- Email: [email protected]
Fast pyrolysis of eucalyptus waste in a conical spouted bed reactor
Bioresource Technology 194 (2015) 225–232
Contents lists available at ScienceDirect
Bioresource Technology journal homepage: www.elsevier.com/locate/biortech
Fast pyrolysis of eucalyptus waste in a conical spouted bed reactor Maider Amutio, Gartzen Lopez, Jon Alvarez, Martin Olazar ⇑, Javier Bilbao Department of Chemical Engineering, University of the Basque Country UPV/EHU, P.O. Box 644, E48080 Bilbao, Spain
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
Conical spouted bed reactor is
suitable for eucalyptus wastes pyrolysis. Higher bio-oil yield (75.4 wt.%) than with other technologies is obtained. Water, phenols and ketones content in bio-oil are 35, 26 and 10 wt.%, respectively. TG analysis is set as a methodology for determining the composition of the biomass.
a r t i c l e
i n f o
Article history: Received 9 June 2015 Received in revised form 8 July 2015 Accepted 9 July 2015 Available online 15 July 2015 Keywords: Pyrolysis Bio-oil Bio-refinery Spouted bed reactor Eucalyptus
a b s t r a c t The fast pyrolysis of a forestry sector waste composed of Eucalyptus globulus wood, bark and leaves has been studied in a continuous bench-scale conical spouted bed reactor plant at 500 °C. A high bio-oil yield of 75.4 wt.% has been obtained, which is explained by the suitable features of this reactor for biomass fast pyrolysis. Gas and bio-oil compositions have been determined by chromatographic techniques, and the char has also been characterized. The bio-oil has a water content of 35 wt.%, and phenols and ketones are the main organic compounds, with a concentration of 26 and 10 wt.%, respectively. In addition, a kinetic study has been carried out in thermobalance using a model of three independent and parallel reactions that allows quantifying this forestry waste’s content of hemicellulose, cellulose and lignin. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Bio-fuel and bio-based chemical production from non-edible biomass provides an excellent opportunity for reducing the dependence on fossil fuels and mitigating the associated environmental impacts. Over the last decades, biomass conversion technologies have been directed towards the development of the biorefinery concept by means of chemical, biochemical and thermochemical processes for the production of fuels and chemicals (FitzPatrick et al., 2010). Flash pyrolysis for bio-oil production has been regarded as one of the most feasible processes on a large scale as it involves several advantages, such as simplicity and low energy ⇑ Corresponding author. Tel.: +34 946012527; fax: +34 946 013 500. E-mail address: [email protected] (M. Olazar). http://dx.doi.org/10.1016/j.biortech.2015.07.030 0960-8524/Ó 2015 Elsevier Ltd. All rights reserved.
requirements and capital investment (Maity, 2015). Thus, bio-oil can be produced in a delocalized way in rural areas where biomass is available and transported to centralized biorefineries for the production of fuels and chemicals as well as heat and power (Bridgwater, 2012). Several reactor configurations such as fluidized bed, transport and circulating fluidized bed, rotating cone, ablative, auger, vacuum moving bed and spouted bed reactors have been developed and scaled-up to pilot or demonstration plants for biomass flash pyrolysis (Bridgwater, 2012). However, the industrial implementation of the biomass pyrolysis process needs to solve several challenges, with one of the most important ones being the regular supply of biomass resources that do not compete with food (Ho et al., 2014). Therefore, the use of wastes derived from the existing forest industries as feedstock for the pyrolysis process is essential
226
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
for the development of this technology at large scale (Arbogast et al., 2012), thus reducing the costs associated with the production of a suitable feedstock, which is one of the steps with the highest energy consumption (Sanna, 2014). These waste materials are highly heterogeneous because they are composed of wood, bark, leaves, and so on, and have therefore varying properties. This feature places biomass fast pyrolysis technologies in the situation of having to face the challenge of being sufficiently versatile so as to produce high bio-oil yields with adequate properties, regardless the heterogeneity of the raw material (Carpenter et al., 2014). Accordingly, the present paper aims at studying the pyrolysis of a waste material composed of branches and leaves coming from the cutting down of eucalyptus trees for the paper manufacturing sector. This waste material accounts for a considerable fraction of the whole tree (around 30–40 wt.%). Furthermore, eucalyptus crops are achieving an increasing importance in the European Mediterranean watershed. This eucalyptus material is highly heterogeneous, which means that its large scale exploitation requires an adequate pyrolysis technology, as well as a simple and reproducible analytical methodology to determine hemicellulose, cellulose and lignin contents. The latter is an essential tool in order to store different waste materials that give way to a regular mixture composition, with the aim of guaranteeing reproducibility in the composition of the pyrolytic products, especially that of bio-oil. In this work, a methodology previously developed for other biomass materials (Amutio et al., 2013a) has been applied, i.e., a thermogravimetric study allowing the quantification of the chemical components (hemicellulose, cellulose and lignin) in the eucalyptus waste. Furthermore, a conical spouted bed reactor (CSBR) is proposed for the fast pyrolysis of this residual biomass as alternative to fluidized beds, given that it performs well by obtaining high bio-oil yields with several biomass materials, such as pinewood (Amutio et al., 2012) or forest shrub wastes with a heterogeneous composition (Amutio et al., 2013b). Furthermore, it is noteworthy that short volatile residence times are suitable for minimizing the catalytic activity of the ashes (Carpenter et al., 2014), which allows obtaining high bio-oil yields (70 wt.%) for rice husk pyrolysis, even though this material has a high ash content (Alvarez et al., 2014a). In addition, this technology has been scaled up to a 25 kg/h pilot plant, in collaboration with IK4-Ikerlan Research Centre, with its performance being excellent for pine and poplar wood pyrolysis (Fernandez-Akarregi et al., 2013; Makibar et al., 2015). 2. Methods 2.1. Raw material Eucalyptus globulus waste from the paper industry sector has been used as feedstock for the pyrolysis process. This material is composed of the wastes (wood, bark and leaves) remaining from the cutting down of the eucalyptus trees. The biomass has been collected, dried and ground to a particle size in the 1–2 mm range. The proximate analysis of the raw material (TGA Q500IR thermogravimetric analyzer) reveals that it is made up of 9.5 wt.% of moisture, 87.4 wt.% of volatile matter, 11.4 wt.% of fixed carbon and 1.2 wt.% of ash. Furthermore, the carbon, hydrogen, nitrogen and oxygen contents are 46.5, 5.1, 0.6 and 46.6 wt.%, respectively (LECO CHNS-932 elemental analyzer). Finally, the higher heating value (HHV) has been set at 17.4 MJ kg1 (Parr 1356 isoperibol bomb calorimeter). 2.2. Conical spouted bed pyrolysis plant The continuous conical spouted bed bench scale plant used in this study is outlined in Fig. 1. This plant has been fine tuned on
the basis of previous studies involving the pyrolysis of other biomass residues, such as pinewood (Amutio et al., 2012), forest shrubs (Amutio et al., 2013b) and rice husk (Alvarez et al., 2014a). Biomass is fed by means of a vessel provided with a vertical shaft connected to a piston, which allows the continuous feeding of up to 200 g h1 of biomass. Nitrogen, whose flow rate is controlled by a mass flow meter, is used as fluidizing agent and it is heated to the reaction temperature by means of a preheater. The reactor is a conical spouted bed with an upper cylindrical section, with a total height of 34 cm and a cylindrical section diameter of 12.3 cm. The height of the conical section is 20.5 cm, with an angle of 28° and a bottom diameter of 2 cm. The gas inlet diameter is 1 cm. Furthermore, the reactor is equipped with a lateral outlet for the continuous and selective removal of the char from the bed throughout the process, which is possible due to the cyclic movement of the particles in the bed (Amutio et al., 2011). The volatile products formed in the pyrolysis process together with the nitrogen used for fluidization pass through the gas cleaning system, which consists of a high efficiency cyclone and a sintered steel filter that are maintained at 280 °C in order to avoid the condensation of the heaviest compounds. The vapor residence time within the fine-particle retention system is less than 1 s, thus avoiding the partial cracking of the organic products before their condensation. The condensation of the bio-oil is carried out by means of a double-shell tube condenser cooled by tap water and two coalescence filters, which ensure the recovery of the heavy compounds. 2.3. Product analysis The pyrolysis volatiles have been analyzed online by means of chromatographic techniques. The reactor outlet stream has been monitored prior to condensation using a gas chromatograph (GC) (Varian 3900) equipped with a flame ionization detector (FID). The line from the reactor outlet to the chromatograph is heated to a temperature of 280 °C in order to avoid the condensation of heavy oxygenated compounds and to ensure that all the volatile products formed during pyrolysis enter the gas chromatograph and are analyzed online. Unlike hydrocarbons, the FID response to oxygenated compounds is not proportional to their mass, and therefore a calibration has been performed. Furthermore, the non-condensable gases leaving the condensation system have been analyzed using a micro-chromatograph (Varian 4900). This micro-GC has also been used to measure the water yield, following a similar procedure to that described for the standard gas chromatograph. The volatile products have been identified by analyzing the bio-oil recovered in the condenser and filters by means of a GC/MS (Shimadzu UP-2010S) and the gaseous products by means of a micro-GC connected to a mass spectrometer (Agilent 5975B). Furthermore, the char fraction has also been characterized by carrying out its ultimate (LECO CHNS-932) and proximate (TGA Q500IR) analyses, as well as measuring its higher heating value (Par 1356). 2.4. Experimental procedure The runs in the bench scale plant have been carried out at 500 °C, which has been set as the optimum temperature for maximizing the bio-oil yield in woody biomass pyrolysis (Amutio et al., 2012). 100 g of biomass have been continuously fed in each run with a feeding rate of 2 g min1. The reactor bed was made up of 100 g of sand with a particle size in the 0.3–0.63 mm range and the nitrogen flow rate has been set up in 10 Nl min1 in order to ensure stable spouting and guarantee high heat transfer rates and bed isothermicity.
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
227
Fig. 1. Schematic diagram of the conical spouted bed pyrolysis bench-scale plant.
Volatile product samples for the online chromatographic analyses have been taken under the same conditions so as to ensure reproducibility of the process. Mass balance closure has been carried out by weighing the char collected by the lateral outlet and in the cyclone, filter and reactor at the end of the continuous run, and by the online chromatographic analysis. Moreover, in order to validate the mass balance, an internal standard (cyclohexane) has been introduced through an inlet located in the heated line running from the reactor to the chromatograph, thus obtaining 95% mass balance closure. Furthermore, the thermogravimetric study has been carried out in a TGA Q500IR thermobalance, in order to study the degradation characteristics of the material and determine its chemical composition prior to pyrolysis in the conical spouted bed plant. The thermogravimetric experiments have been conducted by subjecting 10 mg of the sample with a particle size below 0.2 mm to three heating ramps of 5, 10 and 15 °C min1. Furthermore, the woody part in the eucalyptus wastes has been separated from the bark and leaves in order to study the influence of the biomass composition on its pyrolysis characteristics.
pyrolysis process and gives way to a long tail at high temperatures (Pang et al., 2014). Furthermore, the presence of extractives such as fatty acids, hydrocarbons, phytosterols, carbohydrates, phenol derivates, etc., results in the small shoulders that overlap hemicellulose and lignin decomposition at 200, 225, 380 and 480 °C (Meszaros et al., 2007). Fig. 2b shows that these extractives are in higher content in the bark and leaves of the eucalyptus than in the woody part. The heterogeneous composition of the bark and leaves shifts the DTG curve to lower temperatures and causes the appearance of several shoulders. The DTG curve of the eucalyptus waste biomass has been fitted to a kinetic model that consists of three independent and parallel reactions corresponding to the pyrolysis of the three main biomass constituents (hemicellulose, cellulose and lignin). This model, which has been developed in previous papers, allows for characterizing the pyrolytic behavior of the material and determining its chemical composition, i.e., hemicellulose, cellulose and lignin content (Amutio et al., 2013a). For the sake of simplicity, extractives have not been considered in the model and first order kinetics has been assumed for the degradation of the three main constituents. Therefore, the kinetic equation can be written as:
3. Results and discussion 3.1. Chemical composition of the eucalyptus waste Fig. 2a shows the DTG curves for the eucalyptus waste pyrolysis obtained at different heating rates. Weight loss starts with moisture evaporation at 100 °C and is followed by the pyrolysis of the main biomass constituents, i.e. hemicellulose, cellulose and lignin, which take place in the 150–500 °C range, with the maximum weight loss rate being at 310, 330 and 340 °C, for the heating rates of 5, 10 and 15 °C min1, respectively. It has been reported that hemicellulose degradation corresponds to the first shoulder preceding the highest peak, which is attributed to cellulose pyrolysis, whereas lignin decomposition takes place throughout the whole
dX ¼ c1 k1 ðX 1;1 X 1 Þ þ c2 k2 ðX 1;2 X 2 Þ þ c3 k3 ðX 1;3 X 3 Þ dt
ð1Þ
where conversion is defined as:
Xi ¼
W 0;i W i W 0;i W 1;i
ð2Þ
Xi and X1,i are the conversion at t time and the final conversion of each pseudo-component, and have been calculated according to Eq. (2) based on their mass loss. ci is the mass fraction of each pseudo-component and ki is the kinetic constant, which follows the Arrhenius equation. Subscript 1 has been considered for hemicellulose, 2 for cellulose and 3 for lignin.
228
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
components are 29 wt.% for hemicellulose, 51 wt.% for cellulose and 20 wt.% for lignin. The fitting of the experimental values for the DTG curves and conversions to those calculated by the kinetic model is shown in Fig. 3. The experimental results are adequately fitted, although a deviation is observed at high temperatures, which is probably due to the non-consideration of the additional shoulders related to the extractives. The activation energies obtained are similar to those reported for other woody biomasses in which the same methodology was followed for their determination, i.e., 115, 218 and 35 kJ mol1 for hemicellulose, cellulose and lignin for pinewood (without bark) (Amutio et al., 2011); 98, 161 and 32 kJ mol1 for broom; 99, 153 and 24 kJ mol1 for acacia; and 95, 157 and 28 kJ mol1 for carquesa (also with wood, bark and leaves) (Amutio et al., 2013a). Other authors also obtained similar kinetic parameters applying three parallel and independent reaction models for the pyrolysis of woody biomasses such as pinewood, beech wood or chestnut wood, with the activation energy being in the 83–147 range for hemicellulose, 193–246 for cellulose and 20–181 kJ mol1 for lignin (Branca et al., 2005; Skodras et al., 2006; Varhegyi et al., 2004).
Fig. 2. DTG curves of the eucalyptus waste material at different heating rates (a) and for the woody and bark and leave fractions at 15 °C min1 (b).
The frequency factor (k0)i, activation energy, Ei, and mass concentrations of the pseudo-components, ci, have been calculated by minimizing the following error objective function, where the calculated DTG curve is obtained by deconvolution of Eq. (1) integrated for each pseudocomponent: L h X
EOF ¼
ðDTGÞcalculated ðDTGÞexperimental
j¼1
L
i2 ð3Þ
where L is the number of experimental data available. Eq. (1) has been solved by means of a program written in MATLAB and using the subroutine ode45 based on the Runge–Kutta–Fehlberg pair of orders 4 and 5 and the error objective function minimization (Eq. (3)) has been carried out using the subroutine fminsearch with the Levenberg–Marquardt algorithm. The fitting has been performed by using the experimental results obtained for the three heating rates. The activation energies calculated by the kinetic model are 103, 172 and 25 kJ mol1 for hemicellulose, cellulose and lignin, respectively, whereas the pre-exponential factor values are 3.5 109, 4.8 1014 and 25 min1. Furthermore, the contents of each biomass
Fig. 3. Comparison of experimental results (points) with those estimated using the kinetic model (thick line) for (a) DTG curves and (b) conversion, for a heating rate of 15 °C min1.
229
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232 Table 1 Comparison of the maximum bio-oil yields obtained in eucalyptus pyrolysis with different technologies. Raw material
Reactor
Scale (kg h1)
Temperature (°C)
Bio-oil yield (wt.%)
Reference
Eucalyptus globulus branches (wood, bark and leaves) Eucalyptus tereticornis chips
Conical spouted bed Ablative
0.12
500
75.4
This work
0.15
550
42.4
Eucalyptus grandis wood Eucalyptus grandis Eucalyptus grandis Eucalyptus grandis Eucalyptus grandis woodchips Eucalyptus (debarked) Eucalyptus loxophleba wood Eucalyptus loxophleba leaves Eucalyptus wood Eucalyptus wood Eucalyptus wood Eucalyptus grandis (debarked)
Transport bed Twin screw Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fixed bed
20 10 0.1 1 0.85 0.15 1 1 1 0.1 Batches of 10 g Batches of 200 g
500 500 500 500 500 500 450 450 500 450 450 450
70.8 (dry basis) 60.3 68.9 62.4 62.4 59.2 63 53 (dry basis) 59 71.1 48.2 45.5
Gomez-Monedero et al. (2015) Oasmaa et al. (2010) Joubert et al. (2015) Joubert et al. (2015) Joubert et al. (2015) Carrier et al. (2013) Kim et al. (2013) Garcia-Perez et al. (2008) He et al. (2012) Chang et al. (2013) Heidari et al. (2014) Wan Sulaiman and Lee (2012) Pimenta et al. (1998)
Furthermore, the chemical composition calculated by the model is similar to that determined experimentally for various eucalyptus species, although experimental results also show dissimilarities due to the different origin and type of the waste material used. Carrier et al. (2013) and Joubert et al. (2015) determined extractives, hemicellulose, cellulose and lignin concentrations of 2.6, 24.7, 57.5 and 15.2 wt.%, respectively, for Eucalyptus grandis woodchips. Chang et al. (2013) used a eucalyptus wood made up of 24 wt.% hemicellulose, 44 wt.% cellulose and 28 wt.% acid insoluble fibers, and the eucalyptus wood analyzed by Heidari et al. (2014) was composed of 13.5 wt.% hemicellulose, 46.2 wt.% cellulose and 34 wt.% lignin. 3.2. Pyrolysis in the conical spouted bed reactor plant 3.2.1. Product yields The pyrolysis of eucalyptus wastes in the conical spouted bed reactor leads to a high bio-oil yield, 75.4 wt.% at 500 °C, whereas those for gas and char are 6.2 and 18.4 wt.%, respectively. This is a significant result bearing in mind that the material pyrolyzed is a heterogeneous residue containing bark and leaves, which according to the literature lower the bio-oil yield (He et al., 2012; Oasmaa et al., 2010). These results corroborate the suitability of the CSBR for biomass pyrolysis, which has already been proven in the pyrolysis of several types of agro-forestry residues, such as pinewood (Amutio et al., 2012), rice husk (Alvarez et al., 2014a) and shrubs (Amutio et al., 2013b), with bio-oil yields being in the 70– 80 wt.% range in a bench scale unit. Furthermore, the scale up of the technology to a 25 kg/h pilot plant has been successfully accomplished as evidenced by the high bio-oil yields (65–69 wt.% range) obtained in the pyrolysis of pine and poplar wood (Fernandez-Akarregi et al., 2013; Makibar et al., 2015). The solid cyclic movement of the particles in the reactor favors the isothermicity of the bed and the high gas flow-rate gives way to high heat and mass transfer rates and allows operation with very low gas residence times. These features, together with the continuous char removal from the bed, minimize secondary reactions that reduce bio-oil production. Accordingly, the versatility of this reactor for handling different residues is promising for the development of an industrial scale pyrolysis process. In order to assess the suitability of the CSBR, the maximum bio-oil yields obtained for eucalyptus pyrolysis by other authors in different reactor configurations are compared in Table 1. As observed, the yield obtained in the conical spouted bed reactor is higher than those reported with other reaction systems, even
though in most cases a debarked wood was used as feedstock. Bio-oil production is maximized at temperatures around 450– 550 °C in all cases, with the yields varying in the 42–71 wt.% range. Fluidized bed reactors with continuous biomass feed are the most used configurations because of their suitable characteristics for biomass pyrolysis. However, the lower bio-oil yields obtained in these reactors (65 wt.% on average), together with the simpler design and lower building and operating costs of the CSBR, are very positive aspects for the proposal of the conical spouted bed reactor as alternative to fluidized beds. 3.2.2. Gas composition The gaseous fraction obtained in the CSBR bench-scale plant at 500 °C is mainly composed of carbon monoxide and dioxide, as shown in Table 2. At this temperature the yields and concentrations of both components are similar, given that CO formation is enhanced at high temperatures (above 600 °C) due to secondary cracking reactions, whereas CO2 is mainly formed by the primary decomposition of cellulose and hemicellulose at lower temperatures. Similar gas compositions were obtained in eucalyptus pyrolysis studies carried out in other fast pyrolysis reactors (Garcia-Perez et al., 2008; Gomez-Monedero et al., 2015; Heidari et al., 2014; Joubert et al., 2015). 3.2.3. Bio-oil composition Bio-oil has been thoroughly characterized by means of gas chromatography–mass spectrometry techniques, and 105 compounds have been identified. Table 3 shows the detailed composition of the bio-oil. The identified products have been grouped according to their functional groups into acids, aldehydes, alcohols, furans, ethers, ketones, phenols, saccharides and water. As observed, water is the main single compound, accounting for 35.7 wt.% of the whole bio-oil. This water content results from the
Table 2 Mass yields and volumetric composition of the gaseous fraction. Compound
Yield (wt.%)
Concentration (vol.%)
Hydrogen Carbon monoxide Carbon dioxide Methane Ethylene Ethane Propylene Propane
0.04 2.42 3.07 0.31 0.13 0.06 0.12 0.01
10.6 41.7 33.7 9.3 2.2 1.0 1.3 0.1
230
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
Table 3 Detailed composition of the eucalyptus pyrolysis bio-oil.
Table 3 (continued) Compound
Compound
Concentration (wt.%)
Acids Formic acid Acetic acid Propanoic acid 2-Propenoic acid Butanoic acid 3-Methyl-butanoic acid 4-Pentenoic acid 2-Methyl-2-butenoic acid 3,4-Dimethyl-benzoic acid
4.84 0.10 3.18 0.64 0.10 0.32 0.09 0.13 0.14 0.14
Aldehydes Formaldehyde Acetaldehyde 2-Propenal 2-Methyl-2-propenal Butanedial Glutaraldehyde 5-Methyl-2-furancarboxaldehyde 3-Hydroxy-benzaldehyde 4-Hydroxy-2-methylbenzaldehyde
2.24 0.20 0.21 0.08 0.04 0.16 0.94 0.17 0.32 0.11
Alcohols Methanol 3-Methyl-2-butanol acetate 7-Methyl-4-octanol acetate 4-Chromanol
1.00 0.55 0.11 0.20 0.14
Furans Furan 2-Hydroxytetrahydrofuran Furfural 2-Furanmethanol 2(5H)-Furanone Butyrolactone 3,4-Dimethyl-2,5-dihydrofuran Dihydro-3-methyl-2,5-Furandione 2-(Methoxymethyl) tetrahydrofuran 5-Acetyldihydro-2(3H)-furanone 5-(Hydroxymethyl)dihydro-2(3H)-furanone Coumaran 2-Coumaranone 7-Methylbenzofuran
5.91 0.07 0.29 0.51 0.21 0.51 2.81 0.04 0.16 0.14 0.22 0.38 0.38 0.04 0.16
Ethers Eucalyptol
1.35 1.35
Ketones Acetone 3-Methyl-2-butanone 1-Hydroxy-2-propanone 1-Hydroxy-2-butanone Cyclopentanone 2-Cyclopenten-1-one 1-Hydroxy-2-pentanone 2-Butanone 1-(Acetyloxy)-2-propanone 1-(2-Furanyl)-ethanone 3-Methyl-2-cyclopenten-1-one 4H-Pyran-4-one 4-Methylenecyclohexanone 2-Hydroxy-3-methyl-2-cyclopenten-1-one 2,3-Dimethyl-2-cyclopenten-1-one 3,4-Dimethyl-2-hydroxycyclopent-2-en-1-one 2,3,4-Trimethyl-2-Cyclopenten-1-one 2-Methyl-2-cyclohexen-1-one Acetophenone 3-Ethyl-2-cyclopenten-1-one 4-Heptanone 3-Ethenyl-cyclohexanone 3-Ethyl-2-hydroxy-2-cyclopenten-1-one 2,3-Dihydro-1H-Inden-1-one 3-Methyl-2H-1-benzopyran-2-one
10.66 0.55 0.25 0.82 0.61 0.17 0.52 0.05 0.07 0.18 0.19 1.92 0.11 0.05 2.65 0.19 0.21 0.14 0.10 0.30 0.09 0.05 0.04 0.35 0.14 0.92
Phenols Catechols 1,2-Benzenediol 3-Methyl-1,2-benzenediol
26.25 17.62 5.06 0.51
Hydroquinone Resorcinol 4-Methyl-1,2-benzenediol 2,6-Dimethyl-1,4-benzenediol 2-Methyl-1,3-benzenediol 4-Ethyl-1,3-benzenediol 2-Methyl-1,4-benzenediol 2,6-Dimethyl-1,4-benzenediol Resorcinol monoacetate 1,2,4-Benzenetriol 4-Ethyl-1,2-benzenediol 4,5-Dimethyl-1,3-benzenediol Guaiacols 2-Methoxy-phenol Ethenyloxybenzene 2-Isopropoxyphenol 3-Methoxy-5-methylphenol 2-Methoxy-3-methylphenol 4-Ethyl-2-methoxy-phenol Eugenol Alkyl phenols Phenol 2-Methylphenol 3-Methylphenol 2,5-Dimethyl-phenol 3-Ethylphenol 2,4-Dimethyl-phenol 2,6-Dimethyl-phenol 4-Ethylphenol 3,5-Dimethyl-phenol 2,3-Dimethyl-phenol 3,4-Dimethyl-phenol 2,3,5-Trimethylphenol 4-(1-Methylethyl)phenol 5-Ethyl-2-methylphenol 2-Allylphenol 2-Methyl-5-(1-methylethyl) phenol Thymol 2-Allyl-4-methylphenol Saccharides 1,6-Anhydro-.beta.-D-talopyranose Levoglucosan .Beta.-D-Ribopyranoside, methyl, 3-acetate Unidentified Water Total bio-oil
Concentration (wt.%) 2.75 0.74 2.12 0.07 0.33 1.11 0.97 0.89 0.54 0.29 2.05 0.18 3.88 2.25 0.20 0.19 0.39 0.28 0.46 0.10 4.75 0.87 0.68 0.07 0.13 0.18 0.38 0.16 0.23 0.44 0.17 0.04 0.02 0.04 0.30 0.65 0.07 0.03 0.28 3.25 0.34 2.07 0.85 8.75 35.74 100.00
moisture evaporation (9.5 wt.% of the biomass), cellulose and hemicellulose dehydration reactions and secondary cracking reactions (Demirbas, 2000). The water content obtained in the current study is slightly higher than those reported for eucalyptus wood pyrolysis in fluidized beds, in which the values range from 10 to 31 wt.% (Carrier et al., 2013; Chang et al., 2013; Garcia-Perez et al., 2008; Heidari et al., 2014; Joubert et al., 2015; Kim et al., 2013; Oasmaa et al., 2010). Bark and leaves have been reported to lead to higher water yields due to secondary cracking reactions promoted by their higher ash content (He et al., 2012; Oasmaa et al., 2010). However, the short gas residence times in the CSBR prevent the production of a bio-oil with an excessively high water yield for use as fuel. Phenols, which are formed by the depolymerisation of the lignin that constitutes the original biomass, are the main organic products with a concentration of 26 wt.%, with catechols (bezenediols) being the prevailing compounds. Heidari et al. (2014) also identified several phenolic compounds in the bio-oil resulting from the fluidized bed pyrolysis of eucalyptus wood, with syringol being the most abundant one, but also with a significant contribution of guaiacol and vanillin.
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
The concentration of ketones, and more specifically cyclopentanones, is also remarkable, accounting for 10 wt.% of the bio-oil. These compounds are mainly formed by hemicellulose degradation, together with furans (Demirbas, 2000), whose concentration reaches almost 6 wt.%. Although several acid compounds have been identified in the bio-oil, acetic acid is the major one, with a concentration of 3.2 wt.%. Oasmaa et al. (2010) also observed a 6.3 wt.% concentration of acids in the eucalyptus derived bio-oil, with acetic acid being the most abundant one. Similarly, the main saccharide-type product is levoglucosan, with a concentration of 2 wt.% in the bio-oil. These products are derived from the primary decomposition of the polysaccharides that make up the cellulose and hemicellulose fractions in the eucalyptus. The bio-oil obtained also contains a low concentration of aldehydes, alcohols and ethers. The latter group is made up of eucalyptol, which is the major product in the decomposition of eucalyptus leaves (He et al., 2012). The fast pyrolysis of eucalyptus wood in other reactor types led to a bio-oil with a similar composition as in this study. Thus, Chang et al. (2013) and Kim et al. (2013), operating in fluidized beds, identified similar compounds, as are phenols, cyclopentanones, acetic acid, furans and levoglucosan, although the concentration of the latter was higher in their studies than in this one, probably due to the avoidance of secondary cracking reactions usually promoted by the ash in the bark (Patwardhan et al., 2010). Finally, Gomez-Monedero et al. (2015) pyrolyzed red eucalyptus in an ablative reactor and obtained two fractions, aqueous and organic, with the latter being rich in phenols and the former in acids, ketones, furanes and alcohols. The bio-oil obtained in the pyrolysis of eucalyptus wastes in the conical spouted bed reactor is similar to those obtained in previous studies using several forestry residues such as pinewood (Amutio et al., 2012), broom, acacia, carquesa (Amutio et al., 2013b) and poplar wood (Makibar et al., 2015). Thus, the bio-oils obtained in the CSBR contain water in the 20–38 wt.% range, with the main organic compounds being phenols (especially catechols) and ketones (cyclopentanones), and a significant contribution of furans, acids and saccharides. These bio-oils may be used as a source of chemicals for the pharmaceutical, agricultural and food industries, for the production of renewable phenol–formaldehyde resins, as fuel in boilers, turbines and engines, for the production of fuels and chemicals after subjecting it to upgrading processes, such as hydrodeoxygenation or catalytic upgrading, or for hydrogen production by means of steam-reforming processes (Bridgwater, 2012; Zhang et al., 2007). Therefore, combined pyrolysis of these woody biomasses (with high bark and leave content) is feasible at large scale, which allows a sustainable valorisation of the forestry wastes available in delocalized sites. Accordingly, a standard bio-oil would be obtained, which may be upgraded following the routes mentioned above, and therefore reduce the need for a uniform raw material supply.
Table 4 Properties of the eucalyptus pyrolysis char. Properties Ultimate analysis (wt.%) Carbon Hydrogen Nitrogen Oxygen
76.3 2.2 1.3 13.7
Proximate analysis (wt.%) Volatile matter Fixed carbon Ash HHV (MJ kg1)
14.4 79.1 6.5 27.7
231
3.2.4. Char characterization Table 4 sets out the ultimate and proximate analyses, as well as the higher heating value of the eucalyptus char obtained at 500 °C in the conical spouted bed reactor. As observed, char has a high carbon content, which results in a high HHV value, higher than other conventional solid fuels, such as lignite (20 MJ kg1). These properties allow using this solid fraction as fuel, soil amender (Lee et al., 2010) or active carbon after subjecting it to activation processes (Alvarez et al., 2014b), thereby improving the overall profitability of the pyrolysis process. The eucalyptus char obtained in the conical spouted bed reactor is similar to those obtained by other authors in other fast pyrolysis technologies (Carrier et al., 2013; Garcia-Perez et al., 2008; Heidari et al., 2014), and also to those obtained in the pyrolysis of other woody biomasses in the CSBR (Amutio et al., 2012, 2013b; Makibar et al., 2015). 4. Conclusions The CSBR has proven to be a suitable and versatile technology for the fast pyrolysis of heterogeneous forestry materials made up of wood, bark and leaves, such as the eucalyptus wastes derived from the paper manufacturing sector. The high bio-oil yield obtained, 75.4 wt.%, is a very positive aspect for the proposal of this technology as alternative to fluidized beds. The methodology proposed for the analysis of eucalyptus waste structural composition is a useful tool to foresee reproducibility in bio-oil composition and the performance when the joint valorisation of this material with other biomass varieties is carried out. Acknowledgements This work was carried out with the financial support from the Ministry of Economy and Competitiveness of the Spanish Government (CTQ2013-45105-R), the ERDF funds, the Basque Government (IT748-13) and the University of the Basque Country (UFI 11/39). References Alvarez, J., Lopez, G., Amutio, M., Bilbao, J., Olazar, M., 2014a. Bio-oil production from rice husk fast pyrolysis in a conical spouted bed reactor. Fuel 128, 162– 169. Alvarez, J., Lopez, G., Amutio, M., Bilbao, J., Olazar, M., 2014b. Upgrading the rice husk char obtained by flash pyrolysis for the production of amorphous silica and high quality activated carbon. Bioresour. Technol. 170, 132–137. Amutio, M., Lopez, G., Alvarez, J., Moreira, R., Duarte, G., Nunes, J., Olazar, M., Bilbao, J., 2013a. Pyrolysis kinetics of forestry residues from the Portuguese Central Inland Region. Chem. Eng. Res. Des. 91, 2682–2690. Amutio, M., Lopez, G., Artetxe, M., Elordi, G., Olazar, M., Bilbao, J., 2012. Influence of temperature on biomass pyrolysis in a conical spouted bed reactor. Resour. Conserv. Recycl. 59, 23–31. Amutio, M., Lopez, G., Aguado, R., Artetxe, M., Bilbao, J., Olazar, M., 2011. Effect of vacuum on lignocellulosic biomass flash pyrolysis in a conical spouted bed reactor. Energy Fuels 25, 3950–3960. Amutio, M., Lopez, G., Alvarez, J., Moreira, R., Duarte, G., Nunes, J., Olazar, M., Bilbao, J., 2013b. Flash pyrolysis of forestry residues from the Portuguese Central Inland Region within the framework of the BioREFINA-Ter project. Bioresour. Technol. 129, 512–518. Arbogast, S., Bellman, D., Paynter, J.D., Wykowski, J., 2012. Advanced bio-fuels from pyrolysis oil: the impact of economies of scale and use of existing logistic and processing capabilities. Fuel Process. Technol. 104, 121–123. Branca, C., Albano, A., Di Blasi, C., 2005. Critical evaluation of global mechanisms of wood devolatilization. Thermochim. Acta 429, 133–141. Bridgwater, A.V., 2012. Review of fast pyrolysis of biomass and product upgrading. Biomass Bioenergy 38, 68–94. Carpenter, D., Westover, T.L., Czernik, S., Jablonski, W., 2014. Biomass feedstocks for renewable fuel production: a review of the impacts of feedstock and pretreatment on the yield and product distribution of fast pyrolysis bio-oils and vapors. Green Chem. 16, 384–406. Carrier, M., Joubert, J.E., Danje, S., Hugo, T., Görgens, J., Knoetze, J., 2013. Impact of the lignocellulosic material on fast pyrolysis yields and product quality. Bioresour. Technol. 150, 129–138. Chang, S., Zhao, Z., Zheng, A., Li, X., Wang, X., Huang, Z., He, F., Li, H., 2013. Effect of hydrothermal pretreatment on properties of bio-oil produced from fast
232
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
pyrolysis of eucalyptus wood in a fluidized bed reactor. Bioresour. Technol. 138, 321–328. Demirbas, A., 2000. Mechanisms of liquefaction and pyrolysis reactions of biomass. Energy Convers. Manage. 41, 633–646. Fernandez-Akarregi, A.R., Makibar, J., Lopez, G., Amutio, M., Olazar, M., 2013. Design and operation of a conical spouted bed reactor pilot plant (25 kg/h) for biomass fast pyrolysis. Fuel Process. Technol. 112, 48–56. FitzPatrick, M., Champagne, P., Cunningham, M., Whitney, R., 2010. A biorefinery processing perspective: treatment of lignocellulosic materials for the production of value-added products. Bioresour. Technol. 101, 8915–8922. Garcia-Perez, M., Wang, X., Shen, J., Rhodes, M., Tian, F., Lee, W., Wu, H., Li, C., 2008. Fast pyrolysis of oil mallee woody biomass: effect of temperature on the yield and quality of pyrolysis products. Ind. Eng. Chem. Res. 47, 1846–1854. Gomez-Monedero, B., Bimbela, F., Arauzo, J., Faria, J., Ruiz, M.P., 2015. Pyrolysis of red eucalyptus, camelina straw, and wheat straw in an ablative reactor. Energy Fuels 29, 1766–1775. He, M., Mourant, D., Gunawan, R., Lievens, C., Wang, X.S., Ling, K., Bartle, J., Li, C.Z., 2012. Yield and properties of bio-oil from the pyrolysis of mallee leaves in a fluidised-bed reactor. Fuel 102, 506–513. Heidari, A., Stahl, R., Younesi, H., Rashidi, A., Troeger, N., Ghoreyshi, A.A., 2014. Effect of process conditions on product yield and composition of fast pyrolysis of Eucalyptus grandis in fluidized bed reactor. J. Ind. Eng. Chem. 20, 2594–2602. Ho, D.P., Ngo, H.H., Guo, W., 2014. A mini review on renewable sources for biofuel. Bioresour. Technol. 169, 742–749. Joubert, J.E., Carrier, M., Dahmen, N., Stahl, R., Knoetze, J.H., 2015. Inherent process variations between fast pyrolysis technologies: a case study on Eucalyptus grandis. Fuel Process. Technol. 131, 389–395. Kim, K.H., Kim, T.S., Lee, S.M., Choi, D., Yeo, H., Choi, I.G., Choi, J.W., 2013. Comparison of physicochemical features of biooils and biochars produced from various woody biomasses by fast pyrolysis. Renew. Energy 50, 188–195. Lee, J.W., Kidder, M., Evans, B.R., Paik, S., Buchanan III, A.C., Garten, C.T., Brown, R.C., 2010. Characterization of biochars produced from cornstovers for soil amendment. Environ. Sci. Technol. 44, 7970–7974.
Maity, S.K., 2015. Opportunities, recent trends and challenges of integrated biorefinery: part II. Renew. Sustain. Energy Rev. 43, 1446–1466. Makibar, J., Fernandez-Akarregi, A.R., Amutio, M., Lopez, G., Olazar, M., 2015. Performance of a conical spouted bed pilot plant for bio-oil production by poplar flash pyrolysis. Fuel Process. Technol. 137, 283–289. Meszaros, E., Jakab, E., Varhegyi, G., 2007. TG/MS, Py-GC/MS and THM-GC/MS study of the composition and thermal behavior of extractive components of Robinia pseudoacacia. J. Anal. Appl. Pyrolysis 79, 61–70. Oasmaa, A., Solantausta, Y., Arpiainen, V., Kuoppala, E., Sipila, K., 2010. Fast pyrolysis bio-oils from wood and agricultural residues. Energy Fuels 24, 1380–1388. Pang, C.H., Gaddipatti, S., Tucker, G., Lester, E., Wu, T., 2014. Relationship between thermal behaviour of lignocellulosic components and properties of biomass. Bioresour. Technol. 172, 312–320. Patwardhan, P.R., Satrio, J.A., Brown, R.C., Shanks, B.H., 2010. Influence of inorganic salts on the primary pyrolysis products of cellulose. Bioresour. Technol. 101, 4646–4655. Pimenta, A.S., Vital, B.R., Bayona, J.M., Alzaga, R., 1998. Characterisation of polycyclic aromatic hydrocarbons in liquid products from pyrolysis of Eucalyptus grandis by supercritical fluid extraction and GC/MS determination. Fuel 77, 1133–1139. Sanna, A., 2014. Advanced biofuels from thermochemical processing of sustainable biomass in europe. Bioenergy Res. 7, 36–47. Skodras, G., Grammelis, P., Basinas, P., Kakaras, E., Sakellaropoulos, G., 2006. Pyrolysis and combustion characteristics of biomass and waste-derived feedstock. Ind. Eng. Chem. Res. 45, 3791–3799. Varhegyi, G., Gronli, M., Di Blasi, C., 2004. Effects of sample origin, extraction, and hot-water washing on the devolatilization kinetics of chestnut wood. Ind. Eng. Chem. Res. 43, 2356–2367. Wan Sulaiman, W., Lee, E., 2012. Pyrolysis of Eucalyptus wood in a fluidized-bed reactor. Res. Chem. Intermed., 1–15 Zhang, Q., Chang, J., Wang, T., Xu, Y., 2007. Review of biomass pyrolysis oil properties and upgrading research. Energy Convers. Manage. 48, 87–92.
Contents lists available at ScienceDirect
Bioresource Technology journal homepage: www.elsevier.com/locate/biortech
Fast pyrolysis of eucalyptus waste in a conical spouted bed reactor Maider Amutio, Gartzen Lopez, Jon Alvarez, Martin Olazar ⇑, Javier Bilbao Department of Chemical Engineering, University of the Basque Country UPV/EHU, P.O. Box 644, E48080 Bilbao, Spain
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
Conical spouted bed reactor is
suitable for eucalyptus wastes pyrolysis. Higher bio-oil yield (75.4 wt.%) than with other technologies is obtained. Water, phenols and ketones content in bio-oil are 35, 26 and 10 wt.%, respectively. TG analysis is set as a methodology for determining the composition of the biomass.
a r t i c l e
i n f o
Article history: Received 9 June 2015 Received in revised form 8 July 2015 Accepted 9 July 2015 Available online 15 July 2015 Keywords: Pyrolysis Bio-oil Bio-refinery Spouted bed reactor Eucalyptus
a b s t r a c t The fast pyrolysis of a forestry sector waste composed of Eucalyptus globulus wood, bark and leaves has been studied in a continuous bench-scale conical spouted bed reactor plant at 500 °C. A high bio-oil yield of 75.4 wt.% has been obtained, which is explained by the suitable features of this reactor for biomass fast pyrolysis. Gas and bio-oil compositions have been determined by chromatographic techniques, and the char has also been characterized. The bio-oil has a water content of 35 wt.%, and phenols and ketones are the main organic compounds, with a concentration of 26 and 10 wt.%, respectively. In addition, a kinetic study has been carried out in thermobalance using a model of three independent and parallel reactions that allows quantifying this forestry waste’s content of hemicellulose, cellulose and lignin. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Bio-fuel and bio-based chemical production from non-edible biomass provides an excellent opportunity for reducing the dependence on fossil fuels and mitigating the associated environmental impacts. Over the last decades, biomass conversion technologies have been directed towards the development of the biorefinery concept by means of chemical, biochemical and thermochemical processes for the production of fuels and chemicals (FitzPatrick et al., 2010). Flash pyrolysis for bio-oil production has been regarded as one of the most feasible processes on a large scale as it involves several advantages, such as simplicity and low energy ⇑ Corresponding author. Tel.: +34 946012527; fax: +34 946 013 500. E-mail address: [email protected] (M. Olazar). http://dx.doi.org/10.1016/j.biortech.2015.07.030 0960-8524/Ó 2015 Elsevier Ltd. All rights reserved.
requirements and capital investment (Maity, 2015). Thus, bio-oil can be produced in a delocalized way in rural areas where biomass is available and transported to centralized biorefineries for the production of fuels and chemicals as well as heat and power (Bridgwater, 2012). Several reactor configurations such as fluidized bed, transport and circulating fluidized bed, rotating cone, ablative, auger, vacuum moving bed and spouted bed reactors have been developed and scaled-up to pilot or demonstration plants for biomass flash pyrolysis (Bridgwater, 2012). However, the industrial implementation of the biomass pyrolysis process needs to solve several challenges, with one of the most important ones being the regular supply of biomass resources that do not compete with food (Ho et al., 2014). Therefore, the use of wastes derived from the existing forest industries as feedstock for the pyrolysis process is essential
226
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
for the development of this technology at large scale (Arbogast et al., 2012), thus reducing the costs associated with the production of a suitable feedstock, which is one of the steps with the highest energy consumption (Sanna, 2014). These waste materials are highly heterogeneous because they are composed of wood, bark, leaves, and so on, and have therefore varying properties. This feature places biomass fast pyrolysis technologies in the situation of having to face the challenge of being sufficiently versatile so as to produce high bio-oil yields with adequate properties, regardless the heterogeneity of the raw material (Carpenter et al., 2014). Accordingly, the present paper aims at studying the pyrolysis of a waste material composed of branches and leaves coming from the cutting down of eucalyptus trees for the paper manufacturing sector. This waste material accounts for a considerable fraction of the whole tree (around 30–40 wt.%). Furthermore, eucalyptus crops are achieving an increasing importance in the European Mediterranean watershed. This eucalyptus material is highly heterogeneous, which means that its large scale exploitation requires an adequate pyrolysis technology, as well as a simple and reproducible analytical methodology to determine hemicellulose, cellulose and lignin contents. The latter is an essential tool in order to store different waste materials that give way to a regular mixture composition, with the aim of guaranteeing reproducibility in the composition of the pyrolytic products, especially that of bio-oil. In this work, a methodology previously developed for other biomass materials (Amutio et al., 2013a) has been applied, i.e., a thermogravimetric study allowing the quantification of the chemical components (hemicellulose, cellulose and lignin) in the eucalyptus waste. Furthermore, a conical spouted bed reactor (CSBR) is proposed for the fast pyrolysis of this residual biomass as alternative to fluidized beds, given that it performs well by obtaining high bio-oil yields with several biomass materials, such as pinewood (Amutio et al., 2012) or forest shrub wastes with a heterogeneous composition (Amutio et al., 2013b). Furthermore, it is noteworthy that short volatile residence times are suitable for minimizing the catalytic activity of the ashes (Carpenter et al., 2014), which allows obtaining high bio-oil yields (70 wt.%) for rice husk pyrolysis, even though this material has a high ash content (Alvarez et al., 2014a). In addition, this technology has been scaled up to a 25 kg/h pilot plant, in collaboration with IK4-Ikerlan Research Centre, with its performance being excellent for pine and poplar wood pyrolysis (Fernandez-Akarregi et al., 2013; Makibar et al., 2015). 2. Methods 2.1. Raw material Eucalyptus globulus waste from the paper industry sector has been used as feedstock for the pyrolysis process. This material is composed of the wastes (wood, bark and leaves) remaining from the cutting down of the eucalyptus trees. The biomass has been collected, dried and ground to a particle size in the 1–2 mm range. The proximate analysis of the raw material (TGA Q500IR thermogravimetric analyzer) reveals that it is made up of 9.5 wt.% of moisture, 87.4 wt.% of volatile matter, 11.4 wt.% of fixed carbon and 1.2 wt.% of ash. Furthermore, the carbon, hydrogen, nitrogen and oxygen contents are 46.5, 5.1, 0.6 and 46.6 wt.%, respectively (LECO CHNS-932 elemental analyzer). Finally, the higher heating value (HHV) has been set at 17.4 MJ kg1 (Parr 1356 isoperibol bomb calorimeter). 2.2. Conical spouted bed pyrolysis plant The continuous conical spouted bed bench scale plant used in this study is outlined in Fig. 1. This plant has been fine tuned on
the basis of previous studies involving the pyrolysis of other biomass residues, such as pinewood (Amutio et al., 2012), forest shrubs (Amutio et al., 2013b) and rice husk (Alvarez et al., 2014a). Biomass is fed by means of a vessel provided with a vertical shaft connected to a piston, which allows the continuous feeding of up to 200 g h1 of biomass. Nitrogen, whose flow rate is controlled by a mass flow meter, is used as fluidizing agent and it is heated to the reaction temperature by means of a preheater. The reactor is a conical spouted bed with an upper cylindrical section, with a total height of 34 cm and a cylindrical section diameter of 12.3 cm. The height of the conical section is 20.5 cm, with an angle of 28° and a bottom diameter of 2 cm. The gas inlet diameter is 1 cm. Furthermore, the reactor is equipped with a lateral outlet for the continuous and selective removal of the char from the bed throughout the process, which is possible due to the cyclic movement of the particles in the bed (Amutio et al., 2011). The volatile products formed in the pyrolysis process together with the nitrogen used for fluidization pass through the gas cleaning system, which consists of a high efficiency cyclone and a sintered steel filter that are maintained at 280 °C in order to avoid the condensation of the heaviest compounds. The vapor residence time within the fine-particle retention system is less than 1 s, thus avoiding the partial cracking of the organic products before their condensation. The condensation of the bio-oil is carried out by means of a double-shell tube condenser cooled by tap water and two coalescence filters, which ensure the recovery of the heavy compounds. 2.3. Product analysis The pyrolysis volatiles have been analyzed online by means of chromatographic techniques. The reactor outlet stream has been monitored prior to condensation using a gas chromatograph (GC) (Varian 3900) equipped with a flame ionization detector (FID). The line from the reactor outlet to the chromatograph is heated to a temperature of 280 °C in order to avoid the condensation of heavy oxygenated compounds and to ensure that all the volatile products formed during pyrolysis enter the gas chromatograph and are analyzed online. Unlike hydrocarbons, the FID response to oxygenated compounds is not proportional to their mass, and therefore a calibration has been performed. Furthermore, the non-condensable gases leaving the condensation system have been analyzed using a micro-chromatograph (Varian 4900). This micro-GC has also been used to measure the water yield, following a similar procedure to that described for the standard gas chromatograph. The volatile products have been identified by analyzing the bio-oil recovered in the condenser and filters by means of a GC/MS (Shimadzu UP-2010S) and the gaseous products by means of a micro-GC connected to a mass spectrometer (Agilent 5975B). Furthermore, the char fraction has also been characterized by carrying out its ultimate (LECO CHNS-932) and proximate (TGA Q500IR) analyses, as well as measuring its higher heating value (Par 1356). 2.4. Experimental procedure The runs in the bench scale plant have been carried out at 500 °C, which has been set as the optimum temperature for maximizing the bio-oil yield in woody biomass pyrolysis (Amutio et al., 2012). 100 g of biomass have been continuously fed in each run with a feeding rate of 2 g min1. The reactor bed was made up of 100 g of sand with a particle size in the 0.3–0.63 mm range and the nitrogen flow rate has been set up in 10 Nl min1 in order to ensure stable spouting and guarantee high heat transfer rates and bed isothermicity.
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
227
Fig. 1. Schematic diagram of the conical spouted bed pyrolysis bench-scale plant.
Volatile product samples for the online chromatographic analyses have been taken under the same conditions so as to ensure reproducibility of the process. Mass balance closure has been carried out by weighing the char collected by the lateral outlet and in the cyclone, filter and reactor at the end of the continuous run, and by the online chromatographic analysis. Moreover, in order to validate the mass balance, an internal standard (cyclohexane) has been introduced through an inlet located in the heated line running from the reactor to the chromatograph, thus obtaining 95% mass balance closure. Furthermore, the thermogravimetric study has been carried out in a TGA Q500IR thermobalance, in order to study the degradation characteristics of the material and determine its chemical composition prior to pyrolysis in the conical spouted bed plant. The thermogravimetric experiments have been conducted by subjecting 10 mg of the sample with a particle size below 0.2 mm to three heating ramps of 5, 10 and 15 °C min1. Furthermore, the woody part in the eucalyptus wastes has been separated from the bark and leaves in order to study the influence of the biomass composition on its pyrolysis characteristics.
pyrolysis process and gives way to a long tail at high temperatures (Pang et al., 2014). Furthermore, the presence of extractives such as fatty acids, hydrocarbons, phytosterols, carbohydrates, phenol derivates, etc., results in the small shoulders that overlap hemicellulose and lignin decomposition at 200, 225, 380 and 480 °C (Meszaros et al., 2007). Fig. 2b shows that these extractives are in higher content in the bark and leaves of the eucalyptus than in the woody part. The heterogeneous composition of the bark and leaves shifts the DTG curve to lower temperatures and causes the appearance of several shoulders. The DTG curve of the eucalyptus waste biomass has been fitted to a kinetic model that consists of three independent and parallel reactions corresponding to the pyrolysis of the three main biomass constituents (hemicellulose, cellulose and lignin). This model, which has been developed in previous papers, allows for characterizing the pyrolytic behavior of the material and determining its chemical composition, i.e., hemicellulose, cellulose and lignin content (Amutio et al., 2013a). For the sake of simplicity, extractives have not been considered in the model and first order kinetics has been assumed for the degradation of the three main constituents. Therefore, the kinetic equation can be written as:
3. Results and discussion 3.1. Chemical composition of the eucalyptus waste Fig. 2a shows the DTG curves for the eucalyptus waste pyrolysis obtained at different heating rates. Weight loss starts with moisture evaporation at 100 °C and is followed by the pyrolysis of the main biomass constituents, i.e. hemicellulose, cellulose and lignin, which take place in the 150–500 °C range, with the maximum weight loss rate being at 310, 330 and 340 °C, for the heating rates of 5, 10 and 15 °C min1, respectively. It has been reported that hemicellulose degradation corresponds to the first shoulder preceding the highest peak, which is attributed to cellulose pyrolysis, whereas lignin decomposition takes place throughout the whole
dX ¼ c1 k1 ðX 1;1 X 1 Þ þ c2 k2 ðX 1;2 X 2 Þ þ c3 k3 ðX 1;3 X 3 Þ dt
ð1Þ
where conversion is defined as:
Xi ¼
W 0;i W i W 0;i W 1;i
ð2Þ
Xi and X1,i are the conversion at t time and the final conversion of each pseudo-component, and have been calculated according to Eq. (2) based on their mass loss. ci is the mass fraction of each pseudo-component and ki is the kinetic constant, which follows the Arrhenius equation. Subscript 1 has been considered for hemicellulose, 2 for cellulose and 3 for lignin.
228
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
components are 29 wt.% for hemicellulose, 51 wt.% for cellulose and 20 wt.% for lignin. The fitting of the experimental values for the DTG curves and conversions to those calculated by the kinetic model is shown in Fig. 3. The experimental results are adequately fitted, although a deviation is observed at high temperatures, which is probably due to the non-consideration of the additional shoulders related to the extractives. The activation energies obtained are similar to those reported for other woody biomasses in which the same methodology was followed for their determination, i.e., 115, 218 and 35 kJ mol1 for hemicellulose, cellulose and lignin for pinewood (without bark) (Amutio et al., 2011); 98, 161 and 32 kJ mol1 for broom; 99, 153 and 24 kJ mol1 for acacia; and 95, 157 and 28 kJ mol1 for carquesa (also with wood, bark and leaves) (Amutio et al., 2013a). Other authors also obtained similar kinetic parameters applying three parallel and independent reaction models for the pyrolysis of woody biomasses such as pinewood, beech wood or chestnut wood, with the activation energy being in the 83–147 range for hemicellulose, 193–246 for cellulose and 20–181 kJ mol1 for lignin (Branca et al., 2005; Skodras et al., 2006; Varhegyi et al., 2004).
Fig. 2. DTG curves of the eucalyptus waste material at different heating rates (a) and for the woody and bark and leave fractions at 15 °C min1 (b).
The frequency factor (k0)i, activation energy, Ei, and mass concentrations of the pseudo-components, ci, have been calculated by minimizing the following error objective function, where the calculated DTG curve is obtained by deconvolution of Eq. (1) integrated for each pseudocomponent: L h X
EOF ¼
ðDTGÞcalculated ðDTGÞexperimental
j¼1
L
i2 ð3Þ
where L is the number of experimental data available. Eq. (1) has been solved by means of a program written in MATLAB and using the subroutine ode45 based on the Runge–Kutta–Fehlberg pair of orders 4 and 5 and the error objective function minimization (Eq. (3)) has been carried out using the subroutine fminsearch with the Levenberg–Marquardt algorithm. The fitting has been performed by using the experimental results obtained for the three heating rates. The activation energies calculated by the kinetic model are 103, 172 and 25 kJ mol1 for hemicellulose, cellulose and lignin, respectively, whereas the pre-exponential factor values are 3.5 109, 4.8 1014 and 25 min1. Furthermore, the contents of each biomass
Fig. 3. Comparison of experimental results (points) with those estimated using the kinetic model (thick line) for (a) DTG curves and (b) conversion, for a heating rate of 15 °C min1.
229
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232 Table 1 Comparison of the maximum bio-oil yields obtained in eucalyptus pyrolysis with different technologies. Raw material
Reactor
Scale (kg h1)
Temperature (°C)
Bio-oil yield (wt.%)
Reference
Eucalyptus globulus branches (wood, bark and leaves) Eucalyptus tereticornis chips
Conical spouted bed Ablative
0.12
500
75.4
This work
0.15
550
42.4
Eucalyptus grandis wood Eucalyptus grandis Eucalyptus grandis Eucalyptus grandis Eucalyptus grandis woodchips Eucalyptus (debarked) Eucalyptus loxophleba wood Eucalyptus loxophleba leaves Eucalyptus wood Eucalyptus wood Eucalyptus wood Eucalyptus grandis (debarked)
Transport bed Twin screw Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fluidized bed Fixed bed
20 10 0.1 1 0.85 0.15 1 1 1 0.1 Batches of 10 g Batches of 200 g
500 500 500 500 500 500 450 450 500 450 450 450
70.8 (dry basis) 60.3 68.9 62.4 62.4 59.2 63 53 (dry basis) 59 71.1 48.2 45.5
Gomez-Monedero et al. (2015) Oasmaa et al. (2010) Joubert et al. (2015) Joubert et al. (2015) Joubert et al. (2015) Carrier et al. (2013) Kim et al. (2013) Garcia-Perez et al. (2008) He et al. (2012) Chang et al. (2013) Heidari et al. (2014) Wan Sulaiman and Lee (2012) Pimenta et al. (1998)
Furthermore, the chemical composition calculated by the model is similar to that determined experimentally for various eucalyptus species, although experimental results also show dissimilarities due to the different origin and type of the waste material used. Carrier et al. (2013) and Joubert et al. (2015) determined extractives, hemicellulose, cellulose and lignin concentrations of 2.6, 24.7, 57.5 and 15.2 wt.%, respectively, for Eucalyptus grandis woodchips. Chang et al. (2013) used a eucalyptus wood made up of 24 wt.% hemicellulose, 44 wt.% cellulose and 28 wt.% acid insoluble fibers, and the eucalyptus wood analyzed by Heidari et al. (2014) was composed of 13.5 wt.% hemicellulose, 46.2 wt.% cellulose and 34 wt.% lignin. 3.2. Pyrolysis in the conical spouted bed reactor plant 3.2.1. Product yields The pyrolysis of eucalyptus wastes in the conical spouted bed reactor leads to a high bio-oil yield, 75.4 wt.% at 500 °C, whereas those for gas and char are 6.2 and 18.4 wt.%, respectively. This is a significant result bearing in mind that the material pyrolyzed is a heterogeneous residue containing bark and leaves, which according to the literature lower the bio-oil yield (He et al., 2012; Oasmaa et al., 2010). These results corroborate the suitability of the CSBR for biomass pyrolysis, which has already been proven in the pyrolysis of several types of agro-forestry residues, such as pinewood (Amutio et al., 2012), rice husk (Alvarez et al., 2014a) and shrubs (Amutio et al., 2013b), with bio-oil yields being in the 70– 80 wt.% range in a bench scale unit. Furthermore, the scale up of the technology to a 25 kg/h pilot plant has been successfully accomplished as evidenced by the high bio-oil yields (65–69 wt.% range) obtained in the pyrolysis of pine and poplar wood (Fernandez-Akarregi et al., 2013; Makibar et al., 2015). The solid cyclic movement of the particles in the reactor favors the isothermicity of the bed and the high gas flow-rate gives way to high heat and mass transfer rates and allows operation with very low gas residence times. These features, together with the continuous char removal from the bed, minimize secondary reactions that reduce bio-oil production. Accordingly, the versatility of this reactor for handling different residues is promising for the development of an industrial scale pyrolysis process. In order to assess the suitability of the CSBR, the maximum bio-oil yields obtained for eucalyptus pyrolysis by other authors in different reactor configurations are compared in Table 1. As observed, the yield obtained in the conical spouted bed reactor is higher than those reported with other reaction systems, even
though in most cases a debarked wood was used as feedstock. Bio-oil production is maximized at temperatures around 450– 550 °C in all cases, with the yields varying in the 42–71 wt.% range. Fluidized bed reactors with continuous biomass feed are the most used configurations because of their suitable characteristics for biomass pyrolysis. However, the lower bio-oil yields obtained in these reactors (65 wt.% on average), together with the simpler design and lower building and operating costs of the CSBR, are very positive aspects for the proposal of the conical spouted bed reactor as alternative to fluidized beds. 3.2.2. Gas composition The gaseous fraction obtained in the CSBR bench-scale plant at 500 °C is mainly composed of carbon monoxide and dioxide, as shown in Table 2. At this temperature the yields and concentrations of both components are similar, given that CO formation is enhanced at high temperatures (above 600 °C) due to secondary cracking reactions, whereas CO2 is mainly formed by the primary decomposition of cellulose and hemicellulose at lower temperatures. Similar gas compositions were obtained in eucalyptus pyrolysis studies carried out in other fast pyrolysis reactors (Garcia-Perez et al., 2008; Gomez-Monedero et al., 2015; Heidari et al., 2014; Joubert et al., 2015). 3.2.3. Bio-oil composition Bio-oil has been thoroughly characterized by means of gas chromatography–mass spectrometry techniques, and 105 compounds have been identified. Table 3 shows the detailed composition of the bio-oil. The identified products have been grouped according to their functional groups into acids, aldehydes, alcohols, furans, ethers, ketones, phenols, saccharides and water. As observed, water is the main single compound, accounting for 35.7 wt.% of the whole bio-oil. This water content results from the
Table 2 Mass yields and volumetric composition of the gaseous fraction. Compound
Yield (wt.%)
Concentration (vol.%)
Hydrogen Carbon monoxide Carbon dioxide Methane Ethylene Ethane Propylene Propane
0.04 2.42 3.07 0.31 0.13 0.06 0.12 0.01
10.6 41.7 33.7 9.3 2.2 1.0 1.3 0.1
230
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
Table 3 Detailed composition of the eucalyptus pyrolysis bio-oil.
Table 3 (continued) Compound
Compound
Concentration (wt.%)
Acids Formic acid Acetic acid Propanoic acid 2-Propenoic acid Butanoic acid 3-Methyl-butanoic acid 4-Pentenoic acid 2-Methyl-2-butenoic acid 3,4-Dimethyl-benzoic acid
4.84 0.10 3.18 0.64 0.10 0.32 0.09 0.13 0.14 0.14
Aldehydes Formaldehyde Acetaldehyde 2-Propenal 2-Methyl-2-propenal Butanedial Glutaraldehyde 5-Methyl-2-furancarboxaldehyde 3-Hydroxy-benzaldehyde 4-Hydroxy-2-methylbenzaldehyde
2.24 0.20 0.21 0.08 0.04 0.16 0.94 0.17 0.32 0.11
Alcohols Methanol 3-Methyl-2-butanol acetate 7-Methyl-4-octanol acetate 4-Chromanol
1.00 0.55 0.11 0.20 0.14
Furans Furan 2-Hydroxytetrahydrofuran Furfural 2-Furanmethanol 2(5H)-Furanone Butyrolactone 3,4-Dimethyl-2,5-dihydrofuran Dihydro-3-methyl-2,5-Furandione 2-(Methoxymethyl) tetrahydrofuran 5-Acetyldihydro-2(3H)-furanone 5-(Hydroxymethyl)dihydro-2(3H)-furanone Coumaran 2-Coumaranone 7-Methylbenzofuran
5.91 0.07 0.29 0.51 0.21 0.51 2.81 0.04 0.16 0.14 0.22 0.38 0.38 0.04 0.16
Ethers Eucalyptol
1.35 1.35
Ketones Acetone 3-Methyl-2-butanone 1-Hydroxy-2-propanone 1-Hydroxy-2-butanone Cyclopentanone 2-Cyclopenten-1-one 1-Hydroxy-2-pentanone 2-Butanone 1-(Acetyloxy)-2-propanone 1-(2-Furanyl)-ethanone 3-Methyl-2-cyclopenten-1-one 4H-Pyran-4-one 4-Methylenecyclohexanone 2-Hydroxy-3-methyl-2-cyclopenten-1-one 2,3-Dimethyl-2-cyclopenten-1-one 3,4-Dimethyl-2-hydroxycyclopent-2-en-1-one 2,3,4-Trimethyl-2-Cyclopenten-1-one 2-Methyl-2-cyclohexen-1-one Acetophenone 3-Ethyl-2-cyclopenten-1-one 4-Heptanone 3-Ethenyl-cyclohexanone 3-Ethyl-2-hydroxy-2-cyclopenten-1-one 2,3-Dihydro-1H-Inden-1-one 3-Methyl-2H-1-benzopyran-2-one
10.66 0.55 0.25 0.82 0.61 0.17 0.52 0.05 0.07 0.18 0.19 1.92 0.11 0.05 2.65 0.19 0.21 0.14 0.10 0.30 0.09 0.05 0.04 0.35 0.14 0.92
Phenols Catechols 1,2-Benzenediol 3-Methyl-1,2-benzenediol
26.25 17.62 5.06 0.51
Hydroquinone Resorcinol 4-Methyl-1,2-benzenediol 2,6-Dimethyl-1,4-benzenediol 2-Methyl-1,3-benzenediol 4-Ethyl-1,3-benzenediol 2-Methyl-1,4-benzenediol 2,6-Dimethyl-1,4-benzenediol Resorcinol monoacetate 1,2,4-Benzenetriol 4-Ethyl-1,2-benzenediol 4,5-Dimethyl-1,3-benzenediol Guaiacols 2-Methoxy-phenol Ethenyloxybenzene 2-Isopropoxyphenol 3-Methoxy-5-methylphenol 2-Methoxy-3-methylphenol 4-Ethyl-2-methoxy-phenol Eugenol Alkyl phenols Phenol 2-Methylphenol 3-Methylphenol 2,5-Dimethyl-phenol 3-Ethylphenol 2,4-Dimethyl-phenol 2,6-Dimethyl-phenol 4-Ethylphenol 3,5-Dimethyl-phenol 2,3-Dimethyl-phenol 3,4-Dimethyl-phenol 2,3,5-Trimethylphenol 4-(1-Methylethyl)phenol 5-Ethyl-2-methylphenol 2-Allylphenol 2-Methyl-5-(1-methylethyl) phenol Thymol 2-Allyl-4-methylphenol Saccharides 1,6-Anhydro-.beta.-D-talopyranose Levoglucosan .Beta.-D-Ribopyranoside, methyl, 3-acetate Unidentified Water Total bio-oil
Concentration (wt.%) 2.75 0.74 2.12 0.07 0.33 1.11 0.97 0.89 0.54 0.29 2.05 0.18 3.88 2.25 0.20 0.19 0.39 0.28 0.46 0.10 4.75 0.87 0.68 0.07 0.13 0.18 0.38 0.16 0.23 0.44 0.17 0.04 0.02 0.04 0.30 0.65 0.07 0.03 0.28 3.25 0.34 2.07 0.85 8.75 35.74 100.00
moisture evaporation (9.5 wt.% of the biomass), cellulose and hemicellulose dehydration reactions and secondary cracking reactions (Demirbas, 2000). The water content obtained in the current study is slightly higher than those reported for eucalyptus wood pyrolysis in fluidized beds, in which the values range from 10 to 31 wt.% (Carrier et al., 2013; Chang et al., 2013; Garcia-Perez et al., 2008; Heidari et al., 2014; Joubert et al., 2015; Kim et al., 2013; Oasmaa et al., 2010). Bark and leaves have been reported to lead to higher water yields due to secondary cracking reactions promoted by their higher ash content (He et al., 2012; Oasmaa et al., 2010). However, the short gas residence times in the CSBR prevent the production of a bio-oil with an excessively high water yield for use as fuel. Phenols, which are formed by the depolymerisation of the lignin that constitutes the original biomass, are the main organic products with a concentration of 26 wt.%, with catechols (bezenediols) being the prevailing compounds. Heidari et al. (2014) also identified several phenolic compounds in the bio-oil resulting from the fluidized bed pyrolysis of eucalyptus wood, with syringol being the most abundant one, but also with a significant contribution of guaiacol and vanillin.
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
The concentration of ketones, and more specifically cyclopentanones, is also remarkable, accounting for 10 wt.% of the bio-oil. These compounds are mainly formed by hemicellulose degradation, together with furans (Demirbas, 2000), whose concentration reaches almost 6 wt.%. Although several acid compounds have been identified in the bio-oil, acetic acid is the major one, with a concentration of 3.2 wt.%. Oasmaa et al. (2010) also observed a 6.3 wt.% concentration of acids in the eucalyptus derived bio-oil, with acetic acid being the most abundant one. Similarly, the main saccharide-type product is levoglucosan, with a concentration of 2 wt.% in the bio-oil. These products are derived from the primary decomposition of the polysaccharides that make up the cellulose and hemicellulose fractions in the eucalyptus. The bio-oil obtained also contains a low concentration of aldehydes, alcohols and ethers. The latter group is made up of eucalyptol, which is the major product in the decomposition of eucalyptus leaves (He et al., 2012). The fast pyrolysis of eucalyptus wood in other reactor types led to a bio-oil with a similar composition as in this study. Thus, Chang et al. (2013) and Kim et al. (2013), operating in fluidized beds, identified similar compounds, as are phenols, cyclopentanones, acetic acid, furans and levoglucosan, although the concentration of the latter was higher in their studies than in this one, probably due to the avoidance of secondary cracking reactions usually promoted by the ash in the bark (Patwardhan et al., 2010). Finally, Gomez-Monedero et al. (2015) pyrolyzed red eucalyptus in an ablative reactor and obtained two fractions, aqueous and organic, with the latter being rich in phenols and the former in acids, ketones, furanes and alcohols. The bio-oil obtained in the pyrolysis of eucalyptus wastes in the conical spouted bed reactor is similar to those obtained in previous studies using several forestry residues such as pinewood (Amutio et al., 2012), broom, acacia, carquesa (Amutio et al., 2013b) and poplar wood (Makibar et al., 2015). Thus, the bio-oils obtained in the CSBR contain water in the 20–38 wt.% range, with the main organic compounds being phenols (especially catechols) and ketones (cyclopentanones), and a significant contribution of furans, acids and saccharides. These bio-oils may be used as a source of chemicals for the pharmaceutical, agricultural and food industries, for the production of renewable phenol–formaldehyde resins, as fuel in boilers, turbines and engines, for the production of fuels and chemicals after subjecting it to upgrading processes, such as hydrodeoxygenation or catalytic upgrading, or for hydrogen production by means of steam-reforming processes (Bridgwater, 2012; Zhang et al., 2007). Therefore, combined pyrolysis of these woody biomasses (with high bark and leave content) is feasible at large scale, which allows a sustainable valorisation of the forestry wastes available in delocalized sites. Accordingly, a standard bio-oil would be obtained, which may be upgraded following the routes mentioned above, and therefore reduce the need for a uniform raw material supply.
Table 4 Properties of the eucalyptus pyrolysis char. Properties Ultimate analysis (wt.%) Carbon Hydrogen Nitrogen Oxygen
76.3 2.2 1.3 13.7
Proximate analysis (wt.%) Volatile matter Fixed carbon Ash HHV (MJ kg1)
14.4 79.1 6.5 27.7
231
3.2.4. Char characterization Table 4 sets out the ultimate and proximate analyses, as well as the higher heating value of the eucalyptus char obtained at 500 °C in the conical spouted bed reactor. As observed, char has a high carbon content, which results in a high HHV value, higher than other conventional solid fuels, such as lignite (20 MJ kg1). These properties allow using this solid fraction as fuel, soil amender (Lee et al., 2010) or active carbon after subjecting it to activation processes (Alvarez et al., 2014b), thereby improving the overall profitability of the pyrolysis process. The eucalyptus char obtained in the conical spouted bed reactor is similar to those obtained by other authors in other fast pyrolysis technologies (Carrier et al., 2013; Garcia-Perez et al., 2008; Heidari et al., 2014), and also to those obtained in the pyrolysis of other woody biomasses in the CSBR (Amutio et al., 2012, 2013b; Makibar et al., 2015). 4. Conclusions The CSBR has proven to be a suitable and versatile technology for the fast pyrolysis of heterogeneous forestry materials made up of wood, bark and leaves, such as the eucalyptus wastes derived from the paper manufacturing sector. The high bio-oil yield obtained, 75.4 wt.%, is a very positive aspect for the proposal of this technology as alternative to fluidized beds. The methodology proposed for the analysis of eucalyptus waste structural composition is a useful tool to foresee reproducibility in bio-oil composition and the performance when the joint valorisation of this material with other biomass varieties is carried out. Acknowledgements This work was carried out with the financial support from the Ministry of Economy and Competitiveness of the Spanish Government (CTQ2013-45105-R), the ERDF funds, the Basque Government (IT748-13) and the University of the Basque Country (UFI 11/39). References Alvarez, J., Lopez, G., Amutio, M., Bilbao, J., Olazar, M., 2014a. Bio-oil production from rice husk fast pyrolysis in a conical spouted bed reactor. Fuel 128, 162– 169. Alvarez, J., Lopez, G., Amutio, M., Bilbao, J., Olazar, M., 2014b. Upgrading the rice husk char obtained by flash pyrolysis for the production of amorphous silica and high quality activated carbon. Bioresour. Technol. 170, 132–137. Amutio, M., Lopez, G., Alvarez, J., Moreira, R., Duarte, G., Nunes, J., Olazar, M., Bilbao, J., 2013a. Pyrolysis kinetics of forestry residues from the Portuguese Central Inland Region. Chem. Eng. Res. Des. 91, 2682–2690. Amutio, M., Lopez, G., Artetxe, M., Elordi, G., Olazar, M., Bilbao, J., 2012. Influence of temperature on biomass pyrolysis in a conical spouted bed reactor. Resour. Conserv. Recycl. 59, 23–31. Amutio, M., Lopez, G., Aguado, R., Artetxe, M., Bilbao, J., Olazar, M., 2011. Effect of vacuum on lignocellulosic biomass flash pyrolysis in a conical spouted bed reactor. Energy Fuels 25, 3950–3960. Amutio, M., Lopez, G., Alvarez, J., Moreira, R., Duarte, G., Nunes, J., Olazar, M., Bilbao, J., 2013b. Flash pyrolysis of forestry residues from the Portuguese Central Inland Region within the framework of the BioREFINA-Ter project. Bioresour. Technol. 129, 512–518. Arbogast, S., Bellman, D., Paynter, J.D., Wykowski, J., 2012. Advanced bio-fuels from pyrolysis oil: the impact of economies of scale and use of existing logistic and processing capabilities. Fuel Process. Technol. 104, 121–123. Branca, C., Albano, A., Di Blasi, C., 2005. Critical evaluation of global mechanisms of wood devolatilization. Thermochim. Acta 429, 133–141. Bridgwater, A.V., 2012. Review of fast pyrolysis of biomass and product upgrading. Biomass Bioenergy 38, 68–94. Carpenter, D., Westover, T.L., Czernik, S., Jablonski, W., 2014. Biomass feedstocks for renewable fuel production: a review of the impacts of feedstock and pretreatment on the yield and product distribution of fast pyrolysis bio-oils and vapors. Green Chem. 16, 384–406. Carrier, M., Joubert, J.E., Danje, S., Hugo, T., Görgens, J., Knoetze, J., 2013. Impact of the lignocellulosic material on fast pyrolysis yields and product quality. Bioresour. Technol. 150, 129–138. Chang, S., Zhao, Z., Zheng, A., Li, X., Wang, X., Huang, Z., He, F., Li, H., 2013. Effect of hydrothermal pretreatment on properties of bio-oil produced from fast
232
M. Amutio et al. / Bioresource Technology 194 (2015) 225–232
pyrolysis of eucalyptus wood in a fluidized bed reactor. Bioresour. Technol. 138, 321–328. Demirbas, A., 2000. Mechanisms of liquefaction and pyrolysis reactions of biomass. Energy Convers. Manage. 41, 633–646. Fernandez-Akarregi, A.R., Makibar, J., Lopez, G., Amutio, M., Olazar, M., 2013. Design and operation of a conical spouted bed reactor pilot plant (25 kg/h) for biomass fast pyrolysis. Fuel Process. Technol. 112, 48–56. FitzPatrick, M., Champagne, P., Cunningham, M., Whitney, R., 2010. A biorefinery processing perspective: treatment of lignocellulosic materials for the production of value-added products. Bioresour. Technol. 101, 8915–8922. Garcia-Perez, M., Wang, X., Shen, J., Rhodes, M., Tian, F., Lee, W., Wu, H., Li, C., 2008. Fast pyrolysis of oil mallee woody biomass: effect of temperature on the yield and quality of pyrolysis products. Ind. Eng. Chem. Res. 47, 1846–1854. Gomez-Monedero, B., Bimbela, F., Arauzo, J., Faria, J., Ruiz, M.P., 2015. Pyrolysis of red eucalyptus, camelina straw, and wheat straw in an ablative reactor. Energy Fuels 29, 1766–1775. He, M., Mourant, D., Gunawan, R., Lievens, C., Wang, X.S., Ling, K., Bartle, J., Li, C.Z., 2012. Yield and properties of bio-oil from the pyrolysis of mallee leaves in a fluidised-bed reactor. Fuel 102, 506–513. Heidari, A., Stahl, R., Younesi, H., Rashidi, A., Troeger, N., Ghoreyshi, A.A., 2014. Effect of process conditions on product yield and composition of fast pyrolysis of Eucalyptus grandis in fluidized bed reactor. J. Ind. Eng. Chem. 20, 2594–2602. Ho, D.P., Ngo, H.H., Guo, W., 2014. A mini review on renewable sources for biofuel. Bioresour. Technol. 169, 742–749. Joubert, J.E., Carrier, M., Dahmen, N., Stahl, R., Knoetze, J.H., 2015. Inherent process variations between fast pyrolysis technologies: a case study on Eucalyptus grandis. Fuel Process. Technol. 131, 389–395. Kim, K.H., Kim, T.S., Lee, S.M., Choi, D., Yeo, H., Choi, I.G., Choi, J.W., 2013. Comparison of physicochemical features of biooils and biochars produced from various woody biomasses by fast pyrolysis. Renew. Energy 50, 188–195. Lee, J.W., Kidder, M., Evans, B.R., Paik, S., Buchanan III, A.C., Garten, C.T., Brown, R.C., 2010. Characterization of biochars produced from cornstovers for soil amendment. Environ. Sci. Technol. 44, 7970–7974.
Maity, S.K., 2015. Opportunities, recent trends and challenges of integrated biorefinery: part II. Renew. Sustain. Energy Rev. 43, 1446–1466. Makibar, J., Fernandez-Akarregi, A.R., Amutio, M., Lopez, G., Olazar, M., 2015. Performance of a conical spouted bed pilot plant for bio-oil production by poplar flash pyrolysis. Fuel Process. Technol. 137, 283–289. Meszaros, E., Jakab, E., Varhegyi, G., 2007. TG/MS, Py-GC/MS and THM-GC/MS study of the composition and thermal behavior of extractive components of Robinia pseudoacacia. J. Anal. Appl. Pyrolysis 79, 61–70. Oasmaa, A., Solantausta, Y., Arpiainen, V., Kuoppala, E., Sipila, K., 2010. Fast pyrolysis bio-oils from wood and agricultural residues. Energy Fuels 24, 1380–1388. Pang, C.H., Gaddipatti, S., Tucker, G., Lester, E., Wu, T., 2014. Relationship between thermal behaviour of lignocellulosic components and properties of biomass. Bioresour. Technol. 172, 312–320. Patwardhan, P.R., Satrio, J.A., Brown, R.C., Shanks, B.H., 2010. Influence of inorganic salts on the primary pyrolysis products of cellulose. Bioresour. Technol. 101, 4646–4655. Pimenta, A.S., Vital, B.R., Bayona, J.M., Alzaga, R., 1998. Characterisation of polycyclic aromatic hydrocarbons in liquid products from pyrolysis of Eucalyptus grandis by supercritical fluid extraction and GC/MS determination. Fuel 77, 1133–1139. Sanna, A., 2014. Advanced biofuels from thermochemical processing of sustainable biomass in europe. Bioenergy Res. 7, 36–47. Skodras, G., Grammelis, P., Basinas, P., Kakaras, E., Sakellaropoulos, G., 2006. Pyrolysis and combustion characteristics of biomass and waste-derived feedstock. Ind. Eng. Chem. Res. 45, 3791–3799. Varhegyi, G., Gronli, M., Di Blasi, C., 2004. Effects of sample origin, extraction, and hot-water washing on the devolatilization kinetics of chestnut wood. Ind. Eng. Chem. Res. 43, 2356–2367. Wan Sulaiman, W., Lee, E., 2012. Pyrolysis of Eucalyptus wood in a fluidized-bed reactor. Res. Chem. Intermed., 1–15 Zhang, Q., Chang, J., Wang, T., Xu, Y., 2007. Review of biomass pyrolysis oil properties and upgrading research. Energy Convers. Manage. 48, 87–92.