Article pubs.acs.org/EF
Effects of Lignin Content and Temperature on the Properties of Hybrid Poplar Bio-Oil, Char, and Gas Obtained by Fast Pyrolysis Bethany Klemetsrud,*,† Dominic Eatherton,† and David Shonnard†,‡ †
Department of Chemical Engineering and ‡Sustainable Futures Institute, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan 49931, United States S Supporting Information *
ABSTRACT: Eight genetically different hybrid poplar samples with varying lignin content were pyrolyzed at 500 °C using a micropyrolysis unit, which was directly connected to a GC/MS. Four of these hybrid poplar samples with a range of lignin content were then pyrolyzed at temperatures of 550 and 600 °C to determine the effects of pyrolysis temperature on product distribution among bio-oil, char, and gas. At a pyrolysis temperature of 500 °C, an increase in poplar lignin content from 17% to 22% decreased the relative bio-oil yield from 73% to 65%, increased the char yield from 17.5% to 27.2%, and decreased the yield of lignin-derived phenolic species in the bio-oil by 3%. At the higher pyrolysis temperature of 600 °C, there was neither a decrease in the yield of bio-oil nor an increase in the char yield, and there was an increase in the relative abundamnce of bio-oil phenolics compared to the results obtained at 500 °C. According to these results, higher temperatures are needed to increase the yield of bio-oil and the content of phenolic species in bio-oil.
■
INTRODUCTION By 2022, the United States is required by the Renewable Fuels Standards Act (RFS2) to produce 36 billion gallons of blended transportation fuel. In 2012, the United States produced 13.8 billion gallons of biofuels, with 94% of the biofuel produced coming from corn ethanol.1 The RFS2 requires that, by 2022, 21 billion gallons of the total must be advanced biofuels derived mostly from lignocellulosic biomass instead of the currently used starches, sugars, and fats. Therefore, nearly all growth in the biofuels sector needs to be focused on the development of advanced biofuels. A viable method for the production of advanced biofuels is the thermochemical conversion of biomass to a liquid transportation fuel.2−4 Studies on thermochemical conversion have focused on the properties of the bio-oil, the reaction conditions, and the quality of the bio-oil produced by fast pyrolysis and how these properties are governed by the types of biomass processed.5 Hybrid poplar has been identified as a potential feedstock for biofuel production because of its ability to be genetically altered, its relatively high growth rate, and its suitability for thermochemical conversion.6 Previous studies have shown that biomass feedstock properties have a significant effect on the quality of bio-oil produced by fast pyrolysis.5,7,8 Specifically, the mineral content and ash content of the biomass have been shown to affect the quality of the bio-oil. In general, higher ash contents result in lower bio-oil yields,9−11 whereas higher mineral contents increase the content of lower-molecular-weight products in the obtained bio-oil. Thes changes occur because the pyrolysis products are cracked or broken down by alkali earth metals such as sodium and calcium.10,12,13 Aside from feedstock properties, process conditions such as temperature, pressure, and particle size along with reactor design and configuration are also large factors determining the final quality of the bio-oil produced. © 2017 American Chemical Society
Biomass is comprised of three main components: cellulose, lignin, and hemicellulose. Patwardhan et al.14 studied these individual components to determine which products are produced when they are pyrolyzed individually. Their work showed that hemicellulose generally produces lower-molecularweight gases, organic acids, and furans. Hemicellulose is also one of the first components of biomass to begin degradation, which can occur at temperatures as low as 250 °C. Cellulose generally produces anhydrosugars, such as levoglucosan, and decomposes at a higher temperature, typically about 350−400 °C. Lignin, when pyrolyzed, generally gives a bio-oil that is rich in phenolic structures and has lower organic acid concentrations than the products of hemicellulose pyrolysis. The interactions between cellulose and lignin and between cellulose and hemicellulose have also been studied;15−17 however, there is no overall understanding of how these components interact within the entirety of the biomass structure and how these individual components of biomass can be altered to generate higher-quality bio-oil.5,7,11 Bio-oil has been criticized in several respects, especially when compared to its fossil-fuel counterpart. For example, bio-oil produced by fast pyrolysis generally has poor volatility, high viscosity, and high corrosivity and causes coking within the reactor.18 Because of the presence of low-molecular-weight molecules, especially organic acids, bio-oil is generally acidic, causing it to be corrosive.13 These low-molecular-weight molecules are not easily upgradable because they have high oxygen contents, and may need to be recombined to generate a larger molecule to be within the gasoline range. One of the greatest disadvantages of bio-oil is its high oxygen content. This high oxygen content requires an energy and hydrogen-rich Received: October 28, 2016 Revised: January 18, 2017 Published: February 1, 2017 2879
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels catalytic upgrading process.19 Many of the oxygen-rich products are generated from the hemicellulose and cellulose fractions. The lignin fraction does contribute to the oxygen content, but because of the nature of the phenolic ring, the lignin fraction contributes more significantly to the carbon content of the biooil. Phenolic structures are easier to upgrade than carbohydratederived bio-oil compounds using catalytic hydrotreatment, have higher carbon-to-oxygen ratios, and can therefore produce a more energy-dense biofuel product.19 Previous studies have considered different types of biomass, their characteristics, and the properties of the resulting biooil.8,20−22 Some studies have compared these biomass characteristics and bio-oil properties across different species11,13 to evaluate the key biomass characteristics on which to focus. One comparison of different biomass species showed that an increase in lignin content from 18% to 35% reduced the oxygen content of the resulting bio-oil, decreased the bio-oil yield (because of an increase in biochar yield), and increased the average molecular weight of the bio-oil.13 However, no studies have conducted lignin-related pyrolysis experiments with a single species, and therefore, there is no clear understanding of what occurs when an individual biomass species that has been crossbred to change its biomass components is evaluated across its genotype. In this study, we obtained hybrid poplar that had been crossbred to increase the amount of lignin present in the hybrid poplar clones. Therefore, in this research, we performed micropyrolysis experiments on hybrid poplar species with a range of lignin content. Our hope is that the results of this study will allow for an improved understanding of how changing the lignin content of hybrid poplar affects the quality of the bio-oil produced and the distribution of products among gases, liquids, and solid char. This research allows for a systematic evaluation of changes in the biomass composition of lignin of the same genetic species of hybrid poplar at varying temperatures. The objective of this study was to understand how changes in the biomass structure affect the fast-pyrolysis product distribution and the chemical composition of the biooil produced under various reaction conditions. This work evaluated eight hybrid poplar samples and determined how the char, gas, and bio-oil yields changed with respect to lignin composition. The bio-oil and char compositions were also evaluated with respect to the initial biomass compositions of the poplar samples.
■
Pyrolysis Experiments. The eight hybrid poplar samples were used to understand the effects of the lignin content on the fastpyrolysis product distribution. These experiments were conducted in triplicate at 500 °C. Four of these poplar samples were then used to understand the effects of temperature on the lignin content and were pyrolyzed at 550 and 600 °C. Table 1 lists the samples, their lignin
Table 1. Lignin Content, Syringol-to-Guaiacol (S/G) Ratio, and Experimental Matrix for Hybrid Poplar Samples sample
lignin content (%)
S/G ratio
645 695 648 705 765 506 635 603
17.52 19.76 19.91 20.46 20.50 21.50 21.65 22.07
1.29 1.48 1.42 1.65 1.34 1.54 1.73 1.53
temperature dependence
x x x x
content, and their syringol-to-guaiacol (S/G) ratio and indicates which samples were included in the experiments on temperature dependence. The lignin content ranged from 17% to 22%. Hardwoods, such as hybrid poplar, beech, and chestnut, generally have lignin content of 15−25%, whereas softwoods, such as pine, redwood, and douglas fir, have lignin content ranging from 25% to 40%. The syringol-to-guaiacol ratio was found to increased with increasing lignin content. This indicates that more syringol was generated within the biomass structure for the genotypes that had increased lignin content. Sample numbers are the same as those used in the University of Florida study;23 however, because of the different growing conditions in the two studies, the lignin content in this work varied from those in the original study. Effects of Lignin Content and Pyrolysis Temperature. Hybrid poplar samples ranging in mass from 200 to 600 μg with thicknesses of approximately 200 μm were placed in a quartz vial held between two pieces of quartz wood, as shown in Figure 1. Each poplar fiber sample was then loaded into a CDS 5200 high-pressure/high-temperature pyroprobe, where it was dried at 105 °C for 10 min to remove free moisture and to ensure that any water detected in the experiment was from chemically bound and chemically formed water. The pyroprobe reactor was kept inert with a helium flow at a rate of 20 mL/min. The interface of the pyroprobe was then heated to 300 °C. Once this interface temperature had been reached, the platinum coil was rapidly heated to its predetermined reaction temperature (ranging from 500 to 600 °C). The platinum coil achieved the reaction temperature at a rate of 1000 °C/s and used radiative and convective heat transfer for the biomass sample to undergo fast pyrolysis. The gaseous vapors were swept through the transfer line, which was kept at a temperature of 300 °C, to a gas chromatograph (GC) (Thermo Fisher Trace GC Ultra). The gaseous vapors were then condensed onto the GC column (Restek, Rxi-5 ms, 30 m × 0.25 mm, 0.25 μm film thickness), which was held at a temperature of 35 °C for 2 min. The column was heated at a rate of 5 °C/min to 150 °C and then at a rate of 10 °C/min to 275 °C. Once the column had reached 275 °C, it was held at this temperature for 2 min to ensure that heavier compounds were eluted through the column. After the compounds had eluted through the column, they were sent to a Thermo Fisher DSQII mass spectrometer (MS), and their fragment ions were measured from m/z 15 to m/z 400. The ion source was kept at 275 °C with an electron ionization potential of 70 eV. The dataset was recorded using Thermo Fisher’s Xcalibur software. Experiments were conducted in triplicate. Between experiments, the pyroprobe containing an empty quartz vial was heated to 600 °C and the GC was heated to 275 °C several times to ensure that no residual pyrolysis oil remained within the pyroprobe or GC. The same procedure was used for all hybrid poplar samples; the GC/MS conditions remained the same, with the only change being the reaction temperature of the pyroprobe, which was held at 500, 550, or 600 °C.
MATERIALS AND METHODS
Biomass Preparation. Eight hybrid poplar clones [(Populus trichocarpa × P. deltoids) × (P. trichocarpa × P. deltoids)] were obtained from a University of Florida study.23 These cuts were then grown on the Baraga Plains at the Ford Forestry Center located in Alberta, MI, by researchers at the Michigan Technological University School of Forest Resources. Cuts from these tree plantings occurred after 3 years of growth. The cuts were debarked and chipped using a coffee grinder. The samples were then sieved and sized to a range of 180−250 μm (80−60 Tyler mesh). After the samples had been sized, they were then dried in a drying oven at 105 °C for 24 h and stored in a resealable plastic bag. Two-milligram portions of each of the eight hybrid poplar samples, sized to 180−250 μm, were then sent to the Complex Carbohydrate Research Center at the University of Georgia (Athens, GA) for the determination of their lignin content and syringol-to-guaiacol ratio by pyrolysis molecular beam mass spectrometry (Frontier Laboratories single-shot pyrolyzer and Extrel Core mass spectrometer). The carbon content of these samples were also measured using an elemental analyzer (Costech 4010). 2880
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels
Figure 1. Schematic of the experimental setup for the fast pyrolysis of hybrid poplar samples in a micropyrolysis reactor.31 Bio-Oil Product Identification. To analyze the bio-oil and vapors that were produced during pyrolysis, only chromatogram peaks with contributions of 1% or greater to the total peak area were analyzed and identified. This approach accounted for approximately 70% of the total peak area. Peaks that contributed less than 1% to the peak area were difficult to distinguish from the baseline and generally coeluted with other species, making it difficult to deconvolute these small peaks. Products that contributed 1% or greater to the peak area were identified based on their mass/charge spectra using the library of NIST spectra included in the Xcalibur software. If a product could not be clearly identified using the Xcalibur software, its mass spectrum was compared to spectra in the literature and then confirmed by comparing the compound spectrum to that in the NIST Chemistry WebBook.24 Compounds that were not identified using these methods were grouped into classes based on their unique mass/charge fragments. Table 2 reports the main fractions for specific compounds.23
The char weight was then subtracted from the original mass, and the remaining mass was allocated among bio-oil, gas, and water based on the identified peak areas, thereby determining the char yield and the relative bio-oil and gas yields. The bio-oil and gas compounds were not calibrated with standards because the bio-oil speciation and product distribution were compared across the same hybrid poplar species and varying pyrolysis temperatures within this study. The char was then analyzed using an elemental analyzer (Costech 4010) to determine the amount of carbon present.
■
RESULTS AND DISCUSSION Effect of Lignin Content at a Constant Temperature of 500 °C. The hypothesis behind this research was that, as the amount of lignin present in the same species of poplar increased, the amount of phenolics present in the bio-oil would increase. This hypothesis was supported by ref 25, which reported that bio-oils from coniferous sources with increasing lignin content have substantially more phenolics present but lower bio-oil yields because of the increase in char yield. Therefore, in our study, it was expected that, with an increase in poplar lignin, there would be an increase in the amount of phenolics present in the bio-oil and a higher char yield. As shown in Figure 2a (triangles), the relative bio-oil yields at 500 °C of the eight hybrid poplar samples containing between 17.5% and 22% lignin decreased between 5% and 10% with increasing lignin content. The char yield, as shown in Figure 3a, exhibited the opposite trend (i.e., increased) as the lignin content increased. In previous studies,15,26,27 it was observed that wood samples with higher lignin content are likely to produce more char and, therefore, reduced bio-oil yields (as also observed in this study in Figures 2a and 3). The relative gas yields in our study did not change substantially, as shown in Figure 4, at the top of the bar charts. Therefore, the main tradeoff with increasing lignin content was a decrease in the relative bio-oil yield and an increase in the char yield. Figure 5a shows the variations in the amounts of ligninderived compounds within the bio-oil as a function of the poplar lignin content. It was observed that, with increasing lignin content of the biomass samples, the content of ligninderived compounds within the bio-oil obtained at 500 °C decreased, although, admittedly, this trend cannot be confirmed
Table 2. Classes of Compounds Commonly Found in Pyrolysis Liquids, along with Their Characteristic m/z Peaks from GC/MS Analysis23 class five-carbon hemicellulose (furans) six-carbon cellulose sugar (anhydrosugars) syringyl lignin monomer gualacyl lignin monomer
characteristic m/z peaks 57 + 73 + 85 + 96 + 114 57 + 60 + 73 + 98 + 126 + 144 154 + 167 + 168 + 182 + 194 + 208 + 210 124 + 137 + 138 + 150 + 164 + 178
Compounds were then grouped into six different categories: lignin (compounds containing phenolic structures), small sugars (compounds containing furans), large sugars (primarily anhydrosugars), low-molecular-weight species (compounds eluting during the first 5 min, including aldehydes, ketones and organic acids), gaseous products (corresponding to the first peak in the chromatogram and containing primarily CO2 and CO), and water (compounds contained within the first peak and separated out using the 18 m/z fragment). Other light noncondensable gases such as ethane and propane are produced in pyrolysis, but because of the experimental setup, it was difficult to identify these compounds in the chromatograms. If produced they would have eluted in the first peak of the chromatogram with the CO and CO2. The char weight was measured using a microbalance (Orion Cahn C-35 microbalance, Thermo Scientific) with a sensitivity of 1 μg. 2881
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels
Figure 2. (a) Relative bio-oil yields of different hybrid poplar clones at 500, 550, and 600 °C. (b) Relative changes in bio-oil yield with respect to the 500 °C yield for each hybrid poplar sample.
Figure 3. (a) Char yields for samples with varying lignin content pyrolyzed at 500, 550, and 600 °C. (b) Relative changes in char yield with respect to the 500 °C yield for each hybrid poplar sample.
2882
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels
Figure 4. Comparison of the relative amounts of compounds in the bio-oil and gas and char yields for samples with increasing lignin content (where sample 645 has the lowest content and sample 603 has the highest content) at increasing temperature as indicated by the dashed lines. LMW refers to the low-molecular-weight bio-oil species.
Figure 5. (a) Relative amounts of lignin-derived compounds in the bio-oil yield for samples with varying lignin content pyrolyzed at 500, 550, and 600 °C. (b) Relative changes in the lignin-derived compounds within the bio-oil with respect to the 500 °C results for each hybrid poplar sample.
because of the size of the error bars. These results thus suggest that, instead of being volatilized from the poplar lignin structure into the bio-oil, lignin preferentially remained fixed in the char. At 500 °C, with increasing lignin content in the poplar, the other categories of compounds present in the bio-oil, such as low-molecular-weight compounds or carbohydrate-derived compounds, did not change substantially, as shown in Figure 4. Effect of Increasing Fast-Pyrolysis Temperature. A set of experiments was performed on four of the hybrid poplar samples at 550 and 600 °C to determine whether the lignin could be volatilized more effectively at higher temperatures to
boost the relative bio-oil yield and the amounts of ligninderived phenolic compounds in the bio-oil. Previous studies5,11,13 showed that, as the temperature was increased, the char yields decreased, along with relative bio-oil yields, but the amount of gas produced could increase. When these poplar samples were pyrolyzed at higher temperatures, there was little to no change in the relative bio-oil yields for the two lowerlignin poplar samples, but an increase in the relative bio-oil yields for the poplar samples with higher lignin content, as shown in Figure 2a,b. The hybrid poplar sample with 20.5% lignin actually showed a slight decrease. The char yield with 2883
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels
Figure 6. Amounts of carbon present in the raw biomass and pyrolysis char at various reaction temperatures as a function of the biomass lignin content.
was the poplar sample with a 20.5% lignin content, which exhibited a slight decrease in phenolics content in the bio-oil with increasing pyrolysis temperature (Figure 5b). In this study, the poplar species with 22% lignin (sample 603) had the highest average amount of lignin-containing compounds present in the bio-oil and also had one of the highest average bio-oil yields from the experiments at 550 °C, as shown in Figure 2. Aside from more lignin-containing compounds being present in the bio-oil at 600 °C, the product distributions of gas, char, and water for poplar sample 603 were nearly identical at 550 and 600 °C, as shown in Figure 4. Therefore, according to our study, 550 °C might be the most favorable fast-pyrolysis temperature for enhancing both the relative bio-oil yield and the amount of phenolics present in the bio-oil for these hybrid poplar samples. Although the lignin content in the bio-oil was shown to increase with increasing temperature, it is expected that the relative amounts of other compounds in the bio-oil would change with increasing lignin content and temperature. Among the largest relative changes were the decrease in the carbohydrate fraction with increasing temperature and the increasing amount of CO2 and CO generated, as shown in Figure 4. At the higher temperatures, the hemicellulose is likely converted into gases instead of generating more small carbohydrate compounds such as furans. The increase in pyrolysis gas formed with increasing temperature might also be evidence for the degradation of the lignin structure.30 As the pyrolysis reaction temperature was increased from 500 to 600 °C, the elemental analysis in Figure 6 shows that the amount of carbon within the char increased by about 20−30% compared to that in raw biomass. This increase in C content is fairly consistent across all lignin content in the poplar samples. This trend is in agreement with those observed in previous studies5,13,14 in that, as the biomass was pyrolyzed, the molecular structure of the remaining solid char changed with the severity of the pyrolysis to increase C and reduce O. During pyrolysis, as the biomass is being volatized, the biomass structure is continuously rearranging to develop a more stable structure. It has been suggested that, with increasing temperature, more carbon−carbon bonds form, generating a more carbonaceous char.7 For three of the four biomass samples tested, pyrolysis at 600 °C produced char with the highest C percentage, but any conclusions about the effects of the pyrolysis temperature on the char composition are preliminary because of a lack of replicate measurements.
respect to lignin content did decrease significantly from 500 to 550 °C, as shown in Figure 3a,b. This indicates that, with increasing temperature, more of the lignin was volatilized into the bio-oil instead of remaining fixed in the char. The changes in char yields from 500 to 550 and 600 °C were significant (because the error bars do not overlap) for the higher-lignincontent species but not the lower-lignin-content species, again indicating that more of the lignin remaied fixed in the char at 500 °C and that higher temperatures were needed for the more complete pyrolysis of the biomass. Jia et al.28 suggested that two reaction steps occur during the degradation of the lignin structure, with the first involving larger oligomers and smaller gases breaking off, leading to a more stable char. The char could be further degraded with an increase in residence time or reactor temperature, leading to a larger production of lignin monomers.28 The results from the current study suggest that the second reaction occurs at a much higher rate at higher temperatures than at 500 °C. These results also show trends similar to those reported in previous literature, in which biomass with a higher lignin content had lower bio-oil yields when pyrolyzed at 500 °C.29 This research suggests that higher temperatures can be used to generate lower char yields and higher bio-oil yields; however, it is important to note that the pyrolysis reactions in the earlier study were conducted in a flash reactor in which secondary reactions occurred.29 In contrast, this current research focused on understanding primary pyrolysis reactions, so the product distribution is expected be different from that obtained using a pilot reactor setup in which secondary reactions occur. The data on relative peak areas from the pyrolysis GC/MS experiments were organized into chemical categories to investigate any possible trends with changes in lignin content and temperature. The categories include gases (CO2, CO, H2O), bio-oil compound categories [low-molecular-weight (LMW) compounds, holocellulose-derived carbohydrates, lignin-derived phenolics, unspecified compounds], and char. These bio-oil categories were compared across varying lignin content and reactor temperatures, as shown in Figure 4. Detailed listings of the bio-oil compounds within each of these categories are provided in the Supporting Information. Regarding the speciation of bio-oil and the product distributions in Figures 4 and 5a,b, it can be observed that, with increasing temperature (for most poplar samples), the amount of lignin-derived phenolics present in the bio-oil increased by approximately 20%. The exception to this trend 2884
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels ORCID
Although some trends with respect to the poplar lignin content and fast-pyrolysis temperature were observed in these experiments, the interpretations are not broadly applicable because of the limited range of lignin content investigated. Therefore, it is recommended that more experiments be conducted over a wider range of lignin content for poplar and for other types of woody biomass species. Another consideration for interpreting these results is the manner in which fast pyrolysis was conducted in these experiments. The residence time of the pyrolysis vapors in the reactor zone was very short because of the configuration of the pyroprobe within the reaction interface of the micropyrolysis reactor. Helium gas swept the vapors quickly from the hot pyrolysis reaction zone into a cooler environment in the transfer line to the GC/MS. The reactions measured in these experiments must be interpreted as the primary reactions that liberate volatile vapors from the biomass solid and not secondary reactions that would occur in the gas phase with longer reaction residence times in the reactor. Future experiments might gain additional insights into the fundamental pyrolysis reactions and mechanisms by reconfiguring the micropyrolysis reactor to gain control over the reaction residence time and study secondary reactions that occur. The results in this work focused on the primary products formed for varying lignin content and reaction temperatures. Understanding how lignin content and temperature affect the product distribution of bio-oil allows for a more detailed mechanistic understanding of the thermochemical degradation of biomass.
Bethany Klemetsrud: 0000-0001-8348-2903 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS The authors gratefully acknowledge the National Science Foundation for support of this work through a Sustainable Energy Pathways Grants (Grant MSP/CHE-ENG/ECCS1230803), as well as the Richard and Bonnie Robbins Endowment.
■
■
CONCLUSIONS The main conclusion from this study is that increasing the amount of lignin in hybrid poplar has the potential to increase the amount of lignin-derived phenolics present in the resulting bio-oil, but only with the assistance of increasing pyrolysis temperature of up to 600 °C. However, at the typical fastpyrolysis temperature of 500 °C, increasing the lignin content in the raw biomass produced more char rather than more biooil, with a tendency for more of the lignin to be retained in the solid char. For this study, sample 603 produced the largest amount of phenolics in the bio-oil at a temperature of 600 °C, but it had the highest relative bio-oil yield at 550 °C and was the poplar species with the highest lignin content. This indicates that biomass structures with increased amounts of lignin can generate large bio-oil yields with temperature optimization. When considering varying feedstocks for the generation of pyrolysis bio-oil, micropyrolysis allows for a rapid screening process to identify optimum conditions.
■
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.energyfuels.6b02836. Detailed listings of the bio-oil compounds within each of the categories low-molecular-weight (LMW) compounds, carbohydrate-derived compounds, and ligninderived compounds (PDF)
■
REFERENCES
(1) U.S. Bioenergy Statistics. http://www.ers.usda.gov/dataproducts/us-bioenergy-statistics.aspx (accessed July 2016). (2) Perlack, R. D.; Wright, L. L.; Turhollow, A. F.; Graham, R. L.; Stokes, B. J.; Erbach, D. C. Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply; Technical Report ORNL/TM-2005/66; Oak Ridge National Laboratory: Oak Ridge, TN, 2005. (3) de Wit, M.; Faaij, A. European biomass resource potential and costs. Biomass Bioenergy 2010, 34 (2), 188−202. (4) Elliott, D. C.; Beckman, D.; Bridgwater, A. V.; Diebold, J. P.; Gevert, S. B.; Solantausta, Y. Developments in direct thermochemical liquefaction of biomass: 1983−1990. Energy Fuels 1991, 5 (3), 399− 410. (5) Kan, T.; Strezov, V.; Evans, T. J. Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters. Renewable Sustainable Energy Rev. 2016, 57, 1126−1140. (6) Perlack, R. D.; Stokes, B. J.U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry; Technical Report ORNL/TM-2011/224; Oak Ridge National Laboratory: Oak Ridge, TN, 2011. (7) Collard, F.-X.; Blin, J. A review on pyrolysis of biomass constituents: Mechanisms and composition of the products obtained from the conversion of cellulose, hemicelluloses and lignin. Renewable Sustainable Energy Rev. 2014, 38, 594−608. (8) Fahmi, R.; Bridgwater, A. V.; Donnison, I.; Yates, N.; Jones, J. The effect of lignin and inorganic species in biomass on pyrolysis oil yields, quality and stability. Fuel 2008, 87 (7), 1230−1240. (9) Patwardhan, P. R.; Brown, R. C.; Shanks, B. H. Product distribution from the fast pyrolysis of hemicellulose. ChemSusChem 2011, 4 (5), 636−643. (10) Nik-Azar, M.; Hajaligol, M.; Sohrabi, M.; Dabir, B. Mineral matter effects in rapid pyrolysis of beech wood. Fuel Process. Technol. 1997, 51 (1), 7−17. (11) Bridgwater, A. V. Review of fast pyrolysis of biomass and product upgrading. Biomass Bioenergy 2012, 38, 68−94. (12) Wannapeera, J.; Worasuwannarak, N.; Pipatmanomai, S. Product yields and characteristics of rice husk, rice straw and corncob during fast pyrolysis in a drop-tube/fixed-bed reactor. Songklanakarin J. Sci. Technol. 2008, 30 (3), 393−404. (13) Mohan, D.; Pittman, C. U.; Steele, P. H. Pyrolysis of wood/ biomass for bio-oil: a critical review. Energy Fuels 2006, 20 (3), 848− 889. (14) Patwardhan, P. R. Understanding the Product Distribution from Biomass Fast Pyrolysis. Ph.D. Thesis, Iowa State University, Ames, IA, 2010. (15) Caballero, J. A.; Conesa, J. A.; Font, R.; Marcilla, A. Pyrolysis kinetics of almond shells and olive stones considering their organic fractions. J. Anal. Appl. Pyrolysis 1997, 42 (2), 159−175. (16) Wang, S.; Guo, X.; Wang, K.; Luo, Z. Influence of the interaction of components on the pyrolysis behavior of biomass. J. Anal. Appl. Pyrolysis 2011, 91 (1), 183−189. (17) Hosoya, T.; Kawamoto, H.; Saka, S. Cellulose−hemicellulose and cellulose−lignin interactions in wood pyrolysis at gasification temperature. J. Anal. Appl. Pyrolysis 2007, 80 (1), 118−125.
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. 2885
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
Article
Energy & Fuels (18) Bridgwater, A. V. Principles and practice of biomass fast pyrolysis processes for liquids. J. Anal. Appl. Pyrolysis 1999, 51 (1−2), 3−22. (19) Hilten, R. N.; Speir, R. A.; Kastner, J. R.; Mani, S.; Das, K. Effect of torrefaction on bio-oil upgrading over HZSM-5. Part 1: Product yield, product quality, and catalyst effectiveness for benzene, toluene, ethylbenzene, and xylene production. Energy Fuels 2013, 27 (2), 830− 843. (20) Gani, A.; Naruse, I. Effect of cellulose and lignin content on pyrolysis and combustion characteristics for several types of biomass. Renewable Energy 2007, 32 (4), 649−661. (21) Yang, H.; Yan, R.; Chen, H.; Lee, D. H.; Zheng, C. Characteristics of hemicellulose, cellulose and lignin pyrolysis. Fuel 2007, 86 (12), 1781−1788. (22) Sharma, R. K.; Wooten, J. B.; Baliga, V. L.; Lin, X.; Chan, W. G.; Hajaligol, M. R. Characterization of chars from pyrolysis of lignin. Fuel 2004, 83 (11), 1469−1482. (23) Novaes, E.; Osorio, L.; Drost, D. R.; Miles, B. L.; BoaventuraNovaes, C. R.; Benedict, C.; Dervinis, C.; Yu, Q.; Sykes, R.; Davis, M. Quantitative genetic analysis of biomass and wood chemistry of Populus under different nitrogen levels. New Phytol. 2009, 182 (4), 878−890. (24) Stein, S. E. Mass Spectra. In NIST Chemistry WebBook; NIST Standard Reference Database 69; Linstron, P. J., Mallard, W. G., Eds.; NIST Chemistry WebBook; NIST Standard Reference Database 69; National Institute of Standards and Technology (NIST): Gaithersburg, MD, 2005; available at http://webbook.nist.gov/chemistry/. (25) Oasmaa, A.; Kuoppala, E. Fast pyrolysis of forestry residue. 3. Storage stability of liquid fuel. Energy Fuels 2003, 17 (4), 1075−1084. (26) Di Blasi, C.; Branca, C.; Santoro, A.; Gonzalez Hernandez, E. Pyrolytic behavior and products of some wood varieties. Combust. Flame 2001, 124 (1-2), 165−177. (27) Muley, P. D.; Henkel, C.; Abdollahi, K. K.; Marculescu, C.; Boldor, D. A critical comparison of pyrolysis of cellulose, lignin, and pine sawdust using an induction heating reactor. Energy Convers. Manage. 2016, 117, 273−280. (28) Jia, L.; Le-Brech, Y.; Shrestha, B.; Frowein, M. B.-v.; Ehlert, S.; Mauviel, G.; Zimmermann, R.; Dufour, A. Fast Pyrolysis in a Microfluidized Bed Reactor: Effect of Biomass Properties and Operating Conditions on Volatiles Composition as Analyzed by Online Single Photoionization Mass Spectrometry. Energy Fuels 2015, 29 (11), 7364−7374. (29) Amutio, M.; Lopez, G.; Alvarez, J.; Moreira, R.; Duarte, G.; Nunes, J.; Olazar, M.; Bilbao, J. Flash pyrolysis of forestry residues from the Portuguese Central Inland Region within the framework of the BioREFINA-Ter project. Bioresour. Technol. 2013, 129, 512−518. (30) Newalkar, G.; Iisa, K.; D’Amico, A. D.; Sievers, C.; Agrawal, P. Effect of Temperature, Pressure, and Residence Time on Pyrolysis of Pine in an Entrained Flow Reactor. Energy Fuels 2014, 28 (8), 5144− 5157. (31) Klinger, J.; Bar-Ziv, E.; Shonnard, D. Kinetic study of aspen during torrefaction. J. Anal. Appl. Pyrolysis 2013, 104, 146−152.
2886
DOI: 10.1021/acs.energyfuels.6b02836 Energy Fuels 2017, 31, 2879−2886
