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Exploring the Products from Pinewood Pyrolysis in Three Different Reactor Systems Alexander M Zmiewski, Nicole L Hammer, Rene A Garrido, Trevor G Misera, Charles G Coe, and Justinus A. Satrio Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.5b01214 • Publication Date (Web): 20 Aug 2015 Downloaded from http://pubs.acs.org on August 23, 2015

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Exploring the Products from Pinewood Pyrolysis in Three Different Reactor Systems Alexander M. Zmiewski, Nicole L. Hammer, Rene A. Garrido, Trevor G. Misera ,Charles G., Coe, *Justinus A. Satrio Department of Chemical Engineering, Villanova University, Villanova, Pennsylvania 19085, USA *Corresponding author: [email protected], phone: +1610-519-6658, fax: +1-610519-7354 ABSTRACT: The product yields and selectivity from fast pyrolysis of biomass are highly dependent on the physicochemical properties of the biomass feedstock and the process conditions. The objective of this study was to compare the product yields and selectivity from fast pyrolysis of pinewood using three different reactors systems typically used in research laboratory settings for studying biomass pyrolysis: a micropyrolyzer coupled to a GC/MS system, a batch tubular reactor, and a fluidized-bed (FB) continuous reactor. The pyrolysis of pinewood using the three reactors gave different bio oil yields, altered the amounts and compositions of the non-condensable gases, and gave rise to variations in the amount and types of chemicals in bio-oil produced. The variability in residence times of the three reactors and mechanical factors within the FB altered the degree of secondary reactions of the primary

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pyrolysis vapor leading to the observed changes in composition. Lower yields of carbohydrates were also found to be a consequence of these same intrinsic reactor design constraints. These findings shed significant light on how residence time and the mechanical properties of a reactor configuration affect the products of pyrolysis through the alteration of secondary pyrolytic reactions. 1. INTRODUCTION The increase of environmental awareness and energy demand worldwide has opened the door to alternative energy sources such as biomass utilization. Biomass is the only renewable carbonbased energy resource that can be converted to fuels or other chemical products through thermochemical processes.1 Pyrolysis is a thermochemical process where carbon containing materials, such as biomass, are exposed to an elevated temperature (typically between 400 and 600°C) in the absence of oxygen, which results in the decomposition of the material to produce bio-oil, char, and non-condensable gases (NCG).1-4 One promising category of pyrolysis feedstock is lignocellulosic biomass. The material consists of three major components: cellulose, hemicellulose, and lignin. Cellulose is comprised of chains of glucose molecules that give structure to the biomass.4-6 Hemicellulose, which is much smaller than cellulose, consists of branched polysaccharides and helps to support the fibers.5,6 Lignin has no definite structure. It is comprised of aromatic alcohols called monolignols which are important for giving biomass structural support.4 Each of the components decomposes at a different temperature range. Hemicellulose and cellulose decompose around 200-300°C and 300-400°C, respectively, and lignin decomposes from about 200°C to upwards of 500°C.4,7-10 During pyrolysis, hemicellulose and cellulose primarily decompose into organic acids, aldehydes, carbohydrates, furans, and ketones.8,11,12 Lignin decomposes primarily to form


2

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phenols, while also form some acids, aldehydes, furans, and ketones.9 Furthermore, all three components decompose to form non-condensable gases (NCG), primarily H2, CH4, CO, and CO2.12 It has been known that the distribution and compositions of each decomposition product change depending on feedstock and pyrolysis reactor configuration.1,13-16 Understanding how these affect pyrolysis products is vital for developing scale able processes yielding desired products. In a laboratory environment, reactor types for studying fast pyrolysis can vary from micropyrolyzers or pyroprobes coupled with a GC/MS, to batch or continuous reactors. Micropyrolyzers typically have been used for studying primary reactions of biomass pyrolysis.8,9,11,17,19-21 Micropyrolyzers use less than one milligram of biomass, have very high heating rates, and have vapor residence times less than one second.17-19 The low residence time reduces the impact of secondary reactions which occur in the vapor-phase catalyzed by char or oil formed in the primary pyrolysis step.4,13,14,17 These secondary reactions can increase or decrease the liquid product yields depending on the length of the residence time.14,17,22 For instance, vapor cracking reactions produce secondary char and NCG; which result in the reduction of oil yield and an increase of char yield. Batch reactor systems can operate from slow to fast pyrolysis. Typically, batch reactors operate with moderate to long residence times compared to micropyrolyzers and are classified as intermediate pyrolysis. In addition, batch reactors tend to have oil yields of about 50% compared to 60-75% for continuous reactor systems.5,14,17,23 The lower oil yield is indicative of secondary vapor cracking reactions. Continuous pyrolysis systems, on the other hand, are typically performed with significantly shorter residence time (within two seconds). Continuous pyrolysis reactors produce more oil than batch systems. They range in size from laboratory to industrial scale and have a diverse array of


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configurations, such as fluidized bed, ablative, circulating fluid bed, entrained flow, rotating cone, vacuum, and augur kiln.1,14 The overarching objective of this study was to evaluate the product distribution of pyrolysis of pinewood using three different reactor configurations typically used in research laboratories for studying biomass pyrolysis. The three reactor configurations were a micropyrolyzer coupled with a GC/MS system, a tubular furnace batch reactor (TFBR) system, and a fluidized bed continuous reactor (FBCR) system. In addition, this study elucidated the effects of primary and secondary pyrolytic reactions on lignocellulosic biomass pyrolysis. 2. MATERIALS AND METHODS 2.1. Feedstock. The pinewood material used in this research was obtained from American Wood Fibers, Columbia, Maryland. The pinewood sample was analyzed for its fiber composition and proximate analysis composition. The results of these analyses are shown in Table 1. As received the pinewood particles were less than 60 mesh (250 µm) in diameter. For the batch and continuous fast pyrolysis reactor system, pinewood was used with this particle size. For the experiments using the pyroprobe/GC-MS system, pinewood material was sifted to less than 80 mesh (177 µm) particle diameter. Prior to use in all three reactors, the pinewood samples were dried in a 105°C oven for several hours to remove moisture. 2.2. Micropyrolyzer-GC/MS System. The micropyrolyzer-GC/MS used in this study has been reported earlier by Garrido et al.18 It was an analytical pyrolysis system (CDS Pyroprobe 5200, CDS Analytical, Oxford, PA, USA) connected to a gas chromatogram with mass spectrometer (HP 5890 / HP 5972). A schematic diagram of the micropyrolyzer is shown in Figure 1(a). A typical pyrolysis testing with the system was performed by inserting 0.5-1 mg of biomass sample in a quartz tube then having the tube placed in a platinum coiled filament heater


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which allowed the quartz tube ‘reactor’ to be heated to 500oC at a very high heating rate (> 1000oC/s) and held for 10 seconds. During this short period of time, biomass decomposed into vapors, which subsequently were swept out by helium gas carrier (50 mL/min) and sent to the GC/MS for analysis through a heated transfer line at 300oC. The vapor residence time was less than a second. The details of the analysis procedure for the GC/MS are outlined in section 2.6. To analyze the composition of the non-condensable gases (NCG), the micropyrolyzer was connected to a thermal conductivity gas detector (TCD) CDS Model 5000. CDS Analytical developed this GC/TCD gas detector specifically for analyzing non-condensable gas components complementing bio-oil analysis by the GC/MS. The TCD system was programmed to synchronize with the micropyrolyzer operation, which allowed non-condensable gases produced from the micropyrolyzer to be collected in a gas trap and then sent through a GC column to the TCD for analysis. For the TCD, the GC column was heated to 250oC at a 20oC/min ramping rate. The experiment was repeated two times. 2.3. Fluidized Bed Continuous Reactor (FBCR). A diagram of the fluidized bed continuous reactor used in this study is shown in Figure 1(b). The system, designed for processing biomass up to 300g/hr, consisted of a continuous auger type feeder, a bubbling fluidized bed reactor, two cyclones in series for collecting char, and a bio-oil collection system. The reactor consisted of a stainless-steel tube, 61cm length and 5cm in diameter. The fluidization media consisted of silica sand (40-100 mesh or 149-400µm diameter), which formed 76.2 mm of bed when not fluidized. A clam-shell type heater provides heat to the reactor. The silica bed was fluidized by flowing N2 at 8 L/min (STP). During operation, the reactor was heated to 500°C. The auger feed rate was set to 200g/hr of biomass. Biomass was swept into the fluidizing bed by using N2 at 4 L/min (STP). Inside the reactor, biomass decomposed to form organic vapors, non-condensable gas mixture


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and unreacted biomass. The residence time of the gas/vapor stream in the reactor was calculated to be 6s. Effluent from the reactor passed through two cyclones in series to separate and collect chars. From the cyclones, the remaining effluent passed through the bio-oil collection systems, which consisted of two condensers in series followed by an oil trap filter. The first condenser operated at 85°C while the second operated at 10°C by using circulating water heater and cooling systems, respectively. The oil trap filter was packed tightly with glass wool capturing the remaining oil. The captured oil dripped from the filter and was collected. The gas effluent from the oil collector system then was vented. A portion of the non-condensable gas stream was sent to an infrared-type gas analyzer (De Jaye) to measure the concentration of CO2, CO, H2, and CH4 gas components. The first condenser collected about 30% of the oil that was thick and dark. The second condenser collected about 65% of the oil which was light and watery. The remaining 5% of the oil was collected in the glass-wool trap filter. These oil fractions were analyzed separately and the respective values were then proportioned by weight of original fraction. The experiment was repeated two times. 2.4. Tubular Furnace Batch Reactor (TFBR). A tubular reactor was used for the batch pyrolysis studies. A schematic diagram for the tubular furnace batch reactor is shown in Figure 1(c). It was designed to process up to 20 g of biomass per run. The reactor was a stainless steel tube with 6.7 cm and 61 cm in diameter and length, respectively. It was placed in a single-zone BlueM tubular furnace (46 cm overall length and 30.5 cm heated zone). A tubular basket held the biomass in the tubular reactor. The basket was made from a thin stainless steel tube. It was 6.1 cm and 11 cm in diameter and length, respectively. A 40 cm-long holder made of stainless-steel tube and equipped with a thermocouple was used to hold the basket and slide the basket in and out of the reactor. A liquid collection system to collect the liquid pyrolysis product was placed at


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the outlet of the tube reactor. It consisted of two small glass impingers in series, which acted as condensers, and a liquid trap filter. The impingers were filled with 5 ml of cyclohexane and placed in an ice bath. The gas effluent from the liquid collection system was passed through the infrared gas analyzer previously described above. In a typical run, approximately 15 g of biomass sample was accurately weighed and placed in the reactor basket. The basket was placed inside the tubular reactor at the front end outside the heating zone to prevent the biomass from decomposing prior to operation. Nitrogen gas carrier was introduced to the reactor at a rate of 80 ml/min. After the gas analyzer confirmed that no oxygen was present, the heater was turned on to heat the reactor to 500oC. When the desired temperature was reached, immediately the basket containing biomass was slid into the center of the reactor using the holder. During the pyrolysis reaction, the tip of the thermocouple-containing holder was located in the center of the basket containing biomass, which allowed controlling and monitoring the temperature at the center of the reactor. Typically, it took approximately 6.5 minutes for biomass inside the reactor to reach 500oC. After the desired pyrolysis temperature was reached, the pyrolysis process was left to continue for 10 min. Upon completion, the furnace was shut off and the nitrogen gas valve was closed. In addition, the basket was pulled towards the entrance of the reactor, outside the heating zone, until the reactor cooled off. The experiment was repeated two times. 2.5. Proximate Analysis. Proximate analysis using a thermogravimetric analyzer (TGA) was performed on the char to determine the content of moisture, volatiles, fixed carbon, and ash. The instrument used was the TA TGA Q5000. Proximate analysis method by using TGA has been reported elsewhere.24-26 The procedure was started by setting nitrogen flow to 80 mL/min. The instrument then started to collect time, temperature and weight data as the temperature was ramped to 105°C at a rate of 50°C/min. Each ramp in the procedure was followed by an


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isothermal step of approximately 5 min. Next, the temperature was ramped to 500°C at 100°C/min. Then, air replacing nitrogen was set to flow at 80 mL/min. The temperature was ramped to 800°C at 100°C/min. After this, nitrogen replacing air was set down to 25 mL/min while the instrument was left to cool. From the data collected, mass fractions at 105°C, 500°C, and 800°C were recorded. The point at 105°C corresponded to the sample dry weight. The point at 500°C corresponded to the sample without volatiles, and the point at 800°C corresponded to the ash content. The experiment was repeated two times. 2.6. Bio-oil Analysis by Gas Chromatography-Mass Spectrometry (GC/MS). The constituents of the bio-oil were separated using an HP 5890 Series II Gas Chromatograph and then analyzed by an HP 5972 Series Mass Spectrometer. For micropyrolysis, the reactor effluent was carried to the GC by helium in a 1:100 split. For continuous and batch pyrolysis, bio-oil samples were diluted with methanol in a 1:15 ratio. Then 1 µL of the sample was injected directly into the inlet port using a microliter syringe. The GC/MS program was set similarly to that used by Garrido et al.18 The chromatographic separation of pyrolysis products was performed using an alloy capillary column (Restek RTX-5) having high thermal resistance (30 m x 0.25 mm x .025 µm film thickness with stationary phase consisting of 5% diphenyl/95% dimethyl polysiloxane). The temperature program started with a 3 min delay at 40°C and then ramped to 130°C at 3°C/min. After that, the temperature ramped at 6°C/min to 300°C. Peaks were identified by matching spectra to the National Institute of Standards and Technology (NIST) chemical database. The chemical components were grouped by the following types of compounds: alcohols, aldehydes, carbohydrates, furans, ketones and phenols. 2.7. Analysis of Overall Product Yields. The yields of char, oil, and non-condensable gas from fast pyrolysis using the three reactor systems were assessed by evaluating respective mass


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balances. For each reactor type, the fraction of char was determined by calculating the fraction of biomass remaining after pyrolysis with respect to the original biomass weight. The weight of NCG for the batch and continuous reactor were determined by calculating the total amount of individual gas component that was produced during the pyrolysis reaction time and then adding the amounts from all components together. The gas components analyzed were H2, CO, CO2 and CH4. For the batch and continuous reactor systems, the fraction of bio-oil was determined by calculating the total amount of bio-oil collected divided by the total amount of biomass pyrolyzed. Since not all bio-oil was able to be collected, the fraction of bio-oil was determined by calculating the difference between the total biomass and the fractions of char and NCG added together. It should be noted that water was included as part of the oil.

3. RESULTS AND DISCUSSION 3.1. Overall Product Yields. The overall product yields from pyrolysis for each of the reactor configurations are shown in Figure 2. Among the three reactor systems, the micropyrolyzer system had the highest bio-oil yield (79.1 wt%), which was approximately 92% of the available volatile matter in pinewood (86 wt%, dry basis). The system also produced the lowest yield of char (10 wt%). This was expected since the system had the shortest residence time and the highest pyrolysis heating rates, which prevented secondary reactions from taking place. The absence of secondary reactions in the micropyrolyzer system could be explained in part by analyzing the proximate analysis composition of the char product. As shown in Figure 3, the char remaining from micropyrolysis had the lowest volatile matter (3.4 wt%, dry) and the highest fixed carbon (96.0 wt%, dry) contents. Since it has been reported that longer solid-vapor residence times promote cracking of volatiles towards non-condensable gases (NCG) and


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char,10,13,14,17,22,27 the low volatile matter in the char from the micropyrolyzer implied a minimal cracking of volatiles into char or NCG. The batch reactor system had the lowest yield of bio-oil (58.7 wt%) and the highest yield of char (25 wt%) which was attributed to the system having the slowest heating rates and the longest solid and vapors residence time in the reactor. Other possible reactions of the volatile vapors could be repolymerization and recondensation, which were supported by the increase of char yield and the decrease of oil yield.28,29 Lower heating rates have been reported to give an increase in char yield.12,30 The amount of fixed carbon in the char formed from the batch reactor was 166% of the amount of fixed carbon in the initial biomass. The increase of fixed carbon could be an indicative of secondary char formation from the volatiles. A possible cause for this was through decomposition reactions of levoglucosan in the presence of cellulose and lignin vapors.17,31,32 Researchers have proposed that this mechanism is a thermal polymerization of levoglucosan

by

a

transglycosilation

ring-opening

reaction

or

a

radical-induced

decomposition.31,32 However, there is not enough evidence from the results to confirm if thermal polymerization or a radical decomposition of levoglucosan is occurring. Although the exact mechanism is unknown, the results did confirm that longer residence time and low heating rate during pyrolysis resulted in secondary char formation. Pyrolysis performed using the continuous FB reactor system produced the highest yield of NCG and the lowest yield of char. Based on the fixed carbon content in the original biomass, the yield of char was expected to be 13.9wt%. A possible explanation for the lower char yield from the FB reactor is thermo-mechanical ejection.17,33-35 This phenomenon occurs when shear stresses on the biomass result in solid particles volatilizing and forming aerosols. In the case of the FB reactor, biomass particles experienced shear stresses from the moving sand particles


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within the fluidized bed. One result of the thermo-mechanical ejection was that not all the entrained char particles from the reactor, specifically those with very fine particle sizes, were collected by the cyclones. Researchers also suggest that the entrained biomass undergoes further secondary cracking reactions.17 These secondary reactions were evidenced by the increased NCG and decreased char yields observed. Based on the overall yield (Figure 2) and the proximate analysis (Figure 3), the amount of fixed carbon in the char from the continuous FB reactor was significantly less than the amount of fixed carbon in the original biomass (3.5 wt% vs. 13.9 wt% of biomass). This observation supported the notion of thermo-mechanical ejection described previously. In this case, the non-volatile fixed carbon mass would be ejected as aerosols into the vapor phase. The composition of the NCG produced from the batch and continuous reactors are shown in Figure 4. The NCG effluent from the micropyrolyzer was primarily CO2 and CO. The NCG from the FB reactor, in addition to these carbon oxides, also contained significantly more H2. This result coincides with a study that reported greater H2 yields from a FB reactor than that from a micropyrolyzer.17 It has also been reported that the formation of H2 could be promoted by the secondary reactions of organic vapors catalyzed by the inorganic minerals.36 This is more likely to occur in the FB reactor since small particles of biomass (i.e. char) become entrained within the reactor effluent, where the organic vapors can more easily interact with the biomass. As for the batch reactor, the effluent contained significantly more CH4, but much less CO and H2 than the gas effluent from the FB reactor. According to literature, CH4 and H2 are formed simultaneously by thermal splitting of organic matter.5 This would mean that more H2 should have been produced than what was observed. A possible explanation is the presence of a methanation reaction in which CO and H2 react to form CH4 and water.37 The stoichiometry of the


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methanation reaction indicates that three moles of H2 reacts with every mole of CO. Interestingly, this reaction stoichiometry matches the drop in H2 and CO concentration and the increase in CH4 concentration from the continuous process to the batch process 3.2. Bio-oil Compositions. Figure 5 shows the distributions of chemical products in bio-oil isolated from the three reactors which were grouped based on their common chemical functionality. Table 2 shows the relative amounts of selected representative of chemical components of bio-oil known to be derived from cellulose, hemicellulose, and lignin, respectively. All three oils contained carbohydrates which were derived from cellulose with the majority being in the form of levoglucosan.11,17,38 Among the three reactor systems, the micropyrolyzer produced the highest relative concentration of carbohydrates (27.7%) followed by the FB reactor and batch reactor (10.8% and 4.0%, respectively). The batch reactor had the lowest relative concentrations of carbohydrates and the highest furans. A longer residence time results in greater decomposition of cellulose into lighter components and char products, which could explain the low yield of carbohydrates in the batch reactor and consistent with the BroidoShafizadeh model .10,17 Table 2 shows the relative amounts of levoglucosan, furfural and 2-furanmethanol and how the increased residence time of the batch reactor resulted in much lower production of levoglucosan, but greater production of furfural and 2-furanmethanol. This was likely the result of a longer residence time allowing for prolonged decomposition of the levoglucosan molecule. The concentration of 2-furanmethanol compound was slightly lower in the bio-oil from the FB reactor than that from the micropyrolyzer. Patwardhan et al. recently reported a decrease in 2furanmethanol and an increase in H2 and CH4 from an FB reactor when compared to a micropyrolyzer, which are consistent with the results obtained from this study.17 A possible


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explanation was proposed by Molton and Demmitt showing that interactions with the silicon dioxide in the continuous reactor acted as a catalyst for the decomposition of furans.38 From another study, it has been reported that the lower molecular weight products were not formed only from secondary cracking of levoglucosan, but also formed directly from the decomposition of biomass concurrently with the formation of levoglucosan.39 In Figure 5 it is shown that aldehydes and ketones were also formed in significant relative amounts in the micropyrolyzer, in which the secondary cracking reactions were less likely to take place due to the very short residence time. This observation seemed to support the conclusion of the reported study that the formation of lower molecular weight components could take place from direct the decomposition of biomass. The relative amounts of ketones, which were produced primarily from the degradation of hemicellulose, were similar from both the micropyrolyzer and batch reactor. The FB reactor, on the other hand, had significantly lower contribution of ketones in its bio-oil product. As shown in Table 2 the same trends were evident for a wide variety of ketone-containing compounds of different complexity. Again, both the micropyrolyzer and the batch reactor had very similar relative amounts of these compounds with the batch reactor having slightly greater values. On the other hand, the FB reactor had slightly lower concentrations of 2-hydroxy-3-methyl-2cyclopenten-1-one and 3-methyl-1,2-cyclopentanedione and a similar concentration of cyclohexanone to the batch reactor bio-oil. It is likely that more complex ketones were decomposed further into simpler ones. However, the exact mechanism is unknown. Phenolic compounds in bio-oil were derived from the degradation of the lignin component in biomass. Table 2 shows that the overall contributions of phenolic compounds in the bio-oil produced from micropyrolyzer and batch reactor were relatively equal (approximately 30% of


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the total integration areas) and significantly higher in the FB reactor (approximately 52%). This indicated that the overall degradation of lignin into phenolic compounds may not be significantly affected by the pyrolysis residence time, but more affected by physical reactor conditions. Piskorz et al. have proposed that thermo-mechanical ejection causes the lignin to crack into oligomeric parts which are then broken into small aerosols due to the shear stresses in the reactor and swept out of the reactor.40 To confirm this notion, selected phenolic products having different levels of complexity were examined. Compared to those in the FB reactor, more complex methoxy phenols were formed in larger quantities in both the micropyrolyzer and batch reactor, while the simple phenol compound was produced in lower quantity. A possible explanation, described by Hosoya et al., is that during pyrolysis lignin is decomposed to oligomeric phenols, which subsequently undergo coupling and condensation reactions to form secondary char or vapors consisting of NCG and simpler phenols.41 These secondary vapor phase reactions could be promoted by the catalytic effects of the inorganic components in the primary char, which formed aerosols exiting the FB reactor along with the catalytic vapors. These inorganic-catalyzed secondary reactions would less likely take place in pyrolysis using batch reactors since the primary char never exited the reactors 4. CONCLUSIONS The pyrolysis of pinewood using three reactor configurations gave different bio-oil yields, altered the amounts and composition of the non-condensable gases, and gave rise to variations in the amounts and types of chemicals in bio-oil. Secondary reactions of the primary pyrolysis vapors were strongly influenced by the different residence times and mechanical properties of the different reactor configurations. Pyrolysis with a micropyrolyzer, having the shortest residence time, produced the highest amount of bio-oil with highest relative amount of


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carbohydrates and the lowest amounts of chars and non-condensable gases (NCG). The batch reactor, which had the longest residence time, produced the least amount of bio-oil and the highest amount of chars. Bio-oil from the batch had the least amount of carbohydrates, which could be attributed to a longer residence time and secondary decomposition. The continuous FB reactor produced the highest amount of NCG and the lowest amount of char. Furthermore, the FB reactor produced bio-oil containing the highest concentration of phenolic compounds. These were attributed to the possible effects from thermo-mechanical ejection, due to the intimate contact of biomass particles with the bed sand particles, in conjunction with other secondary reactions within the reactor effluent. Finally, the chars leaving the FB reactor along with the organic vapors could have catalytic effects on further secondary reactions in vapor phase which further promoted the production of lighter molecular weight organic components and NCG components. These findings shed significant light on how residence time and the mechanical properties of a reactor configuration affect the composition and functionality of liquid and gaseous pyrolysis products.


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(a)

(c)

Figure 1. Schematic diagrams of reactors used in the research study. (a) CDS micropyrolyzer system; (b) Fluidized bed continuous reactor system; (c) Tubular furnace batch reactor system.;


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80 70 Weight % (dry basis)

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60 50 40 30 20 10 0 Micropyrolyzer

FB Reactor

Batch Reactor

Reactor Type Char

Oil

NCG

Figure 2. Overall bio-oil, char, and non-condensable gases (NCG) yields of pinewood pyrolysis at 500oC using three pyrolysis reactor systems. The overall bio-oil fraction was determined by difference.


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100 80 Weight % (dry basis)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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60 40 20 0 Micropyrolyzer

FB Reactor Reactor Type

Volatile Matter

Fixed Carbon

Batch Reactor

Inorganic Matter

Figure 3. Proximate analysis composition of chars produced from pinewood pyrolysis at 500oC using three pyrolysis reactor systems.


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Page 19 of 27

100

NCG Composition (mole %)

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Energy & Fuels

80

60

40

20

0 Micropyrolyzer

FB Reactor CO

CO2

CH4

Batch Reactor H2

Figure 4. Composition of the non-condensable gases produced from pinewood pyrolysis at 500oC using three pyrolysis reactor systems.


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Energy & Fuels

60

% Total Integrated Area

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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50 40 30 20 10 0 Micropyrolyzer Alcohols

FB Reactor

Aldehydes

Carbohydrates

Furans

Batch Reactor Ketones

Phenols

Figure 5. GC/MS analysis results of chemical product distribution of bio-oil produced from pinewood pyrolysis at 500oC using three pyrolysis reactor systems.


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 1. Fiber composition and proximate analysis compositions of pinewood Proximate Weight% Fiber Composition Weight% Analysis (dry basis) (dry basis) 86.0 28.5 Volatile Matter Hemicellulose 13.9 39.5 Fixed Carbon Cellulose 0.1 24.2 Inorganic Matter Lignin 7.8 Extractives

Table 2. GC/MS analysis results of chemical product distribution of select compounds in bio-oil produced from pinewood pyrolysis at 500oC using three reactor systems: (a) Selected aldehyde, furan and carbohydrate compounds; (b) selected ketone compounds; (c) selected phenolic compounds. Reactor type Continuous Micropyrolyzer Batch Reactor

FB Reactor

% Total Integrated Area From Cellulose Levoglucosan

11.81±3.62

1.04±0.31

2.81±0.72

Furfural

2.01±0.23

5.21±1.24

2.17±0.31

2-Furanmethanol

1.57±0.21

1.55±0.34

0.72±0.18

Cyclohexanone

2.18±0.25

2.72±0.32

2.77±0.45

2-Hydroxy-3-methyl-2-cyclopenten-1one

0.51±0.11

0.73±0.23

0.17±0.06

3-methyl-1,2-cyclopentanedione

0.27±0.10

1.29±0.15

1.58±0.23

Phenol

0.27±0.09

1.29±0.13

1.58±0.18

2-methylphenol

1.42±0.23

2.95±0.35

0.68±0.10

2-methoxy-4-methylphenol

2.24±0.32

3.48±0.23

1.02±0.15

2-methoxy-4-(1-propenyl)-phenol

2.89±0.17

2.09±0.15

1.05±0.11

From Hemi-cellulose

From Lignin


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Energy & Fuels

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ASSOCIATED CONTENT Supporting Information List of chemical compounds analyzed and their respective chemical group. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author * Tel.: (610) 519-6658. Fax: 610-519-7354. E-mail address: [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENTS Funding for this project partially was provided by the State of Pennsylvania through Keystone Innovation Starter Kit Program (KISK) and by the Villanova University Center of Advancement in Sustainable Engineering (VCASE) seed research program. The authors would like to thank Villanova University undergraduate students Nathan Swain and Charles Ponge, in addition to Northwestern University student Zak Kivitz for their work with the continuous fluidized bed reactor system. REFERENCES (1) Bridgwater, A. V. Review of fast pyrolysis of biomass and product upgrading. Biomass Bioenergy. 2012, 38, 68-94. (2) Koppejan, J.; van Loo, S.; Biomass combustion: an overview. In Thermal Biomass Conversion; Bridgwater, A. V., Hofbauer, H., van Loo, S., Eds.; CPL Press: 2009.


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