCRIPTION ln the method of the present invention, which is schematically illustrated in a flow chart in Fig1, is lignin treated to obtain a lignin product with reduced odour. By "lignin" is meant any lignin,which may be pure lignin or lignin with small amounts of impurities, and with a dry mattercontent above 50% and more than 50% of this dry matter content being lignin, also refered toisolated lignin. According to the present method, the amount or concentration of the odoroussubstances can be reduced in lignin products while it is possible to obtain high yield of lignin.The less odorous or substantially odourless lignin product can be used in a wide range of applications including indoor applications which is a huge advantage.
    Lignin to be treated by the present method is according to one aspect obtained as a by-productfrom an alkaline chemical pulping process. The alkaline chemical pulping process may besulphate, also called kraft, process or soda process. Both processes result in alkaline material bycooking the fibre-based material in white liquor at a cooking temperature of from about 130-200'C to make lignin soluble in the cooking liquor. White liquor is a mixture of sodiumhydroxide and sodium sulphide. By black liquor is meant the cooking liquor obtained duringcooking from the alkaline chemical pulping process. Black liquor contains residues ofwhiteliquor and other pulping chemicals, lignin, hemicelluloses and other extractives from the fibre-based material. Even though the process is exemplified by the above processes may ligninisolated by any process be used in this method, in most cases could the lignin also be treated during the process itself. 11 The fibre-based material from which the isolated lignin is extracted can be softwood, hardwoodor non-wood, such as annual plants. The softwood tree species can be for example, but are notlimited to: spruce, pine, fir, larch, cedar, and hemlock. Examples of hardwood species fromwhich pulp useful as a starting material in the present invention can be derived include, but arenot limited to: birch, oak, poplar, beech, eucalyptus, acacia, maple, alder, aspen, gum trees andgmelina. Preferably, the fibre-based material mainly comprises softwood. The fibre-basedmaterial may comprise a mixture of different softwoods, e.g. pine and spruce. The fibre-basedmaterial may also comprise a non-wood raw material, such as bamboo and bagasse. The fibre-based material may also be a mixture of at least two of softwood, hardwood and/or non-wood.Hence, the origin of the lignin is of less importance and the method should be useful for any lignin regardless of its origin.
    The amount of odorous or odour containing substances can be reduced in the lignin product bymeans of extracting. Especially, organic malodorous substances can be extracted by the presentmethod. Extracting is suitably selective, meaning that substantially mainly the odorous or odourcontaining substances are extracted. The extraction is obtained by means of the addition ofalcohol to a water solution, slurry or a solid body comprising lignin. The odorous substances areextracted in or leached by alcohol, e.g. methanol, ethanol, propanol or butanol, in order toremove odorous substances from the lignin. ln general, Cl-C4 alcohols are considered mostsuitable for this process. The amount ofthe alcohol to be added should be kept at a sufficientlylow level to avoid that lignin is seriously affected. ln general, the amount of alcohol to be addedis less than 30%, and the amount may suitably be 0.2 to about 20%, based on the dry weight oflignin. As previously discussed, the amount of alcohol could be decided based on the desiredlevel of purification and not use more than needed to reach this level. The alcohol including theextracted odorous substances is removed from the process and optionally recirculated at leastpartly back in the process.
    Reference is now made to Fig. 2 in which a process involving the method of the presentinvention is schematically illustrated more in detail The lignin is preferably slurried in water in stage i), and thereafter is alcohol (EtOH) added in step ii), However the method also works if alcohol is mixed into the water before adding to the 12 lignin. ln step iii) may also optionally carboxylic acid (HAc) and/or sodiumsulfite (NazSOg) beadded to the water or lignin slurry. The method may comprise a maturing period of desiredlength that should last for at least 5 minutes, preferably at least 30-60 minutes, or even longerif sufficient storage volume is available. .The maturing period can be adjusted by the skilledperson to different processes and needs. Depending on the state of the lignin, the maturingmay be desired to continue for different times. ln case the lignin is dissolved in a solution ashorter time may be needed compared to if the lignin is present as particles, e.g. from adissolving a wet filter cake. ln case the lignin is present as even larger entities, e.g. as a solid,dry filter cake or larger particles, could even longer time be desired to partly disintegrate thelarger entities and/or allowing the alcohol solution to be better soaked into the solid matterand enable a more efficient leaching operation.
    After leaching is the slurry dewatered obtaining a lignin product with less odour, and explicitlywith a substantial reduction in guaiacol and/or etylguaiacol.
    However, in most applications the lignin needs to be transported so that lignin can be used indifferent applications and solid lignin, either re-precipitated or present as solid matter in theextraction/leaching operation from the process, may thus be subject for dewatering andpossibly filtering, washing and drying if desired. As further illustrated in Fig. 2, the method canthus comprise a step iv) in which lignin in the form of a filter cake is dewatered and/or filtrated.Dewatering can be performed by any means to withdraw water. For example, the dewatering isperformed by using centrifugation, a filter press apparatus, a band filter, a rotary filter, such asa drum filter, or a sedimentation tank, or similar equipment. Filtration can be performed byusing any conventional apparatus suitable for filtration, such as filter press or a band filter. Thefiltrate from the dewatering step can be re-circulated to a recovery system, and the alcohol canbe further recirculated back in the process. Subsequent to dewatering and/or filtration, theobtained lignin in the form of a filter cake is washed in step v). Washing can be performed byusing water and/or small amounts of alcohol, e.g. 0,5-10% by weight based on the weight oflignin, such as ethanoic acid. Also during the wash, it is advantageous ifthe pH is kept acidic,such as from pH 1.5 to pH 5, preferably from pH 1.5 to pH 3.5. ln this way the yield of lignin canbe further increased. After washing, the obtained filter cake is dried in step vi) and a final lignin product with reduced odour is obtained. 13 Lignin to be treated according to the present invention can be obtained from a process forseparation or isolation of lignin which is illustrated in the flow chart of Fig. 3, and which is alsocommercially called for LignoBoostW' process, and Fig.4 illustrates how the Lignoboost processmay be boosted by optionally adding alcohol in differing process positions. ln step a) oftheprocess lignin is precipitated by acidifying black liquor obtained from an alkaline chemicalpulping process. The chemical process is preferably kraft process. . Acídifyíng can be performedby any means suffícient to acidify black liquor. Preferably the acidifying is performed by addingC02 to said black liquor in a carbonating stage. Carbon dioxide is the preferred alternative sincethis acid may be obtained from the pulp mill in form of exhaust gases from the lime kiln. Byusing carbon dioxide in step a) so as to acidify the black liquor approximately to a pH between11.5 and 9, normally around pH 10, a lignin product can be obtained, and the filtrate obtainedfrom subsequent dewatering is still alkaline and may be sent to the black liquor evaporationtrain in the recovery island without changing the pH level of the black liquor flow to saidevaporators. ln stage ( c ) is the dewatered lignin filter cake (still alkaline) resuspended in an acidic slurryusing H2SO4.
    The lignin product can be used as fuel or for the production of chemicals and has reasonablylow ash content and a low tendency to cause corrosion.
    Prior to step a), the process optionally comprises a pre-step in which black liquor can befiltrated for example by membrane filtration. By this mechanical separation it is possible toseparate for example particulate material, hemicelluloses and/or it is possible to mechanicallyfractionate lignin and to obtain a specific fraction of lignin. Another way to achieve fractions oflignin is fractionation by different pH levels and select lignins from a certain pH-window forfurther processing. ln this case may of course alcohols also be used which may improve the overall efficiency in removing odorous substances from the lignin. ln the step b) as illustrated in the flow chart, the obtained lignin is dewatered and/or filtrated ina first dewatering and/or filtration step. Also in this connection the dewatering may beperformed by any means to withdraw water, for example by using centrifugation, a filter pressapparatus, a band filter, a rotary filter, such as a drum filter, or a sedimentation tank, or similar equipment. For example, when using a filter press apparatus the filter cake obtained through 14 dewatering may be blown through by gas or a mixture of gases, preferably compressed air inorder to dispose ofthe remaining liquid, such as black liquor, before resuspending the obtainedcake as set out in step c). The filtrate from the dewatering step can be re-circulated to the pulpmill black liquor recovery system. The pH level adjustment before dewatering/filtration, madeby addition of acid preferably C02 (g), can be combined with an adjustment of ion strength,preferably by using alkali metal ions or multivalent alkaline earth metal ions, most preferredcalcium ions. Higher ion strength gives at a given pH lower yield losses of lignin as the ligninbecomes more stable. Even though it is a dewatering step could small amounts of alcohol be used during this step, e.g. in the end of or after the dewatering step.
    As the first LignoboostW' product produced was in form of fuel pellets, a reduction of inorganiccontent was needed as such content could cause corrosion in power boilers. Thus, the step c)comprises re-suspending the lignin to form an acidic suspension by adding H2SO4. Generally, bya suspension is meant a heterogeneous mixture containing liquid-and small solid particles, suchas about 1 pm or larger. The particles in the suspension are able to settle whereby it is possibleto obtain a filter cake. Also in this step could alcohols be used to increase removal of odorous substances. ln the step d), the pH level is preferably adjusted to below approximately pH 6, and suitablybelow approximately pH 4, and preferably below 3.5, e.g. 2-2.5. The pH level is preferably frompH 1.5 to pH 3.5 to ensure that substantially all lignin is re-suspended and to give good filtrationproperties in the following dewatering filtration step. lt is also important in order to isolate alignin with low content of inorganics. Acidifying can be performed with the same chemicals asin connection with acidifying black liquor and as described above. Alcohols could thus be used herein, possibly together with other acids.
    After acidifying, a second dewatering and/or filtration step e) is performed similarly as the above-defined step b). Alcohol could be used also during this step. ln step f), the obtained filter cake is washed and the washing liquid, such as acidified water, canhave a pH level of below approximately pH 6, preferably below approximately pH 4. The pHlevel is most preferred a pH from 1.5 to 3.5. The washing liquid is dewatered and in one 10 embodiment ofthe invention, the obtained filter cake is treated with the method steps |)-iii) without drying the filter cake before the treatment. This step is suitable to be performed in the presence of alcohols in the washing liquid. ln general, the positive effect of using alcohol treatment in the process above defined by steps a) to f) is probably most efficient if it is used in connection with steps e) and f).
    According to another embodiment the method further comprises the step g) of drying the filter cake, whereby the filter cake can be easily e.g. transported.
    The filter cake obtained from the final dewatering step above, in connection with the methodof treating lignin to reduce odorous substances, either dried in the optional drying step g) or not, may thus be used for the alcohol treatment described in figures 1 and 2. lt is to be notedthat the acidic reslurrying in stage c and d in the Lignoboost process do not effectively reduce content of guaiacol or etylguaiacol.
    With the present method of producing lignin with reduced amount of odorous substances it ispossible to obtain high yield, such as over 80% by weight, based on the weight of the isolatedstart lignin. Even higher yields are possible, such as over 85% and up to about 90-95%. Thus, themethod leads only to a minor material loss which is a major advantage. The high yield can beobtained due to the fact that the extraction method is rather moderate meaning thatsubstantially no fractionation ofthe lignin occurs due to odour reduction process. I/|ainly onlyodorous substances, especially organic odorous substances, are extracted. The odoroussubstances that are extracted with the present method comprise at least guaiacol andetylguaiacol but also one of dimethylsulfide, dimethyldisulphide, dimethyldisulphide,dimethyltetrasulphide, and other phenolic compounds. These substances lead to malodourousgases which have made lignin products difficult to use in indoor applications. The concentrationof the odorous substances may be reduced by at least 50%, the concentration being calculatedfrom a peak area of a respective peak in a chromatogram. Preferably, the concentration oftheodorous substance is reduced by at least 70%. Thermogravimetry analysis (TGA) of the ligninproduct produced by the present process shows that the lignin is essentially not affected by thepresent process. This further supports the conclusion of the present invention that the present process is gentle towards lignin, while the odorous substances can be reduced effectively. 16 Due to the obtained odour reduction, the lignin product is possible to use in many applications.For example lignin can be used as a component in polymer blends, an additive or filler inbuilding materials, as binding agent in adhesives, and/or for the production of a carbon fibre.The lignin product can also be used in building materials that are intended for use indoors.Further application areas are for example manufacturing of fibre boards, as a crosslinking agentin vehicle tyres, as antioxidants and as UV-protectors. The application areas are not limited to the above-mentioned areas, other application areas are possible.
    The invention is further described in the following example.
    Examgle Similar test has been performed as detailed in previously filed SE1451641-3(herebyincorporated by reference), having a filing date of Dec 22, 2014. ln SE1451641-3 has beentested to clean lignin obtained from the LignoBoostW' process, using a process where the ligninis first dissolved in an alkaline solution, adding a 1% (on weight) of EtOH, followed by an additional acidification until lignin precipitates again. ln the tests performed according to the invention, but without dissolving the lignin by analkaline charge and subsequent acidification for precipitation, is the same Lignoboost ligninsimply leached in a water solution with a small charge of EtOH (1% on weight) reaching areduction of guaiacol in the same order as with the cleaning tests of SE1451641-3. This withoutextra charge of alkali for dissolution of the lignin, and extra charge of acidifier to precipitatelignin again. Thus a rather modest charge of 10% EtOH and an addition of 0,1% sodiumsulfite ina water solution obtains a yield of over 90% odour free lignin, and the leaching do not affectthe physical, chemical or mechanical properties of the odour free lignin produced. Thesurprising finding that a simple water leaching with a modest charge of alcohol provides thesame effect as the more complicated process outlined in SE1451641-3 is not fully understood,but the mechanisms may be related to that the guaiacols are bound in small lignin particles or chemically bound to the lignin chains.
    权利要求:
    Claims (6)
    [1] 1. Method for treatment of lignin in order to reduce odour from the lignin characterized in thatsaid method comprise the steps of: 0 providing a lignin containing starting material to be contacted with a watersolution comprising alcohol; 0 dissolving at least guaiacol and etylguaiacol content from the lignin into thewater solution, and 0 draining off the water solution with its content of guaiacol and etylguaiacol;0 obtaining a lignin material with a reduced content guaiacol and etylguaiacol. A method according to claim 1 wherein wherein the lignin containing startingmaterial has a dry matter content above 50 percent, and a lignin content of thisdry matter content exceeding 50%. A method according to claim 1 wherein the lignin containing starting material ismixed with water and alcohol in any order of mixing, and the resulting mixture isallowed to mature during a residence time of at least 5 minutes before drainingoff the water solution. A method according to claim 1 wherein the lignin containing starting material issubjected to a displacement wash using the water solution comprising alcohol. A method according to any preceding claims wherein the content of alcohol in the water solution is in the range of 0,1-50% by weight based on the lignin dry weight. A method according to claim 5 wherein the content of alcohol in the watersolution is in the range of 0,5-10% by weight based on the lignin dry weight. A method according to claim 6 wherein the content of alcohol in the watersolution is below 5% by weight based on the lignin dry weight. A method according to any preceding claims 5-7 wherein the alcohol contentpreferably is ethanol or alternatively any of methanol, propanol or butanol. A method according to any of preceding claims wherein the lignin containingstarting material is obtained from a process comprising the steps of: a. precipitating lignin by acidifying black liquor obtained from the alkalinechemical pulping process; b. dewatering and/or filtrating the obtained lignin to provide a first filtercake; 10. 11. 1
    [2] 2. 1
    [3] 3. 1
    [4] 4. 1
    [5] 5. 1
    [6] 6. 18 c. re-suspending the lignin; d. adjusting the pH of the obtained suspension in step c) to a pH lower than6; e. dewatering and/or filtrating the acidic suspension from step d) to providea second filter cake; and f. washing and dewatering the second filter cake, whereby the lignincontaining starting material is obtained. A method according to any previous claim wherein said alcohol containing liquidphase solution also comprises a carboxylic acid. A method according to any previous claim characterised in that the alcoholcontaining liquid phase solution is used in a method for obtaining lignin from blackliquor in an alkaline chemical pulping process. A method according to any previous claim characterised in that the alcoholcontaining liquid phase solution also comprises another acid. Lignin product obtained and/or obtainable by the method according to any one ofclaims 1-12. Lignin product according to claim 13, wherein the yield of the obtained lignin ismore than 80% by weight, preferably more than 90 %, based on the weight of theisolated lignin before steps |)-iii). Lignin product according to claim 13 or 14, wherein the concentration oftheodorous substances in the obtained lignin product is at least 50% less than in thelignin containing starting material, the concentration being calculated from a peakarea of a respective peak in a chromatogram. Use of the lignin product according to any of claims 13-15 as a component inpolymer blends, an additive or filler in building and construction materials, asbinding agent in adhesives, and/or for the production of a carbon fibre.
    类似技术:
    公开号 | 公开日 | 专利标题
    US10882879B2|2021-01-05|Method of producing lignin with reduced amount of odorous substances
    US9617393B2|2017-04-11|Method of producing lignin with reduced amount of odorous substances
    US20180305502A1|2018-10-25|Method for making a lignin component, a lignin component and its use and a product
    Hubbe et al.2019|Lignin recovery from spent alkaline pulping liquors using acidification, membrane separation, and related processing steps: A review
    JP5894594B2|2016-03-30|Method for producing precipitated lignin from black liquor
    US10035957B2|2018-07-31|Method for treating lignin-based material
    EP3724394B1|2022-03-16|Multi-step process for the isolation of components from miscanthus
    US20200377539A1|2020-12-03|Method of producing lignin with reduced amount of odorous substances
    CA2829438A1|2014-06-28|Lignin precipitation methods
    WO2013002708A1|2013-01-03|Method for purifying lignin
    US11091564B2|2021-08-17|Methods for producing a manure-derived bioplastic and bioproducts
    FI126765B|2017-05-15|A process for the preparation of a lignin component, a lignin component and its use, and a product
    FI127583B|2018-09-28|A method for making a lignin component, a lignin component and its use and a product
    同族专利:
    公开号 | 公开日
    BR112018071990A2|2019-02-12|
    CA3021990A1|2018-01-04|
    EP3475342B1|2020-12-02|
    EP3475342A1|2019-05-01|
    US20200109157A1|2020-04-09|
    US10882879B2|2021-01-05|
    EP3475342A4|2020-03-25|
    WO2018004427A1|2018-01-04|
    SE540485C2|2018-09-25|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US296935A|1884-04-15|Gael febdinand dahl |
    US1856558A|1930-03-12|1932-05-03|Guy C Howard|Process of treating waste sulphite liquor|
    US2057117A|1933-03-28|1936-10-13|Marathon Paper Mills Co|Process of making vanillin|
    US2037001A|1934-07-18|1936-04-14|Northwest Paper Company|Alcoholic treatment of ligneous cellulosic material|
    US2104701A|1937-03-01|1938-01-04|Marathon Paper Mills Co|Process of making vanillin|
    US2166540A|1937-12-17|1939-07-18|Univ Minnesota|Alcoholic treatment of ligneous cellulosic material|
    US2405450A|1944-02-01|1946-08-06|Marathon Corp|Process for making low molecular weight lignin degradation products|
    US2744927A|1952-11-28|1956-05-08|Sonoco Products Co|Solvent extraction of black liquor|
    US3097988A|1958-11-12|1963-07-16|Sterling Drug Inc|Process for regenerating black liquor|
    US4265809A|1979-09-04|1981-05-05|Holsopple Dale B|Method of making epoxide-lignin resins|
    US4764596A|1985-11-05|1988-08-16|Repap Technologies Inc.|Recovery of lignin|
    US20030221804A1|2002-06-03|2003-12-04|Lightner Gene E.|Lignins derived from black liquor|
    US8172981B2|2004-09-14|2012-05-08|Lignoboost Ab|Separating lignin from black liquor by precipitation, suspension and separation|
    SE0402201D0|2004-09-14|2004-09-14|Stfi Packforsk Ab|Method for separating lignin from black liquor|
    CN101503431B|2008-02-04|2011-05-25|西南科技大学|Technology for extracting high purity lignin from pulping black liquor by organic carboxyl acid method|
    AT510812A1|2010-10-29|2012-06-15|Annikki Gmbh|METHOD OF OBTAINING LIGNIN|
    US9790641B2|2011-05-24|2017-10-17|Liquid Lignin Company, Llc|Process for treating lignin|
    EP3494256A4|2011-05-24|2020-03-18|Liquid Lignin Company, LLC|Process for treating lignin|
    JP2013035886A|2011-08-03|2013-02-21|Asahi Organic Chemicals Industry Co Ltd|Lignin, composition containing the lignin and method for producing the lignin|
    EP2597100A1|2011-11-28|2013-05-29|Annikki GmbH|Method for extracting low-molecular lignin |
    CA2858651C|2011-12-09|2021-01-26|Upm-Kymmene Corporation|A method for making a lignin component, a lignin component and its use and a product|
    FI127816B|2012-06-06|2019-03-15|Upm Kymmene Corp|A method for fractionating lignin|
    US20140186627A1|2012-12-28|2014-07-03|Weyerhaeuser Nr Company|Lignin in particulate form|
    EP2948590B1|2013-01-24|2019-05-08|Valmet AB|Method for producing high purity lignin|
    RU2661893C2|2013-01-25|2018-07-23|Рен Фьюэл К2Б Аб|Compositions of biomass materials for refining|
    FI126369B|2014-06-06|2016-10-31|Andritz Oy|Procedure for using lignin separated from black liquor as a blast furnace fuel|
    DE102014108841B3|2014-06-24|2015-05-28|Technische Universität Hamburg-Harburg|Process for deodorising lignin|
    US10053482B2|2014-11-19|2018-08-21|Clemson University|Solvent and recovery process for lignin|
    SE538572C2|2014-12-22|2016-09-20|Innventia Ab|Method of producing lignin with reduced amount of odorous substances|
    SE540485C2|2016-06-22|2018-09-25|Valmet Oy|Method of producing lignin with reduced amount of odorous substances|SE540045C2|2016-06-22|2018-03-06|Valmet Oy|Method of producing lignin with reduced amount of odorous substances, lignin product obtained by the method and use of the lignin product|
    SE540485C2|2016-06-22|2018-09-25|Valmet Oy|Method of producing lignin with reduced amount of odorous substances|
    SE543477C2|2018-09-07|2021-03-02|Valmet Oy|Method of producing lignin with reduced amount of odorous substances|
    FI20196119A1|2019-12-20|2021-06-21|Andritz Oy|A method of removing volatile compounds from a lignin-containing material, use of a distillation method, and a lignin-containing material|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1650898A|SE540485C2|2016-06-22|2016-06-22|Method of producing lignin with reduced amount of odorous substances|SE1650898A| SE540485C2|2016-06-22|2016-06-22|Method of producing lignin with reduced amount of odorous substances|
    EP17820646.2A| EP3475342B1|2016-06-22|2017-06-19|Method of producing lignin with reduced amount of odorous substances|
    US16/311,357| US10882879B2|2016-06-22|2017-06-19|Method of producing lignin with reduced amount of odorous substances|
    PCT/SE2017/050665| WO2018004427A1|2016-06-22|2017-06-19|Method of producing lignin with reduced amount of odorous substances|
    CA3021990A| CA3021990A1|2016-06-22|2017-06-19|Method of producing lignin with reduced amount of odorous substances|
    BR112018071990-0A| BR112018071990A2|2016-06-22|2017-06-19|method for treating lignin, lignin product, and use of a lignin product.|
    [返回顶部]