Patent Application
20180066116
This invention relates to methods for processing lignin-containing biomass and lignin compositions, typically derived therefrom.
Developing renewable sources of feedstocks based on biomass for making lubricants is an area of ongoing interest. Use of biomass as a feedstock source is attractive from a perspective of avoiding depletion of mineral oil and gas sources. However, a variety of challenges remain in developing technologies for harvesting and processing feeds derived from biomass.
U.S. Patent Application Publication No. 2011/0306429 describes grease compositions including poly-phenolic additives derived from plants. Tannin is noted as an example of a poly-phenolic compound derived from plants.
International Publication No. WO/2015/178771 describes methods for fractionating technical lignins using an extraction column. Material including technical lignins is packed into a column as the stationary phase while solvents are passed through the column to separate lignins from the remaining portion of the material.
In various aspects, technical lignin compositions are provided, and methods of forming such technical lignin compositions are also provided. The technical lignin compositions can include at least about 60 wt % phenolic polymers, at least about 75 wt % combined phenolic monomers and phenolic polymers, or a combination thereof. Additionally or alternately, at least about 50 wt % of the hydroxyl groups in the technical lignin composition comprising phenolic hydroxyl groups. Additionally or alternately, at least about 60% of the phenolic hydroxyl groups and/or phenolic ether groups can correspond to phenolic hydroxyl groups and/or phenolic ether groups in an ortho position relative to at least one substituent or to two substituents (e.g., a methyl substituent, an ethyl substituent, a methoxy substituent, a hydroxyl substituent, an ether sub stituent, and/or a combination thereof). Additionally or alternately, about 70% or less of linkages connecting benzylic units in the phenolic polymers and/or the technical lignin composition can correspond to linkages including an ether group or a carbonyl group. Additionally or alternately, about 50% or less of linkages connecting benzylic units in the phenolic polymers and/or the technical lignin composition can correspond to β-O-4 linkages. Additionally or alternately, the phenolic polymers and/or the technical lignin composition can comprise a ratio of aromatic carbons to aliphatic carbons, exclusive of methoxy groups, of at least about 2.3.
In some embodiments, the technical lignin compositions and/or the combined phenolic monomers and phenolic polymers can comprise an effective hydrogen index of about 1.0 or less. In some embodiments, the technical lignin compositions can comprise about 5.0 wt % or less of sugars. In some embodiments, in the technical lignin compositions, about 30 wt % or less (or about 20 wt % or less or about 10 wt % or less) of the phenolic polymers comprise natural lignins. In some embodiments, at least about 60 wt % (or at least about 70 wt % or at least about 80 wt %) of the phenolic polymers comprise technical lignins and/or at least about 60 wt % (or at least about 70 wt % or at least about 80 wt %) of the phenolic polymers comprise pyrolytic lignins. In some embodiments, about 50% or less of linkages connecting benzylic units in the phenolic polymers and/or in the technical lignins comprise an ether group or a carbonyl group.
In some embodiments, the technical lignin compositions may comprise or be pyrolytic lignins formed according to a method comprising: pyrolyzing a biomass feed to form a pyrolysis product, at least a portion of which optionally comprising a pyrolysis oil; optionally fractionating the pyrolysis product to form a first fraction comprising phenolic monomers, phenolic polymers, or a combination thereof and a second lower boiling fraction; mixing at least a portion of the pyrolysis product with water to form a mixture; separating a water phase of the mixture from a second phase comprising the technical lignin composition; and optionally functionalizing at least a portion of the phenolic hydroxyl groups in the pyrolytic lignin composition, such as by performing alkylation and/or by performing a partial acetylation. In such embodiments, the water phase separation can comprise settling the mixture for a settling time to form the water phase and the second phase and separating the formed water phase from the second phase.
In various aspects, systems and methods are provided for forming pyrolytic lignin compositions comprising technical lignins from pyrolyzed biomass. The pyrolytic lignin compositions can comprise at least about 50 wt % phenolic polymers and/or at least about 75 wt % combined phenolic monomers and phenolic polymers. In some aspects, less than about 50 wt % of the linkages between benzylic units in the phenolic polymers and/or in the composition can correspond to β-O-4 linkages. At least about 50 wt % of the hydroxyl groups in the composition can correspond to phenolic hydroxyl groups. In some aspects, at least about 60 wt % of the phenolic hydroxyl groups can correspond to phenolic hydroxyl groups in an ortho position relative to at least one substituent (i.e., ortho to one substituent or ortho to two substituents). Additionally or alternately, at least about 60 wt % of the phenolic ethers in the phenolic monomers and/or polymers can correspond to ethers in an ortho position relative to at least one substituent.
Technical lignins refer to structures derived from lignin compounds in biomass. Natural lignins in biomass can correspond to compounds formed from aromatic (monomer) building blocks corresponding to syringyl alcohol, guaiacyl or conforyl alcohol, and coumaryl alcohol. Technical lignins can be formed from a variety of techniques, such as by hydrothermal processing, Kraft pulping, Organosolv™ extraction or pulping, sulfite pulping, and cellulosic bioethanol refining. In pulping processes, the primary product can correspond to purified cellulose fibers, with technical lignins formed as a side or residual product. Similarly, during hydrothermal processing, the primary product can correspond to a desired fuel boiling range product, with technical lignins formed as a side or residual product. Due to the severity of processes such as pulping processes and hydrothermal processing, technical lignins can correspond to compounds that have been chemically changed relative to the native lignins present in the biomass prior to processing. As a result, the monomers in a technical lignin may not correspond to the traditional monomers found in a natural lignin. The composition of the technical lignins can also vary depending on the nature of the process used to form the technical lignins.
The above methods for making technical lignins can relate to processes for treating biomass to separate of cellulose from other products. Another option for processing of biomass can correspond to methods involving pyrolysis. Pyrolysis of biomass can be used to convert at least a portion of biomass into fractions that may be suitable as substitutes and/or complements to mineral feeds in petroleum processing. Pyrolysis can also result in production of technical lignins as a side product, but conventionally such technical lignins, which can also be referred to as pyrolytic lignins, have been viewed as an undesirable product.
It has been determined that pyrolytic lignin compositions comprising technical lignins derived from pyrolysis of biomass can be suitable for use as antioxidant additives in, for example, lubricating oil compositions. In some aspects, a pyrolytic lignin composition can provide improved antioxidant properties relative to conventional antioxidants derived from mineral oil sources. In this discussion, a “technical lignin composition” or a “pyrolytic lignin composition” can refer to a composition including technical lignins (such as pyrolytic lignins). It is noted that a reference to technical/pyrolytic lignin composition can typically include compounds other than technical lignins. Due to the variety of types of technical lignins that can be present in a technical/pyrolytic lignin composition, such compositions are specified herein by specifying the nature of various components, compounds, and/or functional groups within a composition, such as characterization of phenolic polymers within a composition. Thus, identifying a technical lignin composition as described herein is not dependent on identifying whether particular compounds in a composition strictly meet the definition of a technical lignin.
In this discussion, a benzylic unit can correspond to an aromatic six-member carbon ring structure that is part of a larger compound. Because a benzylic unit is part of a larger compound, by definition a benzylic unit can be substituted at least once. A benzylic unit can be substituted with any convenient number of substituents, including non-aromatic ring substituents.
In this discussion, a phenolic polymer can correspond to a compound including a plurality of benzylic units having at least one hydroxyl substituent and/or at least one ether substituent that can provide a linkage to another benzylic unit. A phenolic monomer that is part of a phenolic polymer can correspond to a portion of a phenolic polymer including a single benzylic unit having at least one hydroxyl substituent and/or an ether substituent providing a linkage to another benzylic unit. A phenolic monomer that is a separate compound (i.e., not part of a phenolic polymer) can correspond to a compound including a single benzylic unit having at least one hydroxyl substituent. A hydroxyl substituent on a benzylic unit can be referred to as a phenolic hydroxyl substituent.
In this discussion, the terms “pyrolyze” and “pyrolyzing” can correspond to the act of converting a compound by pyrolysis. Pyrolysis can correspond to a process for conversion of a feed material into one or more products based on heating of the feed material. Optionally, reactions that can occur by heating in the presence of substantially reactive compounds (e.g., oxygen, hydrogen, sulfur-containing gases, and the like, but not including catalysts) to cause any significant degree of reaction involving (e.g., oxidation of) the feed material, such as by side reactions, can be substantially excluded during pyrolysis. The terms “thermolysis” or “thermal reaction” can be considered as synonyms for the term pyrolysis. According to the present invention, the term “torrefaction” can also be considered within the definition of pyrolysis.
The term “biomass,” for the purposes of the present invention, can correspond to any material not derived from fossil/mineral resources and comprising carbon, hydrogen, and oxygen. Examples of biomass can include, but are not limited to, plant and plant-derived material, algae and algae-derived material, vegetation, agricultural waste, forestry waste, wood waste, paper waste, animal-derived waste, poultry-derived waste, municipal solid waste, cellulose and cellulosics, carbohydrates or derivatives thereof, charcoal, and the like, and combinations thereof. The feedstock can also comprise pyrolyzable components other than biomass, such as fossil/mineral fuels (e.g., coal, crude or refined petroleum feedstocks, and the like, as well as combinations thereof).
Pyrolysis can be used to convert biomass into a composition including technical lignins.
In a fast pyrolysis reactor, biomass 102 can be fed to a pyrolyzer 104 where it can be contacted with a circulating heat transfer medium, typically a fine, hot sand 106, resulting in high heating rates, on the order of 1000° C./sec. Optionally, the heat transfer medium can include catalyst particles. Catalyst included as part of the heat transfer medium can correspond to catalyst for catalyzing the pyrolysis reaction, catalyst for hydrogenating or otherwise stabilizing the resulting pyrolysis products, or a combination thereof. Average temperatures at the outlet of the pyrolyzer are ˜500° C., with a typical residence time of less than two seconds. The biomass 102 can undergo thermal depolymerization of the lignin and cellulose molecules, resulting in a complex mixture of oxygenated organics following rapid cooling. The resulting pyrolysis effluent 109 can then be passed into a separator such as a cyclone 120 for separation of fluid pyrolysis products from solid particles. During pyrolysis, particles of the heat transfer medium (e.g., sand) can become entrained in the upward flow in the reactor. Additionally, particles of char can form during pyrolysis. The char can typically circulate with the sand back to the combustor 130 where it can provide the heat required to bring the sand back to the desired temperature for the pyrolyzer 104. After separation of particles from pyrolysis effluent 109, the fluid pyrolysis products can be passed through various additional types of separation stages. In
A wide range of feedstocks of various types, sizes, and moisture contents can be processed according to aspects of the present invention. Feedstocks that can be used in aspects of the present invention can comprise any hydrocarbon that can be thermally decomposed and/or transformed. Preferably, the feedstock comprises biomass, particularly biomass not typically processed or easily processable through chemical reactions. For example, the feedstocks can be comprised of at least 10 wt %, or at least 30 wt %, or at least 50 wt %, or at least 70 wt %, or at least 90 wt % biomass, such as up to 95 wt % or more, based on total weight of feedstock processed or supplied to the thermal or pyrolysis reactor. In particular, the feedstocks can be comprised of 10 wt % to 100 wt % biomass, or 10 wt % to 95 wt %, or 50 wt % to 100 wt %.
Additional or alternate examples of biomass that can be included as feedstock components include, but are not limited to, timber harvesting residues, softwood chips, hardwood chips, tree branches, tree stumps, leaves, bark, sawdust, off-spec paper pulp, corn, corn cob, corn stover, wheat straw, rice straw, sugarcane, bagasse, switchgrass, miscanthus, animal manure, municipal garbage, municipal sewage, commercial waste, grape pumice, almond shells, pecan shells, coconut shells, coffee grounds, grass pellets, hay pellets, wood pellets, cardboard, paper, plastic, cloth, and combinations thereof.
The biomass to be pyrolyzed may be ground prior to pyrolyzing. For example, the biomass can be ground in a mill until a desired particle size is achieved. In one embodiment, the particle size of the biomass to be pyrolyzed can be sufficient (with or without grinding) to pass through a 30 mm screen, for example a 20 mm screen, a 10 mm screen, a 5 mm screen, or a 1 mm screen, such as down to a 0.5 mm screen. In particular, the particle size of the biomass can be sufficient to pass through a 0.5 mm screen to a 30 mm screen, or 0.5 mm screen to a 20 mm screen, or a 0.5 mm screen to a 10 mm screen.
The example configuration shown in
In
As an example, overhead flow 229 can have a temperature of greater than about 300° C. (or greater than about 340° C.) when entering condenser 242. A pyrolysis oil product 248 can be generated along with a remaining portion passed into electrostatic precipitator 252. Condenser 242 can be operated so that the temperature of the remaining portion passed into electrostatic precipitator 252 can have a temperature of about 100° C. or greater. Electrostatic precipitator 256 can generate a pyrolysis oil product 258 and a remaining portion passed into condenser 262. Electrostatic precipitator 256 can be operated so that the remaining portion passed into condenser 262 can have a temperature of at least about 120° C. Thus, electrostatic precipitator 256 can generate a pyrolysis oil product 258 having a similar and/or overlapping boiling range with pyrolysis product 248, with pyrolysis product 258 potentially including a greater portion of pyrolysis effluent initially in the form of an aerosol. In this type of example, pyrolysis oil products 248 and 258 can correspond to pyrolysis oil fractions containing technical lignins.
The remaining uncondensed portion 290 of the pyrolysis effluent can correspond to a light ends type product containing CO, CO2, C4-hydrocarbons, and other similarly low boiling compounds. The uncondensed portion 290 can be further processed and/or used for any convenient purpose.
After performing pyrolysis of biomass, such as under fast pyrolysis conditions, the resulting pyrolysis products can be separated into a plurality of fractions.
After forming pyrolysis oil fractions, any desired pyrolysis oil fractions containing technical lignins can be further processed to separate a technical lignin composition from at least some other components of the pyrolysis oil. In particular, pyrolysis oil fraction(s) can be further processed to remove at least a portion of any sugars present in the pyrolysis oil fraction(s).
In some aspects, a process for separating sugar from a pyrolysis oil fraction can include washing the sample with water. Mixing with water can lead to precipitation and/or separation of lignins as an insoluble phase and/or an oil-based phase, while the sugars can be retained in an aqueous phase. For example, water can be added to a pyrolysis oil fraction in a convenient ratio. The ratio of water to pyrolysis oil can range from about 0.3 to about 3.0, or about 0.5 to about 3.0, or about 0.3 to about 1.5, such as about 1.0. The mixture of water and pyrolysis oil can then be stirred until the mixture is well mixed. The mixture can then be separated using a physical separation. As an example, the mixture can be allowed to settle for a period of time, followed by using a centrifuge to further separate a lower density portion and a higher density portion. The settling time can correspond to any convenient time, such as about 1 minute to about 24 hours or more, or about 0.5 hours to about 24 hours, or about 0.5 hours to about 10 hours. Optionally, the settling can be accompanied by mild shaking, such as by use of a shaking table, to facilitate settling. The settled mixture can be centrifuged for a convenient amount of time, such as about 1 minute to about 5 hours, or about 5 minutes to about 5 hours. The lower density portion can correspond to a primarily oil-based phase while the higher density portion can correspond to an aqueous phase. The aqueous phase can then be decanted off or otherwise removed from the mixture, leaving behind a washed oil-based phase with a reduced content of sugars. After removal of sugars, an oil-based phase and/or a pyrolytic lignin composition derived from an oil-based phase can have a sugar content of about 5.0 wt % or less, or about 1.0 wt % or less, such as down to about 0.1 wt % or less. In particular, the sugar content can be about 0 wt % to about 5.0 wt %, or about 0.1 wt % to about 5.0 wt %, or about 0 wt % to about 1.0 wt %.
A composition including pyrolytic lignins as described herein can have a variety of compositional features. In order to illustrate potential compositional features,
As an initial note, the structure in
The basic building block of a lignin can correspond to a phenolic monomer, which can correspond to phenol or a phenol derivative (including derivatives where the hydroxyl group of the phenol is converted to an ether). When two or more phenolic monomers are linked by a linkage, the resulting structure can correspond to a phenolic polymer. In some aspects, a pyrolytic lignin composition can comprise at least about 60 wt % of phenolic polymers, or at least about 70 wt %, or at least about 80 wt %, such as up to about 95 wt % or up to about 100 wt %. In particular, a pyrolytic lignin composition can comprise about 60 wt % to about 100 wt % of phenolic polymers, or about 60 wt % to about 95 wt %, or about 70 wt % to about 100 wt %. Additionally or alternately, a pyrolytic lignin composition can include both phenolic monomers and phenolic polymers. In some aspects, a pyrolytic lignin composition can comprise at least about 75 wt % of combined phenolic monomers and phenolic polymers, or at least about 85 wt %, or at least about 95 wt %, such as up to about 98 wt % or up to about 100 wt %. In particular, a pyrolytic lignin composition can comprise about 75 wt % to about 100 wt % of combined phenolic monomers and phenolic polymers, or about 75 wt % to about 98 wt %, or about 85 wt % to about 100 wt %.
The structure shown in
Benzylic units can be connected to each other by linkages. A linkage refers to any bonds and corresponding intervening atoms providing connectivity between two benzylic units.
It is noted that none of the linkages shown in
Another compositional feature shown in
In some aspects, at least about 60 wt % of the phenolic hydroxyl groups in the pyrolytic lignin composition can correspond to phenolic hydroxyl groups in an ortho position relative to at least one substituent (optionally two substituents), or at least about 70 wt %, or at least about 80 wt %, such as up to about 95 wt % or up to about 100 wt %. In particular, about 60 wt % to about 100 wt % of the phenolic hydroxyl groups can correspond to phenolic hydroxyl groups in an ortho position relative to at least one substituent, or about 60 wt % to about 95 wt %, or about 70 wt % to about 100 wt %. Additionally or alternately, in some aspects at least about 60 wt % of the phenolic hydroxyl groups in in technical lignins and/or phenolic monomers and/or phenolic polymers in the pyrolytic lignin composition can correspond to phenolic hydroxyl groups in an ortho position relative to at least one substituent (optionally two substituents), or at least about 70 wt %, or at least about 80 wt %, such as up to about 95 wt % or about 100 wt %. In particular, about 60 wt % to about 100 wt % of the phenolic hydroxyl groups can correspond to phenolic hydroxyl groups in an ortho position relative to at least one substituent, or about 60 wt % to about 95 wt %, or about 70 wt % to about 100 wt %. In some aspects, at least about 60 wt % of the combined phenolic hydroxyl groups and phenolic ethers in the pyrolytic lignin composition can correspond to phenolic hydroxyl groups and phenolic ethers in an ortho position relative to at least one substituent (optionally two substituents), or at least about 70 wt %, or at least about 80 wt %, such as up to about 95 wt % or up to about 100 wt %. In particular, about 60 wt % to about 100 wt % of the combined phenolic hydroxyl groups and phenolic ethers can correspond to phenolic hydroxyl groups and phenolic ethers in an ortho position relative to at least one substituent, or about 60 wt % to about 95 wt %, or about 70 wt % to about 100 wt %. Additionally or alternately, in some aspects at least about 60 wt % of the combined phenolic hydroxyl groups and phenolic ethers in technical lignins and/or phenolic monomers and/or phenolic polymers in the pyrolytic lignin composition can correspond to phenolic hydroxyl groups and phenolic ethers in an ortho position relative to at least one substituent (optionally two substituents), or at least about 70 wt %, or at least about 80 wt %, such as up to about 95 wt % or up to about 100 wt %. In particular, about 60 wt % to about 100 wt % of the combined phenolic hydroxyl groups and phenolic ethers can correspond to phenolic hydroxyl groups and phenolic ethers in an ortho position relative to at least one substituent, or about 60 wt % to about 95 wt %, or about 70 wt % to about 100 wt %. In some aspects, at least about 50 wt % (or at least about 60 wt %, or at least about 70 wt %, such as up to about 95 wt % or up to about 100 wt %) of the phenolic hydroxyl groups and/or phenolic ether groups can be ortho to a methyl substituent, an ethyl substituent, a methoxy substituent, a hydroxyl substituent, an ether substituent, or a combination thereof. In particular, about 50 wt % to about 100 wt %, or about 50 wt % to about 95 wt %, or about 60 wt % to about 100 wt % of the phenolic hydroxyl groups and/or phenolic ether groups can be ortho to a methyl substituent, an ethyl substituent, a methoxy substituent, a hydroxyl substituent, an ether substituent, or a combination thereof.
In the structure shown in
In a second hypothetical example, oxygen bonds 315, 335, and 365 can bond to terminating methyl groups, so that benzylic units 311, 331, and 361 can each include a methoxy substituent. The structure in
In various aspects, a pyrolytic lignin composition can be characterized based on effective hydrogen index (EHI). In some aspects involving pyrolytic lignin formed from relatively sulfur-free biomass (such as less than 500 wppm sulfur), effective hydrogen index for a phenolic monomer, a phenolic polymer, a technical lignin, and/or a composition can be determined based on the number of hydrogen, oxygen, nitrogen, and carbon atoms. The effective hydrogen index can be calculated based on the formula EHI=[H−(2O+3N)/C], where H, O, N, and C correspond to the respective number of hydrogen, oxygen, nitrogen, and carbon atoms in a monomer/polymer/lignin/composition. In other aspects involving pyrolytic lignin formed from biomass with a higher sulfur concentration, effective hydrogen index can be calculated based on the formula EHI=[H−(2O+2S+3N)/C], where H, O, S, N, and C correspond to the respective number of hydrogen, oxygen, nitrogen, and carbon atoms in a monomer/polymer/lignin/composition. In various aspects, the effective hydrogen index for a pyrolytic lignin composition, or for the phenolic monomers and/or phenolic polymers and/or technical lignins in a pyrolytic lignin composition, can be about 1.0 to about 0.5, or about 0.9 to about 0.6.
In some aspects, at least a portion of the phenolic polymers in a pyrolytic lignin composition can correspond to natural lignins. In some aspects, at least a portion of the phenolic polymers can correspond to technical lignins. For example, about 30 wt % or less, or about 20 wt % or less, or about 10 wt % or less of the phenolic polymers can correspond to natural lignins, such as down to about 2 wt % or down to about 0 wt %. In particular, about 30 wt % to about 0 wt % of the phenolic polymers can correspond to natural lignins, or about 30 wt % to about 2 wt %, or about 20 wt % to about 0 wt %. Additionally or alternately, at least about 60 wt %, or at least about 70 wt %, or at least about 80 wt % of the phenolic polymers can correspond to technical lignins, such as up to about 95 wt % or up to about 100 wt %. In particular, about 60 wt % to about 100 wt % of the phenolic polymers can correspond to technical lignins, or about 60 wt % to about 95 wt %, or about 70 wt % to about 100 wt %.
In some aspects, a pyrolytic lignin composition can be characterized based on the heteroatom class for the composition and/or double bond equivalents. Heteroatom class and double bond equivalents can be determined based on Fourier transform—inductively coupled resonance—mass spectrometry (FT-ICR-MS). Heteroatom class can provide a relative abundance of compounds within a composition based on the number and type of heteroatoms in the compounds. Double bond equivalents can refer to the number of hydrogens present at a given carbon number in a composition. It is noted that double bond equivalents can also reflect hydrogen deficiencies due to other reasons, such as the presence of ring structures and/or heteroatoms.
In various aspects, pyrolytic lignin compositions can belong to heteroatom classes corresponding to about 2 oxygens to about 16 oxygens, or about 2 oxygens to about 14 oxygens. At least about 70 wt % of a pyrolytic lignin composition, or at least about 80 wt %, or at least about 90 wt %, such as up to about 98 wt % or up to about 100 wt %, can correspond to compounds belonging to a heteroatom class corresponding to about 2 oxygens to about 16 oxygens, or about 2 oxygens to about 14 oxygens. In particular, about 70 wt % to about 100 wt % of a pyrolytic lignin composition can correspond to compounds belonging to a heteroatom class corresponding to about 2 oxygens to about 16 oxygens, or about 2 oxygens to about 14 oxygens, or about 70 wt % to about 98 wt %, or about 80 wt % to about 100 wt %. Optionally, at least about 70 wt % of a pyrolytic composition, or at least about 80 wt %, or at least about 90 wt %, such as up to about 98 wt % or up to about 100 wt %, can correspond to compounds belonging to a heteroatom class not including nitrogen atoms. In particular, about 70 wt % to about 100 wt %, or about 70 wt % to about 98 wt %, or about 80 wt % to about 100 wt % can correspond to compounds belonging to a heteroatom class not including nitrogen atoms.
A pyrolytic lignin composition can be suitable, for example, for use as an antioxidant additive, e.g., for lubricants and/or greases. Antioxidant capabilities of a pyrolytic lignin composition can be determined, for example, by blending a pyrolytic lignin composition with a lubricant or grease and then performing pressure differential scanning calorimetry (PDSC) on the sample, such as according to ASTM D6186. Pyrolytic lignin compositions can allow for increased times and/or temperatures before initiation of oxidation during a PDSC test.
The pyrolytic lignin compositions described herein can provide beneficial antioxidant properties, for example, when used as an additive for a lubricant or grease. In some aspects, a pyrolytic lignin composition may have limited solubility in a target lubricant or grease. One option for improving the solubility of a pyrolytic lignin composition can be to functionalize a portion of the phenolic hydroxyl groups in the pyrolytic lignin composition. This can increase the hydrophobicity of the pyrolytic lignin composition to improve solubility. An example a suitable process for increasing solubility can be partial acetylation of a composition. Other types of functional groups that can increase hydrophobicity can include, but are not limited to, alkyl groups and/or ester groups, such as alkyl groups and/or ester groups including about 2 to about 20 carbons, or about 2 to about 10 carbons.
Embodiment 1. A technical lignin composition comprising: at least about 60 wt % phenolic polymers, at least about 75 wt % combined phenolic monomers and phenolic polymers, or a combination thereof; at least about 50 wt % of the hydroxyl groups in the technical lignin composition comprising phenolic hydroxyl groups; at least about 60% of the phenolic hydroxyl groups comprising a phenolic hydroxyl group in an ortho position relative to at least one substituent; about 70% or less of linkages connecting benzylic units in the phenolic polymers comprising an ether group or a carbonyl group; and about 50% or less of linkages connecting benzylic units in the phenolic polymers comprising β-O-4 linkages; wherein at least one of the phenolic polymers and the technical lignin composition further comprises a ratio of aromatic carbons to aliphatic carbons, exclusive of methoxy groups, of at least about 2.3.
Embodiment 2. A method for forming a technical lignin composition, comprising: pyrolyzing a biomass feed to form a pyrolysis product; mixing at least a portion of the pyrolysis product with water to form a mixture; and separating a water phase of the mixture from a second phase comprising the technical lignin composition, wherein the technical lignin composition comprises: at least about 60 wt % phenolic polymers, at least about 75 wt % combined phenolic monomers and phenolic polymers, or a combination thereof; at least about 50 wt % of the hydroxyl groups in the technical lignin composition comprising phenolic hydroxyl groups; at least about 60% of the phenolic hydroxyl groups comprising a phenolic hydroxyl group in an ortho position relative to at least one substituent; about 70% or less of linkages connecting benzylic units in the phenolic polymers comprising an ether group or a carbonyl group; and about 50% or less of linkages connecting benzylic units in the phenolic polymers comprising β-O-4 linkages; wherein at least one of the phenolic polymers and the technical lignin composition further comprises a ratio of aromatic carbons to aliphatic carbons, exclusive of methoxy groups, of at least about 2.3.
Embodiment 3. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein at least about 60% of combined phenolic ether groups and phenolic hydroxyl groups comprise a phenolic ether group or a phenolic hydroxyl group in an ortho position relative to at least one substituent.
Embodiment 4. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein the technical lignin composition or pyrolytic lignin composition comprises an effective hydrogen index of about 1.0 or less; or wherein the combined phenolic monomers and phenolic polymers comprise an effective hydrogen index of about 1.0 or less; or a combination thereof.
Embodiment 5. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein the composition comprises about 5.0 wt % or less of sugars.
Embodiment 6. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein the at least about 60% of the phenolic hydroxyl groups comprise a phenolic hydroxyl group in an ortho position relative to two substituents; or wherein the at least about 60% of the combined phenolic ether groups and phenolic hydroxyl groups comprise a phenolic ether group or a phenolic hydroxyl group in an ortho position relative to two substituents; or a combination thereof.
Embodiment 7. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein the at least about 60% of the phenolic hydroxyl groups comprise phenolic hydroxyl groups in an ortho position relative to a methyl substituent, an ethyl substituent, a methoxy substituent, a hydroxyl substituent, an ether substituent, or a combination thereof; or wherein the at least about 60% of the combined phenolic ether groups and phenolic hydroxyl groups comprise phenolic ether groups and phenolic hydroxyl groups in an ortho position relative to a methyl substituent, an ethyl substituent, a methoxy substituent, a hydroxyl substituent, an ether substituent, or a combination thereof.
Embodiment 8. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein about 30 wt % or less of the phenolic polymers comprise natural lignins, or about 20 wt % or less, or about 10 wt % or less.
Embodiment 9. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein at least about 60 wt % of the phenolic polymers comprise technical lignins, or at least about 70 wt %, or at least about 80 wt %; or wherein at least about 60 wt % of the phenolic polymers comprise pyrolytic lignins or at least about 70 wt %, or at least about 80 wt %; or a combination thereof.
Embodiment 10. The technical lignin composition or the method of forming a technical lignin composition of any of the above embodiments, wherein about 50% or less of linkages connecting benzylic units in the phenolic polymers comprise an ether group or a carbonyl group; wherein about 50% or less of linkages connecting benzylic units in the technical lignins comprise an ether group or a carbonyl group; or a combination thereof.
Embodiment 11. The method of forming a technical lignin composition of any of Embodiments 2-10, wherein the at least a portion of the pyrolysis product comprises a pyrolysis oil.
Embodiment 12. The method of forming a technical lignin composition of any of Embodiments 2-11, further comprising fractionating the pyrolysis product to form a first fraction comprising phenolic monomers, phenolic polymers, or a combination thereof and a second lower boiling fraction.
Embodiment 13. The method of forming a technical lignin composition of any of
Embodiments 2-12, wherein separating a water phase of the mixture from a second phase comprises: settling the mixture for a settling time to form the water phase and the second phase; and separating the formed water phase from the second phase.
Embodiment 14. The method of forming a technical lignin composition of any of Embodiments 2-13, further comprising functionalizing at least a portion of the phenolic hydroxyl groups in the pyrolytic lignin composition, the functionalizing at least a portion of the phenolic hydroxyl groups optionally comprising performing alkylation, performing a partial acetylation, or a combination thereof.
Pyrolytic lignin compositions were prepared by two different methods. In a first method, pyrolysis was performed on biomass to form a pyrolysis oil. Water was added to the resulting pyrolysis oil in about a 1:1 ratio to form a mixture. The mixture was allowed to settle for about 30 minutes on a shaker table, followed by centrifugation at ˜2500 rpm for about 15 minutes. The top aqueous phase was then decanted off, leaving behind an oil-based phase. The oil-based phase was then extracted using dichloromethane to form a first composition (Pyrolytic Lignin Composition 1) that appeared to be soluble in dichloromethane and a second composition that appeared to be insoluble in dichloromethane (Pyrolytic Lignin Composition 2). It was believed that Pyrolytic Lignin Composition 1 includes a substantial portion of phenolic monomers, while Pyrolytic Lignin Composition 2 included a substantial portion of phenolic dimers and/or other phenolic polymers.
In another method, pyrolysis was performed on red oak biomass to form a pyrolysis oil. The pyrolysis oil was recovered using a fractionation system, such as a fractionation system similar to the configuration shown in
Pressure differential scanning calorimetry (PDSC) was used to investigate the antioxidant performance of Pyrolytic Lignin Compositions 1-4, relative to two commercially available antioxidant products. One comparative antioxidant was 2,6-di-tert-butyl-4-methylphenol (Reference 1). The other comparative antioxidant, thiobis(ethane-2,1-diyl)bis(3-(3,5-tert-butyl-4-hydroxyphenyl)propanoate corresponded to the structure shown in
For characterization, about 2 wt % of Pyrolytic Lignin Compositions 1-4 and the two comparative antioxidants were added to a commercially available mineral grease and a commercially available synthetic grease. Results from performing PDSC at ˜180° C. on the various samples are shown in
Pyrolytic Lignin Composition 4 was added to a mineral lubricant base oil in an amount of about 1.0 wt %. About 1.0 wt % of Reference 1 was added to another sample. The two samples were then tested using a Rotating Pressure Vessel Oxidation Test (RPVOT), according to ASTM D2272.
When numerical lower limits and numerical upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated. While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.
The present invention has been described above with reference to numerous embodiments and specific examples. Many variations will suggest themselves to those skilled in this art in light of the above detailed description. All such obvious variations are within the full intended scope of the appended claims.
This application claims the benefit of U.S. Provisional Application No. 62/383,815, filed on Sep. 6, 2016, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62383815 | Sep 2016 | US |
