Mixture Of Lignin Research Articles

Pyrolytic Reactions of Lignin within Naturally Occurring Plant Matrices: Challenges in Biomass Pyrolysis Modeling Due to Synergistic Effects

Systematically larger char yields were observed from the pyrolysis of chemically isolated lignins, compared to expected yields from the pyrolysis of lignins embedded in plant material. Naturally occurring lignins are known to be intermeshed with other plant constituents within the composite matrices of lignocellulosic biomass. An attempt was made to simulate their behavior by pyrolyzing pellets prepared from mixtures of lignin and cellulose powders. However, the results gave char yield trends that did not conform to trends observed when pyrolyzing plant derived biomass. These findings are interpreted in terms of entirely different reaction pathways operating when lignins are pyrolyzed within naturally occurring biomass, compared to “pure” lignins or composite particles made from mixtures of fine powders. It appears that char yield trends from the pyrolysis of lignocellulosic biomass are closely linked to the detailed morphology, as well as the chemical makeup, of the highly oxygenated plant derived materi...

Synthesis of soy protein–lignin nanofibers by solution electrospinning

Nanofibers were produced by electrospinning aqueous alkaline solutions containing different mass ratios of soy protein and lignin in the presence of poly(ethylene glycol) coadjutant, all of which presented shear thinning behavior. SEM revealed that the addition of polyethylene oxide as a coadjutant indeed facilitated the formation of defect-free fibers whose diameter increased with lignin concentration, in the range between ≈124 and ≈400nm. Favorable interactions between lignin and soy protein were identified from data provided by differential scanning calorimetry. In addition, an increased hydrogen bonding and the loss of secondary structure of the proteins as the lignin concentration increased were observed from the disappearance of amide II (∼1500cm−1) and III (∼1400–1200cm−1) bands and a red shift of amide I band in the FT-IR spectrum. The unfolding of the protein contributed to a better interaction with lignin macromolecules, which further improved the electrospinning process. It is concluded that mixtures of lignin and soy proteins, two major renewable resources with interesting chemical features, are suitable for the development of composite sub-micron fibers.

Curing kinetics of lignin and cardanol based novolac epoxy resin with methyl tetrahydrophthalic anhydride

Lignin and cardanol based novolac epoxy resin (LCNE) was prepared by reacting epichlorohydrin with the mixture of lignin and cardanol (2/3 in weight ratio). Kinetics of the curing reaction between LCNE and methyl tetrahydrophthalic anhydride (MeTHPA) was studied by differential scanning calorimetry (DSC) and model-free kinetic (MFK) analysis. The apparent activation energy (Ea) of the curing reaction was obtained from Friedman's model-free method. The kinetic model and other kinetic parameters were determined by Málek's method and the reaction process could be simulated favorably by Sestak–Berggren (SB (m, n)) model. Furthermore, the kinetic equation obtained from nonisothermal data was applied to predict the isothermal conversion processes of the crosslinking reaction. The results demonstrated the calculated data from the obtained kinetic equation matched perfectly with the isothermal experimental data.

Effects of lignin on the ionic-liquid assisted catalytic hydrolysis of cellulose: chemical inhibition by lignin

The production of cellulose-derived biofuels and biochemicals, such as bioalcohols and bioplastics, from lignocellulose requires the isolation of cellulose by lignin removal or delignification processes. While the remaining lignin and its phenolic fragments have been reported to inhibit the biological conversion of cellulose, we observed that the catalytic hydrolysis of cellulose also can be inhibited most likely because of an associative interaction between cellulose and lignin. The associative interaction between cellulose and the functional groups of lignin was proven by gel-permeation-chromatography measurement of regenerated mixtures of lignin and cellulose which simulate the lignocellulose-derived cellulose containing lignin as an impurity. Chemical bonds between cellulose and lignin were hypothesized using lignin model compounds containing known functionalities such as hydroxyl, methoxy, phenyl, allyl, and carboxyl groups in order to explain the effects of lignin on the hydrolysis of cellulose. The yield of glucose from cellulose dropped when carboxylic and hydroxyl groups were present possibly because of the formation of ether and ester bonds between the lignin and cellulose. These observations may help develop the chemical processes and therefore convert the inedible biomass resource of lignocellulose-based cellulose containing lignin and its derivatives to the valuable fuels and chemicals.

Toxicity of lignin, cellulose and hemicellulose-pyrolyzed bio-oil combinations: Estimating pesticide resources

Biomass contains varying proportions of lignin, cellulose and hemicellulose, and when pyrolyzed, a liquid bio-oil is produced that can be converted to fuels and value-added products such as biopesticides for insect pest management. The objective of this study was to determine which biomass components are responsible for the insecticidal activity of biomass bio-oil by comparing the individual toxicity (LC50) of lignin, cellulose and hemicellulose bio-oils with the toxicities of mixtures of lignin, cellulose and hemicellulose bio-oils to the Colorado potato beetle (CPB) (Leptinotarsa decemlineata Say). Lignin, cellulose and hemicellulose individually as well as in mixture were pyrolyzed at 550°C in a fluidized bed reactor with nitrogen as the fluidizing gas and silica sand as the bed material. Bio-oil collected from the reactor's condenser (aqueous and organic phases) and electrostatic precipitator (ESP) or demister pyrolyzed from the same biomass were combined proportionally on the basis of their respective yields. The different biomass components were mixed in equal proportions and then pyrolyzed to provide an artificial biomass bio-oil. Of the three individual component bio-oils, lignin was the most active and the ESP portion the most toxic compared to the other components and collections. Alone, it accounted for the majority of the insecticidal activity in the mixtures, but only the cellulose–hemicellulose bio-oil combination was determined to exhibit synergism. In contrast, the lignin–cellulose–hemicellulose bio-oil combination was determined to exhibit an antagonistic effect. Therefore, it is important to consider the type of biomass component or the proportion of lignin that makes up a particular biomass in order to produce a bio-oil for potential pesticide development.

Investigation of curing and thermal behavior of benzoxazine and lignin mixtures

AbstractThis article describes the synthesis and characterization of two types of benzoxazine monomers based on phenol or bisphenol, aniline, and formaldehyde. Their characterization was achieved by Fourier transform infrared, 1H‐nuclear magnetic resonance, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Lignin polymer was characterized by infrared, DSC, and TGA. The curing behavior of mixtures of benzoxazine monomers and lignin was investigated by DSC. The mass ratios of benzoxazine monomers/lignin of a series of samples were 100 : 0, 95 : 05, 90 : 10, 85 : 15, 80 : 20, 75 : 25, and 70 : 30. The results indicate that the maximum curing temperatures of the mixtures were lower than that of the pure benzoxazine monomers, and that they decreased with increasing contents of lignin in the mixture. The heat of polymerization (ΔH) of the benzoxazine monomers and lignin mixtures as a function of the mass ratio and the structure of the benzoxazine monomers shows no definite trend. The samples were cured according to the following conditions: 170°C/2h + 200°C/2h and analyzed by DSC and TGA. In all the samples, the glass transition temperature of the benzoxazines increased upon mixing with increasing amounts of lignin. The changes may be due to the formation of a more compact network structure in the mixtures. The thermal stability of the isothermally cured resins is found to be dependent on the mass ratio of benzoxazine/lignin and structure of the benzoxazine monomers. The more lignin in the mixture, the higher is the char yield in the mixture. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The use of natural abundance stable isotopic ratios to indicate the presence of oxygen-containing chemical linkages between cellulose and lignin in plant cell walls

Qualitative and quantitative understanding of the chemical linkages between the three major biochemical components (cellulose, hemicellulose and lignin) of plant cell walls is crucial to the understanding of cell wall structure. Although there is convincing evidence for chemical bonds between hemicellulose and lignin and the absence of chemical bonds between hemicellulose and cellulose, there is no conclusive evidence for the presence of covalent bonds between cellulose and lignin. This is caused by the lack of selectivity of current GC/MS-, NMR- and IR-based methods for lignin characterisation as none of these techniques directly targets the possible ester and ether linkages between lignin and cellulose. We modified the widely-accepted “standard” three-step extraction method for isolating cellulose from plants by changing the order of the steps for hemicellulose and lignin removal (solubilisation with concentrated NaOH and oxidation with acetic acid-containing NaClO 2, respectively) so that cellulose and lignin could be isolated with the possible chemical bonds between them intact. These linkages were then cleaved with NaClO 2 reagent in aqueous media of contrasting 18O/ 16O ratios. We produced cellulose with higher purity (a lower level of residual hemicellulose and no detectable lignin) than that produced by the “standard” method. Oxidative artefacts may potentially be introduced at the lignin removal stage; but testing showed this to be minimal. Cellulose samples isolated from processing plant-derived cellulose–lignin mixtures in media of contrasting 18O/ 16O ratios were compared to provide the first quantitative evidence for the presence of oxygen-containing ester and ether bonds between cellulose and lignin in Zea mays leaves. However, no conclusive evidence for the presence or lack of similar bonds in Araucaria cunninghamii wood was obtained.

The effects of dissolved solids on the vapor-liquid equilibrium of DMS in black liquor

Researchers determined activity coefficients for use in vapor-liquid equilibrium (VLE) calculations using a headspace gas chromatographic method for dimethyl sulfide (DMS) in water, kraft pulp mill black liquor, and sodium salts and alkali lignin mixtures up to 6 wt%, for temperatures of 20°C to 90°C. Experimental data were regressed to determine DMS-water binary parameters for the nonrandom two-liquid (NRTL) equation. The effects of electrolytes were studied, and a strong correlation was observed between the activity coefficient and the sodium cation content of the solution. This suggested that the shift in vapor-liquid equilibrium in black liquor could be modeled based solely on the sodium concentration. Sodium salts solutions data were regressed to determine binary parameters for the eNRTL equation, an extended form of the NRTL equation used to describe electrolyte effects. We found that the eNRTL equation could be used to accurately predict activity coefficients of DMS in black liquor.

Catalytic effects of potassium on lignin steam gasification with γ-Al2O3 as a bed material

The effects of potassium on the reactivity of biomass-char steam gasification with the presence of a porous material were investigated by using a thermogravimetric reactor with high-heating rates. Lignin was employed as a char-rich biomass model compound. The potassium carbonate (K2CO3) was added to lignin and a mixture of lignin and γ-Al2O3 porous particles by means of aqueous impregnation. The effects of K2CO3 and γ-Al2O3 addition on pyrol- ysis of lignin and steam gasification of lignin-derived char were evaluated in terms of lignin conversion and the gaseous products. Results showed that K2CO3 slightly increased the steam gasification rate of lignin-derived char, but it did not influence the conversion in both the pyrolysis and steam gasification steps. In addition, tar was reduced by adding K2CO3 because of the increment of carbon conversion to gas product. The presence of γ-Al2O3 was found to induce the lower reactivity of resulting char after pyrolysis, reducing the gasification rate and conversion. A significant im- provement in gasification conversion was observed with the presence of both K2CO3 and γ-Al2O3. Especially, almost complete gasification was achieved at a reaction temperature of 1,073 K.

Thermolysis and steam activation of a mixture of lignin and washed-off petroleum waste in the presence of copper acetate

The thermal degradation of a mixture of lignin with washed-off petroleum waste in the presence of 2% Cu(Ac)2 was studied. The ion-exchange interaction of the copper cation with the oxygen-containing acidic groups of mixture components occurred upon mixing the components. On a supramolecular level, this was accompanied by the compaction of carbon layers in a crystallite and a considerable increase in its diameter. In the course of the nonisothermal heating of a mixture with a copper acetate additive over the range 20–950°C, the temperature of the onset of the main thermal degradation decreased by 30 K and the rate of degradation decreased in this region. The single-step steam activation (800°C, 0.5 h) of the mixture with Cu(Ac)2 added allowed us to obtain active carbon with high yield, adsorption capacity for iodine, and micropore volume, as compared with active carbon prepared from the mixture with no additive.

δ13C values of pyrolysis products from cellulose and lignin represent the isotope content of their precursors

We investigated the δ 13C values of pyrolysis products from cellulose and lignin, the main components of wood, to prove that in the pyrolysis process no isotope exchange between different pyrolysis products appears and that hence pyrolysis products represent the isotope content of their precursors. Two cellulose samples and a lignin sample with δ 13C values of −23, −12 and −28‰, respectively, were pyrolysed using Curie point pyrolysis simultaneously coupled to GC/MS and GC/IRMS. All samples were pyrolysed individually and in mixtures of lignin with both isotopically different celluloses in two mixing ratios, e.g. 1:1 and 4:1; the latter is representative for wood. No intermolecular isotope exchange between pyrolysis products from cellulose and lignin was observed. This proves that Curie point pyrolysis is suitable for investigating the isotope content of pyrolysis products in complex mixtures like wood. Pyrolysis products from both celluloses and lignin have δ 13C values similar to the bulk δ 13C value of the respective sample. In mixtures of cellulose and lignin δ 13C values of some pyrolysis products change slightly due to peak overlap and higher background signals. However, detected changes were independent from the isotopic difference between the mixing partners. Pyrolysis products such as 2,6-dimethoxyphenol, 4-methyl-2,6-dimethoxyphenol and trans-4-(2-propenyl)-2,6-dimethoxyphenol for lignin and 2-hydroxymethyl-5-hydroxy-2,3-dihydro-(4 H)-pyrane-4-one and levoglucosane for cellulose were found to represent the isotopic signature from cellulose and lignin in mixtures regardless of the composition of the mixture.

Stabilization effect of lignin in polypropylene and recycled polypropylene

The influence of lignin on the oxidative stability of polypropylene (PP) and recycled polypropylene (recPP) plaques has been examined by differential scanning calorimetry under non-isothermal conditions. Lignin was used as a dry powder in the concentration range from 0.5 to 10 wt%. Further, the mixture of lignin with Irganox 1010 was tested. Onset temperatures of oxidation, protection factors and antioxidant effectiveness were evaluated. The results show that lignin exerts a stabilizing effect in both virgin and recycled polypropylene. The protection factor increases with lignin content in the PP matrix. The mixture of lignin with Irganox 1010 exhibits a synergistic influence in the recycled polypropylene. Moreover, the influence of the lignin content on Vicat softening temperature (VST) was determined for the evaluation of polypropylene heat resistance. VST showed that the presence of lignin improves the heat resistance of PP and recPP plaques.

Partial Oxidative and Catalytic Biomass Gasification in Supercritical Water: A Promising Flow Reactor System

We have developed a flow reactor system that smoothly gasifies glucose and glucose−lignin mixture solution at 673 K, 25.7 MPa. The reactor system consists of three continuous reactors, which are a pyrolysis reactor, an oxidation reactor, and a catalytic reactor. We have investigated the reactions that occurred in each reactor and evaluated favorable residence time. We have succeeded in achieving high gasification efficiency based on carbon up to 96% at 673 K, 25.7 MPa with total residence time of about 1 min. The main gaseous products were H2 and CO2. The results indicated that this three-reactor system is promising for low-temperature (i.e., around 673 K) biomass gasification in supercritical water.

Comparative study of ligno-cellulosic material from wheat straw and of pure and mixed standard compounds via solid state 13C NMR spectroscopy, conventional pyrolysis and TMAH thermochemolysis

The ligno-cellulosic material (LCS) isolated from wheat straw, via successive acid and base treatments, exhibits high complexing capacities, mostly related to the lignin fraction, and may have important applications for metal completion. In the present study LCS was examined via a combination of spectroscopic and pyrolytic methods: solid slate cross polarization/magic angle spinning 13C nuclear magnetic resonance (CP/MAS 13C NMR), conventional Curie point pyrolysis–gas chromatography–mass spectrometry (CuPy–GC–MS) and tetramethylammonium hydroxide (TMAH) thermochemolysis–GC–MS). Parallel experiments were also performed on cellulose and tignin standards and 50:50 cellulose:lignin mixture. These studies afforded information on lignin:cellulose relative abundances in LCS (ca. 15:85) and on the composition of the lignin fraction, including the presence of substantial amounts of carboxylic groups which should be important for metal complexation. Examination of standards and mixture also illustrated (i) the usefulness of TMAH thermochemolysis for the detection of cellulose and of carboxylic groups compared with conventional pyrolysis and (ii) the conspicuous limitations of some of the above methods when applied to ligno-cellulosic materials and resulting biases.

Gasification of Cellulose, Xylan, and Lignin Mixtures in Supercritical Water

We examined the gasification of cellulose, xylan, and lignin mixtures in supercritical water at 623 K and 25 MPa. Our results indicate that the lignin content significantly affects the amount and composition of the product gas. Thus, we surmised that cellulose or xylan is likely to function as a hydrogen donor to lignin. A set of equations developed to estimate the amount and composition of the product gas accurately predicted the actual results using only the lignin fraction as a parameter. This confirmed the importance of the lignin fraction effect on supercritical water gasification characteristics.

Assignment of DSC thermograms of wood and its components

Exotherms in the DSC analysis of wood and its components have been assigned using Akamatsu wood ( Pinus densiflora). Analysis of wood powder indicated two exotherms at around 340 and 475°C. Among isolated components galactoglucomannan has a single exotherm at around 330–360°C, and other commercial amorphous polysaccharides are in the range of 300–370°C. Therefore, the transition at around 340°C in wood thermogram was considered to be due to polysaccharides. On the other hand, the temperature of the exotherm at 475°C in the analysis of wood was similar to that of a lignin–carbohydrate complex (LCC) and not to that of purified lignin (MWL) which was around 530°C. Removing hemicelluloses from LCC by hydrosulphuric acid or cellulase shifted the temperature to around 520°C. It is concluded that the exotherm in wood powder at around 475°C is due to a mixture of lignin and polysaccharides, in which the lignin is closely combined and complexed with the polysaccharides as in LCC.

Electrical energy storage

Storage of electrical energy in an oxidation-reduction polymer material is optimized when the material is lignin and/or hydrazine is added to the material so as to facilitate bonding of the material to graphite. A preferred embodiment of the invention includes a storage device having an electron acceptor component separated from an electron donor component by a barrier which is impregnated with an electrolyte so as to electrically separate the two components while serving as an ion conduit. At least one of the layers includes an oxidation-reduction polymer material which either is lignin or is mixed with hydrazine, or both. The preferred energy storage material is a mixture of lignin, hydrazine and graphite, the latter being either added to the mixture or formed by graphitization upon heating of the lignin.

Black Liquor Gasifier/Gas Turbine Cogeneration

The kraft process dominates pulp and paper production worldwide. Black liquor, a mixture of lignin and inorganic chemicals, is generated in this process as fiber is extracted from wood. At most kraft mills today, black liquor is burned in Tomlinson boilers to produce steam for on-site heat and power and to recover the inorganic chemicals for reuse in the process. Globally, the black liquor generation rate is about 85,000 MWfuel (or 0.5 million tonnes of dry solids per day), with nearly 50 percent of this in North America. The majority of presently installed Tomlinson boilers will reach the end of their useful lives during the next 5 to 20 years. As a replacement for Tomlinson-based cogeneration, black liquor-gasifier/gas turbine cogeneration promises higher electrical efficiency, with prospective environmental, safety, and capital cost benefits for kraft mills. Several companies are pursuing commercialization of black liquor gasification for gas turbine applications. This paper presents results of detailed performance modeling of gasifier/gas turbine cogeneration systems using different black liquor gasifiers modeled on proposed commercial designs.

Alteration of the Surface Energy of Wood Using Lignin-(1-Phenylethene) Graft Copolymers

Abstract Graft copolymers of lignin, made by free radical graft copolymerization of 1-phenylethene on lignin, increased the contact angle of water on birch wood (Betula papyrifera) and decreased the critical surface tension of the wood when coated onto the wood surface from an N, N-dimethylformamide solution. The coating of copolymer changed the wood from hydrophilic (∼50°) to hydrophobic (110°). The most pronounced change in contact angle was produced by benzene-soluble extracts of the reaction product. These extracts contained lignin with long poly(1-phenylethylene) sidechains and pure poly(1-phenylethylene). They produced surfaces with the numerically highest contact angles with water and changed the wetting behavior of the surface more than physical mixtures of lignin and poly(1-phenylethylene) or either of the pure polymers. Despite coating weights of less than 100 mg/cm, the critical surface tension of the birch wood coated with the various lignin-(1-phenylethylene) graft copolymers ranged from 26.9...

クラフトリグニン樹脂接着剤の製造

The preparation of kraft lignin-based wood adhesives with high tensile shear strength and water resistance was investigated. Softwood and hardwood kraft lignins (NKPL and LKPL) were isolated from industrial concentrated waste liquors in yields of 15.8% and 15.0% based on solids, respectively. A mixture of lignin and phenol (85 : 1570 : 30) was hydroxymethylated by reacting with formaldehyde in an alkaline aqueous methanol for 2 hours at 80°C. The reaction products. hydroxymethylated was named a lignin-phenol resin (LP). Walnut powder was added to LP for a lignin-based adhesive (LPA). LPAs produced from NKPL or LKPL containing over 20% of phenol had high dry tensile shear strength bonds when hot-pressed for 615 minutes at 140°C, but their wet strengths after 48-hour boil deteriorated strikingly. Alternative lignin-based adhesives (LPRA) which consisted of 8070% LP, 2030% resorcinol and so forth developed satisfactory bonds in either dry or wet strength when hot-pressed for 615 minutes at only 75100°C. All of 3-ply shinanoki plywoods bonded with LPRAs provided higher wood failure in the wet test than in the dry test. Ether soluble fractions (LP-2) from acidified LP contained hydroxymethylated phenols such as 2, 4, 6-trihydroxymethylphenol, so the resorcinol together with paraformaldehyde was found to be used as crosslinking agents between ether insolubles (LP-1) such as hydroxymethylated lignin-phenol copolymers and LP-2 to form water-insoluble macromolecule for adhesion. LPRA required less energy for bonding and yielded high-quality bonds, indicating that it may be useful as wood adhesives for various kinds of wood products.