characterization of lignin degradation and …...chemistry reu lignin is one of the most abundant...
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Characterization of Lignin Degradation and Repolymerization ProductsShelly Lu, Honzík Bílek, Anastasia Andrianova, Alena Kubátová
Chemistry Department, University of North Dakota
❖ Lignin’s unique structure has the potential for the production of a
new generation of renewable materials
❖ Lignin is a sources of phenolic compounds, e.g., vanillin, phenol,
guaiacol, and vanillic acid
Phenol
❖ TCA confirmed that low MW fractions were rich
in monomeric species, whereas higher MW
fractions featured highly crosslinked polymers
❖ TCA corresponded with GPC and shown there is
non-lignin impurities which elute in GPC before
high MW lignin species
❖ TEM results also suggested that the first eluted
fraction in GPC was structurally different from
lignin
❖ Lignin nanoparticles of uniform size were
observed in narrow MW lignin fractions
❖ Repolymerization is occurring in concentrated
lignin solutions over
InterdisciplinaryRenewable & EnvironmentalChemistry REU
Lignin is one of the most abundant
biopolymers in the world; 50 million tons
produced annually from plants
I would like to thank Dr. Kozliak, Josh Hatton, Brett Nespor, Sarah Reagen, Audrey LaVallie, and Tyson Berg who have assisted and advised me throughout the program.
This material is based upon work supported by the National Science Foundation Research Experience for Undergraduates under Grant No. CHE 1460825. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
Vanillin
Guaiacol
358
580
1480
2340
50306850
8450
19760
2.0
2.5
3.0
3.5
4.0
4.5
0
10000
20000
30000
40000
50000
60000
70000
80000
0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526272829
Calibration curve is
composed of polystyrene
(PS) and polymethyl-
methacrylate (PMMA)
standards Fr. 1 Fr. 2 Fr. 3 Fr. 4 Fr. 5 Fr. 6
Log
MW
Absorb
ance (
230
–750 n
m),
mA
U
Time (min)
• Fraction 3 and 4 are the most
concentrated and they consist
mainly of oligomers
• Fraction 1 is anticipated to
have the highest MW, while
fraction 6 has the lowest MW
❖ Lignin fractionation preparation using gel permeation
chromatography (GPC)
❖ Fraction characterization by TCA
❖ Lignin visual analysis using transmission electron microscopy
(TEM)
❖ Weekly evaluation of extend of lignin repolymerization by
hydrotreated samples using TCA
❖ Characterize lignin heteropolymer to better understand the
composition of lignin for future renewable resource studies
❖ Observe lignin repolymerization to help understand and develop
methods to prevent this phenomenon
❖ Quantify the amount of carbon by thermal carbon analysis (TCA)
to evaluate contribution of monomers, oligomers, and elemental
carbon.
❖ TEM results confirmed that the first eluted
fraction in GPC was structurally different from
lignin
❖ Lignin nanoparticles (NPS) of the uniform size
were observed in fractions of defined
molecular weight (MW)
❖ Intact lignin consists of NPS of various MW
Fraction 3
GPC separation provides 6 fractions
❖The total amount of carbon recovered is 76%
❖Small amounts of carbon can be lost during the filter
drying process, low MW compounds in lignin can be
lost due to low boiling points
❖TCA results show most abundant carbon
concentrations in fractions 3 and 4
TEM Images of Lignin Nanoparticles Formed in Various MW Fractions
Preparative Size Exclusion Chromatography
Methods and Materials
Background
Objectives
Acknowledgement
Conclusions
Future Work
Low MW
Oligomers evolving
Elemental carbon evolving
1. Measure lignin nanoparticle size in the
solution by dynamic light scattering
2. Perform TD/pyr-GC/MS analysis of lignin MW
fractions and GC-MS analysis of low MW
fractions
3. Distinguish the predominant functionalities in
different lignin MW fractions by means of
NMR and FT-IR spectroscopy
4. Achieve the mass balance closure in lignin
fractionation by MW
❖Amount of carbon at 890 °C is decreasing for 25,000
ppm solutions
❖Amount of carbon at Coked is increasing for 25,000
ppm solutions
0
20
40
60
80
100
120
AmbientCO2
Ambientvolatiles
200 °C 300 °C 890 °C Coked Sum
% w
t. o
f In
itia
l Fee
dst
ock
Temperature Step
Day 1-3
Day 8-10
Day 15
Day 25
TCA of Concentrated Lignin Repolymerization
(25,000 ppm)
0
5
10
15
20
25
% w
t. o
f In
itia
l Lig
nin
Temperature Step
Fraction 1 (high MW)
Fraction 2
Fraction 3
Fraction 4
Fraction 5
Fraction 6 (low MW)
TCA Lignin Fractionation
Calibration curve
Carbon Distribution By TCA
THF Concentrated 5.00 µm
Fraction 4 5.00 µm
Fraction 6 5.00 µm
Fraction 2 5.00 µm
Intact Lignin 5.00 µm
5.00 µm
Fraction 5 5.00 µm
Fraction 1 5.00 µm
H
TEM ×8,000 Magnification
TCA Operational Principle TCA Thermogram
sample introduced to TCA