Effect of ionic liquid pretreatment on eucalyptus char structure and its reactivity

doi:10.11949/0438-1157.20201133

Abstract

Abstract:

Biomass is an ideal raw material for renewable energy, and it is difficult to use effectively because of its hard lignin shell protection. Ionic liquid (IL) was a green solvent which could be used in pretreating and improving the use efficiency of the biomass. To investigate the effects of IL on the pyrolytic char structure and its reactivity, eucalyptus powder was pyrolyzed in quartz reactor under 650℃. After being pretreated by IL ([Bmim]Cl, [Bmim]OAc and [Bmim]H₂PO₄) with a concentration of 2%, 4%, 8% at 120℃ for 2 h, the structure of char obtained was characterized by SEM, FTIR, XRD and Raman spectrum. The reactivity of char with air at 450℃ was also evaluated with thermal gravimetric analysis (TGA). The results showed that the yield of the char decreased with the increasing of the IL concentration, while the crystallinity was enhanced. The decrease in I_D1/I_G and an increase of I_G/I_all in Raman spectrum indicated an improvement in the order of the char structure, and the promotion of the transformation of small aromatic ring system into the large one, which led to a decrease reactivity of the biochar. IL pretreatment can adjust the reactivity of the pyrolytic biochar conveniently, and can provide effective way in using biomass with high value added.

Key words: ionic liquid, eucalyptus, pyrolysis, biochar, reactivity

摘要：

生物质是可再生能源的理想原料，由于生物质有坚硬的木质素外壳保护而难以被有效利用。离子液体（IL）是一种绿色溶剂，可用于木质纤维素预处理从而提高其利用的效率。为了研究IL水溶液预处理对桉木热解产半焦的结构及其反应性的影响，将桉木粉经2%、4%和8%（质量）离子液体（[Bmim]Cl、[Bmim]OAc和[Bmim]H₂PO₄）水溶液在120℃下预处理2 h，然后将预处理后的桉木粉在650℃下热解。采用SEM、FTIR、XRD和Raman分析表征热解半焦的结构变化，利用热重分析仪（TGA）测定半焦与空气在450℃下的反应性。结果表明，随着预处理IL浓度的增加，半焦产率下降，半焦的晶化程度提高，在拉曼光谱中，I_D1/I_G变小，I_G/I_all变大，这表明IL预处理使半焦结构有序增大，并促进半焦中小芳香环向大芳香环聚并，因而降低了半焦的反应性。IL预处理可便捷调节热解半焦的反应性，为生物质的高值化利用提供有效的制备方法。

关键词: 离子液体, 桉木, 热解, 半焦, 反应性

CLC Number:

TK 6

HUANG Zhongyi, SHI Liubin, FENG Yajun, LI Lishuo. Effect of ionic liquid pretreatment on eucalyptus char structure and its reactivity[J]. CIESC Journal, 2021, 72(4): 2267-2275.

黄中艺, 史刘宾, 冯亚军, 李立硕. 离子液体预处理对桉木热解半焦结构和反应性的影响[J]. 化工学报, 2021, 72(4): 2267-2275.

Figures/Tables 9

Fig.1 Experimental device

Fig.2 Yield of biochar pretreated with different concentrations of ILs

Fig.3 SEM image of biochar prepared by different IL and concentration

Fig.4 FTIR spectrum of char prepared by different IL pretreatment

Fig.5 XRD of char obtained by pyrolysis of eucalyptus pretreated by different IL

Fig.6 Raman spectra of untreated and IL pretreated eucalyptus pyrolysis to prepare biochar

Fig.7 Curve-fitting of the Raman spectra of biochar from pretreated with 2%[Bmim]Cl

Fig.8 Band ratio of ID1/ IG and IG/ Iall of biochar from eucalyptus pretreated with different concentration ILs

Fig.9 Reaction curve of pyrolysis of eucalyptus coke prepared by different IL pretreatment

References 40

1	孟晓晓, 孙锐, 袁皓, 等. 不同热解温度下玉米秸秆中碱金属K和Na的释放及半焦中赋存特性[J]. 化工学报, 2017, 68(4): 1600-1607.
	Meng X X, Sun R, Yuan H, et al. Effect of different pyrolysis temperature on alkali metal K and Na emission and existence in semi-char [J]. CIESC Journal, 2017, 68(4): 1600-1607.
2	刘德军, 王尤清, 于淑娟, 等. 提高焦炭热态性能的钝化处理技术研究[J]. 中国冶金, 2006, 16(12): 27-30.
	Liu D J, Wang Y Q, Yu S J, et al. Research on passivation treating technology for improving thermal properties of coke[J]. China Metallurgy, 2006, 16(12): 27-30.
3	Keown D M, Hayashi J, Li C. Drastic changes in biomass char structure and reactivity upon contact with steam[J]. Fuel, 2008, 87: 1127-1132.
4	Tilghman M B, Mitchell R E. Coal and biomass char reactivities in gasification and combustion environments[J]. Combustion and Flame, 2015, 162(9): 3220-3235.
5	Surup G R, Foppe M, Schubert D, et al. The effect of feedstock origin and temperature on the structure and reactivity of char from pyrolysis at 1300—2800℃[J]. Fuel, 2019, 235: 306-316.
6	Wang G, Zhang J, Chang W, et al. Structural features and gasification reactivity of biomass chars pyrolyzed in different atmospheres at high temperature[J]. Energy, 2018, 147: 25-35.
7	Septien S, Escudero Sanz F J, Salvador S, et al. The effect of pyrolysis heating rate on the steam gasification reactivity of char from woodchips[J]. Energy, 2018, 142: 68-78.
8	Yu Y, Kong J, Wang M, et al. Structure and oxidation reactivity of char: effects of pyrolysis heating rate and pressure[J]. Journal of Fuel Chemistry and Technology, 2018, 46(9): 1025-1035.
9	Qi X, Guo X, Xue L, et al. Effect of iron on Shenfu coal char structure and its influence on gasification reactivity[J]. Journal of Analytical and Applied Pyrolysis, 2014, 110: 401-407.
10	Li N, Te G, Liu Q, et al. Effect of metal ions on the steam gasification performance of demineralized Shengli lignite char[J]. International Journal of Hydrogen Energy, 2016, 41(48): 22837-22845.
11	Lu R, Wang J, Liu Q, et al. Catalytic effect of sodium components on the microstructure and steam gasification of demineralized Shengli lignite char[J]. International Journal of Hydrogen Energy, 2017, 42(15): 9679-9687.
12	Zhang X, Wang J, Liu Q, et al. The Effects of sodium and alkalinity on the microcrystalline structure and the steam gasification performance of Shengli lignite[J]. Journal of Analytical and Applied Pyrolysis, 2017, 125: 227-233.
13	Verdía P, Brandt A, Hallett J P, et al. Fractionation of lignocellulosic biomass with the ionic liquid 1-butylimidazolium hydrogen sulfate[J]. Green Chemistry, 2014, 16(3): 1617-1627.
14	Ninomiya K, Inoue K, Aomori Y, et al. Characterization of fractionated biomass component and recovered ionic liquid during repeated process of cholinium ionic liquid-assisted pretreatment and fractionation[J]. Chemical Engineering Journal, 2015, 259: 323-329.
15	Swatloski R P, Spear S K, Holbrey J D, et al. Dissolution of cellulose with ionic liquids[J]. J. Am. Chem. Soc., 2002, 124: 4974-4975.
16	Elgharbawy A A, Alam M Z, Moniruzzaman M, et al. Ionic liquid pretreatment as emerging approaches for enhanced enzymatic hydrolysis of lignocellulosic biomass[J]. Biochemical Engineering Journal, 2016, 109: 252-267.
17	Ma H, Zhang B, Zhang P, et al. An efficient process for lignin extraction and enzymatic hydrolysis of corn stalk by pyrrolidonium ionic liquids[J]. Fuel Processing Technology, 2016, 148: 138-145.
18	Khan A S, Man Z, Bustam M A, et al. Efficient conversion of lignocellulosic biomass to levulinic acid using acidic ionic liquids[J]. Carbohydrate Polymers, 2018, 181: 208-214.
19	Bian J, Peng F, Peng X, et al. Effect of [Emim]Ac pretreatment on the structure and enzymatic hydrolysis of sugarcane bagasse cellulose[J]. Carbohydrate Polymers, 2014, 100: 211-217.
20	Putro J N, Soetaredjo F E, Lin S Y, et al. Pretreatment and conversion of lignocellulose biomass into valuable chemicals[J]. RSC Adv., 2016, 6: 46834-46852.
21	Muhammad N, Man Z, Azmi Bustam Khalil M, et al. Studies on the thermal degradation behavior of ionic liquid regenerated cellulose[J]. Waste and Biomass Valorization, 2010, 1(3): 315-321.
22	Khan A S, Man Z, Bustam M A, et al. Kinetics and thermodynamic parameters of ionic liquid pretreated rubber wood biomass[J]. Journal of Molecular Liquids, 2016, 223: 754-762.
23	覃锦程, 郝学密, 刘黎阳, 等. 瞬间弹射蒸汽爆破增强离子液体对水稻秸秆的预处理效果[J]. 化工学报, 2015, 66: 302-307.
	Qin J C, Hao X M, Liu L Y, et al. Enhanced effects of ionic liquid pretreatment on rice straw by instant catapult steam explosion[J]. CIESC Journal, 2015, 66: 302-307.
24	Kim H, Ahn Y, Kwak S. Comparing the influence of acetate and chloride anions on the structure of ionic liquid pretreated lignocellulosic biomass[J]. Biomass and Bioenergy, 2016, 93: 243-253.
25	Ninomiya K, Kohori A, Tatsumi M, et al. Ionic liquid/ultrasound pretreatment and in situ enzymatic saccharification of bagasse using biocompatible cholinium ionic liquid[J]. Bioresource Technology, 2015, 176: 169-174.
26	Xu J, Liu B, Hou H, et al. Pretreatment of eucalyptus with recycled ionic liquids for low-cost biorefinery[J]. Bioresource Technology, 2017, 234: 406-414.
27	Moulthrop J S, Swatloski R P, Moyna G, et al. High-resolution ¹³C NMR studies of cellulose and cellulose oligomers in ionic liquid solutions[J]. Chem. Commun., 2005: 1557-1559.
28	Dawset T R, McCormick C L. The lithium chloride/dimethylacetamide solvent for cellulose: a literature review[J]. J. Macromol. Sci. Rev. Macromol. Chem. Phys., 1990, 30: 405-440.
29	Shim H S, Hurt R H. Thermal annealing of chars from diverse organic precursors under combustion-like conditions[J]. Energy & Fuels, 2000, 14(2): 340-348.
30	Quyn D M, Wu H, Li C. Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal(1): Volatilisation of Na and Cl from a set of NaCl-loaded samples[J]. Fuel, 2002, 81: 143-149.
31	Brandt A, Chen L, Dongen B E, et al. Structural changes in lignins isolated using an acidic ionic liquid water mixture[J]. Green Chemistry, 2015, 17(11): 5019-5034.
32	Yu J, Paterson N, Blamey J, et al. Cellulose, xylan and lignin interactions during pyrolysis of lignocellulosic biomass[J]. Fuel, 2017, 191: 140-149.
33	Lei Z, Hu Z, Zhang H, et al. Pyrolysis of lignite following low temperature ionic liquid pretreatment[J]. Fuel, 2016, 166: 124-129.
34	陈启宇, 王青跃. 离子液体混合溶剂预处理后孟宗竹的热解[J]. 化工学报, 2015, 66(5): 1874-1882.
	Chen Q Y, Wang Q Y. Pyrolysis study of bamboo Phyllostachys edulis pretreated with ionic liquids mixtures[J]. CIESC Journal, 2015, 66(5): 1874-1882.
35	Sevilla M, Fuertes A B. Fabrication of porous carbon monoliths with a graphitic framework[J]. Carbon, 2013, 56: 155-166.
36	Zhang J, Wang Y, Zhang L, et al. Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD[J]. Bioresource Technology, 2014, 151: 402-405.
37	Sadezky A, Muckenhuber H, Grothe H, et al. Raman microspectroscopy of soot and related carbonaceous materials: spectral analysis and structural information[J]. Carbon, 2005, 43: 1731-1742.
38	Li X, Hayashi J, Li C. FT-Raman spectroscopic study of the evolution of char structure during the pyrolysis of a Victorian brown coal[J]. Fuel, 2006, 85(12/13): 1700-1707.
39	Beyssac O, Goff ì B, Petitet J, et al. On the characterization of disordered and heterogeneous carbonaceous materials by Raman spectroscopy[J]. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2003, 59(10): 2267-2276.
40	Zhu X L, Sheng C D. Influences of carbon structure on the reactivities of lignite char reacting with CO₂ and NO [J]. Fuel Processing Technology, 2010, 91: 837-842.

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