Effects of Sugars, Furans, and their Derivatives on Hydrodeoxygenation of Biorefinery Lignin-Rich Wastes to Hydrocarbons

Article abstract of DOI:10.1002/cssc.201801401

Hydrodeoxygenation of biorefinery lignin-rich wastes to jet fuel hydrocarbons offers a significant opportunity for enhancing the overall operational efficiency, carbon conversion efficiency, economic viability, and sustainability of biofuels production. However, these wastes usually mainly contain lignin with sugars, furans, and their derivatives as “impurities”. Although several factors, including reactant structure, solvents, or the decreased ratio of catalyst to reactant, could be responsible for the jet fuel hydrocarbons yield loss, we found evidence that glucose, xylose, and 5-hydroxymethylfurfural dramatically decreased conversion yields. For example, xylose and glucose lowered the final hydrocarbon yield by 78 and 63 %, respectively. The results revealed that these compounds could suppress metal catalysts and inhibit lignin depolymerization and hydrodeoxygenation (HDO) reactions thus decrease yields of jet fuel range hydrocarbons from biomass-derived lignin. The first-principles calculations and TGA results from spent catalysts validated these findings.

Full text of DOI:10.1002/cssc.201801401

Accepted Article
Title: Effects of sugars, furans, and their derivatives on
hydrodeoxygenation of biorefinery lignin-rich wastes to
hydrocarbons
Authors: Hongliang Wang, Yuhua Duan, qiang zhang, and Bin Yang
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the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
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To be cited as: ChemSusChem 10.1002/cssc.201801401
Link to VoR: http://dx.doi.org/10.1002/cssc.201801401
A Journal of
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ChemSusChem
10.1002/cssc.201801401
COMMUNICATION
Effects of sugars, furans, and their derivatives on
hydrodeoxygenation of biorefinery lignin-rich wastes to
hydrocarbons
Hongliang Wang,[a, b] Yuhua Duan,[d] Qian Zhang, and Bin Yang*[a,c]
[e]
Abstract: Hydrodeoxygenation of biorefinery lignin-rich wastes to jet
fuel hydrocarbons offers a significant opportunity for enhancing the
overall operational efficiency, carbon conversion efficiency, economic
viability, and sustainability of biofuels production. However, these
wastes usually mainly contain lignin with sugars, furans, and their
derivatives as “impurities”. Although several factors, including
reactant structure, solvents, or the decreased ratio of catalyst to
reactant, could be responsible for the jet fuel hydrocarbons yield loss,
we found evidence that glucose, xylose, and 5-hydroxymethylfurfural
dramatically decreased conversion yields. For example, xylose and
glucose lowered the final hydrocarbon yield by 78% and 63%,
respectively. The results revealed that these compounds could
suppress metal catalysts and inhibit lignin depolymerization and
hydrodeoxygenation (HDO) reactions thus decrease yields of jet fuel
range hydrocarbons from biomass-derived lignin. The first-principles
calculations and TGA results from spent catalysts validated these
findings.
operation. Efforts are critically needed to transform lignin-rich wastes
into higher value products. Lignin depolymerization and subsequent
HDO conversion to hydrocarbons under catalytic conditions is one of
[
8, 9]
the most promising approaches for its rational utilization.
The
catalytic efficiency as well as the generated products (yield,
composition, and distribution) of lignin HDO approach can be
regulated by several important factors, such as catalysts,
hydrogen pressure, solvents, trapping agents, reaction
temperature, and time.[
7, 11-14]
Extensive research work on these
aspects has been conducted to fully unlock lignin’s potential.[15-17]
Effects of lignin characteristics, including its origins (softwood,
hardwood, or herbaceous plant), molecular weight, and chemical
linkages on its HDO conversion also have been extensively
studied.[10,17-21] However, relatively few studies were devoted to
the determination of effects of impurities (e.g. sugar, furans, and
their derivatives) in lignin-rich wastes on its HDO conversion.
Lignin from biorefinery processes always contains a certain
amount of impurities. The majority of these impurities are
carbohydrates (sugars) or other derivatives from cellulose and
hemicellulose.[21, 22] Potential effects of sugars, furans, and their
Efficient utilization of all available carbons from biomass to produce
biofuels will be required for an economical process. Catalytic
technologies for conversion of biorefinery wastes at high carbon
efficiency for maximal biofuel production are critical for enabling a
derivatives on lignin HDO conversion, including adsorption onto
catalysts, reacting with lignin and its degraded intermediates,
remain unexplored. In this study, to simulate real lignin degraded
intermediates, lignin model compounds were mixed with various
sugars to investigate effects of sugars on the HDO conversion of
lignin, including on the product compositions and distribution, the
efficiency of breaking different C-O-C bonds among lignin
interlinkages. Subsequently, to get more insights into effects of
sugars on real lignin HDO conversion, HDO reactions of lignin
mixed with two typical mono sugars (i.e. glucose and xylose) were
investigated. The lignin used in this study was prepared from
dilute alkali deacetylation and mechanical refining (DMR)
[
1-3]
robust biorefinery industry.
Biorefinery lignin-rich wastes are the
partially dewatered stream containing lignin as well as unconverted
biomass components such as sugars, furans, and their derivatives.
Such wastes are often burned to supply self-sustaining energy to the
biorefinery or discarded. However, the chemical structure of lignin
suggest that it not only can be used to produce energy, but also has
[
4-8]
great potential for production of value-added fuels and chemicals.
[
4-7]
Unlike conversion of carbohydrates to biofuels,
effective
conversion of lignin and lignin-rich biorefinery wastes still remains
[
8-10]
challenging.
If US replaced 25% of transportation fuels with
treatment, a biomass deconstruction process developed at the
National Renewable Energy Laboratory (NREL).[23] The catalyst
system used here was a combination of a super Lewis acid indium
biofuels by 2030, it will produce around 50 billion gallons of cellulosic
ethanol and up to 0.3 billion tons resultant lignin. The amount of lignin
wastes will substantially exceed the power demand of the biorefinery
triflate In(OTf)
3
with an inexpensive noble metal based catalyst
(
Ru/Al ). It was reported that lignin and its phenol derivatives
2 3
O
were successfully converted by the combination of metallic and
[
[
a]
b]
Dr. H Wang and Prof. B Yang
Department of Biological Systems Engineering
Washington State University
Richland, WA 99354, USA
E-mail: binyang@tricity.wsu.edu
Dr. H Wang
Center of Biomass Engineering/College of Agronomy and
Biotechnology
China Agricultural University
Beijing, 100193, China
Prof. B Yang
acidic functions.[
24]
Indium triflate was shown being an
environmentally friendly, inexpensive, reusable, and water-
[25]
tolerant Lewis acid. More importantly, it showed high activity in
hydrolysis of lignin and its model compounds.[24-27] Ruthenium
based catalysts were widely used in lignin HDO conversion,
exhibiting high deoxygenation and hydrogenation activities in
[26-29]
aqueous solution.
Initially in this study, guaiacol was selected as a lignin model
compound for the investigation of effects of carbohydrates and
their derivatives (i.e. glucose, xylose, 5-HMF, cellulose) on lignin
HDO conversion. Six types of HDO main products were detected
[
[
c]
d]
Earth and Biological Sciences Directorate, Pacific Northwest
National Laboratory, Richland, WA 99352, USA.
E-mail: bin.yang@pnnl.gov
Dr. Y Duan
(Table 1). Product
6
was mainly alkylphenols and
National Energy Technology Laboratory, United States Department
of Energy, Pittsburgh, PA 15236, USA
Dr. Q Zhang
alkylcyclohexanols. Although addition of 10 mol% glucose in the
reactant did not significantly change the amount of guaiacol
[
e]
Key Laboratory of Coal Science and Technology of Ministry of
Education and Shanxi Province, Taiyuan University of Technology,
Taiyuan, 030024, Shanxi, China
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ChemSusChem
10.1002/cssc.201801401
COMMUNICATION
converted, it strongly affected the product distribution. As listed in
Table 1 run 1~2, the selectivity of the primary product (product 1,
of guaiacol decreased from 79% to 55% when 10 mol% glucose
was added. Further increase of the glucose content to 30 mol%
1
,2-benzenediol) with 10 mol% glucose addition was much higher
led to a sharp decrease of guaiacol conversion to 30%.
than that with pure guaiacol as reactant. Meanwhile, without
addition of any sugars, the selectivity of aromatic ring
hydrogenated products (product 3~5) was moderate. However,
with the addition of 10 mol% glucose, the selectivity of these
products became fairly low. These results indicated that the
existence of glucose had significant effects on the further
conversion of 1,2-benzenediol to aromatic ring saturated products
although it showed small effect on the conversion of guaiacol to
Meanwhile, the selectivity of aromatic ring saturated products
obviously dropped when glucose was added (run 8~9).
To evaluate the influence of other common carbohydrates
2 3
or their derivatives on guaiacol HDO conversion under Ru/Al O
catalysis, xylose, 5-hydroxymethylfurfural (HMF), and cellulose
were mixed separately with guaiacol under identical reaction
conditions, and results are summarized in Table 1, run 10~12.
Both xylose and HMF significantly suppressed the catalytic
1
,2-benzenediol.
Since both In(OTf)
,2-benzenediol reactions, but only Ru/Al
activity of Ru/Al
HDO catalytic activity of Ru/Al
mono sugars and HMF. Results showed that the inhibition ability
of carbohydrates on Ru/Al decreased as follows: 5-
2
O
3
. The addition of cellulose also decreased the
3
and Ru/Al
2
O
3
can catalyze guaiacol to
can catalyze 1,2-
2 3
O
although not as strong as the
1
2
O
3
benzenediol to products 3~5, the inhibition of 1,2-benzenediol to
2 3
O
aromatic ring saturated products in run 2 is likely due to the
HMF>xylose>glucose>cellulose. This sequence appears to be in
line with the amount of products containing aromatic furan ring
that formed from those carbohydrates under the reaction
conditions. HMF is a dehydration product of hexose and a furan-
based compound, which can compete with guaiacol to adsorb
onto the surface of ruthenium nanoparticle and thus suppress the
HDO conversion of guaiacol.[18] Xylose comes from hemicellulose,
and it can be easily converted into furfural (also contains an
aromatic furan ring) under hydrothermal or acidic conditions.
Compared with xylose, glucose and cellulose are more difficult to
be converted to furan-based compounds. Meanwhile, previous
studies also reported the suppression of catalytic hydrogenation
activities of metals by furan compounds.[21, 22, 30]
deactivation of Ru/Al
hypothesis, In(OTf)
Results showed that, when In(OTf)
2
O
3
by glucose or its derivatives. To test this
and Ru/Al were tested separately.
was used alone, the addition
3
2 3
O
3
of 10 mol% glucose in the reactants had little effect on both
guaiacol conversion and product distribution. 1,2-benzenediol
was found to be the dominant product with both catalysts. When
the glucose content increased to 30 mol%, the guaiacol
conversion slightly decreased 3.9%. Further increasing the
glucose content to 60 mol%, the guaiacol conversion dropped
1
4.4%. These results suggested that glucose had little effect on
the acidic conversion of guaiacol. However, under the catalysis of
Ru/Al , both guaiacol conversion and the product distribution
2 3
O
changed obviously with the addition of glucose. The conversion
Table 1. HDO conversion of guaiacol with carbohydrates and their derivatives[a]
Run
Catalysts
Carbohydrates
--
Conversion
Product selectivity (C %)
(
wt.%)
1
26.1
2
10.3
3
4
5
22.6
6
3.5
1
2
In(OTf)
Ru/Al
In(OTf)
Ru/Al
3
+
72.5
15.1
22.4
2
O
3
3
+
Glucose
(0.1mmol)
--
68.2
55.2
14.2
4.6
8.7
7.6
9.7
2
O
3
3
4
In(OTf)
In(OTf)
3
65.6
64.9
85.3
88.9
12.6
8.2
N.R.
N.R.
N.R.
N.R.
N.R.
N.R.
2.1
2.9
3
3
3
Glucose
(
(
(
0.1mmol)
Glucose
0.3mmol)
Glucose
0.6mmol)
--
5
6
In(OTf)
In(OTf)
61.7
51.2
90.5
94.5
5.0
3.7
N.R.
N.R.
N.R.
N.R.
N.R.
N.R.
4.5
1.8
7
8
Ru/Al
Ru/Al
2
O
3
79.3
55.3
10.2
36.8
6.7
15.3
26.7
11.9
17.4
16.6
30.5
14.1
8.5
5.3
2
O
O
O
O
O
3
Glucose
0.1mmol)
Glucose
0.3mmol)
Xylose
0.1mmol)
5-HMF
0.1mmol)
(
(
(
(
9
Ru/Al
Ru/Al
Ru/Al
Ru/Al
2
2
2
2
3
3
3
3
30.1
48.6
41.7
64.1
48.2
39.9
45.3
28.3
10.7
16.1
18.9
11.9
9.0
9.8
11.3
17.1
9.3
10.3
11.0
9.5
10.5
6.1
9.5
2.1
10
11
12
7.5
Cellulose
0.1mmol)
a] Reaction conditions: nguaiacol+ncarbohydrate=1 mmol, 0.05 mmol In(OTf)
H2=580 psi. N.R. means no product observed.
19.6
14.5
23.6
(
[
P
3 2 3
, 0.025 mmol Ru as 5 wt.% Ru/Al O , 1 ml water as solvent. T=250 °C, t=2 h,
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ChemSusChem
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COMMUNICATION
O [
a]
Table 2. HDO conversion of lignin dimers over the combined catalysis of In(OTf)
3
and Ru/Al
2
3
Selectivity (C%)
Entry
Reactant
Conversion (wt.%)
O
1
56.3
DPE
55.3
80.3
11.7
25.4
8.2
3.1
2.6
1.9
0.8
O
2b
36.8
>99
DPE
BPE
BPE
7.4
3
3
3.9
1.0
14.7
21.0
11.3
9.7
8.6
6.3
27.1
4 b
84.6
>99
4
19.6
5
1
6.9
15.4
11.8
2
7.4
3.6
18.4
15.1
VGE
VGE
6 [b]
78.6
9.1
3
18.3
14.5
Reaction conditions: 0.05 mmol In(OTf)
.9 mmol, glucose 0.1 mmol.
3
, 0.025 mmol Ru as 5 wt.% Ru/Al
O
2 3
, 1 ml water as solvent. T=250 °C, t=2 h, PH2=580 psi. [a] guaiacol 1 mmol. [b]guaiacol
0
In addition to the conversion of guaiacol, effects of sugars
dissociation enthalpy, complete conversion of BPE was achieved
when no sugar was added. However, when 10 mol% of glucose
was added, the conversion of BPE decreased to about 85%. The
addition of glucose also changed the product distribution of BPE
HDO conversion. The selectivity of incomplete hydrogenated
products (aromatics) significantly increased to 88% from 34%
when glucose was added. Similar results were obtained from
HDO conversion of VGE with -O-4 structure, the most prevalent
ether bond in lignin interlinkages. The existence of glucose not
only decreased the VGE conversion but also lowered the
selectivities of deoxygenated and fully hydrogenated products.
Results obtained from HDO conversion of lignin dimers with
glucose were consistent with those obtained from HDO
conversion of guaiacol, revealing that sugars affected the
hydrogenolysis and hydrogenation activities of the catalysis
system.
on the HDO conversion of several lignin dimers, which contain
typical ether linkages of lignin and are usually generated during
lignin HDO, were further explored to provide more fundamental
insights in sugar effects on lignin HDO. Since -O-4, -O-4, 4-O-
5
bonds are the most abundant C-O-C bonds in lignin linkages,
diphenyl ether (DPE), benzyl phenyl ether (BPE), and
veratrylglycero--guaiacyl ether (VGE) (Table 2) were chosen to
represent aryl-O-aryl (4–O–5), aryl-O-benzyl (-O-4), and aryl-O-
alkyl (β-O-4) linkages, respectively, to test effects of sugars on the
breakage of a wide range of C-O-C bonds under lignin HDO
conversion conditions. These model compounds cover various C-
O bond strengths in lignin, typically with bond dissociation
enthalpy (BDE): 4–O–5 > -O-4 >β-O-4. The conversion of these
model compounds and the selectivity of their top five products are
listed in Table 2.
As shown in Table 2, HDO conversion of DPE was 56.3%
and the yield of aromatic ring hydrogenated products was 24%.
The moderate conversion of DPE under the carried reaction
conditions was probably due to the high bond dissociation
enthalpy of 4–O–5 ether bond. DPE conversion dropped to about
In addition, effects of sugars (glucose or xylose) on HDO
conversion of technical lignin were investigated. The conversion
of lignin and the total yield of products are depicted in Figure 1(a).
The generated GC-MS detectable products are shown in Figure
1(b). Results showed that the addition of 10 wt% sugars (either
glucose or xylose) obviously hindered HDO conversion of lignin,
and they showed greater effects on lignin than on lignin model
compounds. Compared to the conversion of lignin model
37% when 10 mol% glucose was added. At the meantime, the
selectivity of aromatic ring hydrogenated products significantly
decreased. Since O-4 ether bond has a relatively low bond
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ChemSusChem
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compounds, the conversion of technical lignin decreased more
rapidly after sugars were added. The macromolecular form of
technical lignin that is disadvantageous in the competitive
adsorption on the metal catalyst can be the primary cause for the
loss in hydrocarbons yield from HDO of technical lignin although
several factors, including reactant structure, solvents, or the
decreased ratio of catalyst to reactant, can be responsible.
Furthermore, xylose was more inhibitory than glucose in terms of
decreasing hydrocarbon yield. Xylose and glucose lowered the
final hydrocarbon yield by 78% and 63%, respectively. Moreover,
we found the color of the ethyl acetate extraction solution with the
addition of sugar was quite different from that without sugar, as
shown in Figure 1(c). The ethyl acetate extraction solution of
products from lignin without adding sugars appeared faint yellow.
On the contrary, with the addition of sugars, the ethyl acetate
extraction solution of products turned brownish black. This is
probably due to the production of humins from the added sugars
under the reaction conditions. Humins can also absorb on the
catalyst surface and thus decrease its catalytic activities.
Scheme 1. Proposed mechanism of carbohydrate effects on lignin
2 3
depolymerization and HDO conversion over Ru/Al O catalyst.
Figure 2. The calculated adsorption energies (Eads) of molecules on Ru (0001)
surface (a) and adsorption geometries of 5-HMF; (b) and phenol; (c) on Ru
(0001) surface.
To prove the proposed mechanism (Scheme 1), we
performed first-principles density functional theory (DFT)
calculations on molecules produced from carbohydrates (furfural,
Figure 1. Effects of sugars on lignin HDO conversion. Reaction conditions: 0.1
5-HMF, Levulinic acid) and from lignin (guaiacol, phenol, cresol)
3 2 3
mmol In(OTf) , 0.05 mmol Ru as 5 wt.% Ru/Al O , 1.2 ml water as solvents.
adsorption on Ru (0001) surface. The obtained adsorption
energies (Eads) of these molecules as well as two example
adsorption configurations are shown in Figure 2. Results show
that the calculated Eads of molecules produced from
carbohydrates are higher than those of molecules produced from
lignin, which means phenol-based molecules produced from
lignin have weaker interaction with Ru catalyst than those furan-
based molecules produced from carbohydrates. When furan-
based molecules co-exist as impurity with lignin, they
competitively bind with catalysts thus reduce the interaction of
phenol-based molecules with catalysts, preventing further
depolymerization and HDO conversion of lignin as depicted in
Scheme 1. Comparing Figure 2(b) with 2(c), results indicate that
in furan-based molecules, mainly the O of carboxyl group binds
with Ru (0001) surface while in phenol-based molecules, the C of
benzene ring binds with Ru surface. The calculated bond-length
of O-Ru in furan-based configurations is 0.1-0.2 Å shorter than
those of C-Ru bonds in phenol-based adsorption systems. These
results indicate that the active sites of Ru (0001) surface are
competitively occupied by furan-based molecules, blocking the
T=250 °C, t=4 h, PH2=580 psi. A: 100 mg lignin; B: 90 mg lignin + 10 mg glucose;
C: 90 mg lignin + 10 mg xylose.
Based on the obtained results, potential mechanism of
effects of carbohydrates and their derivatives on lignin conversion
over catalysis of Ru/Al O is proposed and depicted in Scheme 1.
2 3
Furan-based compounds, including 5-HMF and furfural generated
from carbohydrates through depolymerization and dehydration,
competitively adsorb on the Ru metal particles with lignin, and
thus prevent lignin from hydrogenolysis depolymerization. The
adsorption of furan-based compounds on Ru also hinders HDO
conversion of depolymerized lignin intermediates. Moreover,
humins formed from the polymerization of furan-based
compounds and other carbohydrate derivative products plausibly
cover the Ru particle surface and thus deactivate the metal
catalyst.
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ChemSusChem
10.1002/cssc.201801401
COMMUNICATION
phenol-based molecules to bind with the catalyst surface. Such
poisoning effects caused by furans and their derivatives suppress
the lignin HDO conversion as observed in Figure 1.
spent catalysts. Compared with acidic catalyst (In(OTf)
3
), metal
catalyst (Ru/Al ) was more sensitive to sugars. The generated
2 3
O
furan-based products and humins from sugars are responsible for
the negative effects since these products can competitively
absorb on the metal surface of catalysts and block the absorption
of lignin and its degraded intermediates. The findings of this study
suggest that the development of lignin catalytic system should
fully consider the influence of sugar impurities, and robust
catalysts that are insensitive to sugars and their derivatives
should be developed for effective lignin conversion.
Experimental Section
Chemicals and materials: All the chemicals used in this research are
commercially available and used as received without any treatment. In(OTf)
glucose, xylose, HMF, cellulose (Avicel) were purchased from Sigma-Aldrich.
Ru/Al (reduced) was purchased from Alfa Aesar. Lignin model compounds,
4
,
2 3
O
Figure 3. Thermogravimetric analysis (TGA) of spent catalysts. 1: fresh
including guaiacol, diphenyl ether, and benzyl phenyl ether, were purchased
from Fisher Scientific. Lignin O-4 model compounds were purchased from
GreenLignol, LLC. Lignin was obtained from National Renewable Energy
Laboratory (NREL) via dilute alkali deacetylation and mechanical Refining
(DMR) treatment. All other chemicals were purchased from Fisher Scientific.
Hydrodeoxygenation conversion of lignin model compounds and lignin: A
specific amount of lignin or lignin model compounds, catalysts, and water (1 ml
or 1.2 ml) with or without sugars addition were added to a 3 mL dry glass sleeve.
The sleeve was placed into a high-throughput batch reactor (PNNL-SA-117072)
at the Bioproducts, Science & Engineering Laboratory. The reactor was sealed
Ru/Al
2
O
3
; 2: Ru/Al
2
O
3
after reacting with guaiacol; 3: Ru/Al after reacting with
2
O
3
furfural; 4: Ru/Al
2
O
3
after reacting with HMF; 5: Ru/Al O after reacting with
2 3
glucose.
Furthermore, thermogravimetric analysis (TGA) of spent
catalysts was carried out to determine the carbon deposition on
Ru/Al O . These catalysts were collected from HDO reactions by
2 3
using guaiacol, glucose, HMF, and furfural as reactants,
separately, under identical HDO reaction conditions. The
conversion of these compounds as well as the selectivity of
products were also analyzed. The dehydration of glucose to HMF
was quite slow, and the yield of HMF and its hydrogenated
products (mainly bishydroxymethyl-tetrahydrofuran) was lower
than 20%. Most of glucose was converted into sorbitol (with a
yield of 47 %) under the reaction conditions. While, the formation
of char from glucose is obviously higher than that from other
reactants as indicated by TGA in Figure 3. Char or humins could
be formed from glucose directly or from its dehydration
intermediates. When HMF and furfural were used separately as
reactants, the major products were found to be bishydroxymethyl-
and purged with H
2
three times to exclude air, and then pressured with 580 psi
at room temperature. The reactor was heated to 250 °C and maintained for
or 4 hours depending on the substrate. The metal plate of the high-throughput
H
2
2
reactor was shaking (shaking frequency: 200 r/min) during the reaction to
improve the mass transfer. After each run, the reactor was cooled to room
temperature to terminate reactions. The glass sleeve was removed from the
high-throughput reactor and the liquids were separated from the solids by
centrifugation (8000 r/min for 10 min). The liquid was extracted with 5 ml ethyl
acetate. The solids were extracted with 3 mL ethyl acetate. The ethyl acetate
extraction was combined and diluted in a 20-mL volumetric flask. Certain
amount of vanillin and 3-methylheptane were added as internal standards for
aromatics and hydrocarbons, respectively, in GC analysis.
tetrahydrofuran (with
a yield of 63%) and hydroxymethyl-
tetrahydrofuran (with a yield of 76 %), respectively. The formation
of char from HMF and furfural is lower than that from glucose but
higher than that from guaiacol as shown in Figure 3. These results
indicate that glucose, HMF, and furfural are more easily to form
char or humins than guaiacol under the tested HDO reaction
conditions. Char or humins from carbohydrates covers the metal
Analysis of HDO products: The ethyl acetate diluted liquid samples were
analysed by GC and GC-MS in an Agilent Technologies 7890A GC system with
a DB-5 capillary column (30 m length × 250 μ m I.D. × 0.25 μ m film thickness,
J&W Scientific) in the split-less mode. Typically, 1μl sample was injected with
2 3
surface of Ru/Al O and deactivates the catalyst.
0
.6 ml min−1 of He as the carrier gas into the GC system. The injection port
temperature was set at 300 °C. The GC oven was programmed to 45 °C and
maintained for 6 min. Then the temperature was raised at the rate of 10 °C/min
until it reached 300 °C and maintained at 300 °C for 2 min. Eluting compounds
were detected with a MS (Agilent Technologies 5975C) inert XL EI/CI MSD with
a triple axis detector, and compared using NIST libraries. For model compounds,
the conversion of reactants and the selectivity of the products were calculated
using the internal standard method based on the following formulas:
Conclusions
Valorization of biorefinery lignin-rich wastes improves the
carbon efficiency of the entire process, thus is an attractive but
challenging topic for economic biorefinery design. Sugars and
their derivatives (e.g. HMF) co-exist as impurities with lignin in
biorefinery lignin-rich wastes. Negative effects of these
compounds on lignin HDO conversion were found in this study.
They could hinder lignin from hydrogenolysis depolymerization as
well as further prevent lignin depolymerized intermediates
For the conversion of technical model compounds:
ꢀꢁꢂꢃꢄꢅꢆꢇꢈꢆꢉꢁꢊꢋꢅꢊꢌꢅꢆꢋꢇꢌꢍꢁꢉꢅꢁꢎ
Conversion%= ꢀ
ꢏ 100%
ꢁꢂꢃꢄꢅꢆꢇꢈꢆꢆꢉꢁꢊꢋꢅꢊꢌꢅꢆꢊꢎꢎꢁꢎ
ꢐꢊꢉꢑꢇꢌꢆꢊꢅꢇꢒꢓꢆꢂꢌꢆꢄꢔꢎꢉꢇꢋꢊꢉꢑꢇꢌꢆꢕꢆ
ꢏ 100%
ꢐꢊꢉꢑꢇꢌꢆꢊꢅꢇꢒꢓꢆꢂꢌꢆꢉꢁꢊꢋꢅꢊꢌꢅ
(monomers and dimers) from hydrogenation and deoxygenation
Yield of hydrocarbon A%=
conversion. Such mechanism was further validated by first-
principles DFT calculations and thermogravimetric analysis of
ꢐꢊꢉꢑꢇꢌꢆꢊꢅꢇꢒꢓꢆꢂꢌꢆꢄꢔꢎꢉꢇꢋꢊꢉꢑꢇꢌꢆꢕ
Selectivity of hydrocarbon A%=ꢖꢇꢅꢊꢗꢆꢋꢊꢉꢑꢇꢌꢆꢊꢅꢇꢒꢓꢆꢂꢌꢆꢘꢉꢇꢎꢙꢋꢅꢓ ꢏ 100%
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10.1002/cssc.201801401
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For technical lignin, the calculations of conversion was based on the weight
change of lignin before and after HDO reaction. The yield of lignin HDO products
was calculated by the effective carbon number (ECN) approach.[31] 3-
methylheptane was added as internal standard. The top 20 products were
calculated to determine the total yield of HDO products.
0 °C min-1 under the same atmosphere; (c) when it reached the final
1
temperature, the run was stopped and the temperature of the furnace was
decreased to room temperature. The blank experiments were conducted
following the exact same procedure as above using empty crucible to
compensate for the output drift of the thermobalance, respectively. All of
these experiments were duplicated.
For the conversion of technical lignin:
ꢀ
ꢁꢂꢃꢄꢅꢆꢇꢈꢆꢉꢁꢊꢋꢅꢊꢌꢅꢆꢋꢇꢌꢍꢁꢉꢅꢁꢎ
Conversion%= ꢀ
ꢏ 100%
ꢁꢂꢃꢄꢅꢆꢇꢈꢆꢆꢉꢁꢊꢋꢅꢊꢌꢅꢆꢊꢎꢎꢁꢎ
ꢀ
ꢁꢂꢃꢄꢅꢆꢇꢈꢆꢄꢔꢎꢉꢇꢋꢊꢉꢑꢇꢌꢆꢕꢆꢘꢉꢇꢎꢙꢋꢁꢎ
Yield of hydrocarbon A%=
ꢏ 100%
ꢀ
ꢁꢂꢃꢄꢅꢆꢇꢈꢆꢆꢉꢁꢊꢋꢅꢊꢌꢅꢆꢊꢎꢎꢁꢎ
Acknowledgements
Total hydrocarbon yield=∑ ꢝꢛ ꢜꢞ ꢟ Yieldꢚꢆ
This work was supported by the National Renewable
Energy Laboratory Subcontract # AEV-6–52054-01 under Prime
U.S. Department of Energy (DOE) Award # DE-AC36-08G028308,
the Sun Grant-U.S. Department of Transportation (DOT) Award #
T0013G-A-Task 8, the Joint Center for Aerospace Technology
DFT Calculation details: The calculations performed in this work are
based on first-principles DFT with plane-wave basis sets and pseudo-
potentials to describe the electron-ion interactions. The Vienna ab-initio
simulation package (VASP, https://www.vasp.at) was employed to
calculate molecules adsorption on Ru (0001) surface. In this study, all
calculations were done using the PAW pseudo-potentials and the PBE
exchange-correlation functional. The plane-wave basis sets were used
with a plane-wave cutoff energy of 500 eV and a kinetic energy cutoff for
augmentation charges of 644.9 eV. The 6x6 Ru (0001) surface was
created from optimized Ru crystal with space group P63/mmc (#194). To
reduce the calculation cost, a three-layer Ru (0001) surface slab (108
Innovation with the Bioproducts, Science
& Engineering
Laboratory and Department of Biological Systems Engineering at
Washington State University, and the National Natural Science
Foundation of China (No. 21706277), This work was performed
in part at the William R. Wiley Environmental Molecular Sciences
Laboratory (EMSL), a national scientific user facility sponsored by
the U.S. Department of Energy’s Office of Biological and
Environmental Research and located at the Pacific Northwest
National Laboratory, operated for the Department of Energy by
Battelle. The authors would like to thank Ms. Heather Job and Ms.
Marie S. Swita who helped the high throughput experiments and
collected some GC–MS data for this project. In addition, the
authors thank Dr. Melvin Tucker and Mr. Eric Kuhn from the
National Renewable Energy Laboratory for insightful discussions.
atoms) with 20 Å vacuum separation was used in our calculation.
Compared to the model in ref. [22], our model has larger surface area to
eliminate the unexpected interactions between adsorbed molecules due to
the periodicity. During adsorption calculation, the bottom layer of Ru was
fixed as bulk material. The molecules were introduced on the surface for
adsorption. During calculations, the lattice dimension was fixed. Except for
the bottom layer of Ru, all atoms in the supercell were relaxed to the
equilibrium configurations. A 3x3x1 k-point sampling grids were applied in
all adsorption calculations while for pure molecule systems a 4x4x4 k-point
sampling grids were used. The valence electrons contain s and p orbitals
for H, C and O atoms, s, p, and d orbitals for Ru atoms. The adsorption
Keywords: Lignin
•
Hydrodeoxygenation
•
impurities
•
Hydrocarbons• furan compounds
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COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Effects of impurities on
Hongliang Wang, Bin Yang*
hydrodeoxygenation (HDO) of
lignin to hydrocarbons: Valorization
of biorefinery lignin-rich wastes is
challenging but necessary for an
economical process. This study
revealed that sugars, furans, and their
derivatives as “impurities” in such
wastes could suppress metal catalysts
and inhibit lignin depolymerization and
HDO reactions thus decrease yields of
jet fuel range hydrocarbons from
biomass-derived lignin.
Page No. – Page No.
Effects of sugars, furans, and their
derivatives on hydrodeoxygenation of
biorefinery lignin-rich wastes to
hydrocarbons
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