棕榈壳酶解-温和酸解木质素的结构及热解特性研究

常国璋; 谢建军; 杨会凯; 黄艳琴; 阴秀丽; 吴创之

棕榈壳酶解-温和酸解木质素的结构及热解特性研究

常国璋^{1, 2},
谢建军¹,
杨会凯^{1, 3},
黄艳琴^1, ,,
阴秀丽¹,
吴创之¹

1.
中国科学院广州能源研究所中国科学院可再生能源重点实验室, 广东广州 510640
2.
中国科学院大学, 北京 100049
3.
中国科技大学化学与材料科学学院, 安徽合肥 230026

基金项目:

国家自然科学基金 51176194

详细信息

中图分类号: TK6
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- 被引次数: 0
出版历程
- 收稿日期: 2016-03-11
- 修回日期: 2016-07-04
- 网络出版日期: 2021-01-23
- 刊出日期: 2016-10-10

Structure and pyrolysis characteristics of enzymatic/mild acidolysis lignin isolated from palm kernel shell

1.
CAS Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
2.
University of Chinese Academy of Sciences, Beijing 100049, China
3.
School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China

More Information

Corresponding author: E-mail: huangyq@ms.giec.ac.cn

摘要

摘要: 采用酶解/温和酸解法提取了棕榈壳和麦秆的木质素（EMALs），利用傅里叶红外光谱（FT-IR）、裂解器-气相色谱质谱联用（Py-GC/MS）和热重-红外联用（TG-FTIR）技术，对两种EMALs的化学结构和热解特性进行了对比研究，并采用Ozawa-Flynn-Wall方法计算了其热解反应的活化能。结果表明，棕榈壳EMAL和麦秆EMAL均为HGS型木质素。500℃下，两种EMALs的热解产物主要包括酚类、酸类和少量的醇类、醛酮类等化合物；棕榈壳EMAL热解酚类产物中H、G、S型单体酚类的比例分别为47.61%、25.64%和17.18%，而麦秆EMAL分别为23.66%、51.90%和15.50%。在热解反应主失重区（200-380℃），棕榈壳EMAL的主失重速率（50.80%/min）低于麦秆EMAL（78.63%/min）；但棕榈壳EMAL热解同时存在肩状失重峰（265℃，27.40%/min），这与其较多H结构产物的释放相关。H型结构产物释放的放热效应降低了棕榈壳EMAL热解初期的活化能（20%，127.92 kJ/mol），同时使其热解过程（20%-80%）的平均活化能（152.32 kJ/mol）低于麦秆EMAL（161.75 kJ/mol）。
- 棕榈壳 /
- 木质素 /
- 化学结构 /
- 热解 /
- 活化能
Abstract: Firstly, lignin of palm kernel shell (PKS) and wheat straw (WS) were isolated by enzymatic/mild acidolysis method (EMAL). Then the functional groups and thermal decomposition characteristics of the two EMALs were analyzed with Fourier transform infrared spectroscopy (FT-IR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and TG-FTIR. At last, the Ozawa-Flynn-Wall method was used to calculate the activation energy of pyrolysis of the two EMALs. FT-IR result show that both PKS-EMAL and WS-EMAL are Type HGS. Phenols, acids, few of alcohols, aldehydes and ketones are detected in volatile products from 500℃ pyrolysis of the two EMALs. Meanwhile, H-type, G-type and S-type phenols with proportions of 47.61%, 25.64% and 17.18% are obtained in phenolic products from PKS-EMAL pyrolysis; while they are 23.66%, 51.90% and 15.50%, respectively, in phenolic products of WS-EMAL. During 200-380℃, the main weight loss rate of PKS-EMAL pyrolysis is 50.80%/min, which is obviously lower than that (78.63%/min) of WS-EMAL. A shoulder peak of 27.40%/min at 265℃ is also observed in PKS-EMAL pyrolysis, which is closely related to release of H-derivatives during PKS-EMAL pyrolysis. The activation energy (127.92 kJ/mol) of PKS-EMAL pyrolysis at a conversion of 20% reduced by the exothermic effect corresponding torelease of H-derivatives, which was the main reason that the average activation energy (152.32 kJ/mol) of PKS-EMAL pyrolysis (20%-80%) was lower than that (161.75 kJ/mol) for WS-EMAL pyrolysis.
- palm kernel shell /
- lignin /
- chemical structure /
- pyrolysis /
- activation energy

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图 1 PKS-EMAL、WS-EMAL的FT-IR谱图

Figure 1 FT-IR spectra of EMALs isolated from PKS and WS

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图 2 PKS-EMAL FT-IR谱图中1 595、1 271、1 115 cm^-1峰形的拟合结果

Figure 2 Fitting results of 1 595, 1 271, 1 115 cm^-1 peaks obtained from FT-IR of PKS-EMAL

a: fit peak 1; b: fit peak 2; c: fit peak 3; d: cumulative fit peak; e: subtracted raw data

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图 3 PKS-EMAL、WS-EMAL中G型、S型基本结构的FT-IR信息

Figure 3 Information of G-type and S-type structure in the EMALs of PKS and WS

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图 4 PKS-EMAL、WS-EMAL 500 ℃快速热解的GC/MS总离子流图

Figure 4 Total ion chromatogram obtained by Py-GC/MS of EMALs isolated from PKS and WS

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图 5 PKS-EMAL和WS-EMAL 500 ℃热解酚类生物油的种类分布

Figure 5 Distribution of main types of bio-oils from pyrolysis of PKS-EMAL and WS-EMAL at 500 ℃

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图 6 PKS-EMAL、WS-EMAL热解过程的TG和DTG曲线

Figure 6 TG and DTG curves of pyrolysis of EMALs isolated from PKS and WS

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图 7 PKS-EMAL、 WS-EMAL热解不同时期挥发产物的FT-IR谱图

Figure 7 FT-IR spectra for the volatile components from pyrolysis of EMALs isolated from PKS and WS

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图 8 采用Ozawa-Flynn-Wall 计算两种EMALs热解活化能的拟合线

Figure 8 Regression lines to conversion of 20%-80% based on the Ozawa-Flynn-Wall method for two EMALs at 5, 10, 20, 30 K/min

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表 1 PKS-EMAL、WS-EMAL FT-IR谱图的解析^{[3, 10]}

Table 1 FT-IR spectra analysis of EMALs isolated from PKS and WS

Num. in Figure 1	Wavenumber σ/cm^-1		Band assignment
Num. in Figure 1	PKS-EMAL	WS-EMAL	Band assignment
1	3 403	3 403	O-H stretching
2	2 934	2 923, 2 855	C-H stretching
3	-	1 652	C=O stretching in conjugated aryl ketones
4	1 597	1 601	aromatic skeleton vibrations
5	1 465	1 462	C-H deformations
6	1 427	1 427	aromatic skeleton vibrations & C-H in plane deformations
7	1 367	1 367	aliphatic C-H stretching in-CH₃ and phen.OH
8	1 271	1 269	C-O stretching in-OCH₃ and phen.OH of G type
9	1 229	1 229	C-C+C-O+C=O stretching
10	1 160	1 160	C=O in ester groups, typical for HGS lignins
11	1 115	1 116	C-H stretching of typical S unit
12	1 036	1 036	aromatic C-H in plane deformation & C-O stretching
13	700-900	700-900	Aromatic hydrogen

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表 2 PKS-EMAL、WS-EMAL 500 ℃热解生物油的主要组分及相对含量

Table 2 Main chemical constituents of bio-oils from pyrolysis of PKS-EMAL and WS-EMAL at 500 ℃

Retention time t/min	Components of bio-oil	Structuralformula	Molecular formula	Relative content w/%
Retention time t/min	Components of bio-oil	Structuralformula	Molecular formula	PKS-EMAL	WS-EMAL
Acids & alcohols
2.06	acetic acid		C₂H₄O₂	1.54	-
14.22	1, 6-anhydro-β-glucopyranose		C₆H₁₀O₅	-	2.17
16.61	tetradecanoic acid		C₁₄H₂₈O₂	1.23	1.62
18.36	cis-9-hexadecenoic acid		C₁₆H₃₀O₂	0.86	0.56
18.62	n-hexadecanoic acid		C₁₆H₃₂O₂	4.69	5.54
20.17	6-octadecenoic acid		C₁₈H₃₄O₂	1.28	2.88
20.42	octadecanoic acid		C₁₈H₃₆O₂	4.46	5.00
22.04	eicosanoic acid		C₂₀H₄₀O₂	0.34	0.56
22.73	dehydroabietic acid		C₂₀H₂₈O₂	-	2.13
23.45	phthalicacid, 2-ethylhexylester		C₁₆H₂₂O₄	3.25	3.99
	total			17.65	24.45
Aldehydes & ketones
3.38	furfural		C₅H₄O₂	2.23	-
11.08	(Z)-pent-2-en-1-yl acetate		C₇H₁₂O₂	1.35	-
22.29	diisooctyladipate		C₂₂H₄₂O₄	0.10	0.57
	others			0.78	0.41
	total			4.46	0.98
Phenols
6.54	Phenol		C₆H₆O	6.49	0.26
7.94	2-methoxy-phenol		C₇H₈O₂	1.42	2.39
7.99	phenol, 4-methyl-		C₇H₈O	0.64	-
9.28	4-methyl-2-methoxyphenol		C₈H₁₀O₂	2.88	2.64
10.21	1, 2-benzenediol		C₆H₆O₂	1.86	2.34
10.54	1, 2-benzenediol, 3-methoxy-		C₇H₈O₃	1.07	0.51
10.72	phenol, 4-ethyl-2-methoxy-		C₉H₁₂O₂	0.63	0.46
10.97	1, 2-benzenediol, 3-methyl-		C₇H₈O₂	0.48	1.35
11.00	1, 2-benzenediol, 4-methyl-		C₇H₈O₂	1.52	-
11.21	2-methoxy-4-vinylphenol		C₉H₁₀O₂	2.95	4.06
11.36	2, 6-dimethoxyphenol		C₈H₁₀O₃	1.92	2.17
11.77	phenol, 2-methoxy-3-(2-propenyl)-		C₁₀H₁₂O₂	0.30	0.89
11.90	2-methoxy-4-(1-propenyl)phenol		C₁₀H₁₂O₂	0.19	4.18
11.91	phenol, 2-methoxy-4-propyl-		C₁₀H₁₄O₂	-	0.18
12.34	vanillin		C₈H₈O₃	0.54	1.70
12.42	2-methoxy-4-(1-propenyl)-phenol		C₁₀H₁₂O₂	0.24	-
12.58	4-ethylcatechol		C₈H₁₀O₂	-	0.90
12.93	3-methoxy-4-hydroxybenzoicacid		C₈H₈O₄	3.06	-
13.42	4-acetyl-2-methoxyphenol		C₉H₁₀O₃	0.36	0.92
13.95	homovanillic acid		C₉H₁₀O₄	0.65	4.53
14.35	benzoicacid, 4-hydroxy-		C₇H₆O₃	16.1	10.3
14.79	4-allyl-2, 6-dimetoxyphenol		C₁₁H₁₄O₃	5.41	4.03
15.44	siringic aldehyde		C₉H₁₀O₄	0.51	-
15.61	coniferylic alcohol		C₁₀H₁₂O₃	-	1.54
16.24	acetosyringone		C₁₀H₁₂O₄	0.57	-
16.29	p-coniferaldehyde		C₁₀H₁₀O₃	-	2.65
	others			5.85	2.55
	total			55.64	50.55
Others
21.89	1-phenanthrenecarboxylicac		C₂₁H₃₀O₂	-	0.63
24.43	(-)-pterocarpin		C₁₇H₁₄O₅	-	0.35
25.47	squalene		C₃₀H₅₀	-	2.99
	loss of column & unknowns			20.31	17.25
	total			20.31	21.22

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表 3 Ozawa-Flynn-Wall 计算拟合线的相关系数与活化能

Table 3 Correlation coefficient (R²) and activation energy (E_a) calculated from the Ozawa-Flynn-Wall method

Conversion x/%	PKS-EMAL		WS-EMAL
Conversion x/%	E_a/(kJ·mol^-1)	R²	E_a/(kJ·mol^-1)	R²
20	127.92	0.980 1	244.34	0.959 9
30	135.76	0.969 3	139.75	0.993 9
40	139.71	0.949 5	134.28	0.997 9
50	140.39	0.956 7	130.98	0.998 9
60	139.88	0.961 8	128.80	0.998 9
70	153.43	0.974 9	129.68	0.998 7
80	229.16	0.985 5	224.44	0.979 1
Average	152.32	0.968 2	161.75	0.989 6

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