Primary conversion of lignocellulosic biomass for the production of furfural and levulinic acid

332 Pages·2014·7.44 MB·English

Primary conversion of
lignocellulosic biomass for the
production of furfural and
levulinic acid
Karla Dussan Rojas
Thesis presented for the award of Doctor of Philosophy
Under the supervision of Dr. J.J. Leahy
and Dr. Buana Girisuta
Submitted to the University of Limerick
Chemical and Environmental Sciences Department
Limerick, Ireland
September, 2014

Acknowledgements
First and foremost, I would like to thank Dr. J.J. Leahy and Prof. Michael
Hayes for their absolute support and guidance throughout the last four years.
DIBANET has been a great opportunity to learn how to learn and to think big.
I would like to thank Dr. Buana Girisuta for his unconditional, patient help, and
generous teaching.
I would like to thank my colleagues and friends at the Carbolea Research group
for being on my site during the hard and the good times; in special, to Junjun,
Dee, Yina, Mawy and Silvi for their friendship and academic comradery.
Quisiera agradecer a mi familia: Mimi, Juan Carlos, y Sergio. Gracias por ani-
marme siempre a seguir lo que creo y no dejarme escapar.
”The beginning is always today” Mary Shelley

v
Abstract
The production of energy and chemicals from renewable resources has gained sig-
nificant attention as a means to support the transition from fossil fuels towards
clean and sustainable technologies. Due to its availability and rich carbohy-
drate composition, lignocellulosic biomass represents a valuable starting mate-
rial and requires primary processes to unlock its components. The main focus
of this research was to study and develop further knowledge on the primary
steps of conversion of lignocellulosic materials, i.e. biomass fractionation, cellu-
lose/hemicellulose hydrolysis, and the production of furanic compounds (furfural,
5-hydroxymethylfurfural) and levulinic acid.
In an initial stage, the fractionation of Miscanthus × giganteus and sugarcane
bagasse was investigated using hydrogen peroxide in formic acid solutions. This
treatment removed more than 70% of the lignin in the feedstocks after 13 h at
room temperature and after 15 min at temperatures over 150 oC. The use of
hydrogen peroxide in formic acid under transient temperature facilitated the sep-
aration of >90% of the lignin and 80-98% of hemicellulose sugars, resulting in
nearly pure cellulosic pulps. Likewise, lignin was recovered from the liquor and
presented aromaticity properties proper of Organosolv lignins.
The conversion of lignocellulosic biomass to levulinic acid and furfural via acid
hydrolysis was undertaken using sulphuric acid as catalyst. Biomass feedstocks,
including agricultural, municipal wastes (paper) and rotational crops from Brazil
and Ireland, led to levulinic acid yields between 150 and 400 kg/ton dry biomass.
Additionally, the kinetics of acid hydrolysis of Miscanthus to produce levulinic
acid and furfural were studied at mild temperatures (150-200 oC) and high acid
concentrations (0.10-0.53 M H SO ). A two-stage process was found to maximise
2 4
furfural (27.3 mol%) in a first reactor operated at 185 oC with 0.5 M H SO . A
2 4
second stage leads to levulinic acid yields between 58-72 mol% at temperatures
of 160-200 oC.
A kinetic modelling study of the dehydration reactions of xylose, arabinose and
glucose was carried out using formic acid as catalyst. Experimental data was ob-
tained from the conversion of xylose, arabinose, glucose and furfural at 130-170
oC and high formic acid concentrations (10-64 wt%). High temperatures (>160
oC) favoured the formation of furfural (62-68 mol%) from xylose and arabinose;
however, fundamentaldifferencesinthereactionmechanismsfollowedbythepen-
toses were found. Formic acid was not an effective catalyst of the conversion of
glucose at temperatures under 150 oC. Temperatures above 200 oC favoured the
formation of 5-hydroxymethylfurfural (20 mol%), while levulinic acid was max-
imised (40 mol%) at milder temperatures (170-200 oC). Experimental evidence
was obtained in relation to the side reactions affecting the conversion of xylose
in liquors from the fractionation of Miscanthus. The conversion of xylose, ara-
binose, and glucose and the formation of 5-hydroxymethylfurfural and levulinic
acid in the liquors were described satisfactorily by the kinetic models. However,
when lignin was not separated prior to the reaction, the furfural concentrations
observed were significantly 40% lower than those predicted by the models. By
inducing the lignin separation from the liquor, no losses in the selectivity of fur-
fural were observed. The effect of lignin model compounds and polymeric soluble
lignin on the selectivities of the dehydration of xylose and glucose was investi-
gated at 150 and 170 oC and acid concentrations of 60-62 wt% HCOOH. The
results confirmed that the oligomeric soluble lignin led to detrimental effects on
the selectivity of the furfural formation from xylose.
Keywords: biomass, fractionation, acid hydrolysis, levulinic acid, formic acid, furfural, lignin.

Declaration
The work presented in this thesis is the original work of the author, conducted
under the supervision of Dr. J.J. Leahy and Dr. Buana Girisuta, and due re-
ference has been made, where necessary, to the work of others. No part of this
thesis has been previously submitted to this or any other University.
Limerick, 15 September 2014
Karla Duss´an Rojas

Contents
Acknowledgements iii
Nomenclature and abbreviations xviii
List of Figures xix
List of Tables xxvii
List of Schemes xxxi
1. Introduction 1
1.1. Energy consumption and the environment . . . . . . . . . . . . . 1
1.2. Biorefining: From 1st to 2nd Generation . . . . . . . . . . . . . . . 5
1.3. The DIBANET project and the aim of this work . . . . . . . . . . 7
1.4. Outline of the thesis . . . . . . . . . . . . . . . . . . . . . . . . . 8
2. Biorefining processes and platform chemicals 11
2.1. Primary fractionation and conversion in biorefining technologies . 11
2.1.1. Enzymatic bioconversion of biomass . . . . . . . . . . . . . 12
2.1.2. Thermocatalytic conversion of biomass . . . . . . . . . . . 14
2.2. Aqueous upgrading of carbohydrates . . . . . . . . . . . . . . . . 37
2.3. Platform chemicals from acid conversion of carbohydrates . . . . . 47
2.3.1. 5-hydroxymethylfurfural and levulinic acid . . . . . . . . . 47
2.3.2. Furfural . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.4. Lignin as a feedstock for the chemical industry . . . . . . . . . . . 54
3. Materials and methods 61
3.1. Biomass and solids characterisation . . . . . . . . . . . . . . . . . 61
3.1.1. Sampling methodology . . . . . . . . . . . . . . . . . . . . 61
3.1.2. Ash content . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.1.3. Extractives content . . . . . . . . . . . . . . . . . . . . . . 62
3.1.4. Carbohydrates and Klason lignin content . . . . . . . . . . 63
3.1.5. Acid-soluble lignin content . . . . . . . . . . . . . . . . . . 64
3.1.6. Elemental analysis . . . . . . . . . . . . . . . . . . . . . . 65
3.1.7. Thermogravimetric Analysis . . . . . . . . . . . . . . . . . 66
3.2. Chromatography methods . . . . . . . . . . . . . . . . . . . . . . 66
3.2.1. Detection of furanic compounds and organic acids . . . . . 70
3.2.2. Simultaneousdetectionoffuraniccompoundsandmonosac-
charides . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
3.2.3. Detection of monosaccharides . . . . . . . . . . . . . . . . 72
x Contents
3.3. Advanced characterisation . . . . . . . . . . . . . . . . . . . . . . 73
3.3.1. ScanningElectronMicroscopy/EnergyDispersiveX-raySpec-
troscopy (SEM/EDX) . . . . . . . . . . . . . . . . . . . . 73
3.3.2. X-Ray Diffractometry . . . . . . . . . . . . . . . . . . . . 74
3.3.3. Fourier Transform-Infrared Spectroscopy . . . . . . . . . . 75
3.4. Estimation methods . . . . . . . . . . . . . . . . . . . . . . . . . 76
3.4.1. Determination of the effective acid concentration . . . . . 76
4. Oxidative treatments for the fractionation of lignocellulosic biomass 81
4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
4.2. Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . 85
4.2.1. Biomass feedstocks and chemicals . . . . . . . . . . . . . . 85
4.2.2. Aqueous acidic hydrogen peroxide pretreatment enhanced
by ferric salts (Fe3+) . . . . . . . . . . . . . . . . . . . . . 85
4.2.3. Formic acid/peroxide pretreatment at room temperature . 86
4.2.4. Formic acid/peroxide pretreatment at transient temperature 87
4.2.5. Lignin isolation . . . . . . . . . . . . . . . . . . . . . . . . 89
4.2.6. Biomass, pulp and carbohydrates measurement and char-
acterisation . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.2.7. Dissolved lignin measurement . . . . . . . . . . . . . . . . 90
4.2.8. Characterization of lignin . . . . . . . . . . . . . . . . . . 90
4.3. Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . 91
4.3.1. Soaking treatment of Miscanthus in mixtures of hydrogen
peroxide in aqueous acidic solutions . . . . . . . . . . . . . 91
4.3.2. Soaking treatment of Miscanthus in mixtures of hydrogen
peroxide and concentrated formic acid . . . . . . . . . . . 92
4.3.3. Oxidative Formosolv Pretreatment at Transient Temperature101
4.4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
5. Acid hydrolysis of Lignocellulosic Biomass: Levulinic Acid and Fur-
fural 121
5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
5.2. Experimental procedure . . . . . . . . . . . . . . . . . . . . . . . 129
5.2.1. Materials and methods . . . . . . . . . . . . . . . . . . . . 129
5.2.2. Characterisation of biomass . . . . . . . . . . . . . . . . . 129
5.2.3. Neutralising capacity of biomass . . . . . . . . . . . . . . . 129
5.2.4. ExploratoryexperimentsofIrishandBrazilianbiomassfeed-
stocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
5.2.5. Kineticexperimentsoftheacid-catalysedhydrolysisofMis-
canthus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
5.3. Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . 133
5.3.1. Characterisation of lignocellulosic feedstocks . . . . . . . . 133
5.3.2. Levulinic Acid Production from Lignocellulosic Feedstocks
from Brazil and Ireland . . . . . . . . . . . . . . . . . . . . 135
5.3.3. Kinetics of Levulinic Acid and Furfural Production from
Miscanthus × giganteus . . . . . . . . . . . . . . . . . . . 142
5.4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164