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Conversion of biomass into high-quality bio-oils by degradative solvent extraction combined with subsequent pyrolysis Xianqing Zhu, Shan Tong, Xian LI, Yaxin Gao, Yang Xu, Omar D Dacres, Ryuichi Ashida, Kouichi Miura, Wenqiang Liu, and Hong Yao Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.6b03162 • Publication Date (Web): 14 Mar 2017 Downloaded from http://pubs.acs.org on March 20, 2017
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Energy & Fuels
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Conversion of biomass into high-quality bio-oils by degradative
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solvent extraction combined with subsequent pyrolysis
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Xianqing Zhua, Shan Tonga, Xian Lia,*, Yaxin Gaoa, Yang Xua, Omar D. Dacresa, Ryuichi Ashidab, Kouichi
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Miurac, Wenqiang Liua, Hong Yaoa,*
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a
University of Science and Technology, Wuhan 430074, Hubei Province, PR China;
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b
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Department of Chemical Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan;
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State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong
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Institute of Advanced Energy, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
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*Corresponding Author.
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E-mail address:
[email protected] (X. Li);
[email protected](H. Yao)
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Tel/Fax: +86-27-87545526
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Graphical abstract
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Biomass
Degradative solvent extraction Deoxygenation
First stage
Soluble
Deposit/Residue
Pyrolysis Second stage Bio-oil
Low oxygen content Low acid content more aromatic hydrocarbons
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Proposed two-stage method for high-quality bio-oils production from raw biomass
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Abstract
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The rapid depletion of fossil fuels has attracted more attention being geared towards the fast pyrolysis of
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biomass in order to produce bio-oils. However, the produced bio-oils usually contain high water, oxygen and
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acids contents and low calorific values, which have limited their wide application. Therefore, in this study, a
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novel two-stage method combining degradative solvent extraction with subsequent pyrolysis, was proposed
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in order to improve the quality of derived bio-oils. The raw biomass was initially dewatered and
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deoxygenated, by using a degradative solvent extraction method, to obtain a low-molecular-weight extract
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(named “Soluble”). The Solubles were then pyrolyzed at 500 oC to prepare bio-oils. The carbon contents and
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calorific values of bio-oils produced from the Solubles were as high as 90.09% and 44.63 MJ/kg respectively,
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which were 1.5-2.0 times higher than those from the raw biomasses. In addition, the water and oxygen
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contents of bio-oils from the Solubles were significantly lower than the bio-oils from the raw biomasses.
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Furthermore, the bio-oils from the Solubles contained much fewer corrosive and reactive acids, and more
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value-added aromatic hydrocarbons compared to those from raw biomasses. In summary, the quality of the
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bio-oils produced from the Solubles was obviously superior to the bio-oils from the direct pyrolysis of the
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raw biomasses. It was shown that degradative solvent extraction combined with subsequent pyrolysis is an
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effective method to convert raw biomasses into high-quality bio-oils.
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Keywords: Biomass; Degradative solvent extraction; Deoxygenation; Pyrolysis; Bio-oils
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1. Introduction
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With the fast depletion of fossil oils, renewable resources are increasingly considered as potential
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substitutes for energy production.1 Among various renewable resources, biomass is the only sustainable
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carbon resource that can be directly converted into fuels or chemicals via biochemical conversion processes
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(such as hydrolysis and fermentation) and thermochemical conversion processes (such as pyrolysis,
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gasification, liquefaction, hydrothermal carbonization).2-6 Fast pyrolysis of biomass has been growingly
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taken as a promising technology which converts biomass feedstock into bio-oil, char and gas products under
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inert atmosphere in a very short residence time (< 2 s).7-11 The bio-oils, whose yield can reach up to 60%,
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have shown the potential to be used as fuels in furnaces or engines and feedstocks for value-added chemicals
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production.12 The bio-oils, however, are always not suitable for direct commercial application. Due to the
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high oxygen contents of biomass, the bio-oils produced from direct pyrolysis of biomasses are a complex
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mixture consisting of hundreds of oxygenated compounds with high water and oxygen contents (35%-45%),
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high corrosive acids contents and low calorific value.13,14 These drawbacks have limited the widespread
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application of the bio-oils.
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Various methods have been developed to improve the quality of bio-oils, such as hydro-treating of the
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produced bio-oils, catalytic reforming of pyrolysis vapors, emulsification, and thermochemical pretreatment
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of biomass prior to pyrolysis such as torrefaction.15-18 Generally, these methods are found to be effective for
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bio-oils upgrading to some extent. However, there are some issues needed to be resolved for the practical
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utilization of these methods, such as complicated equipment, severe conditions, catalyst deactivation, and
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ash-related problems.
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Recently, a novel method, named degradative solvent extraction (DSE), has been put forward by the
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authors to achieve the deoxygenation and upgrading of a diversity of biomass wastes.19,20 In this method, the
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biomass feedstocks were treated a non-polar solvent at mild temperature (lower than 350 oC). Raw
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biomasses are decomposed and separated into three major solid products: an unextractable component ACS Paragon Plus Environment
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(named “Residue”) and two extracts (one is a solvent-insoluble component at ambient temperature, termed
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as “Deposit”, and another is a solvent-soluble component at ambient temperature, termed as “Soluble”). The
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solid Soluble is then acquired by evaporating the solvent using vacuum distillation. The Soluble exhibits
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high carbon content (more than 80%), low oxygen content (less than 15%) and moderate molecular weight
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of approximately 300. Furthermore, the Solubles contain nearly no moisture and ash. In view of the
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favorable properties of the Solubles, it seems highly feasible for further pyrolysis of the Solubles to produce
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high-quality bio-oils for fuels or chemical precursors.
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Therefore, in this study, the feasibilities of a two-stage conversion of biomass feedstocks (combining
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the degradative solvent extraction with subsequent pyrolysis) to prepare high-quality bio-oils were explored.
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Two typical biomasses, a non-woody biomass and a woody biomass, were initially treated by degradative
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solvent extraction to produce the Solubles, and then the Solubles were further pyrolyzed to obtain bio-oils.
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The properties and compositions of bio-oils prepared from the pyrolysis of the Solubles and raw biomasses
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were investigated and compared in detail.
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2. Experimental
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2.1. Biomass sample and solvent used
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Two representative biomass samples from China, a non-woody biomass (rice straw, abbreviated to RS)
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and a woody biomass (fir sawdust, abbreviated to SD), were used as raw materials. The properties of the raw
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materials are listed in Table 1. 1-Methylnaphthalene, which is a non-polar and stable solvent and can’t
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dissolve water and inorganic compounds, was selected for the DSE experiments. 19
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2.2. Degradative solvent extraction
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The diagram of the reaction apparatus for the DSE experiments is presented in Fig. 1. This apparatus
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consisted of an autoclave and a reservoir. A filter was installed at the bottom of the autoclave. The autoclave
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and the reservoir were collected by a valve. On each trial, the autoclave was first loaded with the mixture of
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approximately 30 g of raw biomass and 300 mL of 1-Methylnaphthalene.21 After being purged by N2 several ACS Paragon Plus Environment
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times, the autoclave was sealed with N2 and heated up to 350 oC with the heating rate of 5 oC/min, and held
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for 60 min. Afterwards, the valve above the reservoir was quickly opened to transfer the mixture of the
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solvent and the extracts into the reservoir, achieving the separation of the extracts and Residue. Then the
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autoclave and the reservoir were quenched to ambient temperature. A portion of the extracts, which
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precipitated in the reservoir at ambient temperature, was obtained by filtration and was called “Deposit”.
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The other portion of the solid extracts, which remained soluble in the solvent at ambient temperature, was
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acquired by evaporating the solvent through vacuum distillation and was called “Soluble”. Subsequently, the
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residual solvent remaining in the three solid products (Deposit, Soluble and Residue) was adequately
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removed by further drying in a vacuum oven at 150 oC for more than 8 h. The gaseous products (Gas) were
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collected and quantitatively analyzed by the Agilent MicroGC3000 gas chromatograph. The liquid products
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produced during the degradative solvent process were called "Liquid". When the reservoir was cooled down,
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the Liquid was mixed with the solvent. And most of the Liquid was removed together with the solvent
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during the separation of solvent and the Soluble by rotary evaporator. The yields of Residue, Deposit,
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Soluble, and Gas were calculated by their mass fractions. Then the Liquid yield was determined by mass
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balance. Duplicate experiments were conducted and the average values of the yields were reported.
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2.3. Pyrolysis experiment procedure.
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The raw biomasses and the Solubles were pyrolyzed in a fixed bed reactor, as shown in Fig. 2. The fixed
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bed reactor was mainly composed of a horizontal tube furnace, and two ice-water condensers. On each trial,
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around 1 g of raw biomass or Soluble was loaded into the quartz boat and placed at the entrance of furnace
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which was cooled down by circulating cooling water. The reactor was kept in an inert atmosphere by a flow
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of highly pure nitrogen (500 mL/min, 99.999%) during the pyrolysis process. After the reactor was heated to
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500 oC, the quartz boat was moved swiftly from the entrance to the constant temperature zone (500 oC) of the
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reactor. Then the sample was rapidly heated and decomposed. The condensable volatiles (bio-oil) that
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evolved out were collected by two ice-water condensers whereas the non-condensable volatiles (gas ACS Paragon Plus Environment
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products) were cleaned by two glass wool filters and collected by a gas bag. The collected gas products were
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quantitatively measured using the Agilent MicroGC3000 gas chromatograph. The yields of the pyrolysis
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char and gas products were determined by their respective weights. The yield of the bio-oil (including water)
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was determined by mass balance. Each pyrolysis trial was conducted more than three times, and the mean
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values were reported with the experiment error less than 3.0%.
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2.4. Products characterization
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The elemental analyses of the samples were carried out by the Vario CHN EL-2 elemental analyzer, and
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the proximate analyses of the samples were conducted in a muffle furnace based on GB/T212-2008. The
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chemical structures of solid samples were analyzed using a solid-sate 13C-Nuclear Magnetic Resonance
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(NMR) spectrometer. The solid-sate
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were recorded and curve-fitted into several Gaussian peaks and Lorentz peaks prior to integration. Thermal
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degradation behaviors of biomasses and the Solubles were measured by thermogravimetric analysis using
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the PerkinElmer TG/DTA analyzer. On each run, around 10 mg of sample was heated to 900 oC under inert
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atmosphere at the heating rate of 10 oC/min.
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C NMR spectra with Cross-Polarization Magic Spinning (CP/MAS)
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It is rather difficult to collect all of the bio-oils during the pyrolysis process for the chemical constitution
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analysis. Therefore, the Py-GC/MS analyses of the Solubles and raw biomasses were also performed for the
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chemical constitution characterization. The Py-GC/MS apparatus was a pyrolyzer (Frontier PY-3030D)
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directly connected to a GC/MS system (Agilent 7890/5975). The pyrolysis temperature was also at 500 oC.
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The chromatographic separation of the produced volatiles was carried out using a DB-5MS capillary
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column. Highly pure helium (99.999%) was employed as the carrier gas (1 mL/min). The oven temperature
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was initially maintained at 40 oC for 10 mins, and then heated up to 280 oC with the heating rate of 10
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o
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based on the NIST MS library and previous publications. The Py-GC/MS experiments were repeated to
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guarantee the validity and reproducibility.
C/min, and sustained for another 5 mins at 280 oC. The peaks of chromatographic spectra were determined
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3. Results and Discussion
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3.1. Yields and basic properties of DSE products
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Fig. 3 shows the distributions of products yields for DSE of SD and RS. It was found that the Solubles
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were the main solid product. The yields of Solubles produced from RS and SD were 24.3% and 40.2%
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respectively. A respectable amount of CO2 and Liquids were formed during the extraction. It was reported in
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our previous works that the Liquid mainly consisted of H2O.19 This indicates a large amount of oxygen in
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raw biomasses is removed as H2O and CO2. Table 1 presents the basic properties of the raw biomasses and
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the extraction products. In comparison to raw biomasses, the Solubles and Deposits had rather higher carbon
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content (more than 80%) and lower oxygen content (less than 12%), suggesting that remarkable
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deoxygenation reactions took place during the DSE process. Also, the significantly lower H/C as well as
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O/C ratios in the Soluble, as shown in Table 1, indicates that the Solubles may contain more aromatic
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structures compared to raw biomasses. Moreover, the Solubles contained virtually no ash, making them
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advantageous in mitigating the ash-related problems during the subsequent pyrolysis process. Another
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product (Deposit) can be used for other purposes, such as additives for coke-making blends to improve coke
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quality.21 This work focused on the bio-oils production from the Solubles.
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3.2. Chemical structure characterization and decomposition behaviors of raw biomasses and Solubles
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The chemical structures of raw materials for pyrolysis will significantly influence the chemical
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compositions and quality of bio-oils. Hence, it is essential to analyze the chemical structures of the Solubles
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and raw biomasses before their pyrolysis process commencing. The CP/MAS
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Solubles and raw biomasses were carried out to evaluate their chemical structure differences, as displayed in
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Fig. 4. The determination of each carbon type was identified according to literatures.22,23 From Fig. 4, it can
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be observed that the Solubles and the raw biomasses exhibited completely different chemical structures. The
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spectra of RS and SD revealed obvious peaks of oxygenated aliphatic carbons (especially 50-90 ppm),
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which were the typical carbon species ascribed to the cellulose and hemicellulose in raw biomasses. Only ACS Paragon Plus Environment
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C NMR analyses of the
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weak signals attributed to aromatic carbons (110-170 ppm) were observed in the spectra of raw RS and SD.
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Differing from raw RS and SD, the characteristic structures of biomasses (oxygen-substituted alkyl carbons,
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O-alkyl) were no longer present in the Solubles, while the intensities of the peaks attributed to the methyl
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carbons (–CH3), methylene carbons (–CH2), aromatic carbons (Ar-C and Ar-H) greatly increased.
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To further quantitatively characterize the chemical structures of the materials, the overlap
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C NMR
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spectra of the Solubles and their raw biomasses were deconvolved and curve-fitted into several Gaussian
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peaks and Lorentz peaks prior to integration based on previous studies.24,25 Fig. 5 shows the deconvolution
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spectrum of
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estimated according to the fitted peaks and presented in Table 2. The O-alkyl carbons in RS and SD were as
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high as 75.2% and 58.9% respectively, while those in the Solubles were nearly 0, suggesting that the
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oxygen-containing functional groups were dramatically removed during the DSE process. This is in
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agreement with the ultimate analysis shown in Table 1. The aromaticities of raw RS and SD were as low as
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8.0% and 22.7%, while those of their Solubles increased to 48.3% and 56.7% respectively. The low contents
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of the oxygen-containing functional groups and high contents of aromatic carbons in the Solubles are
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expected to produce bio-oils having low oxygen contents and more value-added aromatic hydrocarbons,
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which is beneficial to the utilizations of the bio-oils not only as high calorific value liquid fuels but also as
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precursors for chemicals.
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C NMR spectrum of RS-Soluble as an example. The distributions of carbon were then
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Prior to the pyrolysis process, the thermal degradation behaviors of raw biomasses and the obtained
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Solubles were probed and explicated by thermogravimetric analysis for the pyrolysis conditions
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confirmation, as displayed in Fig. 6. It was observed that prominent differences existed between the
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decomposition behaviors of the Solubles and raw biomasses. The Solubles exhibited much smaller weight
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decreasing rate within a rather broad decomposition temperature band (200-500 oC). These differences
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should be attributed to the chemical structure differences between the Solubles and raw biomasses, as shown
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in Fig. 4. The weight losses of both raw biomasses and the Solubles after 500 oC were negligible, so 500 oC ACS Paragon Plus Environment
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was selected as the pyrolysis temperature for the subsequent pyrolysis.
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3.3. Yields and basic properties of pyrolysis products.
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Fig. 7 demonstrates the yield distributions of pyrolysis products of raw biomasses and the Solubles. The
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bio-oil yields of RS-Soluble and SD-Soluble were 48.14% and 58.83% respectively, slightly higher than the
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yields of the bio-oils from the corresponding raw biomasses. In contrast, the gas yields from the Solubles
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pyrolysis were a bit lower.
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The properties of the pyrolysis products are another important concern. Table 3 shows the elemental
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composition, ash content and higher heating value (HHV) of the bio-oils and chars. The HHV was
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calculated by Dulong equation.26 The carbon contents of the bio-oils from SD-Soluble and RS-Soluble were
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90.09% and 87.49% respectively, remarkably higher than those from raw SD and RS. Furthermore, the
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oxygen contents of the bio-oils from SD-Soluble and RS-Soluble were as low as 0.92% and 0.62%
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respectively, extremely lower than those of the raw biomasses. Hence, the bio-oils from the Solubles
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contained significantly lower O/C atomic ratios than those of the raw biomasses. The relative higher H/C
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atomic ratios of the bio-oils from raw biomasses mainly resulted from their high water contents. 27 It is
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worthy to note that the water contents of the bio-oils derived from the Solubles should be lower than 1.0%,
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since the total oxygen content of the bio-oils (including water) prepared from Solubles were lower than
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1.0%, as shown in Table 3. Additionally, the HHVs of the bio-oils from RS-Soluble and SD-Soluble were
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44.63 and 42.32 MJ/kg respectively, which are approximate to the HHVs of commercial gasoline or diesel
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(42-46 MJ/kg), 28,29 and significantly higher than those of the raw biomasses.
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The char is also an important by-product for biomass pyrolysis technologies. The high carbon contents
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(as high as 89.21%) and approximately zero ash contents of the chars from the Solubles pyrolysis, as shown
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in Table 3, implies that these chars could be used for some value-added applications, such as carbon material
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production and high-quality solid fuel. This is an additional advantage of the proposed two-stage method
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over other technologies. ACS Paragon Plus Environment
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The elemental composition evolution of the two-stage method was visually described in the form of the
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Van Krevelen diagram,30 as displayed in Fig. 8. It was observed that the first step: the degradative solvent
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extraction process, from raw biomasses to the Solubles, generally corresponded to the trends of
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decarboxylation and dehydration processes. And the second step: namely the pyrolysis process, from the
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Solubles to bio-oils, experienced further decarboxylation process.
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3.4. Chemical constitution of produced bio-oils.
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Fig. 9 shows the relative contents of the organic constituents of the bio-oils produced from raw
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biomasses and the Solubles by normalization of the peak areas of the GC−MS spectra. The constituents of
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the bio-oils were classified into oxygen-containing compounds (ketones and ethers, phenols, acids),
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hydrocarbons (aromatic hydrocarbons and aliphatic hydrocarbons), and others (such as nitrogen-containing
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compounds and unidentified compounds). It was found that distinct differences existed between the
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compositions of the bio-oils from raw biomasses and the corresponding Solubles. The bio-oils obtained from
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raw biomasses mainly consisted of oxygen-containing compounds (such as ketones, ethers, phenols and
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acids), which accounted for 66.97% and 72.36% for RS and SD, respectively. On the other hand, the
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oxygen-containing compounds in the bio-oils from RS-Soluble and SD-Soluble were as low as 16.82% and
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24.34% respectively. It is well established that a majority of oxygen-containing compounds in bio-oil have
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high reactivity, acidity, and will therefore cause a series of problems for the storage and utilization of
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bio-oils, such as low thermal stability and high corrosiveness.31 The bio-oils from the Solubles mainly
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consisted of aromatic hydrocarbons, which accounted for 66.04% and 48.06% for RS-Soluble and
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SD-Soluble, respectively. This is a result of the rich aromatic structures in the Solubles, as shown in Table 2.
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Consequently, the remarkable oxygen removal during the DSE process of raw biomass, significantly
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reduced the formation of oxygen-containing compounds and improved the contents of aromatic
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hydrocarbons in the bio-oils during the subsequent pyrolysis process of the Solubles. Hence, the high yields
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of the aromatic hydrocarbons in the produced bio-oils from the Solubles pyrolysis are very meritorious, ACS Paragon Plus Environment
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because such aromatic hydrocarbons are highly value-added products and have tremendous potential in
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being utilized as chemicals.31,33
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3.5. Comparison of the proposed two-stage method with other main bio-oil production/upgrading
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technologies.
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The differences between the proposed two-stage method with other main bio-oil production/upgrading
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technologies (direct biomass pyrolysis without catalyst,4,18,34,35 catalytic pyrolysis,36-38 hydrodeoxygenation
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of bio-oil,39-42 and pyrolysis after torrefaction43-46) were briefly compared, as presented in Table 4. The total
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mass yield, carbon-based yield, and energy yield are all based on dry raw biomass. The mass yields of the
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bio-oils produced by the proposed two-stage method were somewhat lower than those produced by other
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technologies, such as direct biomass pyrolysis without catalyst and catalytic pyrolysis. However, the water
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contents and the oxygen contents of the bio-oils produced by the two-stage method were extremely lower
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than those produced by other technologies. This resulted in the HHVs of the bio-oils produced by the
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two-stage method, to be approximately 1.5-2.0 times higher than those produced by the other technologies.
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Also, the carbon-based yields and energy yields of the bio-oils produced by the two-stage method were
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comparable to those produced by the other technologies. In addition, another advantage of the proposed
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two-stage method is that it does not require any catalyst. Thus, the significant advantages of bio-oils
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production from the Solubles were shown. Through further optimizations of the conditions in the first stage
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of the DSE and in the second stage of pyrolysis, the bio-oil yield could be further improved and more
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acceptable in our future work. Consequentially, the two-stage method could be one of the promising
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methods for high-quality bio-oil production.
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4. Conclusion
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The combination of degradative solvent extraction of biomass with subsequent pyrolysis of the low
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-molecular-weight extract (the Solubles) to produce high-quality bio-oils was proposed in this study. The
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biomass was initially dewatered, deoxygenated and fractionated by degradative solvent extraction to obtain ACS Paragon Plus Environment
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the Solubles. The Solubles was then pyrolyzed at 500 oC to prepare bio-oils. The Solubles had much lower
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oxygen contents and more aromatic structures in comparison with raw biomasses. Meanwhile, the carbon
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contents and HHVs of the bio-oils from the Solubles were as high as 90.09% and 44.63 MJ/m3 respectively,
276
which were remarkably higher than the bio-oils from the raw biomasses. The oxygen and water contents of
277
bio-oils prepared from the Solubles pyrolysis were significantly lower than the bio-oils from the
278
corresponding biomasses. In comparison with the bio-oils from raw biomasses, the bio-oils from the
279
Solubles contained fewer corrosive acids, and more value-added aromatic hydrocarbons. In conclusion, the
280
quality of the bio-oils produced from the pyrolysis of Solubles was obviously superior to the bio-oils from
281
the direct pyrolysis of raw biomasses. Additionally, the carbon-based yields and energy yields of the bio-oils
282
produced by the two-stage method were comparable to those produced by the other bio-oil upgrading
283
technologies. Therefore, the high feasibilities of the two-stage method to produce high-quality bio-oils were
284
shown.
285
AUTHOR INFORMATION
286
Corresponding Authors
287
* E-mail:
[email protected] ; Tel/Fax: +86-27-87545526
288
* E-mail:
[email protected]; Tel/Fax: +86-27-87545526
289
Notes
290
The authors declare no competing financial interest.
291
Acknowledgments
292
This study was sponsored by National Natural Science Foundation of China (grant numbers U1510119,
293
21306059, 51306063), International Science & Technology Cooperation Program of China (grant number
294
2015DFA60410), and Graduates' Innovation Fund, Huazhong University of Science and Technology. The
295
authors also greatly appreciate the measurements assistances provided by the Analytical and Testing Center ACS Paragon Plus Environment
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of Huazhong University of Science and Technology.
297 298
References:
299
(1) Ullah, K., Kumar Sharma, V., Dhingra, S., Braccio, G., Ahmad, M., Sofia, S. Assessing the lignocellulosic biomass
300
resources potential in developing countries: A critical review. Renewable Sustainable Energy Rev. 2015, 51, 682-698.
301
(2) Wang, B., Cao, J., Zhao, X., Bian, Y., Song, C., Zhao, Y., Fan, X., Wei, X., Takarada, T. Preparation of nickel-loaded
302
on lignite char for catalytic gasification of biomass. Fuel Process. Technol. 2015, 136, 17-24.
303
(3) Calucci, L., Rasse, D. P., Forte, C. Solid-state nuclear magnetic resonance characterization of chars obtained from
304
hydrothermal carbonization of corncob and miscanthus. Energy Fuels 2012, 27, 303-309.
305
(4) Zhang, L., Xu, C. C., Champagne, P. Overview of recent advances in thermo-chemical conversion of biomass. Energy
306
Convers. Manage. 2010, 51, 969-982.
307
(5) Wang, G., Li, W., Li, B., Chen, H. TG study on pyrolysis of biomass and its three components under syngas. Fuel 2008,
308
87, 552-558.
309
(6) Song, C., Hu, H., Zhu, S., Wang, G., Chen, G. Nonisothermal catalytic liquefaction of corn stalk in subcritical and
310
supercritical water. Energy Fuels 2004, 18, 90-96.
311
(7) Subagyono, R. R. D. J., Qi, Y., Jackson, W. R., Chaffee, A. L. Pyrolysis-GC/MS analysis of biomass and the bio-oils
312
produced from CO/H2O reactions. J. Anal. Appl. Pyrolysis 2016, 120, 154-164.
313
(8) Wiinikka, H., Carlsson, P., Johansson, A., Gullberg, M., Ylipää, C., Lundgren, M., Sandström, L. Fast Pyrolysis of Stem
314
Wood in a Pilot-Scale Cyclone Reactor. Energy Fuels 2015, 29, 3158-3167.
315
(9) Cao, J., Xiao, X., Zhang, S., Zhao, X., Sato, K., Ogawa, Y., Wei, X., Takarada, T. Preparation and characterization of
316
bio-oils from internally circulating fluidized-bed pyrolyses of municipal, livestock, and wood waste. Bioresour. Technol.
317
2011, 102, 2009-2015.
318
(10) Meesuk, S., Cao, J., Sato, K., Ogawa, Y., Takarada, T. Fast pyrolysis of rice husk in a fluidized bed: effects of the gas
319
atmosphere and catalyst on bio-oil with a relatively low content of oxygen. Energy Fuels 2011, 25, 4113-4121.
320
(11) Worasuwannarak, N., Sonobe, T., Tanthapanichakoon, W. Pyrolysis behaviors of rice straw, rice husk, and corncob by
ACS Paragon Plus Environment
14
Page 15 of 33
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
Energy & Fuels
321
TG-MS technique. J. Anal. Appl. Pyrolysis 2007, 78, 265-271.
322
(12) Bridgwater, A. V. Renewable fuels and chemicals by thermal processing of biomass. Chem. Eng. J. 2003, 91, 87-102.
323
(13) Huang, X., Cao, J., Shi, P., Zhao, X., Feng, X., Zhao, Y., Fan, X., Wei, X., Takarada, T. Influences of pyrolysis
324
conditions in the production and chemical composition of the bio-oils from fast pyrolysis of sewage sludge. J. Anal. Appl.
325
Pyrolysis 2014, 110, 353-362.
326
(14) Neves, D., Thunman, H., Matos, A., Tarelho, L., Gómez-Barea, A. Characterization and prediction of biomass
327
pyrolysis products. Prog. Energy Combust. Sci. 2011, 37, 611-630.
328
(15) Chen, Y., Yang, H., Yang, Q., Hao, H., Zhu, B., Chen, H. Torrefaction of agriculture straws and its application on
329
biomass pyrolysis poly-generation. Bioresour. Technol. 2014, 156, 70-77.
330
(16) Elliott, D. C., Hart, T. R., Neuenschwander, G. G., Rotness, L. J., Olarte, M. V., Zacher, A. H., Solantausta, Y.
331
Catalytic hydroprocessing of fast pyrolysis bio-oil from pine sawdust. Energy Fuels 2012, 26, 3891-3896.
332
(17) Jiang, X.,Ellis, N. Upgrading bio-oil through emulsification with biodiesel: mixture production. Energy Fuels 2009, 24,
333
1358-1364.
334
(18) Zhang, Q., Chang, J., Wang, T., Xu, Y. Review of biomass pyrolysis oil properties and upgrading research. Energy
335
Convers. Manage. 2007, 48, 87-92.
336
(19) Zhu, X., Xue, Y., Li, X., Zhang, Z., Sun, W., Ashida, R., Miura, K., Yao, H. Mechanism study of degradative solvent
337
extraction of biomass. Fuel 2016, 165, 10-18.
338
(20) Wannapeera, J., Li, X., Worasuwannarak, N., Ashida, R., Miura, K. Production of High-Grade Carbonaceous Materials
339
and Fuel Having Similar Chemical and Physical Properties from Various Types of Biomass by Degradative Solvent
340
Extraction. Energy Fuels 2012, 26, 4521-4531.
341
(21) Zhu, X., Li, X., Xiao, L., Zhang, X., Tong, S., Wu, C., Ashida, R., Liu, W., Miura, K., Yao, H. Novel carbon-rich
342
additives preparation by degradative solvent extraction of biomass wastes for coke-making. Bioresour. Technol. 2016, 207,
343
85-91.
344
(22) Cao, X., Pignatello, J. J., Li, Y., Lattao, C., Chappell, M. A., Chen, N., Miller, L. F., Mao, J. Characterization of wood
ACS Paragon Plus Environment
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Energy & Fuels
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 16 of 33
345
chars produced at different temperatures using advanced solid-state 13C NMR spectroscopic techniques. Energy Fuels 2012,
346
26, 5983-5991.
347
(23) Gupta, R. Advanced coal characterization: a review. Energy Fuels 2007, 21, 451-460.
348
(24) Lin, X., Wang, C., Ideta, K., Miyawaki, J., Nishiyama, Y., Wang, Y., Yoon, S., Mochida, I. Insights into the functional
349
group transformation of a chinese brown coal during slow pyrolysis by combining various experiments. Fuel 2014, 118,
350
257-264.
351
(25) Wang, S., Tang, Y., Schobert, H. H., Guo, Y. N., Su, Y. FTIR and 13C NMR investigation of coal component of late
352
Permian coals from southern China. Energy Fuels 2011, 25, 5672-5677.
353
(26) Mott, R. A.,Spooner, C. E. The calorific value of carbon in coal: the Dulong relationship. Fuel 1940, 19, 242.
354
(27) Mohan, D., Pittman, C. U., Steele, P. H. Pyrolysis of Wood/Biomass for Bio-oil: A Critical Review. Energy Fuels
355
2006, 20, 848-889.
356
(28) Ma, Y., Huang, S., Huang, R., Zhang, Y., Xu, S. Ignition and combustion characteristics of n-pentanol–diesel blends in
357
a constant volume chamber. Appl. Energ. 2017, 185, Part 1, 519-530.
358
(29) Yücesu, H. S., Topgül, T., Çinar, C., Okur, M. Effect of ethanol–gasoline blends on engine performance and exhaust
359
emissions in different compression ratios. Appl. Therm. Eng. 2006, 26, 2272-2278.
360
(30) Van Krevelen, D. W. Graphical-statistical method for the study of structure and reaction processes of coal. Fuel 1950,
361
29, 269-284.
362
(31) Meng, J., Moore, A., Tilotta, D. C., Kelley, S. S., Adhikari, S., Park, S. Thermal and Storage Stability of Bio-Oil from
363
Pyrolysis of Torrefied Wood. Energy Fuels 2015, 29, 5117-5126.
364
(32) Carlson, T. R., Cheng, Y., Jae, J., Huber, G. W. Production of green aromatics and olefins by catalytic fast pyrolysis of
365
wood sawdust. Energy Environ. Sci. 2011, 4, 145-161.
366
(33) Vispute, T. P., Zhang, H., Sanna, A., Xiao, R., Huber, G. W. Renewable chemical commodity feedstocks from
367
integrated catalytic processing of pyrolysis oils. Science 2010, 330, 1222-1227.
368
(34) Lehto, J., Oasmaa, A., Solantausta, Y., Kytö, M., Chiaramonti, D. Review of fuel oil quality and combustion of fast
ACS Paragon Plus Environment
16
Page 17 of 33
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
Energy & Fuels
369
pyrolysis bio-oils from lignocellulosic biomass. Appl. Energ. 2014, 116, 178-190.
370
(35) Bridgwater, A. V. Review of fast pyrolysis of biomass and product upgrading. Biomass Bioenergy 2012, 38, 68-94.
371
(36) Wang, P., Zhan, S., Yu, H., Xue, X., Hong, N. The effects of temperature and catalysts on the pyrolysis of industrial
372
wastes (herb residue). Bioresour. Technol. 2010, 101, 3236-3241.
373
(37) Pütün, E. Catalytic pyrolysis of biomass: Effects of pyrolysis temperature, sweeping gas flow rate and MgO catalyst.
374
Energy 2010, 35, 2761-2766.
375
(38) Zhang, H., Xiao, R., Wang, D., Zhong, Z., Song, M., Pan, Q., He, G. Catalytic fast pyrolysis of biomass in a fluidized
376
bed with fresh and spent fluidized catalytic cracking (FCC) catalysts. Energy Fuels 2009, 23, 6199-6206.
377
(39) Elkasabi, Y., Mullen, C. A., Pighinelli, A. L. M. T., Boateng, A. A. Hydrodeoxygenation of fast-pyrolysis bio-oils from
378
various feedstocks using carbon-supported catalysts. Fuel Process. Technol. 2014, 123, 11-18.
379
(40) Kim, T., Oh, S., Kim, J., Choi, I., Choi, J. W. Study on the hydrodeoxygenative upgrading of crude bio-oil produced
380
from woody biomass by fast pyrolysis. Energy 2014, 68, 437-443.
381
(41) Wang, Y., He, T., Liu, K., Wu, J., Fang, Y. From biomass to advanced bio-fuel by catalytic pyrolysis/hydro-processing:
382
Hydrodeoxygenation of bio-oil derived from biomass catalytic pyrolysis. Bioresour. Technol. 2012, 108, 280-284.
383
(42) de Miguel Mercader, F., Groeneveld, M. J., Kersten, S. R., Geantet, C., Toussaint, G., Way, N. W., Schaverien, C. J.,
384
Hogendoorn, K. J. Hydrodeoxygenation of pyrolysis oil fractions: process understanding and quality assessment through
385
co-processing in refinery units. Energy Environ. Sci. 2011, 4, 985-997.
386
(43) Chen, Y., Yang, H., Yang, Q., Hao, H., Zhu, B., Chen, H. Torrefaction of agriculture straws and its application on
387
biomass pyrolysis poly-generation. Bioresour. Technol. 2014, 156, 70-77.
388
(44) Boateng, A. A.,Mullen, C. A. Fast pyrolysis of biomass thermally pretreated by torrefaction. J. Anal. Appl. Pyrolysis
389
2013, 100, 95-102.
390
(45) Zheng, A., Zhao, Z., Chang, S., Huang, Z., Wang, X., He, F., Li, H. Effect of torrefaction on structure and fast
391
pyrolysis behavior of corncobs. Bioresour. Technol. 2013, 128, 370-377.
392
(46) Zheng, A., Zhao, Z., Chang, S., Huang, Z., He, F., Li, H. Effect of torrefaction temperature on product distribution
ACS Paragon Plus Environment
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393
from two-staged pyrolysis of biomass. Energy Fuels 2012, 26, 2968-2974.
394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416
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417 418
Table captions
419
Table 1 The basic properties of raw biomasses and the extraction products
420
Table 2 Different types of carbon (ppm) distribution (%) in raw biomasses and Solubles
421
Table 3 The properties of pyrolysis products of raw biomasses and the Solubles
422
Table 4 A brief comparison of the proposed two-stage method with other main bio-oil production/upgrading (direct
biomass
pyrolysis
without
catalyst,4,18,32,33
423
technologies
424
hydrodeoxygenation of bio-oil,37-40 and pyrolysis after torrefaction41-44).
425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455
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catalytic
pyrolysis,34-36
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456 457 458 459 460
Table 1 The basic properties of raw biomasses and the extraction products
Sample
RS
SD
461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493
Ultimate analysis(wt %, db*)
T(oC)
C
H
N
O
RS
44.12
6.05
0.73
Soluble
78.90
6.55
Deposit
74.74
Residue
49.59
SD
a
Proximate analysis(wt %,db*)
Atomic ratio H/C O/C
HHV (MJ/kg)
VM
A
FC
39.12
75.39
9.98
14.63
1.63
0.67
16.59
0.42
14.13
74.06
0.00
25.94
0.99
0.13
35.16
5.39
0.43
19.43
48.37
0.00
51.63
0.86
0.20
32.49
3.79
0.74
11.46
36.89
34.43
28.69
0.91
0.17
20.16
52.46
6.80
0.08
39.43
84.39
1.23
14.37
1.54
0.56
20.43
Soluble
80.32
6.97
1.37
11.34
75.71
0.00
24.29
1.03
0.11
33.58
Deposit
78.98
5.70
1.81
13.51
53.88
0.00
46.12
0.86
0.13
29.54
Residue
73.42
4.75
0.22
13.41
46.31
8.20
45.49
0.77
0.14
29.25
a: by difference *:dry basis VM: volatile matter A: ash FC: fixed carbon
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495 496 497
Table 2 Different types of carbon (ppm) distribution (%) in raw biomasses and Solubles.
Samples RS RS-Soluble SD SD-Soluble
Carbonyl
Carboxyl
Ar-O
Ar-C
Ar-H
O-alkyl
O-CH3
CH2
CH3
235-187
187-171
171-148
148-129
110-129
110-60
60-50
50-25
25-0
0.0 7.4 0.0 8.1
2.9 2.3 6.9 0.0
1.5 6.2 8.3 0.0
0.0 31.2 3.4 30.8
6.4 11.0 11.0 25.9
75.2 0.0 58.9 0.0
4.9 2.7 4.5 6.8
1.2 13.5 4.3 14.1
7.8 25.9 2.7 14.2
498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536
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Aromaticity 8.0 48.3 22.7 56.7
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537 538 539 540
Table 3 The properties of pyrolysis products of raw biomasses and the Solubles Sample RS RS-Soluble SD SD- Soluble
541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580
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Char Bio-oil Char Bio-oil Char Bio-oil Char Bio-oil
a: by difference
Ultimate analysis(wt %, db*) C H N Oa 56.13 2.35 0.75 11.74 42.19 13.44 1.25 43.12 89.21 3.01 1.96 5.83 87.49 10.51 1.38 0.62 71.67 3.01 0.16 20.06 53.48 11.98 0.08 34.47 72.11 3.76 0.12 24.01 90.09 8.34 0.65 0.92
Ash (wt %, db*) 29.04 0 5.10 0 -
*:dry basis
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Atomic ratio H/C O/C 0.50 0.16 3.80 0.77 0.40 0.05 1.43 0.01 0.50 0.21 2.67 0.48 0.62 0.25 1.10 0.01
HHV (MJ/kg) 20.25 25.87 33.45 44.63 24.95 29.14 25.48 42.32
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581 582 583 584 585 586
Table 4 A brief comparison of the proposed two-stage method with other main bio-oil production/upgrading technologies (direct biomass pyrolysis without catalyst,4,18,34,35 catalytic pyrolysis,36-38 hydrodeoxygenation of bio-oil,39-42 and pyrolysis after torrefaction43-46).
Technologies Direct biomass pyrolysis
Two-stage method (RS) Two-stage method (SD)
587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620
Energy & Fuels
Catalytic pyrolysis Hydrodeoxygenation Pyrolysis after torrefaction a: based on dry raw biomass
Mass yielda wt%
Water content wt%
Oxygen content wt%
Carbon-based yielda wt%
HHV, MJ/kg
Energy-y ielda wt%
Catalyst
35-65 11.7 23.7 30-48 12-35 17-50
20-30
