Subscriber access provided by UNIV OF SCIENCES PHILADELPHIA
Kinetics, Catalysis, and Reaction Engineering
Influence of Interactions among Three Biomass Components on the Pyrolysis Behavior Shilin Zhao, Meng Liu, Liang Zhao, and Lingli Zhu Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b00593 • Publication Date (Web): 28 Mar 2018 Downloaded from http://pubs.acs.org on April 3, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
1
Influence of Interactions among Three Biomass Components
2
on the Pyrolysis Behavior
3
Shilin Zhao a, Meng Liu a, *, Liang Zhao b, Lingli Zhu a
4
a
5
Energy and Environment, Southeast University, Nanjing, 210096, China
6
b
7
China
8
Abstract: Pyrolysis experiments between 25-800 °C for three main components
9
(cellulose, hemicellulose and lignin) mixed in different proportions were conducted
10
on a thermogravimetric analyzer (TGA) and pyrolysis - gas chromatography / mass
11
spectrometer (Py-GC/MS). The interactions between the three main components
12
during the pyrolysis of biomass were explored from two aspects, namely
13
thermogravimetric properties and pyrolysis products. The results indicate the
14
interactions existed among the three biomass components in the co-pyrolysis process.
15
The presence of lignin significantly reduces the pyrolysis rate of cellulose and inhibits
16
the formation of sugars (mainly levoglucosan) in the pyrolysis of cellulose and
17
hemicellulose. However, the existence of cellulose or hemicellulose greatly promotes
18
the pyrolysis of lignin to produce phenolic compounds. This finding is meaningful for
19
the application of biomass pyrolysis.
20
Keywords： ：Biomass components; Interactions; Pyrolysis; TGA; Py-GC/MS
21
1. Introduction
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of
College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, 210037,
22
As an environmentally friendly, CO2 neutral, cost-effective and low sulfur
23
content renewable material, plant biomass can be used for heat and fuel production [1].
24
It consists of cellulose, hemicellulose, lignin, and a small amount of extractives and
25
inorganic minerals. The amount of cellulose, hemicellulose and lignin accounts for
26
more than 90% of the total mass [2]. Pyrolysis of biomass components is a process
27
that biomass is converted to bio-oil, biochar and syngas in the absence of oxygen. The
28
fundamental mechanism of biomass pyrolysis can be divided into two parts, one is
29
kinetic characteristics of biomass, i.e. thermal mass loss, and the other is the
30
formation pathway of biomass pyrolysis products.
31
The pyrolysis behavior of biomass is considered as a comprehensive expression
32
of the thermal cracking process of biomass components. Biagini et al. [3] coupled
33
thermogravimetric analysis with infrared spectroscopy to discover the devolatilization 1
ACS Paragon Plus Environment
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
34
of various biomass fuels, such as different origin, properties, and composition, and
35
biomass components, results of which showed that no interaction existed among the
36
components. Yang et al. [4] investigated the chemical structure and physical
37
characteristics of solid residues and gas-releasing properties during the pyrolysis of
38
palm oil waste and biomass shell at different temperatures, which aimed to understand
39
the process mechanism better. It was reported that the interactions among the three
40
biomass components was negligible. Long et al [5] investigated the interactions of
41
biomass components during co-pyrolysis by a thermogravimetric analyzer (TGA) and
42
Macro-TGA, which concluded that the pyrolysis of xylan was not significantly
43
influenced by cellulose, while xylan affected the pyrolysis of cellulose markedly. In
44
addition, interactions between components in Macro-TGA were stronger than that in
45
TGA because of more considerable heat and mass transfer effect. Liu et al. [6]
46
conducted the experiments on the pyrolysis of synthetic biomass samples by adopting
47
the TGA coupled with Fourier transform infrared spectrometer (TG-FTIR), results of
48
which indicated that lignin affected hemicellulose at the temperature of lower than
49
327 °C while hemicellulose influenced cellulose above the specified temperature.
50
Sungsuk et al [7] investigated the effects of cellulose, hemicellulose and lignin, on
51
chemical kinetics of biomass pyrolysis through the prediction of pyrolysis kinetic
52
parameters from biomass constituents based on simplex-lattice mixture design,
53
finding that the interaction among biomass components had an important effect on the
54
kinetic parameters. Wu et al. [8] used pyrolysis - gas chromatography / mass
55
spectrometer (Py- GC/MS) to study the interactions between cellulose and lignin
56
during fast pyrolysis. Results showed that co-pyrolysis of cellulose and lignin
57
promoted low weight molecular products, such as esters, aldehydes, ketones, and
58
cyclic ketones, to form cellulose and lignin-derived products, but inhibited the
59
formation of anhydrosugars, especially levoglucosan. Zhang et al [9] observed the
60
interactions between cellulose-hemicellulose and cellulose-lignin by comparing the
61
pyrolysis products from their native mixture, physical mixture, and superposition of
62
individual components, which found that negligible interactions occurred for the both
63
binary physical mixtures as well as native cellulose-hemicellulose mixture either.
64
Based on these researches, it can be seen the interactions among the biomass
65
components are still unclear with no consistent conclusions. In addition, lots of the
66
researches on the interactions among the three biomass components were studied by
67
the thermogravimetric characteristics while few of them were conducted by 2
ACS Paragon Plus Environment
Page 2 of 21
Page 3 of 21
68
Py-GC/MS. The mechanism behind the pyrolysis of biomass needs to be studied
69
further.
70
In this study, the pyrolysis experiments on the three main biomass components
71
with different mixing ratios were conducted on a TGA and Py-GC/MS. Two aspects,
72
including thermogravimetric characteristics of thermal mass loss and distribution of
73
fast pyrolysis products, were considered. The objective is to explore the interactions
74
among the biomass components during the pyrolysis, which hopes to provide a
75
guidance for the application of biomass pyrolysis and try to give more insight on
76
understanding biomass chemical pathways during thermal treatment.
77
2. Materials and methods
78
2.1 Materials
79
For different dry biomass materials, the three main components, namely,
80
cellulose, hemicellulose, and lignin, accounted for 40-60 %, 20-40 %, and 10-25 % of
81
the total weight, respectively, while the trace amount of minerals and extractives
82
occupied lower than 10 % of the value [10]. Considering the compositional analyses,
83
several mixing ratios of 1:1:0, 1:0:1, 0:1:1, 3:3:3, 4:3:2, 5:3:1, 5:1:3, 5:2:2 and 6:1:2
84
(cellulose: hemicellulose: lignin) were selected to study the interactions among
85
biomass components, as shown in Figure 1. Microcrystalline cellulose, beechwood
86
xylan and alkaline lignin, purchased from Sigma-Aldrich Company, were used as
87
commercial samples of three biomass components. Here, xylan was chosen as the
88
representative models of hemicellulose [6]. The average particle size of cellulose and
89
lignin was about 50 µm and that of hemicellulose was approximately 100 µm. The
90
ultimate and proximate analysis of the three biomass components is shown in Table 1. 0.00
0.25
1.00
0.50
0.50
e los llu
Lig nin
(w t.% )
0.75
ce mi He ) t.% (w
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Industrial & Engineering Chemistry Research
0.75
0.25
1.00 0.00
91
0.00 0.25
0.50
0.75
Cellulose (wt.%)
3
ACS Paragon Plus Environment
1.00
Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 21
92
Figure 1 Mixing ratios of cellulose, hemicellulose, lignin in the synthetic mixtures
93
Table.1 Ultimate and proximate analysis of the three biomass components Ultimate analysis /% Sample
Proximate analysis /%
C
H
O
N
S
Mad
Vad
Aad
FCad
Celloluse
44.06
5.98
49.49
0.41
0.06
6.59
88.85
0.21
4.35
Hemicellulose
40.25
5.76
53.62
0.32
0.05
6.51
76.16
5.02
12.31
Lignin
63.10
5.45
25.43
0.37
5.65
6.87
67.10
2.94
23.09
94 95
Note：Mad-Moisture，Vad-Volatile，Aad-Ash,，FCad- Fixed carbon，ad-Air dried base
2.2 Methods
96
The pyrolysis experiments of the three biomass components were carried out on
97
a TGA (SETSYS-1750 CS Evol). About 10mg of the samples were heated with a
98
linear heating rate of 10 °C /min from 25 0 C to 800 °C . To better characterize the
99
pyrolysis in an inert atmosphere, carrier gas of nitrogen with purity over 99.999% and
100
a flow rate of 120 mL/min was chosen.
101
In addition, the fast pyrolysis of the biomass components was performed on a
102
Pyroprobe 5200 pyrolyzer (CDS Analytical), which was connected to a 7890A/
103
5975C gas chromatography / mass spectrometer (GC/MS, Agilent Technologies). The
104
sample was placed in the middle of a quartz tube, and quartz wool was placed on the
105
two sides to fix it. For each pyrolysis, the weight of samples was precisely controlled
106
at 0.50 ± 0.01mg. The condition of 600 °C, 10s was selected for the fast pyrolysis
107
experiments of the samples. A platinum spiral coil, which could realize heating
108
samples quickly and accurately, was used to provide heat for the prepared quartz tube.
109
Then pyrolytic volatiles from pyrolysis reactor were introduced into the gas
110
chromatography / mass spectrometer immediately. A DB-5ms capillary column was
111
adopted for the chromatographic separation. And the carrier gas with 99.999% of
112
helium at flow rate of 1 mL/min was selected. The MS was operated in EI mode with
113
m/z in the range of 25-500 amu. Pre-heat temperature for the oven was programmed
114
originally at 50 °C kept for 1 min, then increased to 290 °C at a ramping rate of 8 °C
115
/min, and kept for 2 min. Chromatographic peaks were identified based on the
116
reference to the NIST MS library.
117
3. Results and discussion
118
3.1 Thermogravimetric analysis
119
3.1.1Thermal mass loss of biomass single component
120
The derivative thermogravimetric (DTG) curves of cellulose, hemicellulose and 4
ACS Paragon Plus Environment
Page 5 of 21
121
lignin are shown in Figure 2. It indicates that DTG curves of each single component
122
of biomass have a weak dehydration mass loss peak at the initial stage (
