Lignins: from plants to applications In biopolymers course ...
Transcript of Lignins: from plants to applications In biopolymers course ...
Lignins: from plants to applications
In biopolymers course - CHEM-E2155
15.03.2021Chamseddine Guizani
Lignin in few lines
• Most abundant aromatic biopolymer in Nature.
• Main component of plant biomass (15-35 wt.%).
• Amorphous and polydisperse mixture of methoxylated polyphenols.
• Light to dark brown color.
• Dissolved from wood chips during pulping processes (black liquor).
• Black liquor combusted for materials and energy recovery.
• Lignin is under valorized as a material.
• A victim of prejudices: “You can make anything out of lignin – except money”
O
HO O
HO
OMe
Lecture content
Lignin in plant
Availability of lignins and
isolation processes
Lignin characterization
Lignin applications and
engineering
1. Lignin in plants
Component Woody feedstock,wt.% d.b
Nonwoody feedstock,wt.% d.b
Cellulose 40-45 30-45Hemicelluloses 25-35 20-35
Lignin 20-30 10-25Extractives 2-5 5-15
Proteins < 0.5 5-10Inorganics 0.1-1 0.5-10
SiO2 <0.1 0.5-7
Typical composition of woody and non-woody feedstocks [1]
[1] : Stenius, P. et al., 2000, Papermaking Science and Technology, Book 3.Forest Products Chemistry. Fapet Oy, Jyväskylä.
Lignin content in lignocellulosic biomass
Average chemical composition of Scots pine and Silver birch [1]
40 40
27,5 32,5
27,5 22,55 5
Pine Birch
Cellulose Hemicelluloces Lignin Extractives
Pine (softwood)
Birch (hardwood)
[1] : Stenius, P. et al., 2000, Papermaking Science and Technology, Book 3.Forest Products Chemistry. Fapet Oy, Jyväskylä.
• Lignins fills the space between plant cell-walls (Glue).• Covers microfibrils and has strong interactions with the carbohydrates in the plant cell walls.• Has several functions in the plant: strength, barrier, water transport.
Lignin in plant cell walls
Ultrastructure of wood cell wall: middle lamella (ML), primary wall
(P), secondary wall (S1, S2, S3 layers). Coté, (1967).
Transverse section TEM image of earlywood tracheids in tamarack
wood. Sjostrom, E (1993).Distribution of lignin, cellulose, and
hemicellulose in a softwood. Meier H (1964)
Lignin biosynthesisLignin is synthesized in cell walls through an enzyme initiated radical polymerization of three monolignols.
Phenylalanine Monolignols Lignin
Enzyme initiated dehydrogenation and radical
Polymerization of monolignols
OHO
NH2
Shikimic acidGlucose
Metabolic routes producing monolignols
from glucose
Photosynthesis of glucose
There are structural differences in lignins according to their botanical origin
Softwoods(Pine)
Hardwoods (Birch)
Grasses(Esparto)
G-lignin GS-lignin HGS-lignin
O
OOMe
OOMeMeO
OOMe
OOMeMeO
OOMe
GG
G
S HS
Major structural units
6
54
3
21
C
C
C
O
O C
α
β
γ
C
C
C
O
O C C
C
C
O
O C
C
C
C
OOC
C
C
C
O
O C
O
COC
C
C
Ethers
β-O-4(40-60 %)
α-O-4(5-10 %)
γ-O-4(< 5 %)
5-O-4(5-10 %)
γ-O- α(< 5 %)
Glycerldehyde or glycerol 2-aryl ether
(< 5 %)
C
C
C
O
C
O
C
C
C
O
C
O
5-5 (and 5-6)(5-20 %)
β -5 (both ring and open structure)(5-20 %)
C
C
C
O
C
C
C
O
β - β(< 5 %)
C
C
C
O
O
β - 1(< 5 %)
C
C
C
O
O
C
β – 6 (and β – 2) (< 5 %)
C-C bonds
Esters
C
C
C
O
O C C
O
α-ester(< 5 %)
C
C
C
O
O C C
O
γ-ester(< 5 %)
Source: Stenius, P. et al., 2000, Papermaking Science and Technology,Book 3.Forest Products Chemistry. Fapet Oy, Jyväskylä.
Functional groups
[1] Stenius, P. et al., 2000, Papermaking Science and Technology, Book3.Forest Products Chemistry. Fapet Oy, Jyväskylä.
Functional group Softwood lignin Hardwood lignin
Phenolic hydroxyl 20-30 10-20
Aliphatic hydroxyl 115-120 110-115
Methoxyl 90-95 140-160
Carbonyl 20 15
Functional groups of native lignin (per 100 C6C3 units) [1]
Elemental ratio: C:H:O=64:6:30 C:H:O=59:6:35
OH
OMe
HO
O
O
OMe
OMe
OMe
HO
HO
HOHO
O
OMe
OH
O
OH
O
OMe
OH
OMe
HO
O
HO
OH
O
OMe
O
HO
OMe
OH
OH OH
MeO
O
HO
MeO
OH
O
OHOMeHO
HO
O
OMeO
OH
O OMe
O
HO
OMeHO
O
HO
OMe
OH
HO
O
OMe
O
OH
HO
O
O
OMe
OMe
O
OOH
O
O
HO
HOOMe
OHMeO
OMe
A β O 4, β
ether
B β-5, phenylcoumaran
C β−β, resinol
D 5-5/β-O-4, dibenzodioxocin
E 5-O-4, biphenyl etherF spirodienoneX1 cinnamyl alcohol endgroupX7 glycerol endgroup
Models of lignin structure
Lignin polymer model for a softwood based on the ligninfication theory
Source: Ralph, J. et al. Handbook of Plant Science, 2, 1123-1132, 2007
More on lignin structure using NMR
Models of lignin structure
Aalto lignin modelBalakshin M, et al (2020) Green Chem 22:3985–4001.
Lignin polymer model for spruce milled woodlignin based on the state of the art analytical data
2. Lignin availability and isolation methods
Sources of lignin
Pulp
mill
s
Kraft(Kraft lignin, potential market 3.5-14 Mt/year)
Sulfite(Lignosulfonates, commercial product, 1 Mt/year)
Soda(Soda lignin, 5-10 kt/year)
Organosolv(Organosolv lignin)
Bior
efin
erie
sHydrothermal treatment
Acid hydrolysis
Steam explosion
Supercritical water hydrolysis
Pulping lignins
Biorefineries lignins(high production
potential)
How much lignin is available ?
• 50 million tons of extracted lignin inPulp and & Paper industry (2004).
• Limited markets and focus on low valueproducts: dispersing or binding agents.
• ~ 2% used commercially with theremainder burned as a low value fuel.
Source: Gosselink RJA et al (2004). Ind Crops Prod 20:121–129
1 0,1
49
~ 50 M TONS/YEAR
Lignosulfonates products
Kraft lignins products
Burned as fuel
Sources of lignin
Lignin source
Potential production,
Mt/y
Purity Feedstock range
Process flexibility
Cost Application value
Additional revenue,
%
Pulping 5-20 Med-high narrow narrow Med-high Med-high 5-20**
Biorefinery >200 Low wide wide Low Low-high* ~50-100
*According to the current research**For Kraft lignins
[1] Balakshin MY et al (2020). ChemSusChem 1016–1036.
Comparison of pulping and biorefinery lignins [1].
Isolation of lignin from spent pulping liquors
[1] Sewring, T. et al. (2019). J. Wood Chem. Tech., 39, 1-13. [2] Beisl, S. et al (2020). Molecules 2020, 25, 1388. [3] Sumerskii, Iet al. (2015) Rsc Advances, 5(112), 92732-92742.
Acid precipitation from alkaline solutions (e.g., from Kraft process black liquor) [1].
Antisolvent precipitation: adding water to an organic solvent containing dissolved lignin (e.g., in Organosolv processes) [2].
Ultrafiltration and adsorption [3].
https://boku.ac.at
Beisl, S. et al (2020).
Commercial lignin isolation processes
[1] Tomani P (2010). Cellul Chem Technol 44:53–58[2] Kouisni, L et al (2012). J. Sc. & Tech. For. Prod. Proc. 2, 6-10.
Based on pH reduction using CO2 inducing lignin precipitation at pH 10.
The Lignoboost technology invented by Innventia and acquired by Valmet [1].
The Lignoforce technology oxidizes the lignin before CO2 precipitation [2].
3. Lignin characterization
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0,40
0,60
0,80
1,00
0,0 2,0 4,0 6,0
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tiaal
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Log(MM)
012345678
0,01 1 100
Volu
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frac
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%
Particle Size, µm
Lignin properties• Molecular structure: functional groups, molecular weight distribution,
structural units and interunit linkages.
• Elemental composition: C, H, O, N, S and minerals.
• Purity: presence of carbohydrates and proteins.
• Physical properties: particle size, morphology, thermal and otherspecific material properties.
Analytical tools for lignin characterization• Numerous analytical methods for characterizing lignin properties.
• An exhaustive characterization is too time consuming and often not necessary.
• Be pragmatic: keep in mind your application and the key lignin properties in relation to it.
Key lignin propertiesto measure
Performance in applications
Examples of analytical tools for lignin characterizationNuclear Magnetic Resonance spectroscopy
[1] Balakshin MY, Capanema EA (2015). RSC Adv 5:87187–87199.
• NMR spectroscopy applies a magnetic field to a specific atomicnucleus in the lignin sample (e.g., the most common stableisotopes 1H, 13C, 31P…) and radio frequency pulses tocharacterize the resonant frequency of that atomic nucleus.
• The environment around the specific nuclei in the ligninmolecule changes the nuclei resonance frequency.
• The “shifts” in the resonance frequency give details on theelectronic structure and the functional groups in the lignin.
• 13C NMR delivers a wealth of quantitative structuralinformation [1].
Source: Wikipedia
Examples of analytical tools for lignin characterization
[1] Trogen M et al (2021). Carbohydr Polym 252:117133. [2] Balakshin MY, Capanema EA (2015). RSC Adv 5:87187–87199.
Quantification of various structural features in spruce and beech lignin by 13C NMR [1] [2]
SL BLper 100Ar mmol/g per 100Ar mmol/g
CO nonconjugated 9 0.51 9 0.48CO conjugated 5 0.28 10 0.54
total CO 14 0.79 19 1.02COOR nonconjugated 6 0.34 6 0.32
COOR conjugated 1 0.06 1 0.05total COOR 7 0.40 7 0.38
OMe 85 4.80 115 6.18G2 90 5.08 35 1.88
S2,6 90 4.84H (apprx.) 4 0.23 1 0.05
S+G+H 94 5.31 81 4.35S/G ratio na na 1.29
ArH 200 11.30 189 10.16DC, % 96 39
90-78 ppm 19 1.07 27 1.4578-67 ppm 17 0.96 28 1.5167-58 ppm 42 2.37 64 3.44
Oxygeneted Aliphatic 78 4.41 119 6.40Saturated Aliphatic 105 5.93 97 5.22
side chain 204 11.53 242 13.01b-O-4 5 0.28 7 0.38
Carbohydrates <1 <1EtO-ether 8 0.45 9 0.48EtO-ester 4 0.23 3 0.16EtO-total 12 0.68 12 0.65
M-Ar, g/mole 177 186
Examples of analytical tools for lignin characterizationChemical degradations of lignin
• Reductive treatments: thioacidolysis…
• Oxidative treatments: nitrobenzene oxidation,cupric oxide oxidation…
• Gas or liquid chromatography coupled to a specificdetector for the quantification of the degradationproducts.
[1] Lin SY, Dence CW (1992) Methods in Lignin Chemistry.
Nitrobenzene and cupric oxide oxidation products of lignins (a) and (b) analysis of Nitrobenzene degradation products using GC-MS [1]
(a)
(b)
Size exclusion chromatography
• Chromatographic method in which ligninmolecules in solution are separated by their size.
• SEC possible in aqueous or organic eluant.• Lignin must be fully dissolved and have low
interactions with the SEC columns material• Indirect (using calibrants and UV or RI) and direct
(using light scattering detection) molecular weightmeasurements.
Examples of analytical tools for lignin characterization
Aqueous phase SEC of lignosulfonate. Sulfonated polystyrene calibrants. UV
detection at 280 nm [1].
Time
[1] Guizani C, Lachenal D (2017). Int J Mol Sci 18.
Examples of analytical tools for lignin characterizationMorphology and size
012345678
0,01 0,1 1 10 100
Volu
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frac
tion,
%
Particle Size, µm
Particle size distribution of a softwood Kraft lignin using laser diffraction
Scanning electron microscopy image of a softwood Kraft lignin
4. Commercial applications of lignin
Sources of lignins, types and products from lignin (LigniMatch project)
product routes in commercial markets today
routes of most interest to develop further
Lignin and lignin-based solid biofuel
Lignin as a solid biofuel
Source: Per Tomani et al (2011) LignoBoost Kraft Lignin, a New Renewable Fuel and a Valuable Fuel Additive. International bioenergy and bioproducts confrence, 11-14 March 2011, Atlanta GA USA.
Fuel properties Lignin Coal Wood chips Bark pelletsMoisture, wt.% 30-40 9 50 10.3
Ash, wt.% 0.02-1 11.7 2-3 3-6HHV, MJ/kg d.b 26-27 29.8 20 21LHV, MJ/kg d.b 17-19 25.9 7.7 17.7
Sulphur, wt.% d.b 2-3 0.4 0.05 0.04Chloride, wt.% 0.01 0.04 0.03 0.02
Bulk density, kg/m3 630-720 d.b 800 200-300 550-700
Lignoboost® Kraft lignin fuel characteristicswith comparison to other solid fuels
More on lignoboost process anduse of lignin as a biofuel
Lignin as a solid biofuel
Kraft lignin pellets (100%) or asadditive (1-10%) in wood pellets [2].
[1] Kuparinen K, et al (2017). BioResources 12:4031–4048.[2] Berghel J et al (2013). Fuel Process Technol 112:64–69.
Lime kiln fuel in P&P mill [1]CaCO3+→CaO+CO2
Co-firing with coal in power plants
Lignin in adhesive applications
The phenol-formaldehyde (PF) resins • Phenol-Formaldehyde (PF) resins production ~ 3.0 Mt in 2009• Market ~ $2.3 billion.• Average annual growth ~ 3.9% from 2009 to 2013.• PF obtained by the catalyzed polycondensation of phenol and formaldehyde
More on PF resins synthesis
The phenol-formaldehyde (PF) resins
PF resins
High adhesive strength
Moisture resistance
Good thermal stability
High mechanical
strengthWood particle board
Plywood
Lignin as substitute to phenol in PF resinsQuestion: could lignin be a good substitute to phenol in the synthesis of
lignin-phenol-formaldehyde resins ?
Phenol Lignin
Lignin as substitute to phenol in PF resins• Part of the phenol is substituted by lignin
during the synthesis of LPF resins (10-50wt.%)
• Lignin performance in adhesive applicationis evaluated using the standardized ABESsystem (ASTM standard test method D7998-5)
Automated Bonding Evaluation System (ABES) for evaluating lignin performance in adhesives applications
(https://www.adhesiveevaluationsystems.com/)
LPF resins
Lignin
PhenolCH2O
Lignin as substitute to phenol in PF resinsNo significant correlation between the shear strength (ABES test) and the number of reactivecenters, and thus no real disadvantage for hardwood lignins.
Balakshin and Capanema, 14th EWLP, V.I, 63 (2016)
0
1
2
3
4
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6
7
110 120 130 140 150
Shea
r st
reng
th, M
Pa
Press temperature, °C
PFSHR-50SW KraftD.Fir OSAlcellAspen SodaBirch KraftBagasse Soda
ABES test, 30% plywood PF substitution, Press time 90 sec.
Reactive centers mmol/g
Control0.652.362.611.221.111.042.26
OH
12
345
6
OCH3
OH
12
345
6
OCH3
OH
H3CO
12
345
6
H
S
G
Lignin as substitute to phenol in PF resins• Problems related to lignin reactivity:
• Lignin reactivity <<< phenol reactivity : larger molecular structure and less reactive sites.• Higher reaction temperatures and longer reaction time in the LPF synthesis.
• Solutions to make lignin more reactive:• Chemical modification: methylolation and phenolation of lignin [1].• Thermochemical treatment: depolymerization [2].
[1] Vázquez G, et al. (1997). Bioresour Technol 60:191–198.[2] Solt P, et al. (2018). Polymers 10:1162.
Base catalyzed depolymerization of KL resulted in high adhesive performance of the lignin oligomeric fraction [2]
Lignin in thermoplastic applications
Lignin in thermoplasticsArboform® bioplastic (liquid wood)
•A lignin-based thermoplastic.
•Pelletized mixture of lignin (up to 50%), fine fibers of wood, hemp or flax, and wax.
•Liquifies at 170°C (PP ~160°C, PE~105-120°C, PS~240°C).
•Thermally stable up to 105°C.
•Can be used in injection molding like conventional plastic.Illustration of the molding process
Commercial uses of lignosulfonates
Lignosulfonates• Lignosulfonates, or sulfonated lignin
produced during sulfite pulping. Lignin isextracted using various salts of sulfurousacid.
• Sulfonate groups are introduced in thelignin structure during pulping.
• 330-540 kg of LS/1000 kg of wood• Lignosulfonate is a lypohydrophilic
molecule: hydrophobic aromatic structureand hydrophilic sulfonate groups. Theyare water-soluble anionic polyelectrolytepolymers
Several hundred applications:• flow modifier in cement
and concrete,• dispersing agent, emulsion
stabilizer….
World revenue generatedfrom lignosulfonatesestimated at 490-550 M $
Properties of lignosulfonatesAverage molecular weight: 20-80 kDaPolydispersity: 8-6
0 2 4 6 8
log10
(M [Da])
0.5
1
1.5
2
2.5
Diff
eren
tial w
eigh
t fra
ctio
n [-]
10 -3 =280nm
LS-Rep1LS-Rep2
Sulfonate groups: 0.6-1.2 per monomerOrganic sulfur: 4-8 wt.%
Highly soluble in water at all pH, insoluble in most organic solvents
Color: very light to very brown
Nontoxic: LD50> 5g/kg
Use of lignosulfonates as dispersants
Adding LS disperses the coal particles and decreases the viscosity of CWS [2]
Adding LS disperses the cement particles, ↑ the cement flowability and workability [1]
Flow modifier in cement and concrete formulation
• Concrete = water + cement+ sand + stone• Strength ↓ when H2O wt.% ↑
Coal–water slurry (CWS) dispersant
[1] Ouyang X et al. (2006). Colloids Surfaces A 282–283:489–497.[2] Yang D, et al. (2007). Energy Convers Manag 48:2433–2438.
• Combustible mixture of fine coal particles suspended in water
Vanillin from lignosulfonates
[1] https://www.bioref-integ.eu/fileadmin/bioref-integ/user/documents/Martin_Lersch__Borregaard_-_Creating_value_from_wood_-_The_Borregaard_biorefinery.pdf[2] Bjørsvik H-R, Minisci F (1999). Org Process Res Dev 3:330–340.
• Alkaline catalytic oxidative depolymerization of LS • Temperature: 170-200 °C, pH>7, Cu catalyst,
pressurized O2 [2].• Cu catalyst is recycled
https://www.vanillin.com/Products/eurovanillin-natural
Yield: 3 kg of vanillin /1000 kg of wood [1]. Higheryields are reported in the literature [2].
~20 % of vanillin is produced from lignin and ~80% from crude oil using the guaiacol route
Applications under R&D
Emerging applications
Emerging applications
BTX
Natural dyeing agent
Pyrolysis oil
Biobased Carbon fibers
Activated carbons
Lignin nanoparticles
Adsorption of pollutants from water
Electrodes in energy storage devices
5. Lignin engineering
Lignin engineering: concept, methodology and tools
Botanical origin and processing
steps
Lignin properties
Performance in a target
application
How to engineer the best lignin candidate for your application?
Reading assignment
You will have to read certain chapters of three peer-reviewedpublications and answer to the questions given in theassignment document available in MyCourses platform.