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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
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Industrial & Engineering Chemistry Research
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Influence of Interactions among Three Biomass Components
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on the Pyrolysis Behavior
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Shilin Zhao a, Meng Liu a, *, Liang Zhao b, Lingli Zhu a
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a
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Energy and Environment, Southeast University, Nanjing, 210096, China
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b
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China
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Abstract: Pyrolysis experiments between 25-800 °C for three main components
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(cellulose, hemicellulose and lignin) mixed in different proportions were conducted
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on a thermogravimetric analyzer (TGA) and pyrolysis - gas chromatography / mass
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spectrometer (Py-GC/MS). The interactions between the three main components
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during the pyrolysis of biomass were explored from two aspects, namely
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thermogravimetric properties and pyrolysis products. The results indicate the
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interactions existed among the three biomass components in the co-pyrolysis process.
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The presence of lignin significantly reduces the pyrolysis rate of cellulose and inhibits
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the formation of sugars (mainly levoglucosan) in the pyrolysis of cellulose and
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hemicellulose. However, the existence of cellulose or hemicellulose greatly promotes
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the pyrolysis of lignin to produce phenolic compounds. This finding is meaningful for
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the application of biomass pyrolysis.
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Keywords: :Biomass components; Interactions; Pyrolysis; TGA; Py-GC/MS
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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,
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As an environmentally friendly, CO2 neutral, cost-effective and low sulfur
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content renewable material, plant biomass can be used for heat and fuel production [1].
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It consists of cellulose, hemicellulose, lignin, and a small amount of extractives and
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inorganic minerals. The amount of cellulose, hemicellulose and lignin accounts for
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more than 90% of the total mass [2]. Pyrolysis of biomass components is a process
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that biomass is converted to bio-oil, biochar and syngas in the absence of oxygen. The
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fundamental mechanism of biomass pyrolysis can be divided into two parts, one is
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kinetic characteristics of biomass, i.e. thermal mass loss, and the other is the
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formation pathway of biomass pyrolysis products.
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The pyrolysis behavior of biomass is considered as a comprehensive expression
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of the thermal cracking process of biomass components. Biagini et al. [3] coupled
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thermogravimetric analysis with infrared spectroscopy to discover the devolatilization 1
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of various biomass fuels, such as different origin, properties, and composition, and
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biomass components, results of which showed that no interaction existed among the
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components. Yang et al. [4] investigated the chemical structure and physical
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characteristics of solid residues and gas-releasing properties during the pyrolysis of
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palm oil waste and biomass shell at different temperatures, which aimed to understand
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the process mechanism better. It was reported that the interactions among the three
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biomass components was negligible. Long et al [5] investigated the interactions of
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biomass components during co-pyrolysis by a thermogravimetric analyzer (TGA) and
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Macro-TGA, which concluded that the pyrolysis of xylan was not significantly
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influenced by cellulose, while xylan affected the pyrolysis of cellulose markedly. In
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addition, interactions between components in Macro-TGA were stronger than that in
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TGA because of more considerable heat and mass transfer effect. Liu et al. [6]
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conducted the experiments on the pyrolysis of synthetic biomass samples by adopting
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the TGA coupled with Fourier transform infrared spectrometer (TG-FTIR), results of
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which indicated that lignin affected hemicellulose at the temperature of lower than
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327 °C while hemicellulose influenced cellulose above the specified temperature.
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Sungsuk et al [7] investigated the effects of cellulose, hemicellulose and lignin, on
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chemical kinetics of biomass pyrolysis through the prediction of pyrolysis kinetic
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parameters from biomass constituents based on simplex-lattice mixture design,
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finding that the interaction among biomass components had an important effect on the
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kinetic parameters. Wu et al. [8] used pyrolysis - gas chromatography / mass
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spectrometer (Py- GC/MS) to study the interactions between cellulose and lignin
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during fast pyrolysis. Results showed that co-pyrolysis of cellulose and lignin
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promoted low weight molecular products, such as esters, aldehydes, ketones, and
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cyclic ketones, to form cellulose and lignin-derived products, but inhibited the
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formation of anhydrosugars, especially levoglucosan. Zhang et al [9] observed the
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interactions between cellulose-hemicellulose and cellulose-lignin by comparing the
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pyrolysis products from their native mixture, physical mixture, and superposition of
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individual components, which found that negligible interactions occurred for the both
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binary physical mixtures as well as native cellulose-hemicellulose mixture either.
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Based on these researches, it can be seen the interactions among the biomass
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components are still unclear with no consistent conclusions. In addition, lots of the
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researches on the interactions among the three biomass components were studied by
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the thermogravimetric characteristics while few of them were conducted by 2
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Py-GC/MS. The mechanism behind the pyrolysis of biomass needs to be studied
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further.
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In this study, the pyrolysis experiments on the three main biomass components
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with different mixing ratios were conducted on a TGA and Py-GC/MS. Two aspects,
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including thermogravimetric characteristics of thermal mass loss and distribution of
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fast pyrolysis products, were considered. The objective is to explore the interactions
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among the biomass components during the pyrolysis, which hopes to provide a
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guidance for the application of biomass pyrolysis and try to give more insight on
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understanding biomass chemical pathways during thermal treatment.
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2. Materials and methods
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2.1 Materials
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For different dry biomass materials, the three main components, namely,
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cellulose, hemicellulose, and lignin, accounted for 40-60 %, 20-40 %, and 10-25 % of
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the total weight, respectively, while the trace amount of minerals and extractives
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occupied lower than 10 % of the value [10]. Considering the compositional analyses,
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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
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(cellulose: hemicellulose: lignin) were selected to study the interactions among
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biomass components, as shown in Figure 1. Microcrystalline cellulose, beechwood
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xylan and alkaline lignin, purchased from Sigma-Aldrich Company, were used as
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commercial samples of three biomass components. Here, xylan was chosen as the
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representative models of hemicellulose [6]. The average particle size of cellulose and
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lignin was about 50 µm and that of hemicellulose was approximately 100 µm. The
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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
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Industrial & Engineering Chemistry Research
0.75
0.25
1.00 0.00
91
0.00 0.25
0.50
0.75
Cellulose (wt.%)
3
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Figure 1 Mixing ratios of cellulose, hemicellulose, lignin in the synthetic mixtures
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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
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The pyrolysis experiments of the three biomass components were carried out on
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a TGA (SETSYS-1750 CS Evol). About 10mg of the samples were heated with a
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linear heating rate of 10 °C /min from 25 0 C to 800 °C . To better characterize the
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pyrolysis in an inert atmosphere, carrier gas of nitrogen with purity over 99.999% and
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a flow rate of 120 mL/min was chosen.
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In addition, the fast pyrolysis of the biomass components was performed on a
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Pyroprobe 5200 pyrolyzer (CDS Analytical), which was connected to a 7890A/
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5975C gas chromatography / mass spectrometer (GC/MS, Agilent Technologies). The
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sample was placed in the middle of a quartz tube, and quartz wool was placed on the
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two sides to fix it. For each pyrolysis, the weight of samples was precisely controlled
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at 0.50 ± 0.01mg. The condition of 600 °C, 10s was selected for the fast pyrolysis
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experiments of the samples. A platinum spiral coil, which could realize heating
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samples quickly and accurately, was used to provide heat for the prepared quartz tube.
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Then pyrolytic volatiles from pyrolysis reactor were introduced into the gas
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chromatography / mass spectrometer immediately. A DB-5ms capillary column was
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adopted for the chromatographic separation. And the carrier gas with 99.999% of
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helium at flow rate of 1 mL/min was selected. The MS was operated in EI mode with
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m/z in the range of 25-500 amu. Pre-heat temperature for the oven was programmed
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originally at 50 °C kept for 1 min, then increased to 290 °C at a ramping rate of 8 °C
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/min, and kept for 2 min. Chromatographic peaks were identified based on the
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reference to the NIST MS library.
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3. Results and discussion
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3.1 Thermogravimetric analysis
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3.1.1Thermal mass loss of biomass single component
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The derivative thermogravimetric (DTG) curves of cellulose, hemicellulose and 4
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lignin are shown in Figure 2. It indicates that DTG curves of each single component
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of biomass have a weak dehydration mass loss peak at the initial stage (