Article pubs.acs.org/EF
Step Collection of Bio-oil from Pyrolysis of Steam Exploded Sumac Marc and Activated Carbon Prepared from Pyrolysis Residues Hongzhang Chen,*,† Guanhua Wang,†,‡ and Guozhong Chen† †
State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China ‡ Graduate University of Chinese Academy of Sciences, Beijing 100039, China ABSTRACT: Sumac marc, residue from sumac fruit after oil and flavonoids extraction, was used as a raw material for pyrolysis due to its higher lignocellulosic content in the present work. Time-step and temperature-gradient collections of bio-oil from pyrolysis of sumac mar were established to overcome the disadvantage of high aqueous phase content and low heating value of bio-oil from traditional pyrolysis. In addition, the pyrolysis residues were further applied to prepare activated carbon by chemical activation. Experimental results showed that the aqueous phase content of bio-oil decreased from 94.02% to 28.65% by time-step collection at pyrolysis temperature 500 °C with a heating rate 40 °C/min in a sweeping gas reactor. In the temperature-gradient collection, the aqueous phase content of bio-oil obtained at 500 °C was 15.93% and that gave a promising method to obtain high quality bio-oil preparations from pyrolysis. Under the optimized activation conditions, the iodine and methylene blue absorptivities of activated carbon prepared by pyrolysis residues were 1060 mg/g and 250 mg/g respectively, which were accorded with the international quality standards of first grade activated carbon. Consequently, the pyrolysis of sumac marc to produce bio-oil and preparation of activated carbon from pyrolysis residues provide a new approach of sumac marc application, which achieves a total biomass utilization of sumac marc.
1. INTRODUCTION Recently, increasing attention has been focused on renewable energy due to the environmental reasons from fossil fuels and the problems of energy assurance. In contrast to other renewables that give heat and power, biomass represents the only source of liquid, solid, and gaseous fuels. Due to the low energy density of biomass obtained directly from nature, effective conversion techniques from biomass to high-value fuels and chemicals are needed. Pyrolysis is probably the most attractive conversion process by which biomass is heated to moderate temperatures in an oxygen/air free atmosphere to yield solid, liquid, and gaseous products.1,2 Compared with other thermochemical processes, pyrolysis is regarded as an efficient and economical technology for converting biomass into higher value fuels. Currently, most of biomass pyrolysis studies have been focused on the fast pyrolysis3−5 owing to its higher yield of liquid products compared to the traditional pyrolysis. In fact, traditional pyrolysis has advantages of lower investment and running costs, simpler operation parameters and richer products and is more suitable for the situation of distributed biomass resources in China.6,7 Generally, due to the water from feedstock and produced during the pyrolysis process, the liquid product of biomass pyrolysis has considerable moisture and can be divided into two distinct phase (aqueous phase and organic phase) by organic solvent extraction.8,9 The organic phase is rich in organic content which can be applied as fuels directly or upgraded to high grade fuels and chemical materials. Whereas the aqueous phase consisted of a large amount of water and hydrophilic compounds, such as acetic acid, hydroxyacetone, and furfural, cannot be used as fuels directly.8 As described above, the water of aqueous phase comes from both the initial moisture of © 2013 American Chemical Society
feedstock and the formed water from dehydration reactions in the pyrolysis process.10 Therefore, many factors influence the aqueous phase content of bio-oil including the composition of raw material,11,12 the pyrolysis temperature,13,14 and other pyrolysis conditions such as the heating rate, vapor residence time,15 and catalysts.16 Yao et al.17 studied the fluidized bed pyrolysis of distilled spirits lees and found that the chemical oxygen demand (COD) values of collected liquid increased when the pyrolysis temperature increased to 450 °C, which indicated that dehydration was the dominant reaction and relatively lower organic liquid was obtained at lower temperatures. Uzun et al.18 studied the effect of pyrolysis temperature on product yield in pyrolysis of corn stalk. They also found similar results that the water content of bio-oil decreased as the temperature increased from 400 to 600 °C. Sumac (Rhus chinensis) is a wild medicinal plant widely distributed in subtropical and warm temperate regions of the world. The oil content of sumac fruit is about 12.0−20.8% (wt %) and most of the oils are unsaturated fatty acids with high nutritional value and health care function.19 Besides, the sumac fruit is also rich in flavonoids, which show good potential in antibacterial and antioxidant activities reported by a number of literatures.20−22 After extraction of oil and flavonoids, the residue of sumac fruit, termed as sumac marc, contains mainly lignocelluloses and a small amount of residual oil. These features make it a suitable raw material for pyrolysis. Besides, the solid byproduct from sumac marc pyrolysis, rich in carbon content, can be further activated to prepare activated carbon.23 Received: July 18, 2013 Revised: November 2, 2013 Published: November 4, 2013 7432
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Activated carbon shows excellent absorptive properties owing to its unique pore structure and surface functional groups. It is widely used for different purposes, for example, the removal of pollutants from aqueous and gaseous phases and the purification or recovery of chemicals.24,25 In the present work, time-step and temperature-gradient collections of liquid products from pyrolysis of sumac marc were established according to the aqueous phase content variation of bio-oil at different time and different temperature in the pyrolysis process. The changes of bio-oil yield in the pyrolysis process were studied to determine the optimal conditions for bio-oil production. Moreover, pyrolysis residues were activated to prepare valuable activated carbon under optimized conditions to achieve a total biomass utilization of sumac marc.
Figure 1. Schematics diagram of pyrolysis unit. 1. Nitrogen bottle. 2. Pressure gauge. 3. Control valve. 4. Pyrolysis furnace,. 5. Temperature controller. 6. Condenser. 7. Collecting bottles. 8. Dryer. 9. Filter. 10. Vacuum table. 11. Vacuum pump. 12. Thermocouple.
2. MATERIALS AND METHODS 2.1. Experimental Materials. Sumac (Rhus chinensis) fruit was collected in Anhui Province, China. After cleaning, it was dried and stored at room temperature until use. The prepared fruit was pretreated by steam explosion under previously established optimal conditions (steam pressure 1.5 MPa, maintaining time 3 min) to enhance the access of solvent and increase the yield oil and flavonoids.26,27 The pretreated sumac fruit was mashed to 1 mm in the grinding mill and then extracted by petroleum ether at 65 °C for about 8−10 h using Soxhlet extractor.26 After oil extraction, the residue was further applied for flavonoids extraction by 70% (v/v) ethanol solution at a solvent-to-solid ratio of 10 (mL/g) at 80 °C for 2 h.27 The sumac marc after oil and flavonoids extraction was collected, dried at 60 °C for overnight, and stored for usage. The main compositions of the sumac fruit and sumac marc after oil and flavonoids extraction were shown in Table 1. After extraction, the sumac marc only contained 2.01% oil and its main compositions were lignocelluoses, which accounted for 65.47% of total biomass.
2.3. Step Collection of Bio-oil. 2.3.1. Time-Step Collection of Bio-oil. The pyrolysis experiments were performed in two different atmospheres: static pyrolysis under vacuum atmosphere and sweeping gas (N2) pyrolysis with a flow rate of 40 cm3/min. In each experiment 20 g sumac fruit marc was placed in the pyrolysis reactor then heated up to the final temperature with different heating rates (10, 20, 30, 40 °C/min). Time-step collection started from the first drop of bio-oil, every 5 min for one collection. The bio-oil yield was calculated according to eq 1. The liquid product was extracted by n-hexane (sample solution: hexane = 1:1, V/V) and separated into the n-hexane soluble phase and aqueous phase.2 The aqueous phase content of biooil was calculated according to eq 2.
Yield (%) =
Bio‐oil × 100 Total bio‐oil
Aqueous phase content (%) =
Table 1. Main Compositions of Sumac Fruit before (Sumac Fruit) and after Oil and Flavonoids Extraction (Sumac Marc) sumac fruit
sumac marc
Klason lignin hemicellulose cellulose oil flavonoids protein ash others
35.25 11.82 6.40 17.30 1.85 8.34 3.20 15.08
48.79 7.46 9.21 2.01 0.17 5.34 2.85 18.12
(2)
Here, Bio-oil presents the weight of bio-oil (g) in every step collection during the pyrolysis process; total bio-oil is the overall weight of bio-oil (g); aqueous phase is the weight of aqueous phase (g). 2.3.2. Temperature-Gradient Collection of Bio-oil. A 50 g sample of sumac marc was placed into the reactor and pyrolyzed at 300 °C for 10 min with a heating rate of 40 °C/min to get the first collection of bio-oil. The system temperature was subsequently raised to 400 °C with the same heating rate and held for another 10 min to obtain the second collection. Finally, the pyrolysis reaction was carried out at 500 °C for 10 min to obtain the last collection. Pyrolysis products yield of the three collections were weighed and calculated, respectively. The liquid phase consisting of aqueous and organic phase was separated by adding n-hexane, as described in section 2.3.1. The aqueous phase content of bio-oil was calculated according to eq 2, and the n-hexane soluble fraction was dried by a rotary evaporation to remove hexane and get the organic phase content. The n-hexane soluble phase after rotary evaporation was subjected to GC/MS while the aqueous phase was subjected to GC/MS directly.2 2.4. Preparation and Adsorption Properties Test of Activated Carbon. 2.4.1. Preparation of Activated Carbon. Dry pyrolysis char (30 g) sample was added into different ZnCl2 concentration solutions according to a requested solid−liquid ratio and mixed sufficiently for 24 h. The mixtures were placed into the pyrolysis reactor and activated chemically at 400, 500, and 600 °C. Nitrogen was swept into the reactor to keep oxygen free. Heating was terminated when the desired reaction time (3, 4, and 5 h) was attained, and the system was cooled to room temperature. Thereafter, ZnCl2 was recycled by soaking and boiling with 20% hydrochloric acid. The activation products were washed to neutral by hot water and dried to constant weight to obtain activated carbon.28 2.4.2. Determination of Adsorption Properties of Activated Carbon. Adsorptive properties of activated carbon were measured
content (wt %) composition
Aqueous phase × 100 Bio‐oil
(1)
2.2. Pyrolysis Reactor. The pyrolysis experiments were conducted in a tubular fixed-bed reactor, as shown in Figure 1. The length and diameter of the reactor were 50.0 and 7.6 cm, respectively. The maximum operating temperature and heating rate were 650 and 40 °C/min. The device was equipped with a vacuum pump and a gas inlet, which could be used as static pyrolysis reactor under vacuum atmosphere and sweeping gas reactor with preheated nitrogen. Gas from the pyrolysis furnace came out immediately into a condenser tube, and bio-oil was condensed into the collection bottle through the appropriate rotation of collector to achieve step collections. Gas-phase part was pumped through the filter by the vacuum pump, while solidphase part was obtained directly from the reactor after the pyrolysis reaction. Pyrolysis temperature (detected in the reactor chamber) and heating rate could be fully automatically controlled within an accuracy of ±5 °C by the temperature control system. The nitrogen flow rate could be adjusted through the control valve. 7433
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by using methylene blue and iodine as adsorbates. Methylene blue serves as a model compound for adsorption of organic contaminants from aqueous solution while the iodine absorptivity gives information on the surface area contributed by pores larger than 1 nm.29 The adsorption of methylene blue on the activated carbon samples were obtained by adding 0.1 g of activated carbon to flasks containing 50 mL methylene blue solution with known concentration. These flasks were kept in a shaker at 25 °C for 24 h. The concentration of methylene blue was determined spectrophotometrically at 612.5 nm absorbance wavelength. The iodine adsorption was determined using the sodium thiosulfate volumetric method (ASTM D 4607-86). The 0.5 g samples were placed into a 250 mL dry flask and mixed with 50.0 mL 0.1 mol/L standard iodine solution. After 30 s of equilibrium time, the residual iodine concentration was determined by titration with standard sodium thiosulfate with starch as an indicator.28
3. RESULTS AND DISCUSSION 3.1. Bio-oil Compositions of Time-Step Collection in Different Pyrolysis Conditions. 3.1.1. Effects of Pyrolysis Atmosphere on Time-Step Collection of Bio-oil. Compared with static pyrolysis under vacuum atmosphere, pyrolysis under sweeping gas atmosphere could enhance the interior heat transfer2 and then increase the pyrolysis conversion rate. As showed in Figure 2, at the same pyrolysis temperature and with
Figure 3. Effects of pyrolysis atmosphere (static pyrolysis under vacuum atmosphere and pyrolysis under sweeping gas atmosphere) on components of pyrolysis products. The pyrolysis temperature was 500 °C, and the heating rate was 40 °C/min.
process was completed, the pyrolysis reaction did not occur immediately as heat transfer in the material was insufficient in a short time owing to the low thermal conductivity of sumac marc. With the sufficient heat transfer of the marc, bio-oil was generated a few minutes after the desired reaction temperature was attained. As shown in Figure 4, higher pyrolysis
Figure 2. Bio-oil yields in static pyrolysis reactor under vacuum atmosphere and sweeping gas (N2) atmosphere. The pyrolysis temperature was 500 °C and the heating rate was 40 °C/min. Figure 4. Effects of pyrolysis temperature on bio-oil yields of time-step collection. The pyrolysis was carried out in a sweeping gas reactor with a heating rate of 40 °C/min.
the identical heating rate, pyrolysis conversion rate under sweeping gas atmosphere was slightly higher than that of static pyrolysis and the duration time of pyrolysis reaction reduced 5−10 min. Since the nitrogen flow could remove more volatiles, the yield of bio-oil and gas in sweeping gas reactor was higher than that in static pyrolysis reactor (Figure 3). The yield of char in sweeping gas reactor decreased from 25.65% to 22.60%, which also supported this explanation. Therefore, the results indicated that sweeping gas reactor was more favorable to produce bio-oil than static pyrolysis reactor. 3.1.2. Effects of Pyrolysis Temperature on Time-Step Collection of Bio-oil. As the whole duration time of pyrolysis reaction should to be considered in the time-step collection of bio-oil, not only the atmosphere of pyrolysis reactor (Figure 2) but also pyrolysis temperature and heating rate influence the reaction time. Therefore, these two factors were further studied to determine the appropriate step collection time in sweeping gas reactor. To determine the effects of final pyrolysis temperature on the reaction duration and the product yield, the experiments were preformed in a sweeping gas reactor with a nitrogen flow rate of 40 cm3/min and a heating rate of 40 °C/min. When the heating
temperature accelerated the generation of bio-oil and shortened the duration time of pyrolysis reactions, which was mainly attributed to shorter heat transfer time and higher conversion rate at higher temperature. From previous studies, it is known that pyrolysis temperature has a significant impact on product distributions.13,30,31 The effect of final temperature on the product yields for the pyrolysis of sumac marc was given in Figure 5. When final pyrolysis temperature was increased from 400 to 600 °C, the yields of solid product decreased gradually from 36.51% to 24.37% and the gaseous product yields increased from 30.55% to 43.40%. At the pyrolysis temperature of 500 °C, the liquid yield had a value of 33.80% as the highest yield, since it was decreased to the value of 32.95% when the final temperature was 600 °C. The liquid yield showed an increase from 400 to 500 °C as a result of sufficient thermal decomposition for materials at higher temperature. While the decrease occurred at temperatures above 500 °C was attributed to the secondary 7434
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Figure 7. Effects of heating rate on components of pyrolysis products in time-step collection. The pyrolysis was carried out in a sweeping gas reactor and the final pyrolysis temperature was 500 °C.
Figure 5. Effects of pyrolysis temperature on the components of products in time-step collection. The pyrolysis was carried out in a sweeping gas reactor with a heating rate of 40 °C/min.
heating rate of 40 °C/min. At the same time, raising heating rate from 10 °C/min to 40 °C/min increased the bio-oil yields from 28.01 to 33.43%. The decrease in liquid and gaseous yield of slower heating rate was suggested as being due to a longer retention time at low temperature for pyrolysis materials. Such long retention time relatively reduced the dehydration and carbonization reactions of cellulose and lignin in the sumac marc and improved the char yield.18 3.1.4. Aqueous Phase Content of Bio-Oil in Time-Step Collection. For higher yield of liquid product, pyrolysis of sumac marc was carried out at 500 °C with the heating rate of 40 °C/min and bio-oil was collected every 5 min. The aqueous phase content of time-step collected bio-oil was given in Table 2. As expected, the aqueous phase content gradually decreased
cracking of produced vapors to noncondensable products.1 The secondary decomposition of char to form noncondensable gaseous products was intensified at higher temperatures since gas yield increased and solid yield decreased at higher temperature.32 3.1.3. Effects of Heating Rate on Time-Step Collection of Bio-oil. The effect of heating rate on the reaction duration and the product yield were examined with the heating rate of 10, 20, 30, 40 °C/min and pyrolysis temperature was fixed at 500 °C. As shown in Figure 6, the increase heating rate speeded up bio-
Table 2. Water Phase Content of Time-Step Collection of Bio-oila collection time (min)
quality ratio (%)b
20−25 25−30 30−35 35−40
49.85 35.57 9.85 4.73
aqueous phase content (%)c 94.02 58.54 44.79 28.65
± ± ± ±
0.96 0.64 0.75 0.36
yield (%) 33.23 ± 0.59
a The pyrolysis temperature 500 °C, heating rate 40 °C/min, nitrogen flow rate 40 cm3/min. bThe quality ratio present to the bio-oil amount of step collection to the total bio-oil amount. cEach data indicates the mean ± SD, which were measured from three independent experiments.
Figure 6. Effects of heating rate on bio-oil yields of time-step collection. The pyrolysis was carried out in a sweeping gas reactor and the final pyrolysis temperature was 500 °C.
from 94.02% in the first 5 min to 28.65% in the last 5 min. As shown in Table 2, water was generated during the whole pyrolysis process but mainly formed in the primary stage, which was primarily consisted of evaporation of free and bound water and intramolecular rearrangement such as dehydration reactions.17 3.2. Compositions of Bio-oil in Temperature-Gradient Collection. As discussed in section 3.1.4, water was mostly generated in the primary stage of pyrolysis process. Due to the low thermal conductivity of sumac marc, the reaction temperature in the primary pyrolysis stage was relatively low compared with the later pyrolysis stage, which meant that water was more likely to form at lower temperature in the pyrolysis process. Therefore, collection temperature was another factor
oil generation and decreased duration time of pyrolysis reaction which was about 15−20 min with different heating rates. When the desired temperature was attained, bio-oil was generated a few minutes later with the heating rate of 30 and 40 °C/min. However, the bio-oil was formed immediately with the heating rate of 10 and 20 °C/min when the pyrolysis temperature reached 500 °C. This was because the higher heating rate required longer time for heat transfer in the sumac since the heating time was shorter compared to that of lower hating rate. The results of pyrolysis products yield with different heating rates are given in Figure 7. Raising the heating rate led to higher yields of liquid and gas products but lower yield of char. As could be seen from the results, the char yield with heating rate of 10 °C/min was 33.23%, whereas it decreased to 22.58% with 7435
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Table 3. Main Compounds of Aqueous Phase and n-Hexane Soluble Phase of Bio-oil and Their Relative Contents
to further reduce the aqueous phase content on the basis of time-step collection of bio-oil from sumac marc pyrolysis. In this section, collections of liquid products at gradient temperatures, which included 300, 400, and 500 °C, were carried out to obtain bio-oil with lower aqueous phase content. The results (Figure 8) indicated that the bio-oil collected at
aqueous phase
n-hexane soluble phase
Figure 8. Component analysis of bio-oil from temperature-gradient collection.
gradient temperature 300, 400, and 500 °C had a gradual decrease of liquid product yield. The first part of bio-oil collected at 300 °C had the highest aqueous phase mass, which showed a continuous decrease from 8.36 to 2.03 g and 0.61 g when the collection temperature had raised to 400 and 500 °C, respectively. Compared with time-step collection, temperature-gradient collection had a longer retention time at lower temperature (300 °C) and that resulted in sufficient formation of water.17 So the aqueous phase content dropped from 95.00% to 41.15% when the collection temperature was increased from 300 to 400 °C since the main aqueous phase was formed in the first collection at 300 °C. The aqueous phase content of bio-oil obtained at 500 °C was 15.93%, which was significantly lower compared with that of ordinary bio-oil.33 Besides, the main compounds of aqueous phase and n-hexane soluble phase were analyzed, and the results are shown in Table 3. It was found that the main composition of aqueous phase was water.2,8 Acetic acid, 1-hydroxy-2-propanone and furfural derived from pyrolysis of cellulose and hemicelluloses were also produced.2,9 The n-hexane soluble phase was mainly phenolic compounds derived from lignin,9 which could be recovered as commercial phenolic chemicals or upgrated to produce marketable fuels.8 As higher content of n-hexane soluble phase and lower content of aqueous phase, bio-oil collected at 500 °C had closest physical and chemical properties to diesel. Thus, the results of this study successfully provided a new method to obtain highquality bio-oil from biomass pyrolysis and further simplify subsequent refining process to get valuable fuels and chemicals. 3.3. Conditions Optimization of Activated Carbon Preparation from Pyrolysis Residues. High quality activated carbon was prepared by chemical activation of pyrolysis char. Activation temperature, activation time, catalyst ZnCl2 concentration, and ratio of solid to liquid were several factors that affected the absorptivity of activated carbon. The effects of different activation conditions on activated carbon
compd.
content (wt %)
acetic acid 1-hydroxy-2-propanone methanol furfural acetone 2-furanmethanol propanic acid 1-hydroxyl-2-butanone 2,3-butanedione acetaldehyde 1,3-butadiene water and other compounds 2,6-dimethoxyphenol 2-methoxy-4-methyl phenol 2-methoxyphenol guaiacol 2,6-dimethoxy-methyl phenol phenol 2,5-dimethoxybenzyl alcohol p-cresol vanilline syringaldehyde o-cresol 4-ethyl-2-methoxyphenol other compounds
8.12 6.24 5.93 2.01 1.68 1.51 0.66 0.59 0.48 0.39 0.26 72.02 11.23 8.26 7.67 7.39 5.83 4.97 3.65 3.51 3.07 2.86 2.39 0.96 38.22
absorptivity are shown in Table 4. Activation temperature had the greatest impact on the iodine absorptivity. The iodine Table 4. Effects of Different Activation Conditions on Activated Carbon Absorptivity factor temp. (°C)
time (h)
ZnCl2 (%)
liquid-to-solid ratio
level 400 500 600 3 4 5 20 30 40 3 4 5
iodine adsorption value (mg/g)a 937 1034 850 920 997 940 874 979 1004 907 964 986
± ± ± ± ± ± ± ± ± ± ± ±
41 29 9 30 43 49 18 31 52 35 44 43
Each data indicates the mean ± SD, which were measured from three independent experiments.
a
absorptivity increased from 937 to 1034 mg/g when the activation temperature was increased from 400 to 500 °C. Further increment of activation temperature caused a decrease and the iodine absorptivity was 850 mg/g at 600 °C. The significant decrease of activated carbon absorptivity at higher temperature was probably caused by a shrinkage effect, which considerably destroyed the walls between adjacent pores and led to a reduction in porosity and absorptivity.34,35 The ZnCl2 concentration and the liquid−solid ratio showed a positive effect on the activated carbon absorptivity due to the sufficient activation by enhancing catalyst content.36 In comparison with 7436
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(4) Bridgwater, A. Principles and practice of biomass fast pyrolysis processes for liquids. J. Anal. Appl. Pyrol. 1999, 51, 3−22. (5) Czernik, S.; Bridgwater, A. Overview of applications of biomass fast pyrolysis oil. Energy Fuels 2004, 18, 590−598. (6) Williams, P. T.; Besler, S. The influence of temperature and heating rate on the slow pyrolysis of biomass. Renewable Energy 1996, 7, 233−250. (7) Hu, S.; Jess, A.; Xu, M. Kinetic study of Chinese biomass slow pyrolysis: Comparison of different kinetic models. Fuel 2007, 86, 2778−2788. (8) Zhang, S.; Yan, Y.; Li, T.; Ren, Z. Upgrading of liquid fuel from the pyrolysis of biomass. Bioresour. Technol. 2005, 96, 545−550. (9) Mullen, C. A.; Boateng, A. A.; Hicks, K. B.; Goldberg, N. M.; Moreau, R. A. Analysis and comparison of bio-oil produced by fast pyrolysis from three barley biomass/byproduct streams. Energy Fuels 2009, 24, 699−706. (10) Zhang, Q.; Chang, J.; Wang, T.; Xu, Y. Review of biomass pyrolysis oil properties and upgrading research. Energ Convers Manage 2007, 48, 87−92. (11) Cascarosa, E.; Fonts, I.; Mesa, J.; Sánchez, J.; Arauzo, J. Characterization of the liquid and solid products obtained from the oxidative pyrolysis of meat and bone meal in a pilot-scale fluidised bed plant. Fuel Process. Technol. 2011, 92, 1954−1962. (12) Yanik, J.; Kornmayer, C.; Saglam, M.; Yüksel, M. Fast pyrolysis of agricultural wastes: Characterization of pyrolysis products. Fuel Process. Technol. 2007, 88, 942−947. (13) Mohan, D.; Pittman, C. U.; Steele, P. H. Pyrolysis of wood/ biomass for bio-oil: A critical review. Energy Fuels 2006, 20, 848−889. (14) Amutio, M.; Lopez, G.; Artetxe, M.; Elordi, G.; Olazar, M.; Bilbao, J. Influence of temperature on biomass pyrolysis in a conical spouted bed reactor. Resour. Conserv. Recy. 2012, 59, 23−31. (15) Bridgwater, A. Principles and practice of biomass fast pyrolysis processes for liquids. J. Anal. Appl. Pyrol. 1999, 51, 3−22. (16) Aho, A.; Kumar, N.; Eränen, K.; Salmi, T.; Hupa, M.; Murzin, D. Y. Catalytic pyrolysis of woody biomass in a fluidized bed reactor: Influence of the zeolite structure. Fuel 2008, 87, 2493−2501. (17) Yao, C.; Dong, L.; Wang, Y.; Yu, J.; Li, Q.; Xu, G.; Gao, S.; Yi, B.; Yang, J. Fluidized bed pyrolysis of distilled spirits lees for adapting to its circulating fluidized bed decoupling combustion. Fuel Process. Technol. 2011, 92, 2312−2319. (18) Uzun, B. B.; Sarioglu, N. Rapid and catalytic pyrolysis of corn stalks. Fuel Process. Technol. 2009, 90, 705−716. (19) Jia, L.; Zhou, J. Chinese Oil Plant; Science Press: Beijing, 1987; pp 297−298. (20) Bozan, B.; Kosar, M.; Tunalier, Z.; Ozturk, N.; Baser, K. Antioxidant and free radical scavenging activities of Rhus coriaria and Cinnamomum cassia extracts. Acta Alimentaria 2003, 32, 53−61. (21) Candan, F.; Sö k men, A. Effects of Rhus coriaria L. (Anacardiaceae) on lipid peroxidation and free radical scavenging activity. Phytother. Res. 2004, 18, 84−86. (22) Nasar-Abbas, S. M.; Halkman, A. K.; Ai-Haq, M. I. Inhibition of some foodborne bacteria by alcohol extract of sumac (Rhus coriaria L.). J. Food Safety 2004, 24, 257−267. (23) Heschel, W.; Klose, E. On the suitability of agricultural byproducts for the manufacture of granular activated carbon. Fuel 1995, 74, 1786−1791. (24) Derbyshire, F.; Jagtoyen, M.; Andrews, R.; Rao, A.; MartinGullon, I.; Grulke, E. A. Carbon materials in environmental applications. Chem. Phys. Carbon 2001, 27, 1−66. (25) Kadirvelu, K.; Kavipriya, M.; Karthika, C.; Radhika, M.; Vennilamani, N.; Pattabhi, S. Utilization of various agricultural wastes for activated carbon preparation and application for the removal of dyes and metal ions from aqueous solutions. Bioresour. Technol. 2003, 87, 129−132. (26) Chen, G.; Chen, H. Enhancement of oil extraction from sumac fruit using steam-explosion pretreatment. J. Am. Oil Chem. Soc. 2011, 88, 151−156.
the activation temperature and catalyst content, activation time appeared to have slight influence on the activated carbon absorptivity. From the perspective of cost, the activation conditions were optimized to be ZnCl2 concentration 30%, solid−liquid ratio 1:4, temperature 500 °C, and reaction time 4 h. In these conditions, the activated carbon yield was 21.76% relative to the total mass of sumac fruit and 96.37% relative to the mass of pyrolysis residue. The iodine and methylene blue adsorption absorptivity were 1060 mg/g and 250 mg/g respectively and met the international quality standards of first grade activated carbon (iodine value ≥ 1000 mg/g, methylene blue adsorption value ≥ 135 mg/g).37
4. CONCLUSIONS Time-step and temperature-gradient collections of liquid products from pyrolysis of sumac marc were established in this study based on the changes of aqueous phase content of bio-oil at different time and different temperature during the pyrolysis process. In the time-step collection, aqueous phase content dropped from 94.02% to 28.65% at pyrolysis temperature 500 °C with a heating rate 40 °C/min in a sweeping gas reactor. Compared with time-step collection, temperature-gradient collection had a longer retention time at lower temperature. 15.93% aqueous phase content was obtained in the temperature-gradient collection at 500 °C, effectively reducing the aqueous phase content and increasing the value of bio-oil as fuels and chemicals. Therefore, the step collection of liquid products gave a promising method to obtain high quality bio-oil from pyrolysis of sumac marc. The iodine and methylene blue absorptivity of activated carbon prepared by chemically activation of the pyrolysis residue were accorded with the international quality standards of first grade activated carbon by optimizing activation conditions. Consequently, a total biomass utilization of sumac marc was achieved by bio-oil production and activated carbon preparation from pyrolysis residue.
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AUTHOR INFORMATION
Corresponding Author
*Tel.: +86 01082627071 E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS Financial support for this study was provided by the National Basic Research Program of China (973 Project, No. 2011CB707401), the National High Technology Research and Development Program of China (863 Program, SS2012AA022502), the National Key Project of Scientific and Technical Supporting Program of China (No. 2011BAD22B02).
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dx.doi.org/10.1021/ef401381m | Energy Fuels 2013, 27, 7432−7438
