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Accepted Manuscript Investigating pyrolysis characteristics of moso bamboo through TG-FTIR and Py-GC/MS Fang Liang, Ruijuan Wang, Xiang Hongzhong, Xiaomeng Yang, Tao Zhang, Wanhe Hu, Bingbing Mi, Zhijia Liu PII: DOI: Reference:
S0960-8524(18)30162-7 https://doi.org/10.1016/j.biortech.2018.01.140 BITE 19497
To appear in:
Bioresource Technology
Received Date: Revised Date: Accepted Date:
4 January 2018 29 January 2018 30 January 2018
Please cite this article as: Liang, F., Wang, R., Hongzhong, X., Yang, X., Zhang, T., Hu, W., Mi, B., Liu, Z., Investigating pyrolysis characteristics of moso bamboo through TG-FTIR and Py-GC/MS, Bioresource Technology (2018), doi: https://doi.org/10.1016/j.biortech.2018.01.140
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Investigating pyrolysis characteristics of moso bamboo through TG-FTIR and Py-GC/MS Fang Liang, Ruijuan Wang, Xiang Hongzhong, Xiaomeng Yang, Tao Zhang, Wanhe Hu, Bingbing Mi, Zhijia Liu*
International Centre for Bamboo and Rattan, Beijing, China, 100102
#Co-First Author: Ruijuan Wang, equal contributor as first author
Corresponding author: Dr. Zhijia Liu, [email protected], Tel: 86-10-84789869
Abstract: This study was carried out to investigate pyrolysis characteristics of moso bamboo (Phyllostachys pubescens), including outer layer (OB), middle layer (MB) and inner layer (IB) and bamboo leaves (BL), through TG-FTIR and Py-GC/MS. The results showed that 70% of weight loss occurred at rapid pyrolysis stage with temperature of 200-400 . With increase in heating rate, pyrolysis process shifted toward higher temperature. IB, OB, MB and BL had a different activation energy at different conversion rates. BL had a higher activation energy than IB, OB and MB. The volatiles of bamboo was complicated with 2-30 of C atoms. IB, OB and MB mainly released benzofuran, hydroxyacetaldehyde and 2-Pentanone. BL released furan, acetic acid and phenol. The main pyrolysis products included H2O, CH4, CO2, CO, carboxylic acids, NO, NO2. Pyrolysis products of IB was the most and that of BL was the lowest. MB had the lowest pyrolysis temperature. Keywords: Moso bamboo; Pyrolysis; Kinetic; TG-FTIR; Py-GC/MS.
1. Introduction 1
Biomass is one of renewable energy sources that can be converted into gas, liquid and solid-state energy products. Development and utilization of biomass energy can contribute to improving the world's energy consumption and reducing greenhouse gas emissions (Mekhilef et al., 2011). In China, moso bamboo is seen as one of important biomass resources due to its rich cultivation, covering a wide area and the high economic value. It has widely been used in some fields such as construction, handicrafts, furniture, man-made board and papermaking, etc (Erfa et al., 2001). The utilization percentage of bamboo for most industrial products is lower than 50%. So there are a lot of wastes during processing, which has great potential as a bio-energy resource of the future. Biomass can be converted to high energy density products and high value-added chemicals through pyrolysis technology (Mohan et al. 2006). It was confirmed that many factors have an effect on biomass pyrolysis, such as biomass types, pyrolysis temperature and pyrolysis reactors, etc. Chen et al. (2018) found that H2 was the main component and the yield of CH4 and CO decreased at higher temperature zone during bamboo pyrolysis. Lo et al. (2017) reported that the main gas product of straw, rice husk, corn stalks, bagasse, sugar cane bark, waste coffee grounds and bamboo leaves were H2 (18-25vol%), CH4 (6-8vol%), CO (51-59vol%), and CO2 (10-14vol%). Pyrolysis behavior could also be characterized by kinetic parameters associated with the decomposition reaction, the activation energy, and pre-exponential factor (Dhyani et al. 2018). Yu et al. (2015) found that pretreatment with echinodontium taxodii reduced the negative impact of bamboo extractives on pyrolysis and pretreated sample had a lower activation energy. Chen et al. (2014) confirmed that activation energy of bamboo increased with increase in heating rate and heating rate had different effects on the pyrolysis products, including biochar, bio-oil and non-condensable gas. Bamboo is divided into out layer (OB), middle layer (MB) and inner layer (IB) due to different physical and chemical performances, which affect pyrolysis characteristics of bamboo. Liu et al. (2016) found that the main polar chemical groups of OB included hydroxyl group and ester carbonyl. Some new polar chemical groups, such 2
as aromatic ethers and phenolic hydroxyl, appeared on the IB surface. Furthermore, bamboo pyrolysis is a complex process including the simultaneous occurrence of different reactions, such as dehydration, recombination, polymerization and carbonation. To the best of our knowledge, there is the lack of sufficient information concerning pyrolysis characteristics of different part of bamboo. It is very helpful to investigate the pyrolysis behaviors and mechanism of bamboo materials. Thermogravimetric analyzer coupled with other techniques have been used to detect the chemical changes of biomass during pyrolysis process. Harun et al. (2013) used thermogravimetry coupled with mass spectrometry (PY-MS) to determine the gaseous products of agriculture and forestry biomass. They found that the degradation rate of combustible gas was about 20-30% at temperature of 200 and 230 , and the degradation of combustible gases was more than 30% when the temperature increased from 260 to 290 . Chen et al. (2016) investigated the bio-oil chemical composition of pine sawdust by Py-GC/MS and monitored the characteristic of ion fargments (H2, CH4, CO, and CO2). Kozlov et al. (2015) found that radical species concentration in gas produced from biomass gasification was too small to change gas-phase composition significantly. It is confirmed that PY-MS cannot accurately identify the molecular structure when the species have the same mass-to-charge ratio (m/z). Thermogravimetric coupled with Fourier Transform Infrared Spectroscopy (TG-FTIR) can effectively identify the compounds according to their functional groups and covalent bonding (Kai et al., 2017). Chen et al. (2015) used TG-FTIR to analyze the pyrolysis characteristics of moso bamboo and found that the changes in the absorbance of volatiles during pyrolysis agreed with the weight loss in the derivative thermogravimetric curve. Meng et al. (2013) found that the main pyrolysis gaseous products of corn cob, tree root and bagasse were CO2, CO, H2O, CH4, NH3, acid and aldehydes. Due to the complex reaction of pyrolysis process, the combination of Py-GC/MS and TG-FTIR can more accurately identify the gas released in the pyrolysis process. However, there were little information on bamboo pyrolysis, determined by the combination of Py-GC/MS and TG-FTIR, especially for OB, MB, 3
IB and bamboo leaves (BL). In this paper, pyrolysis characteristics of OB, MB, IB and BL were therefore determined through Py-GC/MS and TG-FTIR. The objective is to get pyrolysis information of moso bamboo with different parts and provided a theoretical guidelines to design manufacturing process of bio-energy from moso bamboo by thermal chemical conversion methods. 2. Material and methods 2.1 Material Moso bamboo aged 4 years old was taken from a bamboo plantation located in Zejiang Province, China. Bamboo tubes were cut off to 25 mm (longitudinal) by 4 mm (radial). OB was taken from out layer of bamboo with 1mm thickness and IB was taken from inner layer of bamboo with 1mm. Other residues were MB, which was cut off to 25mm (longitudinal) by 1mm (radial) by 1mm (tangential). BL was taken from the same bamboo. OB, MB, IB and BL were respectively broken down into particles using a Wiley mill and the size of bamboo particles was about 250-425µm. They were dried at temperature 105
until their mass stabilized.
2.2 The determination of pyrolysis characteristics Pyrolysis characteristics were observed in terms of global mass loss though TA Instrument TGA Q 500 thermogravimetric analyzer (TA Instrument, USA) under the nitrogen atmosphere. 5-8 mg samples were evenly and loosely distributed in an open pan. Pyrolysis temperature was controlled from room temperature (30±5 ) to 800 with heating rates of 10 /min, 20 /min, 30 /min, 40 /min. The high purity nitrogen flow rate of 60 mL/min was continuously passed into the furnace to prevent any unwanted oxidative decomposition. Three replicates of each TGA experiment were performed. 2.3 Kinetic model The fundamental rate equation used in all kinetics studies is generally described as: 4
dα = kf (α ) dt
(1)
Where, k is the rate constant and f(α) is the reaction model, a function depending on the actual reaction mechanism. Eq. (1) expresses the rate of conversion, dα/dt at a constant temperature as a function of the reactant conversion loss and rate constant. In this study, the conversion rate α is defined as:
α=
(w 0 - wt ) (w 0 - wf )
(2)
Where, wt, w0 and wf are time t, initial and final weight of the sample, respectively. The rate constant k is generally given by the Arrhenius equation:
- Ea k = Aexp RT
(3)
Where, Ea is the apparent activation energy (kJ/mol), R is the gas constant (8.314 J/K mol), A is the pre-exponential factor (min-1), T is the absolute temperature (K). The combination of Eqs. (1) and (3) gives the following relationship: dα - Ea = Aexp f (α ) dt RT
(4)
For a dynamic TGA process, including the heating rate, β=dT/dt, into Eq. (4), Eq. (5) is obtained as: d α A - Ea = exp f (α ) dT β RT
(5)
Eqs. (4) and (5) are the fundamental expressions of analytical methods to calculate kinetic parameters on the basis of TGA data. Flynn-Wall-Ozawa (FWO) method was used in this research, showed in Equation (6). As a representative model of the model-free kinetic model, which had high applicability to biomass pyrolysis (Ma et al., 2015; Apaydin-Varol et al., 2014). 5
A ⋅ Ea 0.4567 ⋅ Ea − 2.315 − log( βi ) = log R ⋅ Tα , i R ⋅ g(α )
(6)
Where, g(α) is usually constant and based on the integral reaction model at a specific conversion rate, so the formula: g(α)=α/(1-α), only consider the first order of the study. 2.4 The determination of pyrolysis compounds The thermogravimetric analyzer (CDS5200, USA) coupled with a quadrupole mass spectrometer (Agilent 6890N/5973i, USA) to investigate the distribution of volatiles from bamboo pyrolysis against reaction temperature. About 10 ± 0.02 mg of samples was loaded in the pyrolysis tube and the pyrolysis temperature was controlled from room temperature (30±5 ) to 500
at a heating rate of 10 /min. The dwelling
time of samples at temperature of 500
was set to be 3.0 min in order to ensure that
most of the solid sample was pyrolyzed. A high purity nitrogen stream (flow rate of 60 mL/min) was continuously passed into the furnace. The evolved volatiles were identified by GC/MS with the conditions given as: the injector temperature was kept at 280℃; the chromatographic separation was performed with a TR-35MS capillary column; the mass spectra were operated in electron ionization (EI) mode at 70 eV. The mass spectra were obtained from m/z 50 to 650. The yield of the compounds can be determined by the characterized GC/MS spectrums, according to the database of NIST library. Three replicates of each experiment were performed. 2.5 The determination of volatile gas TG-FTIR test was carried out using a combination of thermogravimetry (TA Instrument, USA) and Fourier transform infrared spectrometer (Bruker IFS 66/S, Bruker Optics, Billerrica, MA). Samples of 20±0.02mg were placed into crucible and heated from room temperature (30±5 ) to 800
at a heating rate of 10 /min. High
purity nitrogen as a purge and protective gas at a flow rate of 60ml/min. The sample pan was placed close to the end of the furnace, which combined with the high gas 6
flow to minimize the residence time of the evolved gases in the hot zone. To avoid liquefaction of the volatile gas when it passed through the capillary bundle, the temperature of the capillary bundle were heated to 250 . The system collected FTIR spectra every 30s and sample temperature and mass were logged every 3s. FTIR spectrum was collected in the range of 4000-400cm-1 at a resolution of 4cm-1. Three replicates of each experiment were performed. 3. Results and discussion 3.1 Pyrolysis characteristics Fig. 1 showed the TG and DTG curves of IB, MB, OB and BL at different
heating rates. There were three stages during pyrolysis process of samples. The pyrolysis temperature of lower than 200
was the first stage and weight loss was
mainly due to the evaporation of water in the bamboo and the release of a small amount of volatiles (Biswas et al., 2017). The main weight loss occurred at the second stage corresponding to pyrolysis temperature of 200-400 . The weight loss was about 70% of total sample weight, which was attributed to thermal degradation of volatiles, cellulose, hemicelluloses and partial lignin. Wang et al. (2018) found that cellulose pyrolysis mainly occurred at 300-400 , hemicellulose pyrolysis mainly occurred at 200-300
and lignin pyrolysis was from 200
until the end of pyrolysis process. It
was also found three small significant peaks in the DTG curve, corresponding to thermal degradation of protein, carbohydrate and lipid from three main chemical components of samples (Shuping et al., 2010). The three stage occurred at temperature of higher than 400
and weight loss was due to the slowly thermal
decomposition of fixed carbon. Fig. 1 showed that the pyrolysis curves of all samples shifted toward the higher temperature with increase in heating rates. This phenomenon is mainly attributed to uneven heating of sample particles (Maiti et al., 2007). Table 1 showed pyrolysis characteristics of IB, MB, OB and BL at heating rate
of 10 /min. Other pyrolysis characteristics at heating rate of 20 /min, 30 /min and 7
40 /min were not showed because they had a similar change trend with heating rate of 10 /min. The weight loss of IB, OB, MB, and BLwas 13.2%, 13.1%, 10.9% and 10.3% in the first stage, indicating that the quality of water and volatiles in BL was slightly lower than IB, MB, OB. Liu et al. (2016) found that BL had the lowest content of volatiles compared with OB, MB and IB. Similar, the weight loss of IB, OB, MB and BL was about 70% and the maximum of weight loss rate were 1.003%/ , 1.024%/ , 0.951%/
and 0.64%/ , respecively corresponding to
pyrolysis temperature of 346.1 , 348.1 , 337.9
and 318.4
in the second stage.
The main prolysis temperature range of BL was 237.6-408.5
and its reaction rate
was also the lowest. This phenonmenon was attributed to the difference of chemical components in the samples. Peng et al. (2013) found that BL had a higher H/C and O/C value, resulting in BL was more difficult to pyrolysis. The weight loss of IB, OB, MB, and BL was 6.6%, 8.7%, 5.8% and 9.3% in the three stage, respectively. The residues of IB, MB, OB and BL were 16.7%, 19.4%, 18.5%, 24.9%, respectively. 3.2 Kinetic analysis from FWO model Pyrolysis reaction parameters are helpful to accurately understand the microscopic reactions occurred in the pyrolysis process of biomass. Fig. 2 showed the linear relationship between 1/T and log(βi) at different conversion rates of samples in the FWO model. The linear equations at different conversion rates were nearly parallel, indicating that the activation energy of IB, OB, MB and BL at different conversion rates was approximate (Chen et al., 2014). Table 3 showed kinetic parameters of IB, OB, MB and BL at different conversion rates. The correlation coefficient of the linear relationship (R2 value) was higher, indicating that FWO model was suitable for obtaining activation energy of the samples. The frequency factor (A) can be used to characterize the reaction speed in pyrolysis process. The frequency factor varied at different conversion rates for IB, OB, MB and BL. The maximum of frequency factor corresponded to conversion rate of 0.5, 0.7, 0.6, 0.5 for IB, OB, MB and BL, respectively. The activation energy and frequency factor of all samples including IB, OB, MB and BL had the similar trend with increase in 8
conversion rate. The activation energy of IB varied in the ranges of 128.61-176.73KJ/mol and its maximum of activation energy was found at the conversion rate of 0.5. The activation energy of OB varied in the ranges of 141.02-224.41KJ/mol and its maximum of activation energy was found at the conversion rate of 0.7. The activation energy of MB varied in the ranges of 137.85-160.69KJ/mol and its maximum of activation energy was found at the conversion rate of 0.6. The activation energy of BL varied in the ranges of 159.69-187.56KJ/mol and its maximum of activation energy was found at the conversion rate of 0.5. This phenomenon was mainly related to the chemical composition and sytucture in different parts. Liu et al. (2016) confirmed that IB, OB, MB and BL had different contents of C, H, O, N and S, indicating they had different chemical compositions. Furthmore, three main chemical components were different pyrolysis characteristics. Cellulose is a semi-crystalline sturcture, whose pyrolysis occured from amorphous region to crystalline region. While lignin and hemicellulose are non-crystalline, whose pyrolysis needed lower activation energy than cellulose (Chen et al., 2014). They resulted in the different activation energy at different conversion rates for IB, OB, MB and BL. The lower activation energy indicated that biomass was easier to occur thermo-chemical conversion. Therefore, IB, OB, MB and BL should designed a different thermo-chemical conversion processes when they were used as raw materials to produce bioenergy or biochemicals. 3.2 Py-GC/MS analysis Fig.3 showed pyrolysis products distribution of IB, OB, MB and BL from
Py-GC/MS. There were mainly 6 families of compounds, including aldehyde, furan, phehol, ketone, ester, alcohol and acid. Moso bamboo contained a large number of phenol and a small amount of alcohol. The ketone and acid of MB were significantly lower than IB, OB and BL, but its contents of furan and phenolic compounds were obviously higher than other parts. The contents and types of chemical components of IB, MB, OB and BL had a great impact on these volatiles during pyrolysis process. Collard and Blin (2014) found that the depolymerization of lignin produced various 9
phenols. Hemicellulose mainly produced acetic acid, furfural and hydroxyacetone, etc (Wang et al., 2015). The different chemical compounds of bamboo resulted in different types and levels of volatiles (Sheng et al., 2002). Table 3 showed the typical precipitation materials of moso bamboo at different temperatures. It was confirmed that the composition of the precipitated material was very complicated and the number of C atoms varied from 2 to 30, containing aldehydes, ketones, carboxylic acids, esters, etc. IB, OB and MB mainly contained benzofuran, hydroxyacetaldehyde and 2-Pentanone, etc. However, the precipitated species of BL mainly included furan, acetic acid and phenol, etc. Compared with BL, the content of 2,3-dihydro-coumarone in the main products of IB, OB and MB were the higher, accounting for 11.06%, 9.54% and 6.30% of the total volatiles, respectively. 3-Hydroxy-4-methoxybenzoic acid was also main products of IB, OB and MB, but it was not found in the pyrolysis products of BL. Each part of moso bamboo had the unique product, such as butanoic acid-methyl ester for IB, p-Xylene and propanoic acid for OB, 2-Cyclohexen-1-ol, benzoic acid and 3, 4-dihydroxy- for MB, toluene and D-Limonene for BL. These detected substances with small molecular substances were firstly released due to their low thermal decomposition. With increase in pyrolysis temperature, some volatiles with the macromolecular substances were gradually released. These volatiles were divided into ketones, aldehydes and furans, which mainly come from the cracking, polymerization of lignin and the condensation of cellulose (Huang et al., 2011). It is well known that benzene ring was not easy to open loop in the pyrolysis process, so the organic matter in the product was mainly from Pyran ring opens of glucopyranose monomer and the fracture of C-C bond in the ring. These pyrolysis products could be used as the main intermediate of bioenergy and chemicals (Jimenez et al., 2017). 3.3 TG-FTIR analysis Moso bamboo contains natural macromolecular polymers, such as cellulose, hemicellulose and lignin. These macromolecules occur the reaction of cross-link polymerization and dehydrogenation oxidation in the pyrolysis process, which were often accompanied by the production of small molecule gases (Stefanidis et al., 2014). 10
Fig. 4 showed TG-FTIR spectra of IB, OB, MB and BL at heating rate of 10 /min. It
was found that pyrolysis products of moso bamboo varies greatly with increase in pyrolysis temperature. TG-FTIR spectra of IB, OB, MB and BL had acromion peaks at the temperature range from 100
to 400 . According to the widely used
Lambert-Beer law, the absorption spectrum at a specific wave number was linearly dependent on gas concentration (Gao et al., 2013). Thus, most of the gas was evolved at this temperature range during pyrolysis process of samples. The total intensity of IB was the highest and that of BL was the lowest, which were consistent with the results of Py-GC/MS. It can be determined the species of pyrolysis products based on FTIR spectrum. The absorbance peak at 3356cm-1 corresponded to the release of absorbed water (H2O). The absorbance peak at 2927cm-1 was the release of methane gas (CH4). The absorbance peak at 2359cm-1 indicated the release of carbon dioxide (CO2). The absorbance peak at 2179cm-1 appeared when carbon monoxide (CO) was released. The absorbance peak at 1770cm-1 was attributed to the release of carboxylic acids. The absorbance peak at 1684cm-1 confirmed the release of nitric oxide (NO). The absorbance peak at 1559cm-1was the release of nitrogen dioxide (NO2). The absorbance peak at 1119cm-1 was the release of phenol (Ma et al., 2015). Fig.5 showed the main pyrolysis products of IB, OB, MB and BL as a function
of temperature. MB and IB had the strongest intensity of H2O release, but the peak temperature corresponding to the maximum intensity of H2O release by IB was shifted to higher temperature. H2O released mainly from the evolution of bulk water, bound water and crystallization water in mineral substance in samples. With the temperature increases, the pyrolysis water forms also from the cracking or reaction of oxygen functional groups occurred in sample pyrolysis (Gao et al., 2013). BL contained less water content because it had the lowest intensity of H2O release. The main released temperature range of H2O was 150-350 . Carbon is the main type pf chemical compounds in bamboo. Carbon compounds were released during bamboo pyrolysis such as CH4, CO2 and CO. The evolution of CH4, CO2 and CO was mainly ascribed to the cleavage of functional groups (e.g. methoxyl group, ether group, 11
carboxyl and carbonyl group) and the secondary cracking of those phenolic compounds (Zhao et al., 2014). IB had a the strongest intensity of CH4 release and BL had the lowest intensity of CH4 release. The peak temperature corresponding to the maximum intensity of CH4 release was the lowest for MB. BL had two main release peaks of CH4. A weak peak of CH4 appeared at 500-600
presumably due to the
secondary decomposition of the organic compounds such as aldehydes, alcohols, acids and ketones leading to the breakage of the chains and the reforming reaction. The temperature ranges of CH4 release were 150-350 OB, 150-500
for MB, 150-400
for IB and
for BL. The CO2 was a type of main pyrolysis products for sampels.
The intensity of CO2 release for IB, OB and MB was obviously higher than that of BL. MB had the lowest peak temperature of the maximum CO2 release. It was found that the CO release had a similar trend with CO2 release. With increase in pyrolysis temperature, the peak intensity of CO2 and CO constantly changed. However, C=O and C-O showed acromion at the temperature of 150-350 , which was due to the pyrolysis of aliphatic compounds in hemicellulose (Jiang et al., 2012). The NO and NO2 release occured at the total temperature ranges and the variation was more obviously than other pyrolysis products. MB and IB had a obvious NO and NO2 release peak at temperature of 600-700 . For carboxylic acids and phenol, their release mianly occured at temperature of 150-400
and each sample had two main
peaks. In conclusion, the peak intensity of a specific wavenumber represented the release concentration of pyrolysis products (Granada et al., 2012). The results indicated that pyrolysis products of IB was the most and that of BL was the lowest. MB had the lowest release temperature of all pyrolysis products. 4. Conclusion
The pyrolysis process of IB, OB, MB and BL was similar, but the pyrolysis characteristics were different. With the increase of the heating rate, the pyrolysis process shifted toward higher temperature. IB, OB, MB and BL had a different activation energy at different conversion rates. Temperature had an important impact on the pyrolysis products of moso bamboo. Even though there were mainly 6 families 12
of compounds, including aldehyde, furan, phehol, ketone, ester, alcohol and acid, their distribution of each sampels was different. The main pyrolysis products included H2O, CH4, CO2, CO, carboxylic acids, NO, NO2 and phenol. Acknowledgments
This research was financially supported by ‘13th Five Years Plan-Study on manufacturing technology of bamboo wastes and its mechanism (Grant No. 2016YFD0600906). References
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pubescens Mazel) leaves. Carbohydr. Polym. 95, 262-271. Sheng, Z.Q., Jie, G.M., Lan, J.W., 2002. Variation of Moso Bamboo Chemical Compositions During Mature Growing Period. J. Nanjing Fores. Unvers. 26, 7-10. Stefanidis, S.D., Kalogiannis, K.G., Iliopoulou, E.F., Michailof, C.M., Pilavachi, P.A., Lappas, A.A., 2014. A study of lignocellulosic biomass pyrolysis via the pyrolysis of cellulose, hemicellulose and lignin. J. Anal. Appl. Pyrolysis 105, 143-150. Yu, H., Liu, F., Ke, M., Zhang, X., 2015. Thermogravimetric analysis and kinetic study of bamboo waste treated by Echinodontium taxodii using a modified three-parallel-reactions model. Bioresour. Technol. 185, 324-330. Wang, R.J., Liang, F., Jiang, C.L., Jiang, Z.H., Wang, J.X., Fei, B,H., Nan, N., 2018. Pyrolysis kinetics of moso bamboo. Wood Fib. Sci. 50, 1-11. Wang, S., Ru, B., Dai, G., Sun, W., Qiu, K., Zhou, J., 2015. Pyrolysis mechanism study of minimally damaged hemicellulose polymers isolated from agricultural waste straw samples. Bioresourc. Technol. 190, 211-218. Zhao, J., Wang, X., Hu, J., Liu, Q., Shen, D., & Xiao, R., 2014. Thermal degradation of softwood lignin and hardwood lignin by tg-ftir and PY-GC/MS. Polym. Degrad. Stab. 108, 133-138. Zou, S.P., Wu, Y.L., Yang, M.D., Li, C.,Tong, J.M., 2010. Pyrolysis characteristics and kinetics of the marine microalgae Dunaliella tertiolecta using thermogravimetric analyzer. Bioresour. Technol. 101, 359-365.
16
1.2
1.2
0.6
60
40
0.3
20
80
300
400
500
600
700
10 20 30 40
/min /min /min /min
0.6 60
0.3
40
0.0 100
200
300
400
500
600
700
Temperature ( )
Temperature ( ) 1.2
Mass loss (%)
80
60
1.2 100
0.9
0.6
40 0.3 20
(d)
10 20 30 40
)
(c)
Derivative mass loss (%/ Mass loss (%)
100
0.9
80
/min /min /min /min
0.6 60
0.3
40
20
0.0
0.9
)
200
/min /min /min /min
20
0.0 100
10 20 30 40
)
0.9
(b)
Derivative mass loss (%/
100
Derivative mass loss (%/
Mass loss (%)
80
/min /min /min /min
)
10 20 30 40
Mass loss (%)
(a)
Derivative mass loss (%/
100
0.0
0 100
200
300
400
500
600
700
100
Temperature ( )
200
300
400
500
600
700
Temperature ( )
Fig.1 The pyrolysis process of moso bamboo at different heating rates
(a. IB; b. OB; c. MB; d. BL)
17
1.7
1.7
(b)
(a)
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.5
log(β)
1.4 1.3
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.6 1.5 1.4
log(β)
1.6
1.3
1.2
1.2
1.1
1.1
1.0
1.0
0.0015
0.0016
0.0017
0.0018
0.0019
0.0020
0.00152
0.00160
1/T
0.00184
1.7
(c)
(d)
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.5 1.4 1.3
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.6 1.5 1.4
log(β)
1.6
log(β)
0.00176
1/T
1.7
1.3
1.2
1.2
1.1
1.1 1.0
1.0 0.00152
0.00160
0.00168
0.00176
0.00184
0.00192
0.00200
0.00135
0.00150
0.00165
0.00180
0.00195
0.00210
1/T
1/T
Fig.2
0.00168
Non-isothermal plot of FWO method at different conversion rates (a. IB; b. OB; c. MB; d. BL) 18
30
IB OB MB BL
25
Peak area (%)
20
15
10
5
0
eh Ald
yde
n e ol Fura Phen Keton
l r Este Alcoho
Acid
Fig.3 Pyrolysis products distribution of IB, OB, MB and BL from Py-GC/MS
20
0.14
IB OB MB BL
0.12 0.10
Intensity
0.08 0.06 0.04 0.02 0.00 100
200
300
400
500
Temperature (
21
)
600
700
Fig. 4 TG-FTIR spectra of sampels at heating rate of 10 /min
22
0.035
3566
0.020
IB OB MB BL
0.030 0.025
2927
IB OB MB BL
0.015
Intensity
Intensity
0.020 0.015 0.010
0.010
0.005
0.005 0.000
0.000 -0.005
-0.005
100
200
300
400
500
Temperature (
600
700
100
200
)
300
400
500
Temperature (
600
700
)
0.020
0.14
2359
2179
IB OB MB BL
0.12 0.10
0.015
Intensity
Intensity
0.08 0.06
IB OB MB BL
0.04
0.010
0.005
0.02 0.000
0.00 100
200
300
400
500
Temperature (
0.10
600
100
700
300
400
500
600
700
)
0.025
1770
1684
IB OB MB BL
0.08
0.015
Intensity
0.04
IB OB MB BL
0.020
0.06
Intensity
200
Temperature (
)
0.010
0.005 0.02 0.000 0.00 100
200
300
400
500
600
700
100
200
Temperature ( )
300
400
500
Temperature (
0.025
600
700
)
0.045
IB OB MB BL
1559 0.020
0.015
0.040
IB OB MB BL
1119
0.035 0.030
Intensity
Intensity
0.025 0.010
0.005
0.020 0.015 0.010 0.005
0.000
0.000 -0.005
-0.005 100
200
300
400
500
Temperature (
600
700
100
)
200
300
400
500
Temperature (
600
700
)
Fig. 5 The main pyrolysis products of sampels as a function of temperature
24
Table 1 Pyrolysis characteristics of moso bamboo at different heating rates
The first step
Samples
Start
End
The second step
Weight
Start
End
loss ( )
( )
(%)
Weight
The third step
Start
( )
(%)
( )
Residues
loss
(%)
End
loss ( )
Weight
( ) (%)
31.2
261.8
13.2
261.8
395.7
63.4
395.7
736.6
6.6
16.7
±1.6
±3.5
±0.9
±3.5
±3.8
±1.2
±3.8
±9.8
±0.2
±0.07
30.5
281.4
13.1
281.4
402.7
58.2
402.7
725.1
8.7
19.4
±1.0
±5.6
±1.6
±5.6
±4.3
±1.9
±4.3
±6.8
±0.4
±0.05
30.6
252.9
10.9
252.9
421.5
64.5
421.5
758.9
5.8
18.5
±1.5
±6.7
±1.3
±6.7
±9.6
±1.2
±9.6
±8.3
±0.5
±0.1
30.7
237.6
10.3
237.6
408.5
55.3
408.5
721.9
9.3
24.9
±1.6
±6.4
±1.2
±6.4
±7.8
±2.1
±7.8
±9.1
±1.3
±0.5
IB
OB
MB
BL
25
Table 2 The kinetic parameters of samples at different conversion rates
Samples
Cr
Linear equation
R2
Ea (KJ/mol)
A (min-1)
0.1
y= -7064.49x+14.62
0.8070
128.61
3.00E+12
0.2
y= -8604.87x+16.51
0.9447
156.65
4.30E+14
IB
26
OB
MB
BL
0.3
y= -9258.39x+17.08
0.9449
168.54
2.54E+15
0.4
y= -9660.55x+17.28
0.9525
175.87
5.96E+15
0.5
y= -9707.99x+16.95
0.9738
176.73
4.19E+15
0.6
y= -9375.48x+16.15
0.9789
170.68
1.04E+15
0.7
y= -9279.02x+15.72
0.9980
168.92
6.08E+14
0.1
y= -7746.39x+15.27
0.9733
141.02
1.23E+13
0.2
y= -8047.74x+15.08
0.9900
146.51
1.71E+13
0.3
y= -8571.49x+15.45
0.9938
156.04
6.38E+13
0.4
y= -9089.25x+15.87
0.9938
165.47
2.47E+14
0.5
y= -9317.33x+15.95
0.9958
169.62
4.34E+14
0.6
y= -9244.46x+15.59
0.9923
168.29
2.90E+14
0.7
y= -12326.89x+19.89
0.9899
224.41
6.73E+18
0.1
y= -7572.29x+15.58
0.9386
137.85
2.56E+13
0.2
y= -8089.38x+15.55
0.9752
147.26
4.97E+13
0.3
y= -7963.07x+14.78
0.9189
144.96
1.49E+13
0.4
y= -8187.09x+14.77
0.9184
149.04
2.19E+13
0.5
y= -8654.51x+15.22
0.9631
157.55
8.83E+13
0.6
y= -8826.69x+15.24
0.9982
160.69
1.34E+14
0.7
y= -8411.49x+14.22
0.7208
153.13
2.12E+13
0.1
y= -7572.29x+15.58
0.9386
159.69
1.03E+16
27
0.2
y= -8089.38x+15.55
0.9752
177.56
9.97E+16
0.3
y= -7963.07x+14.78
0.9189
179.63
4.55E+16
0.4
y= -8187.09x+14.77
0.9184
182.47
3.12E+16
0.5
y= -8654.51x+15.22
0.9631
187.56
4.29E+16
0.6
y= -8826.69x+15.24
0.9982
168.19
2.95E+14
0.7
y= -8411.50+14.22
0.7208
165.13
4.50E+12
Cr is cinversion rate; R2 is correlation coefficient value; Ea is activation energy; A is exponential factor.
28
Table 3 The typical precipitation materials of moso bamboo at different temperatures 29
Temperature
Area (%)
Molecular m/z
Family
Compounds
formula
( )
IB
OB
MB
BL
25.99
82
C5H6O
Furan
Furan,2-methyl-
0.145
－
0.821 5.697
28.89
60
C2H4O2
Acid
Acetic acid
1.775
1.264
1.075 2.403
41.88
86
C5H10O
Ketone
2-Pentanone
－
－
2.163
－
51.43
92
C7H8
Benzene
Toluene
－
－
－
0.737
77.95
102
C5H10O2
Ester
0.344
－
－
－
－
0.691
－
－
－
0.254
－
－
－
－
Butanoic acid, methyl ester
81.76
106
C8H10
Benzene
87.68
102
C4H6O3
Ester
p-Xylene Propanoic acid, 2-oxo-, methyl ester
92.7
103
C4H9NO2
Amino acid
L-Alanine,N-methyl-
0.594
－
98.44
96
C5H4O2
Aldehyde
Furfural
2.517
2.791
121.64
136
C10H16
Alkene
D-Limonene
－
－
－
2.137
136.62
98
C6H10O
Alcohol
2-Cyclohexen-1-ol
－
－
0.281
－
139.7
94
C6H6O
Phenol
Phenol
0.72
0.591
0.656 1.166
150.09
84
C4H4O2
Ketone
2(5H)-Furanone
0.866
0.939
0.965 1.072
160.97
114
C4H6N2O2
Ketone
0.906
1.661
0.95
2.897 3.275
2,4-Imidazolidinedion 0.991
e, 3-methyl-
169.55
108
C7H8O
Phenol
Phenol, 4-methyl- 4
0.402
0.443
0.374 0.824
179.64
124
C7H8O2
Phenol
Phenol, 2-methoxy-
2.124
2.142
2.284 0.682
30
2-Cyclopenten-1-one, 187.86
126
C7H10O2
Ketone
0.269
－
－
0.281
0.346
－
0.273
－
－
1.096
－
－
0.456
－
－
－
3-ethyl-2-hydroxy-
197.22
122
C8H10O
Phenol
206.95
138
C8H10O2
Phenol
C4H4N2O3
Pyrimidine
C8H8O
Furan
C9H12O2
Phenol
Phenol, 4-ethylPhenol, 2-methoxy -3-methyl2,4,5-Trihydroxypyri
213.05
219.15
128
120
midine Benzofuran,
11.06
2,3-dihydro-
1
6.295
9.547 0.793
0.877
0.991
1.054 0.533
－
0.606
－
0.325
－
0.722
－
－
－
0.51
－
－
－
－
0.266
－
0.809
0.409
2.641 0.395
2.252
3.788
0.777 0.568
2.19
3.161
1.659
Phenol, 229.97
152
4-ethyl-2-methoxy-
231.78
212
C15H32
Alkane
240.48
162
C10H10O2
Ketone
C11H14O2
Ester
C7H6O4
Acid
C7H6O2
Aldehyde
C10H12O2
Phenol
C8H8O4
Acid
Pentadecane Ethanone,1,1'-(1,4-ph enylene)bisBenzoic acid, butyl
250.63
178
ester Benzoic
260.78
154
acid,3,4-dihydroxyBenzaldehyde,
271.9
122
4-hydroxyPhenol, 2-methoxy
280.72
164
-4-(1-propenyl)-,(E)3-Hydroxy-4-methox
288.39
168
ybenzoic acid 31
－
2-Cyclohexen-1-one, 302.78
168
C10H16O2
Ketone
0.368
－
－
0.457
5.818
－
5.865
3.948
2.082
－
dimethoxy-4-(2-prope 1.485
1.59
6.897 3.344
0.661
0.473
0.264
－
6.818
5.854
1.668
－
0.303
－
－
－
－
0.564
0.274
－
0.32
0.266
0.766
－
2-hydroxy-4,4,6,6-tetr
－
amethylBenzoic acid, 307.67
182
C9H10O4
Ester
4-hydroxy-3-methoxy 0.458 -, methylester 4-Methyl-2,5-dimetho
318.91
180
C10H12O3
Aldehyde xybenzaldehyde Phenol, 2,6-
323.92
194
C11H14O3
Phenol
nyl)N-(4-Methoxyphenyl) 336.97
194 C9H10N2O3
Acetamide
-2-hydroxyimino-acet amide 3-Hydroxy-4-methox
348.63
194
C10H10O4
Acid ycinnamic acid Hexanedioic acid,
359.69
258
C14H26O4
Ester
bis(2-methylpropyl) ester 1,2-Benzenedicarbox ylic acid,
370.08
278
C16H22O4
Ester bis(2-methylpropyl) ester 2-Propenoic acid,3-
381.99
208
C11H12O4
Acid
(4-hydroxy3-methoxyphenyl)-, 32
methyl ester 391.47
278
C16H22O4
Ester
Dibutyl phthalate
0.88
3.391
0.789 1.104
3.096
－
－
－
1.131
0.739
1.823
－
0.443
1.137
－
－
1.973
－
0.613 0.555
－
－
0.789
－
0.886
－
－
－
E)-2,6,10,14,18,22Tet racosahexaene,2,6,10, 404.46
410
C30H50
Carbene 15,19,23-hexamethyl, (all-E)3,5-Dimethoxy-4-hyd
420.11
208
C11H12O4
Aldehyde roxycinnamaldehyde 2-Hepten-4-one,6-hyd roxy-2-methyl-6(4-m
435.46
236
C15H24O2
Ketone ethyl-3-cyclohexen-1yl)Hexanedioic acid,
442.22
370
C22H42O4
Ester
bis(2-ethylhexyl) ester (+-)-3-(2-Carboxy-tra ns-propenyl)-2,2-dim
467.78
198
C10H14O4
Alkane
ethylcyclopropane-tra ns-1-carboxylicacid,[ 1.alpha., 3.beta.(E)] (E,Z)-2,6-Undecadien oic acid,
467.84
238
C15H26O2
Acid 7-ethyl-3-methyl-, methyl ester, (E,Z)-
33
>Pyrolysis process of all samples included three stages. > The faster is heating rate, the higher is pyrolysis temperature; > A different activation energy pf bamboo corresponded to different conversion rates. > Bamboo pyrolysis included 6 families compounds. > Pyrolysis products included H2O, CH4, CO2, CO, carboxylic acids, NO, NO2 and phenol.
36
S0960-8524(18)30162-7 https://doi.org/10.1016/j.biortech.2018.01.140 BITE 19497
To appear in:
Bioresource Technology
Received Date: Revised Date: Accepted Date:
4 January 2018 29 January 2018 30 January 2018
Please cite this article as: Liang, F., Wang, R., Hongzhong, X., Yang, X., Zhang, T., Hu, W., Mi, B., Liu, Z., Investigating pyrolysis characteristics of moso bamboo through TG-FTIR and Py-GC/MS, Bioresource Technology (2018), doi: https://doi.org/10.1016/j.biortech.2018.01.140
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Investigating pyrolysis characteristics of moso bamboo through TG-FTIR and Py-GC/MS Fang Liang, Ruijuan Wang, Xiang Hongzhong, Xiaomeng Yang, Tao Zhang, Wanhe Hu, Bingbing Mi, Zhijia Liu*
International Centre for Bamboo and Rattan, Beijing, China, 100102
#Co-First Author: Ruijuan Wang, equal contributor as first author
Corresponding author: Dr. Zhijia Liu, [email protected], Tel: 86-10-84789869
Abstract: This study was carried out to investigate pyrolysis characteristics of moso bamboo (Phyllostachys pubescens), including outer layer (OB), middle layer (MB) and inner layer (IB) and bamboo leaves (BL), through TG-FTIR and Py-GC/MS. The results showed that 70% of weight loss occurred at rapid pyrolysis stage with temperature of 200-400 . With increase in heating rate, pyrolysis process shifted toward higher temperature. IB, OB, MB and BL had a different activation energy at different conversion rates. BL had a higher activation energy than IB, OB and MB. The volatiles of bamboo was complicated with 2-30 of C atoms. IB, OB and MB mainly released benzofuran, hydroxyacetaldehyde and 2-Pentanone. BL released furan, acetic acid and phenol. The main pyrolysis products included H2O, CH4, CO2, CO, carboxylic acids, NO, NO2. Pyrolysis products of IB was the most and that of BL was the lowest. MB had the lowest pyrolysis temperature. Keywords: Moso bamboo; Pyrolysis; Kinetic; TG-FTIR; Py-GC/MS.
1. Introduction 1
Biomass is one of renewable energy sources that can be converted into gas, liquid and solid-state energy products. Development and utilization of biomass energy can contribute to improving the world's energy consumption and reducing greenhouse gas emissions (Mekhilef et al., 2011). In China, moso bamboo is seen as one of important biomass resources due to its rich cultivation, covering a wide area and the high economic value. It has widely been used in some fields such as construction, handicrafts, furniture, man-made board and papermaking, etc (Erfa et al., 2001). The utilization percentage of bamboo for most industrial products is lower than 50%. So there are a lot of wastes during processing, which has great potential as a bio-energy resource of the future. Biomass can be converted to high energy density products and high value-added chemicals through pyrolysis technology (Mohan et al. 2006). It was confirmed that many factors have an effect on biomass pyrolysis, such as biomass types, pyrolysis temperature and pyrolysis reactors, etc. Chen et al. (2018) found that H2 was the main component and the yield of CH4 and CO decreased at higher temperature zone during bamboo pyrolysis. Lo et al. (2017) reported that the main gas product of straw, rice husk, corn stalks, bagasse, sugar cane bark, waste coffee grounds and bamboo leaves were H2 (18-25vol%), CH4 (6-8vol%), CO (51-59vol%), and CO2 (10-14vol%). Pyrolysis behavior could also be characterized by kinetic parameters associated with the decomposition reaction, the activation energy, and pre-exponential factor (Dhyani et al. 2018). Yu et al. (2015) found that pretreatment with echinodontium taxodii reduced the negative impact of bamboo extractives on pyrolysis and pretreated sample had a lower activation energy. Chen et al. (2014) confirmed that activation energy of bamboo increased with increase in heating rate and heating rate had different effects on the pyrolysis products, including biochar, bio-oil and non-condensable gas. Bamboo is divided into out layer (OB), middle layer (MB) and inner layer (IB) due to different physical and chemical performances, which affect pyrolysis characteristics of bamboo. Liu et al. (2016) found that the main polar chemical groups of OB included hydroxyl group and ester carbonyl. Some new polar chemical groups, such 2
as aromatic ethers and phenolic hydroxyl, appeared on the IB surface. Furthermore, bamboo pyrolysis is a complex process including the simultaneous occurrence of different reactions, such as dehydration, recombination, polymerization and carbonation. To the best of our knowledge, there is the lack of sufficient information concerning pyrolysis characteristics of different part of bamboo. It is very helpful to investigate the pyrolysis behaviors and mechanism of bamboo materials. Thermogravimetric analyzer coupled with other techniques have been used to detect the chemical changes of biomass during pyrolysis process. Harun et al. (2013) used thermogravimetry coupled with mass spectrometry (PY-MS) to determine the gaseous products of agriculture and forestry biomass. They found that the degradation rate of combustible gas was about 20-30% at temperature of 200 and 230 , and the degradation of combustible gases was more than 30% when the temperature increased from 260 to 290 . Chen et al. (2016) investigated the bio-oil chemical composition of pine sawdust by Py-GC/MS and monitored the characteristic of ion fargments (H2, CH4, CO, and CO2). Kozlov et al. (2015) found that radical species concentration in gas produced from biomass gasification was too small to change gas-phase composition significantly. It is confirmed that PY-MS cannot accurately identify the molecular structure when the species have the same mass-to-charge ratio (m/z). Thermogravimetric coupled with Fourier Transform Infrared Spectroscopy (TG-FTIR) can effectively identify the compounds according to their functional groups and covalent bonding (Kai et al., 2017). Chen et al. (2015) used TG-FTIR to analyze the pyrolysis characteristics of moso bamboo and found that the changes in the absorbance of volatiles during pyrolysis agreed with the weight loss in the derivative thermogravimetric curve. Meng et al. (2013) found that the main pyrolysis gaseous products of corn cob, tree root and bagasse were CO2, CO, H2O, CH4, NH3, acid and aldehydes. Due to the complex reaction of pyrolysis process, the combination of Py-GC/MS and TG-FTIR can more accurately identify the gas released in the pyrolysis process. However, there were little information on bamboo pyrolysis, determined by the combination of Py-GC/MS and TG-FTIR, especially for OB, MB, 3
IB and bamboo leaves (BL). In this paper, pyrolysis characteristics of OB, MB, IB and BL were therefore determined through Py-GC/MS and TG-FTIR. The objective is to get pyrolysis information of moso bamboo with different parts and provided a theoretical guidelines to design manufacturing process of bio-energy from moso bamboo by thermal chemical conversion methods. 2. Material and methods 2.1 Material Moso bamboo aged 4 years old was taken from a bamboo plantation located in Zejiang Province, China. Bamboo tubes were cut off to 25 mm (longitudinal) by 4 mm (radial). OB was taken from out layer of bamboo with 1mm thickness and IB was taken from inner layer of bamboo with 1mm. Other residues were MB, which was cut off to 25mm (longitudinal) by 1mm (radial) by 1mm (tangential). BL was taken from the same bamboo. OB, MB, IB and BL were respectively broken down into particles using a Wiley mill and the size of bamboo particles was about 250-425µm. They were dried at temperature 105
until their mass stabilized.
2.2 The determination of pyrolysis characteristics Pyrolysis characteristics were observed in terms of global mass loss though TA Instrument TGA Q 500 thermogravimetric analyzer (TA Instrument, USA) under the nitrogen atmosphere. 5-8 mg samples were evenly and loosely distributed in an open pan. Pyrolysis temperature was controlled from room temperature (30±5 ) to 800 with heating rates of 10 /min, 20 /min, 30 /min, 40 /min. The high purity nitrogen flow rate of 60 mL/min was continuously passed into the furnace to prevent any unwanted oxidative decomposition. Three replicates of each TGA experiment were performed. 2.3 Kinetic model The fundamental rate equation used in all kinetics studies is generally described as: 4
dα = kf (α ) dt
(1)
Where, k is the rate constant and f(α) is the reaction model, a function depending on the actual reaction mechanism. Eq. (1) expresses the rate of conversion, dα/dt at a constant temperature as a function of the reactant conversion loss and rate constant. In this study, the conversion rate α is defined as:
α=
(w 0 - wt ) (w 0 - wf )
(2)
Where, wt, w0 and wf are time t, initial and final weight of the sample, respectively. The rate constant k is generally given by the Arrhenius equation:
- Ea k = Aexp RT
(3)
Where, Ea is the apparent activation energy (kJ/mol), R is the gas constant (8.314 J/K mol), A is the pre-exponential factor (min-1), T is the absolute temperature (K). The combination of Eqs. (1) and (3) gives the following relationship: dα - Ea = Aexp f (α ) dt RT
(4)
For a dynamic TGA process, including the heating rate, β=dT/dt, into Eq. (4), Eq. (5) is obtained as: d α A - Ea = exp f (α ) dT β RT
(5)
Eqs. (4) and (5) are the fundamental expressions of analytical methods to calculate kinetic parameters on the basis of TGA data. Flynn-Wall-Ozawa (FWO) method was used in this research, showed in Equation (6). As a representative model of the model-free kinetic model, which had high applicability to biomass pyrolysis (Ma et al., 2015; Apaydin-Varol et al., 2014). 5
A ⋅ Ea 0.4567 ⋅ Ea − 2.315 − log( βi ) = log R ⋅ Tα , i R ⋅ g(α )
(6)
Where, g(α) is usually constant and based on the integral reaction model at a specific conversion rate, so the formula: g(α)=α/(1-α), only consider the first order of the study. 2.4 The determination of pyrolysis compounds The thermogravimetric analyzer (CDS5200, USA) coupled with a quadrupole mass spectrometer (Agilent 6890N/5973i, USA) to investigate the distribution of volatiles from bamboo pyrolysis against reaction temperature. About 10 ± 0.02 mg of samples was loaded in the pyrolysis tube and the pyrolysis temperature was controlled from room temperature (30±5 ) to 500
at a heating rate of 10 /min. The dwelling
time of samples at temperature of 500
was set to be 3.0 min in order to ensure that
most of the solid sample was pyrolyzed. A high purity nitrogen stream (flow rate of 60 mL/min) was continuously passed into the furnace. The evolved volatiles were identified by GC/MS with the conditions given as: the injector temperature was kept at 280℃; the chromatographic separation was performed with a TR-35MS capillary column; the mass spectra were operated in electron ionization (EI) mode at 70 eV. The mass spectra were obtained from m/z 50 to 650. The yield of the compounds can be determined by the characterized GC/MS spectrums, according to the database of NIST library. Three replicates of each experiment were performed. 2.5 The determination of volatile gas TG-FTIR test was carried out using a combination of thermogravimetry (TA Instrument, USA) and Fourier transform infrared spectrometer (Bruker IFS 66/S, Bruker Optics, Billerrica, MA). Samples of 20±0.02mg were placed into crucible and heated from room temperature (30±5 ) to 800
at a heating rate of 10 /min. High
purity nitrogen as a purge and protective gas at a flow rate of 60ml/min. The sample pan was placed close to the end of the furnace, which combined with the high gas 6
flow to minimize the residence time of the evolved gases in the hot zone. To avoid liquefaction of the volatile gas when it passed through the capillary bundle, the temperature of the capillary bundle were heated to 250 . The system collected FTIR spectra every 30s and sample temperature and mass were logged every 3s. FTIR spectrum was collected in the range of 4000-400cm-1 at a resolution of 4cm-1. Three replicates of each experiment were performed. 3. Results and discussion 3.1 Pyrolysis characteristics Fig. 1 showed the TG and DTG curves of IB, MB, OB and BL at different
heating rates. There were three stages during pyrolysis process of samples. The pyrolysis temperature of lower than 200
was the first stage and weight loss was
mainly due to the evaporation of water in the bamboo and the release of a small amount of volatiles (Biswas et al., 2017). The main weight loss occurred at the second stage corresponding to pyrolysis temperature of 200-400 . The weight loss was about 70% of total sample weight, which was attributed to thermal degradation of volatiles, cellulose, hemicelluloses and partial lignin. Wang et al. (2018) found that cellulose pyrolysis mainly occurred at 300-400 , hemicellulose pyrolysis mainly occurred at 200-300
and lignin pyrolysis was from 200
until the end of pyrolysis process. It
was also found three small significant peaks in the DTG curve, corresponding to thermal degradation of protein, carbohydrate and lipid from three main chemical components of samples (Shuping et al., 2010). The three stage occurred at temperature of higher than 400
and weight loss was due to the slowly thermal
decomposition of fixed carbon. Fig. 1 showed that the pyrolysis curves of all samples shifted toward the higher temperature with increase in heating rates. This phenomenon is mainly attributed to uneven heating of sample particles (Maiti et al., 2007). Table 1 showed pyrolysis characteristics of IB, MB, OB and BL at heating rate
of 10 /min. Other pyrolysis characteristics at heating rate of 20 /min, 30 /min and 7
40 /min were not showed because they had a similar change trend with heating rate of 10 /min. The weight loss of IB, OB, MB, and BLwas 13.2%, 13.1%, 10.9% and 10.3% in the first stage, indicating that the quality of water and volatiles in BL was slightly lower than IB, MB, OB. Liu et al. (2016) found that BL had the lowest content of volatiles compared with OB, MB and IB. Similar, the weight loss of IB, OB, MB and BL was about 70% and the maximum of weight loss rate were 1.003%/ , 1.024%/ , 0.951%/
and 0.64%/ , respecively corresponding to
pyrolysis temperature of 346.1 , 348.1 , 337.9
and 318.4
in the second stage.
The main prolysis temperature range of BL was 237.6-408.5
and its reaction rate
was also the lowest. This phenonmenon was attributed to the difference of chemical components in the samples. Peng et al. (2013) found that BL had a higher H/C and O/C value, resulting in BL was more difficult to pyrolysis. The weight loss of IB, OB, MB, and BL was 6.6%, 8.7%, 5.8% and 9.3% in the three stage, respectively. The residues of IB, MB, OB and BL were 16.7%, 19.4%, 18.5%, 24.9%, respectively. 3.2 Kinetic analysis from FWO model Pyrolysis reaction parameters are helpful to accurately understand the microscopic reactions occurred in the pyrolysis process of biomass. Fig. 2 showed the linear relationship between 1/T and log(βi) at different conversion rates of samples in the FWO model. The linear equations at different conversion rates were nearly parallel, indicating that the activation energy of IB, OB, MB and BL at different conversion rates was approximate (Chen et al., 2014). Table 3 showed kinetic parameters of IB, OB, MB and BL at different conversion rates. The correlation coefficient of the linear relationship (R2 value) was higher, indicating that FWO model was suitable for obtaining activation energy of the samples. The frequency factor (A) can be used to characterize the reaction speed in pyrolysis process. The frequency factor varied at different conversion rates for IB, OB, MB and BL. The maximum of frequency factor corresponded to conversion rate of 0.5, 0.7, 0.6, 0.5 for IB, OB, MB and BL, respectively. The activation energy and frequency factor of all samples including IB, OB, MB and BL had the similar trend with increase in 8
conversion rate. The activation energy of IB varied in the ranges of 128.61-176.73KJ/mol and its maximum of activation energy was found at the conversion rate of 0.5. The activation energy of OB varied in the ranges of 141.02-224.41KJ/mol and its maximum of activation energy was found at the conversion rate of 0.7. The activation energy of MB varied in the ranges of 137.85-160.69KJ/mol and its maximum of activation energy was found at the conversion rate of 0.6. The activation energy of BL varied in the ranges of 159.69-187.56KJ/mol and its maximum of activation energy was found at the conversion rate of 0.5. This phenomenon was mainly related to the chemical composition and sytucture in different parts. Liu et al. (2016) confirmed that IB, OB, MB and BL had different contents of C, H, O, N and S, indicating they had different chemical compositions. Furthmore, three main chemical components were different pyrolysis characteristics. Cellulose is a semi-crystalline sturcture, whose pyrolysis occured from amorphous region to crystalline region. While lignin and hemicellulose are non-crystalline, whose pyrolysis needed lower activation energy than cellulose (Chen et al., 2014). They resulted in the different activation energy at different conversion rates for IB, OB, MB and BL. The lower activation energy indicated that biomass was easier to occur thermo-chemical conversion. Therefore, IB, OB, MB and BL should designed a different thermo-chemical conversion processes when they were used as raw materials to produce bioenergy or biochemicals. 3.2 Py-GC/MS analysis Fig.3 showed pyrolysis products distribution of IB, OB, MB and BL from
Py-GC/MS. There were mainly 6 families of compounds, including aldehyde, furan, phehol, ketone, ester, alcohol and acid. Moso bamboo contained a large number of phenol and a small amount of alcohol. The ketone and acid of MB were significantly lower than IB, OB and BL, but its contents of furan and phenolic compounds were obviously higher than other parts. The contents and types of chemical components of IB, MB, OB and BL had a great impact on these volatiles during pyrolysis process. Collard and Blin (2014) found that the depolymerization of lignin produced various 9
phenols. Hemicellulose mainly produced acetic acid, furfural and hydroxyacetone, etc (Wang et al., 2015). The different chemical compounds of bamboo resulted in different types and levels of volatiles (Sheng et al., 2002). Table 3 showed the typical precipitation materials of moso bamboo at different temperatures. It was confirmed that the composition of the precipitated material was very complicated and the number of C atoms varied from 2 to 30, containing aldehydes, ketones, carboxylic acids, esters, etc. IB, OB and MB mainly contained benzofuran, hydroxyacetaldehyde and 2-Pentanone, etc. However, the precipitated species of BL mainly included furan, acetic acid and phenol, etc. Compared with BL, the content of 2,3-dihydro-coumarone in the main products of IB, OB and MB were the higher, accounting for 11.06%, 9.54% and 6.30% of the total volatiles, respectively. 3-Hydroxy-4-methoxybenzoic acid was also main products of IB, OB and MB, but it was not found in the pyrolysis products of BL. Each part of moso bamboo had the unique product, such as butanoic acid-methyl ester for IB, p-Xylene and propanoic acid for OB, 2-Cyclohexen-1-ol, benzoic acid and 3, 4-dihydroxy- for MB, toluene and D-Limonene for BL. These detected substances with small molecular substances were firstly released due to their low thermal decomposition. With increase in pyrolysis temperature, some volatiles with the macromolecular substances were gradually released. These volatiles were divided into ketones, aldehydes and furans, which mainly come from the cracking, polymerization of lignin and the condensation of cellulose (Huang et al., 2011). It is well known that benzene ring was not easy to open loop in the pyrolysis process, so the organic matter in the product was mainly from Pyran ring opens of glucopyranose monomer and the fracture of C-C bond in the ring. These pyrolysis products could be used as the main intermediate of bioenergy and chemicals (Jimenez et al., 2017). 3.3 TG-FTIR analysis Moso bamboo contains natural macromolecular polymers, such as cellulose, hemicellulose and lignin. These macromolecules occur the reaction of cross-link polymerization and dehydrogenation oxidation in the pyrolysis process, which were often accompanied by the production of small molecule gases (Stefanidis et al., 2014). 10
Fig. 4 showed TG-FTIR spectra of IB, OB, MB and BL at heating rate of 10 /min. It
was found that pyrolysis products of moso bamboo varies greatly with increase in pyrolysis temperature. TG-FTIR spectra of IB, OB, MB and BL had acromion peaks at the temperature range from 100
to 400 . According to the widely used
Lambert-Beer law, the absorption spectrum at a specific wave number was linearly dependent on gas concentration (Gao et al., 2013). Thus, most of the gas was evolved at this temperature range during pyrolysis process of samples. The total intensity of IB was the highest and that of BL was the lowest, which were consistent with the results of Py-GC/MS. It can be determined the species of pyrolysis products based on FTIR spectrum. The absorbance peak at 3356cm-1 corresponded to the release of absorbed water (H2O). The absorbance peak at 2927cm-1 was the release of methane gas (CH4). The absorbance peak at 2359cm-1 indicated the release of carbon dioxide (CO2). The absorbance peak at 2179cm-1 appeared when carbon monoxide (CO) was released. The absorbance peak at 1770cm-1 was attributed to the release of carboxylic acids. The absorbance peak at 1684cm-1 confirmed the release of nitric oxide (NO). The absorbance peak at 1559cm-1was the release of nitrogen dioxide (NO2). The absorbance peak at 1119cm-1 was the release of phenol (Ma et al., 2015). Fig.5 showed the main pyrolysis products of IB, OB, MB and BL as a function
of temperature. MB and IB had the strongest intensity of H2O release, but the peak temperature corresponding to the maximum intensity of H2O release by IB was shifted to higher temperature. H2O released mainly from the evolution of bulk water, bound water and crystallization water in mineral substance in samples. With the temperature increases, the pyrolysis water forms also from the cracking or reaction of oxygen functional groups occurred in sample pyrolysis (Gao et al., 2013). BL contained less water content because it had the lowest intensity of H2O release. The main released temperature range of H2O was 150-350 . Carbon is the main type pf chemical compounds in bamboo. Carbon compounds were released during bamboo pyrolysis such as CH4, CO2 and CO. The evolution of CH4, CO2 and CO was mainly ascribed to the cleavage of functional groups (e.g. methoxyl group, ether group, 11
carboxyl and carbonyl group) and the secondary cracking of those phenolic compounds (Zhao et al., 2014). IB had a the strongest intensity of CH4 release and BL had the lowest intensity of CH4 release. The peak temperature corresponding to the maximum intensity of CH4 release was the lowest for MB. BL had two main release peaks of CH4. A weak peak of CH4 appeared at 500-600
presumably due to the
secondary decomposition of the organic compounds such as aldehydes, alcohols, acids and ketones leading to the breakage of the chains and the reforming reaction. The temperature ranges of CH4 release were 150-350 OB, 150-500
for MB, 150-400
for IB and
for BL. The CO2 was a type of main pyrolysis products for sampels.
The intensity of CO2 release for IB, OB and MB was obviously higher than that of BL. MB had the lowest peak temperature of the maximum CO2 release. It was found that the CO release had a similar trend with CO2 release. With increase in pyrolysis temperature, the peak intensity of CO2 and CO constantly changed. However, C=O and C-O showed acromion at the temperature of 150-350 , which was due to the pyrolysis of aliphatic compounds in hemicellulose (Jiang et al., 2012). The NO and NO2 release occured at the total temperature ranges and the variation was more obviously than other pyrolysis products. MB and IB had a obvious NO and NO2 release peak at temperature of 600-700 . For carboxylic acids and phenol, their release mianly occured at temperature of 150-400
and each sample had two main
peaks. In conclusion, the peak intensity of a specific wavenumber represented the release concentration of pyrolysis products (Granada et al., 2012). The results indicated that pyrolysis products of IB was the most and that of BL was the lowest. MB had the lowest release temperature of all pyrolysis products. 4. Conclusion
The pyrolysis process of IB, OB, MB and BL was similar, but the pyrolysis characteristics were different. With the increase of the heating rate, the pyrolysis process shifted toward higher temperature. IB, OB, MB and BL had a different activation energy at different conversion rates. Temperature had an important impact on the pyrolysis products of moso bamboo. Even though there were mainly 6 families 12
of compounds, including aldehyde, furan, phehol, ketone, ester, alcohol and acid, their distribution of each sampels was different. The main pyrolysis products included H2O, CH4, CO2, CO, carboxylic acids, NO, NO2 and phenol. Acknowledgments
This research was financially supported by ‘13th Five Years Plan-Study on manufacturing technology of bamboo wastes and its mechanism (Grant No. 2016YFD0600906). References
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1.2
1.2
0.6
60
40
0.3
20
80
300
400
500
600
700
10 20 30 40
/min /min /min /min
0.6 60
0.3
40
0.0 100
200
300
400
500
600
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Temperature ( )
Temperature ( ) 1.2
Mass loss (%)
80
60
1.2 100
0.9
0.6
40 0.3 20
(d)
10 20 30 40
)
(c)
Derivative mass loss (%/ Mass loss (%)
100
0.9
80
/min /min /min /min
0.6 60
0.3
40
20
0.0
0.9
)
200
/min /min /min /min
20
0.0 100
10 20 30 40
)
0.9
(b)
Derivative mass loss (%/
100
Derivative mass loss (%/
Mass loss (%)
80
/min /min /min /min
)
10 20 30 40
Mass loss (%)
(a)
Derivative mass loss (%/
100
0.0
0 100
200
300
400
500
600
700
100
Temperature ( )
200
300
400
500
600
700
Temperature ( )
Fig.1 The pyrolysis process of moso bamboo at different heating rates
(a. IB; b. OB; c. MB; d. BL)
17
1.7
1.7
(b)
(a)
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.5
log(β)
1.4 1.3
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.6 1.5 1.4
log(β)
1.6
1.3
1.2
1.2
1.1
1.1
1.0
1.0
0.0015
0.0016
0.0017
0.0018
0.0019
0.0020
0.00152
0.00160
1/T
0.00184
1.7
(c)
(d)
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.5 1.4 1.3
0.1 0.2 0.3 0.4 0.5 0.6 0.7
1.6 1.5 1.4
log(β)
1.6
log(β)
0.00176
1/T
1.7
1.3
1.2
1.2
1.1
1.1 1.0
1.0 0.00152
0.00160
0.00168
0.00176
0.00184
0.00192
0.00200
0.00135
0.00150
0.00165
0.00180
0.00195
0.00210
1/T
1/T
Fig.2
0.00168
Non-isothermal plot of FWO method at different conversion rates (a. IB; b. OB; c. MB; d. BL) 18
30
IB OB MB BL
25
Peak area (%)
20
15
10
5
0
eh Ald
yde
n e ol Fura Phen Keton
l r Este Alcoho
Acid
Fig.3 Pyrolysis products distribution of IB, OB, MB and BL from Py-GC/MS
20
0.14
IB OB MB BL
0.12 0.10
Intensity
0.08 0.06 0.04 0.02 0.00 100
200
300
400
500
Temperature (
21
)
600
700
Fig. 4 TG-FTIR spectra of sampels at heating rate of 10 /min
22
0.035
3566
0.020
IB OB MB BL
0.030 0.025
2927
IB OB MB BL
0.015
Intensity
Intensity
0.020 0.015 0.010
0.010
0.005
0.005 0.000
0.000 -0.005
-0.005
100
200
300
400
500
Temperature (
600
700
100
200
)
300
400
500
Temperature (
600
700
)
0.020
0.14
2359
2179
IB OB MB BL
0.12 0.10
0.015
Intensity
Intensity
0.08 0.06
IB OB MB BL
0.04
0.010
0.005
0.02 0.000
0.00 100
200
300
400
500
Temperature (
0.10
600
100
700
300
400
500
600
700
)
0.025
1770
1684
IB OB MB BL
0.08
0.015
Intensity
0.04
IB OB MB BL
0.020
0.06
Intensity
200
Temperature (
)
0.010
0.005 0.02 0.000 0.00 100
200
300
400
500
600
700
100
200
Temperature ( )
300
400
500
Temperature (
0.025
600
700
)
0.045
IB OB MB BL
1559 0.020
0.015
0.040
IB OB MB BL
1119
0.035 0.030
Intensity
Intensity
0.025 0.010
0.005
0.020 0.015 0.010 0.005
0.000
0.000 -0.005
-0.005 100
200
300
400
500
Temperature (
600
700
100
)
200
300
400
500
Temperature (
600
700
)
Fig. 5 The main pyrolysis products of sampels as a function of temperature
24
Table 1 Pyrolysis characteristics of moso bamboo at different heating rates
The first step
Samples
Start
End
The second step
Weight
Start
End
loss ( )
( )
(%)
Weight
The third step
Start
( )
(%)
( )
Residues
loss
(%)
End
loss ( )
Weight
( ) (%)
31.2
261.8
13.2
261.8
395.7
63.4
395.7
736.6
6.6
16.7
±1.6
±3.5
±0.9
±3.5
±3.8
±1.2
±3.8
±9.8
±0.2
±0.07
30.5
281.4
13.1
281.4
402.7
58.2
402.7
725.1
8.7
19.4
±1.0
±5.6
±1.6
±5.6
±4.3
±1.9
±4.3
±6.8
±0.4
±0.05
30.6
252.9
10.9
252.9
421.5
64.5
421.5
758.9
5.8
18.5
±1.5
±6.7
±1.3
±6.7
±9.6
±1.2
±9.6
±8.3
±0.5
±0.1
30.7
237.6
10.3
237.6
408.5
55.3
408.5
721.9
9.3
24.9
±1.6
±6.4
±1.2
±6.4
±7.8
±2.1
±7.8
±9.1
±1.3
±0.5
IB
OB
MB
BL
25
Table 2 The kinetic parameters of samples at different conversion rates
Samples
Cr
Linear equation
R2
Ea (KJ/mol)
A (min-1)
0.1
y= -7064.49x+14.62
0.8070
128.61
3.00E+12
0.2
y= -8604.87x+16.51
0.9447
156.65
4.30E+14
IB
26
OB
MB
BL
0.3
y= -9258.39x+17.08
0.9449
168.54
2.54E+15
0.4
y= -9660.55x+17.28
0.9525
175.87
5.96E+15
0.5
y= -9707.99x+16.95
0.9738
176.73
4.19E+15
0.6
y= -9375.48x+16.15
0.9789
170.68
1.04E+15
0.7
y= -9279.02x+15.72
0.9980
168.92
6.08E+14
0.1
y= -7746.39x+15.27
0.9733
141.02
1.23E+13
0.2
y= -8047.74x+15.08
0.9900
146.51
1.71E+13
0.3
y= -8571.49x+15.45
0.9938
156.04
6.38E+13
0.4
y= -9089.25x+15.87
0.9938
165.47
2.47E+14
0.5
y= -9317.33x+15.95
0.9958
169.62
4.34E+14
0.6
y= -9244.46x+15.59
0.9923
168.29
2.90E+14
0.7
y= -12326.89x+19.89
0.9899
224.41
6.73E+18
0.1
y= -7572.29x+15.58
0.9386
137.85
2.56E+13
0.2
y= -8089.38x+15.55
0.9752
147.26
4.97E+13
0.3
y= -7963.07x+14.78
0.9189
144.96
1.49E+13
0.4
y= -8187.09x+14.77
0.9184
149.04
2.19E+13
0.5
y= -8654.51x+15.22
0.9631
157.55
8.83E+13
0.6
y= -8826.69x+15.24
0.9982
160.69
1.34E+14
0.7
y= -8411.49x+14.22
0.7208
153.13
2.12E+13
0.1
y= -7572.29x+15.58
0.9386
159.69
1.03E+16
27
0.2
y= -8089.38x+15.55
0.9752
177.56
9.97E+16
0.3
y= -7963.07x+14.78
0.9189
179.63
4.55E+16
0.4
y= -8187.09x+14.77
0.9184
182.47
3.12E+16
0.5
y= -8654.51x+15.22
0.9631
187.56
4.29E+16
0.6
y= -8826.69x+15.24
0.9982
168.19
2.95E+14
0.7
y= -8411.50+14.22
0.7208
165.13
4.50E+12
Cr is cinversion rate; R2 is correlation coefficient value; Ea is activation energy; A is exponential factor.
28
Table 3 The typical precipitation materials of moso bamboo at different temperatures 29
Temperature
Area (%)
Molecular m/z
Family
Compounds
formula
( )
IB
OB
MB
BL
25.99
82
C5H6O
Furan
Furan,2-methyl-
0.145
－
0.821 5.697
28.89
60
C2H4O2
Acid
Acetic acid
1.775
1.264
1.075 2.403
41.88
86
C5H10O
Ketone
2-Pentanone
－
－
2.163
－
51.43
92
C7H8
Benzene
Toluene
－
－
－
0.737
77.95
102
C5H10O2
Ester
0.344
－
－
－
－
0.691
－
－
－
0.254
－
－
－
－
Butanoic acid, methyl ester
81.76
106
C8H10
Benzene
87.68
102
C4H6O3
Ester
p-Xylene Propanoic acid, 2-oxo-, methyl ester
92.7
103
C4H9NO2
Amino acid
L-Alanine,N-methyl-
0.594
－
98.44
96
C5H4O2
Aldehyde
Furfural
2.517
2.791
121.64
136
C10H16
Alkene
D-Limonene
－
－
－
2.137
136.62
98
C6H10O
Alcohol
2-Cyclohexen-1-ol
－
－
0.281
－
139.7
94
C6H6O
Phenol
Phenol
0.72
0.591
0.656 1.166
150.09
84
C4H4O2
Ketone
2(5H)-Furanone
0.866
0.939
0.965 1.072
160.97
114
C4H6N2O2
Ketone
0.906
1.661
0.95
2.897 3.275
2,4-Imidazolidinedion 0.991
e, 3-methyl-
169.55
108
C7H8O
Phenol
Phenol, 4-methyl- 4
0.402
0.443
0.374 0.824
179.64
124
C7H8O2
Phenol
Phenol, 2-methoxy-
2.124
2.142
2.284 0.682
30
2-Cyclopenten-1-one, 187.86
126
C7H10O2
Ketone
0.269
－
－
0.281
0.346
－
0.273
－
－
1.096
－
－
0.456
－
－
－
3-ethyl-2-hydroxy-
197.22
122
C8H10O
Phenol
206.95
138
C8H10O2
Phenol
C4H4N2O3
Pyrimidine
C8H8O
Furan
C9H12O2
Phenol
Phenol, 4-ethylPhenol, 2-methoxy -3-methyl2,4,5-Trihydroxypyri
213.05
219.15
128
120
midine Benzofuran,
11.06
2,3-dihydro-
1
6.295
9.547 0.793
0.877
0.991
1.054 0.533
－
0.606
－
0.325
－
0.722
－
－
－
0.51
－
－
－
－
0.266
－
0.809
0.409
2.641 0.395
2.252
3.788
0.777 0.568
2.19
3.161
1.659
Phenol, 229.97
152
4-ethyl-2-methoxy-
231.78
212
C15H32
Alkane
240.48
162
C10H10O2
Ketone
C11H14O2
Ester
C7H6O4
Acid
C7H6O2
Aldehyde
C10H12O2
Phenol
C8H8O4
Acid
Pentadecane Ethanone,1,1'-(1,4-ph enylene)bisBenzoic acid, butyl
250.63
178
ester Benzoic
260.78
154
acid,3,4-dihydroxyBenzaldehyde,
271.9
122
4-hydroxyPhenol, 2-methoxy
280.72
164
-4-(1-propenyl)-,(E)3-Hydroxy-4-methox
288.39
168
ybenzoic acid 31
－
2-Cyclohexen-1-one, 302.78
168
C10H16O2
Ketone
0.368
－
－
0.457
5.818
－
5.865
3.948
2.082
－
dimethoxy-4-(2-prope 1.485
1.59
6.897 3.344
0.661
0.473
0.264
－
6.818
5.854
1.668
－
0.303
－
－
－
－
0.564
0.274
－
0.32
0.266
0.766
－
2-hydroxy-4,4,6,6-tetr
－
amethylBenzoic acid, 307.67
182
C9H10O4
Ester
4-hydroxy-3-methoxy 0.458 -, methylester 4-Methyl-2,5-dimetho
318.91
180
C10H12O3
Aldehyde xybenzaldehyde Phenol, 2,6-
323.92
194
C11H14O3
Phenol
nyl)N-(4-Methoxyphenyl) 336.97
194 C9H10N2O3
Acetamide
-2-hydroxyimino-acet amide 3-Hydroxy-4-methox
348.63
194
C10H10O4
Acid ycinnamic acid Hexanedioic acid,
359.69
258
C14H26O4
Ester
bis(2-methylpropyl) ester 1,2-Benzenedicarbox ylic acid,
370.08
278
C16H22O4
Ester bis(2-methylpropyl) ester 2-Propenoic acid,3-
381.99
208
C11H12O4
Acid
(4-hydroxy3-methoxyphenyl)-, 32
methyl ester 391.47
278
C16H22O4
Ester
Dibutyl phthalate
0.88
3.391
0.789 1.104
3.096
－
－
－
1.131
0.739
1.823
－
0.443
1.137
－
－
1.973
－
0.613 0.555
－
－
0.789
－
0.886
－
－
－
E)-2,6,10,14,18,22Tet racosahexaene,2,6,10, 404.46
410
C30H50
Carbene 15,19,23-hexamethyl, (all-E)3,5-Dimethoxy-4-hyd
420.11
208
C11H12O4
Aldehyde roxycinnamaldehyde 2-Hepten-4-one,6-hyd roxy-2-methyl-6(4-m
435.46
236
C15H24O2
Ketone ethyl-3-cyclohexen-1yl)Hexanedioic acid,
442.22
370
C22H42O4
Ester
bis(2-ethylhexyl) ester (+-)-3-(2-Carboxy-tra ns-propenyl)-2,2-dim
467.78
198
C10H14O4
Alkane
ethylcyclopropane-tra ns-1-carboxylicacid,[ 1.alpha., 3.beta.(E)] (E,Z)-2,6-Undecadien oic acid,
467.84
238
C15H26O2
Acid 7-ethyl-3-methyl-, methyl ester, (E,Z)-
33
>Pyrolysis process of all samples included three stages. > The faster is heating rate, the higher is pyrolysis temperature; > A different activation energy pf bamboo corresponded to different conversion rates. > Bamboo pyrolysis included 6 families compounds. > Pyrolysis products included H2O, CH4, CO2, CO, carboxylic acids, NO, NO2 and phenol.
36