Study of typical chemical cleavage during catalytic oxidation of lignin

doi:10.11949/0438-1157.20230941

Abstract

Abstract:

Lignin is the most abundant renewable aromatic resource in nature and the basic aromatic units are linked by C—O and C—C bonds. Oxidative depolymerization can significantly reduce the chemical bond energy, and is particularly effective in cleavage of C—C bonds in the lignin structure, and generates highly functionalized high-value products such as aromatic aldehydes, acids and ketones. According to the cleavage of different bonds, the desired products can be prepared in a directional way, such as the cleavage of C _β —O bond is easy to produce phenols and ketones, the cleavage of C _α —C _β bond is easy to produce aromatic aldehydes and carboxylic acid products, and the cleavage of C _α —C_ary bond can effectively remove side chain alkyls. The article reviews the current state of research on the above three types of chemical bonds, focusing on the perspective of bond-breaking pathways, and also describes the research on catalysts for various types of chemical bond-breaking as well as progress in the oxidative depolymerization of real lignin. On this basis, the future research direction of lignin oxygen decomposition polymerization is prospected to realize the high-grade transformation of lignin.

Key words: biomass, lignin, oxidation, bond cleavage type, catalyst

摘要：

木质素是自然界中含量最丰富的可再生芳香资源，各芳香基本单元通过C—O和C—C键连接。氧化解聚能显著降低化学键键能，对木质素结构中C—C键的裂解尤为有效，并生成芳香醛、酸、酮等高度功能化的高值产物。针对不同键的断裂能定向制备所需产物，如C _β —O键断裂易生产苯酚类以及酮类产物，C _α —C _β 键断裂易制备芳香醛类和羧酸类产物，C _α —C_ary键断裂能有效去除侧链烷基等。文章重点从断键路径的角度综述了以上三种化学键的研究现状，同时介绍了各种化学键断裂的催化剂研究以及真实木质素氧化解聚进展。在此基础上，展望了未来木质素氧化解聚的研究方向，以实现木质素的高价值转化。

关键词: 生物质, 木质素, 氧化, 断键类型, 催化剂

CLC Number:

TK 6

Haonan CHEN, Xiaohong HU, Longlong MA, Qi ZHANG. Study of typical chemical cleavage during catalytic oxidation of lignin[J]. CIESC Journal, 2023, 74(11): 4367-4382.

陈浩楠, 胡晓虹, 马隆龙, 张琦. 木质素催化氧化过程中典型化学键断键研究[J]. 化工学报, 2023, 74(11): 4367-4382.

Figures/Tables 10

References 100

1	Zhang C F, Shen X J, Jin Y C, et al. Catalytic strategies and mechanism analysis orbiting the center of critical intermediates in lignin depolymerization[J]. Chemical Reviews, 2023, 123(8): 4510-4601.
2	Ragauskas A J, Beckham G T, Biddy M J, et al. Lignin valorization: improving lignin processing in the biorefinery[J]. Science, 2014, 344(6185): 1246843.
3	Kleinert M, Barth T. Phenols from lignin[J]. Chemical Engineering & Technology, 2008, 31(5): 736-745.
4	Shuai L, Saha B. Towards high-yield lignin monomer production[J]. Green Chemistry, 2017, 19(16): 3752-3758.
5	Xu C P, Arancon R A D, Labidi J, et al. Lignin depolymerisation strategies: towards valuable chemicals and fuels[J]. Chemical Society Reviews, 2014, 43(22): 7485-7500.
6	Chio C, Sain M, Qin W S. Lignin utilization: a review of lignin depolymerization from various aspects[J]. Renewable and Sustainable Energy Reviews, 2019, 107: 232-249.
7	Wang H L, Ruan H, Pei H S, et al. Biomass-derived lignin to jet fuel range hydrocarbons via aqueous phase hydrodeoxygenation[J]. Green Chemistry, 2015, 17(12): 5131-5135.
8	Chatel G, Rogers R D. Review: oxidation of lignin using ionic liquids—an innovative strategy to produce renewable chemicals[J]. ACS Sustainable Chemistry & Engineering, 2014, 2(3): 322-339.
9	Cheng C B, Wang J Z, Shen D K, et al. Catalytic oxidation of lignin in solvent systems for production of renewable chemicals: a review[J]. Polymers, 2017, 9(12): 240.
10	Ma R S, Guo M, Zhang X. Recent advances in oxidative valorization of lignin[J]. Catalysis Today, 2018, 302: 50-60.
11	Ma R S, Xu Y, Zhang X. Catalytic oxidation of biorefinery lignin to value-added chemicals to support sustainable biofuel production[J]. ChemSusChem, 2015, 8(1): 24-51.
12	Vangeel T, Schutyser W, Renders T, et al. Perspective on lignin oxidation: advances, challenges, and future directions[J]. Topics in Current Chemistry, 2018, 376(4): 30.
13	Balakshin M, Capanema E. On the quantification of lignin hydroxyl groups with P-31 and C-13 NMR spectroscopy[J]. Journal of Wood Chemistry and Technology, 2015, 35(3): 220-237.
14	Carvajal J C, Gómez Á, Cardona C A. Comparison of lignin extraction processes: economic and environmental assessment[J]. Bioresource Technology, 2016, 214: 468-476.
15	汪俊豪. 木质素磺酸盐预处理及应用的研究[D]. 天津: 天津科技大学, 2022.
	Wang J H. Study on pretreatment and application of lignosulfonate[D]. Tianjin: Tianjin University of Science & Technology, 2022.
16	Behling R, Valange S, Chatel G. Heterogeneous catalytic oxidation for lignin valorization into valuable chemicals: what results? what limitations? what trends?[J]. Green Chemistry, 2016, 18(7): 1839-1854.
17	Tolbert A, Akinosho H, Khunsupat R, et al. Characterization and analysis of the molecular weight of lignin for biorefining studies[J]. Biofuels, Bioproducts and Biorefining, 2014, 8(6): 836-856.
18	胡育珍, 张琦, 王晨光, 等. 木质素催化氧化解聚研究进展[J]. 高校化学工程学报, 2019, 33(3): 505-515.
	Hu Y Z, Zhang Q, Wang C G, et al. Progress in catalytic oxidative depolymerization of lignin[J]. Journal of Chemical Engineering of Chinese Universities, 2019, 33(3): 505-515.
19	王宇鹏. 木质素解聚及其结构的研究[D]. 北京: 北京化工大学, 2022.
	Wang Y P. Study on depolymerization and structure of lignin[D]. Beijing: Beijing University of Chemical Technology, 2022.
20	Ahmad E, Jäger N, Apfelbacher A, et al. Integrated thermo-catalytic reforming of residual sugarcane bagasse in a laboratory scale reactor[J]. Fuel Processing Technology, 2018, 171: 277-286.
21	Tong X L, Zheng J X, Xue S, et al. High-entropy materials as the catalysts for valorization of biomass and biomass-derived platform compounds[J]. ACS Sustainable Chemistry & Engineering, 2023, 11(28): 10203-10218.
22	Yamaguchi A, Hiyoshi N, Sato O, et al. Gasification of organosolv-lignin over charcoal supported noble metal salt catalysts in supercritical water[J]. Topics in Catalysis, 2012, 55(11): 889-896.
23	闫景春. 基于铁基钙钛矿载氧体的生物质化学链催化气化特性研究[D]. 南京: 东南大学, 2021.
	Yan J C. Study on catalytic gasification characteristics of biomass chemical chain based on iron-based perovskite oxygen carrier[D]. Nanjing: Southeast University, 2021.
24	Wang Y N, Wei L H, Hou Q D, et al. A review on catalytic depolymerization of lignin towards high-value chemicals: solvent and catalyst[J]. Fermentation, 2023, 9(4): 386.
25	Zhu D C, Liang N A, Zhang R X, et al. Insight into depolymerization mechanism of bacterial laccase for lignin[J]. ACS Sustainable Chemistry & Engineering, 2020, 8(34): 12920-12933.
26	Yao S G, Mobley J K, Ralph J, et al. Mechanochemical treatment facilitates two-step oxidative depolymerization of kraft lignin[J]. ACS Sustainable Chemistry & Engineering, 2018, 6(5): 5990-5998.
27	Zhu G D, Jin D X, Zhao L S, et al. Microwave-assisted selective cleavage of C _α —C _β bond for lignin depolymerization[J]. Fuel Processing Technology, 2017, 161: 155-161.
28	沈晓骏, 黄攀丽, 文甲龙, 等. 木质素氧化还原解聚研究现状[J]. 化学进展, 2017, 29(1): 162-178.
	Shen X J, Huang P L, Wen J L, et al. Research status of lignin oxidative and reductive depolymerization[J]. Progress in Chemistry, 2017, 29(1): 162-178.
29	More A, Elder T, Jiang Z H. A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids[J]. Holzforschung, 2021, 75(9): 806-823.
30	Yamamura M, Hattori T, Suzuki S, et al. Microscale alkaline nitrobenzene oxidation method for high-throughput determination of lignin aromatic components[J]. Plant Biotechnology, 2010, 27(4): 305-310.
31	Wang Y Y, Sun S N, Li F F, et al. Production of vanillin from lignin: the relationship between β-O-4 linkages and vanillin yield[J]. Industrial Crops and Products, 2018, 116: 116-121.
32	Kumar A, Biswas B, Kaur R, et al. Hydrothermal oxidative valorisation of lignin into functional chemicals: a review[J]. Bioresource Technology, 2021, 342: 126016.
33	Irmak S, Kang J, Wilkins M. Depolymerization of lignin by wet air oxidation[J]. Bioresource Technology Reports, 2020, 9: 100377.
34	D'Anna F, Marullo S, Vitale P, et al. The effect of the cation π-surface area on the 3D organization and catalytic ability of imidazolium-based ionic liquids[J]. European Journal of Organic Chemistry, 2011, 2011(28): 5681-5689.
35	Xu X W, Li P H, Zhong Y D, et al. Review on the oxidative catalysis methods of converting lignin into vanillin[J]. International Journal of Biological Macromolecules, 2023, 243: 125203.
36	Wang M, Li L H, Lu J M, et al. Acid promoted C—C bond oxidative cleavage of β-O-4 and β-1 lignin models to esters over a copper catalyst[J]. Green Chemistry, 2017, 19(3): 702-706.
37	Hu Y Z, Yan L, Zhao X L, et al. Mild selective oxidative cleavage of lignin C—C bonds over a copper catalyst in water[J]. Green Chemistry, 2021, 23(18): 7030-7040.
38	Ma Y Y, Du Z T, Liu J X, et al. Selective oxidative C—C bond cleavage of a lignin model compound in the presence of acetic acid with a vanadium catalyst[J]. Green Chemistry, 2015, 17(11): 4968-4973.
39	Hanson S K, Wu R L, Silks L A. C—C or C—O bond cleavage in a phenolic lignin model compound: selectivity depends on vanadium catalyst[J]. Angewandte Chemie International Edition, 2012, 51(14): 3410-3413.
40	Jiang Y Y, Yan L, Yu H Z, et al. Mechanism of vanadium-catalyzed selective C—O and C—C cleavage of lignin model compound[J]. ACS Catalysis, 2016, 6(7): 4399-4410.
41	Wang M, Ma J P, Liu H F, et al. Sustainable productions of organic acids and their derivatives from biomass via selective oxidative cleavage of C—C bond[J]. ACS Catalysis, 2018, 8(3): 2129-2165.
42	Nichols J M, Bishop L M, Bergman R G, et al. Catalytic C—O bond cleavage of 2-aryloxy-1-arylethanols and its application to the depolymerization of lignin-related polymers[J]. Journal of the American Chemical Society, 2010, 132(36): 12554-12555.
43	Song Q, Wang F, Cai J Y, et al. Lignindepolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation-hydrogenolysis process[J]. Energy & Environmental Science, 2013, 6(3): 994-1007.
44	Zhou M H, Tang C J, Xia H H, et al. Ni-based MOFs catalytic oxidative cleavage of lignin models and lignosulfonate under oxygen atmosphere[J]. Fuel, 2022, 320: 123993.
45	Kim S, Chmely S C, Nimlos M R, et al. Computational study of bond dissociation enthalpies for a large range of native and modified lignins[J]. The Journal of Physical Chemistry Letters, 2011, 2(22): 2846-2852.
46	Nguyen J D, Matsuura B S, Stephenson C R J. A photochemical strategy for lignin degradation at room temperature[J]. Journal of the American Chemical Society, 2014, 136(4): 1218-1221.
47	Zhang G Q, Scott B L, Wu R L, et al. Aerobic oxidation reactions catalyzed by vanadium complexes of bis(phenolate) ligands[J]. Inorganic Chemistry, 2012, 51(13): 7354-7361.
48	Zhang C F, Li H J, Lu J M, et al. Promoting lignin depolymerization and restraining the condensation via an oxidation-hydrogenation strategy[J]. ACS Catalysis, 2017, 7(5): 3419-3429.
49	Deuss P J, Scott M, Tran F, et al. Aromatic monomers by in situ conversion of reactive intermediates in the acid-catalyzed depolymerization of lignin[J]. Journal of the American Chemical Society, 2015, 137(23): 7456-7467.
50	Wang M, Lu J M, Zhang X C, et al. Two-step, catalytic C—C bond oxidative cleavage process converts lignin models and extracts to aromatic acids[J]. ACS Catalysis, 2016, 6(9): 6086-6090.
51	Rahimi A, Ulbrich A, Coon J J, et al. Formic-acid-induced depolymerization of oxidized lignin to aromatics[J]. Nature, 2014, 515(7526): 249-252.
52	Lancefield C S, Ojo O S, Tran F, et al. Isolation of functionalized phenolic monomers through selective oxidation and C—O bond cleavage of the β-O-4 linkages in lignin[J]. Angewandte Chemie (International Ed. in English), 2015, 54(1): 258-262.
53	Yang W S, Du X, Liu W, et al. Highly efficient lignin depolymerization via effective inhibition of condensation during polyoxometalate-mediated oxidation[J]. Energy & Fuels, 2019, 33(7): 6483-6490.
54	Rawat S, Gupta P, Singh B, et al. Molybdenum-catalyzed oxidative depolymerization of alkali lignin: selective production of vanillin[J]. Applied Catalysis A: General, 2020, 598: 117567.
55	Guo S Y, Tong X L, Meng L W, et al. A sustainable iron-catalyzed aerobic oxidative C—C and C—O bond cleavage of a lignin model to phenol and methyl benzoate[J]. Catalysis Science & Technology, 2023, 13(6): 1748-1754.
56	Liu M Y, Zhang Z R, Shen X J, et al. Stepwise degradation of hydroxyl compounds to aldehydes via successive C—C bond cleavage[J]. Chemical Communications, 2019, 55(7): 925-928.
57	Ninomiya K, Ochiai K, Eguchi M, et al. Oxidative depolymerization potential of biorefinery lignin obtained by ionic liquid pretreatment and subsequent enzymatic saccharification of eucalyptus[J]. Industrial Crops and Products, 2018, 111: 457-461.
58	Salar-García M J, Ortiz-Martínez V M, Hernández-Fernández F J, et al. Ionic liquid technology to recover volatile organic compounds (VOCs)[J]. Journal of Hazardous Materials, 2017, 321: 484-499.
59	Cox B J, Ekerdt J G. Depolymerization of oak wood lignin under mild conditions using the acidic ionic liquid 1-H-3-methylimidazolium chloride as both solvent and catalyst[J]. Bioresource Technology, 2012, 118: 584-588.
60	Badgujar K C, Bhanage B M. Factors governing dissolution process of lignocellulosic biomass in ionic liquid: current status, overview and challenges[J]. Bioresource Technology, 2015, 178: 2-18.
61	Dai J H, Patti A F, Saito K. Recent developments in chemical degradation of lignin: catalytic oxidation and ionic liquids[J]. Tetrahedron Letters, 2016, 57(45): 4945-4951.
62	Prado R, Erdocia X, de Gregorio G F, et al. Willow lignin oxidation and depolymerization under low cost ionic liquid[J]. ACS Sustainable Chemistry & Engineering, 2016, 4(10): 5277-5288.
63	Yang Y Y, Fan H L, Meng Q L, et al. Ionic liquid [OMIm][OAc] directly inducing oxidation cleavage of the β-O-4 bond of lignin model compounds[J]. Chemical Communications, 2017, 53(63): 8850-8853.
64	Gao H L, Wang J B, Liu M X, et al. Enhanced oxidative depolymerization of lignin in cooperative imidazolium-based ionic liquid binary mixtures[J]. Bioresource Technology, 2022, 357: 127333.
65	Kang Y, Lu X M, Zhang G J, et al. Metal-free photochemical degradation of lignin-derived aryl ethers and lignin by autologous radicals through ionic liquid induction[J]. ChemSusChem, 2019, 12(17): 4005-4013.
66	Mehta M J, Kulshrestha A, Sharma S, et al. Room temperature depolymerization of lignin using a protic and metal based ionic liquid system: an efficient method of catalytic conversion and value addition[J]. Green Chemistry, 2021, 23(3): 1240-1247.
67	Wang M, Wang F. Lignin: catalytic scissoring of lignin into aryl monomers[J]. Advanced Materials, 2019, 31(50): e1901866.
68	Zhang C F, Wang F. Sell a dummy: adjacent functional group modification strategy for the catalytic cleavage of lignin β-O-4 linkage[J]. Chinese Journal of Catalysis, 2017, 38(7): 1102-1107.
69	Hou T, Luo N, Li H, et al. Yin and yang dual characters of CuO _x clusters for C—C bond oxidationdriven by visible light[J]. ACS Catalysis, 2017, 7(6): 3850-3859.
70	Liu H F, Li H J, Lu J M, et al. Photocatalytic cleavage of C—C bond in lignin models under visible light on mesoporous graphitic carbon nitride through π-π stacking interaction[J]. ACS Catalysis, 2018, 8(6): 4761-4771.
71	Vom Stein T, den Hartog T, Buendia J, et al. Ruthenium-catalyzed C—C bond cleavage in lignin model substrates[J]. Angewandte Chemie (International Ed. in English), 2015, 54(20): 5859-5863.
72	Dabral S, Hernández J G, Kamer P C J, et al. Organocatalytic chemoselective primary alcohol oxidation and subsequent cleavage of lignin model compounds and lignin[J]. ChemSusChem, 2017, 10(13): 2707-2713.
73	Sedai B, Baker R T. Copper catalysts for selective C—C bond cleavage of beta-O-4 lignin model compounds[J]. Advanced Synthesis & Catalysis, 2014, 356(17): 3563-3574.
74	Kim S A, Kim S E, Kim Y K, et al. Copper-catalyzed oxidative cleavage of the C—C bonds of β-alkoxy alcohols and β-1 compounds[J]. ACS Omega, 2020, 5(49): 31684-31691.
75	Liu H F, Li H J, Luo N C, et al. Visible-light-induced oxidative lignin C—C bond cleavage to aldehydes using vanadium catalysts[J]. ACS Catalysis, 2020, 10(1): 632-643.
76	Shen X J, Xin Y, Liu H Z, et al. Product-oriented direct cleavage of chemical linkages in lignin[J]. ChemSusChem, 2020, 13(17): 4367-4381.
77	Huang X M, Ludenhoff J M, Dirks M, et al. Selective production of biobased phenol from lignocellulose-derived alkylmethoxyphenols[J]. ACS Catalysis, 2018, 8(12): 11184-11190.
78	Zhang J G, Lombardo L, Gözaydın G, et al. Single-step conversion of lignin monomers to phenol: bridging the gap between lignin and high-value chemicals[J]. Chinese Journal of Catalysis, 2018, 39(9): 1445-1452.
79	Wang Y L, Wang Q Y, He J H, et al. Highly effective C—C bond cleavage of lignin model compounds[J]. Green Chemistry, 2017, 19(13): 3135-3141
80	Wang M, Liu M J, Li H J, et al. Dealkylation of lignin to phenol via oxidation-hydrogenation strategy[J]. ACS Catalysis, 2018, 8(8): 6837-6843.
81	Voitl T, Rudolf von Rohr P. Oxidation of lignin using aqueous polyoxometalates in the presence of alcohols[J]. ChemSusChem, 2008, 1(8/9): 763-769.
82	兰海瑞. 应用两种杂多酸催化氧化木质素制备芳香化合物[D]. 昌吉: 昌吉学院, 2019.
	Lan H R. Preparation of aromatic compounds by oxidation of lignin catalyzed by two heteropolyacids[D]. Changji: Changji College, 2019.
83	Ren X R, Wang P, Han X Y, et al. Depolymerization of lignin to aromatics by selectively oxidizing cleavage of C—C and C—O bonds using CuCl₂/polybenzoxazine catalysts at room temperature[J]. ACS Sustainable Chemistry & Engineering, 2017, 5(8): 6548-6556.
84	Salonen H E P, Mecke C P A, Karjomaa M I, et al. Copper catalyzed alcohol oxidation and cleavage of β-O-4 lignin model systems: from development to mechanistic examination[J]. ChemistrySelect, 2018, 3(44): 12446-12454.
85	Xiang Q, Lee Y Y. Production of oxychemicals from precipitated hardwood lignin[J]. Applied Biochemistry and Biotechnology, 2001, 91: 71-80.
86	Sales F G, Abreu C A M, Pereira J. Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production[J]. Brazilian Journal of Chemical Engineering, 2004, 21(2): 211-218.
87	Deng W P, Zhang H X, Wu X J, et al. Oxidative conversion of lignin and lignin model compounds catalyzed by CeO₂-supported Pd nanoparticles[J]. Green Chemistry, 2015, 17(11): 5009-5018.
88	Song W L, Dong Q M, Hong L A, et al. Activating molecular oxygen with Au/CeO₂ for the conversion of lignin model compounds and organosolv lignin[J]. RSC Advances, 2019, 9(53): 31070-31077.
89	Cabral Almada C, Kazachenko A, Fongarland P, et al. Supported-metal catalysts in upgrading lignin to aromatics by oxidative depolymerization[J]. Catalysts, 2021, 11(4): 467.
90	Deng H B, Lin L, Liu S J. Catalysis of Cu-doped Co-based perovskite-type oxide in wet oxidation of lignin to produce aromatic aldehydes[J]. Energy & Fuels, 2010, 24(9): 4797-4802.
91	Deng H B, Lin L, Sun Y, et al. Activity and stability of perovskite-type oxide LaCoO₃ catalyst in lignin catalytic wet oxidation to aromatic aldehydes process[J]. Energy & Fuels, 2009, 23(1): 19-24.
92	Abdelaziz O Y, Meier S, Prothmann J, et al. Oxidative depolymerisation of lignosulphonate lignin into low-molecular-weight products with Cu-Mn/δ-Al₂O₃ [J]. Topics in Catalysis, 2019, 62(7): 639-648.
93	Prado R, Erdocia X, Labidi J. Effect of the photocatalytic activity of TiO₂ on lignin depolymerization[J]. Chemosphere, 2013, 91(9): 1355-1361.
94	刘苗苗. 在Pb/PbO₂和Cu电极间电催化氧化还原降解碱性竹木质素制备有价值化学品的研究[D]. 天津: 河北工业大学, 2020.
	Liu M M. Study on the preparation of valuable chemicals by electrocatalytic redox degradation of alkaline bamboo lignin between Pb/PbO₂ and Cu electrode[D]. Tianjin: Hebei University of Technology, 2020.
95	Wang Y S, Yang F, Liu Z H, et al. Electrocatalytic degradation of aspen lignin over Pb/PbO₂ electrode in alkali solution[J]. Catalysis Communications, 2015, 67: 49-53.
96	Abdelaziz O Y, Clemmensen I, Meier S, et al. On the oxidative valorization of lignin to high-value chemicals: a critical review of opportunities and challenges[J]. ChemSusChem, 2022, 15(20): e202201232.
97	van Aelst K, van Sinay E, Vangeel T, et al. Reductive catalytic fractionation of pine wood: elucidating and quantifying the molecular structures in the lignin oil[J]. Chemical Science, 2020, 11(42): 11498-11508.
98	Li K N, Al-Rudainy B, Sun M Z, et al. Membrane separation of the base-catalyzed depolymerization of black liquor retentate for low-molecular-mass compound production[J]. Membranes, 2019, 9(8): 102.
99	Gomes E D, Rodrigues A E. Recovery of vanillin from kraft lignin depolymerization with water as desorption eluent[J]. Separation and Purification Technology, 2020, 239: 116551.
100	Alherech M, Omolabake S, Holland C M, et al. From lignin to valuable aromatic chemicals: lignin depolymerization and monomer separation via centrifugal partition chromatography[J]. ACS Central Science, 2021, 7(11): 1831-1837.

木质素类型	提取过程	木质素分子量	优点	缺点
硫酸盐木质素	NaOH和Na₂S蒸煮，温度在150~180℃	1000~3000 Da	适用于木材生物质，灰分低，最佳提取木质素方法	含硫量及缩聚程度高
碱木质素	NaOH处理，温度在90~150℃	1000~3000 Da	适用于非木材生物质，不含硫，灰分低	碱消耗量大，木质素结构易改变
木质素磺酸盐	亚硫酸盐[Na₂SO₃、CaSO₃、(NH₄)₂SO₃等]蒸煮，温度在150~180℃	5700~61000 Da	适用于木材生物质，低成本，水溶性好	含硫/灰分多及缩聚程度高
有机溶剂木质素	有机溶液萃取，温度在90~210℃	3000~4500 Da	不含硫，可溶于碱性溶液，木质素结构改变小	有机溶液需要回收，且成本高，难溶于水
热解木质素	高温加热	300~600 Da	处理时间短，不含硫	温度高，消耗能量大
酶解木质素	酶或者真菌处理	4500~9500 Da	不含硫	处理时间长

木质素类型	提取过程	木质素分子量	优点	缺点
硫酸盐木质素	NaOH和Na₂S蒸煮，温度在150~180℃	1000~3000 Da	适用于木材生物质，灰分低，最佳提取木质素方法	含硫量及缩聚程度高
碱木质素	NaOH处理，温度在90~150℃	1000~3000 Da	适用于非木材生物质，不含硫，灰分低	碱消耗量大，木质素结构易改变
木质素磺酸盐	亚硫酸盐[Na₂SO₃、CaSO₃、(NH₄)₂SO₃等]蒸煮，温度在150~180℃	5700~61000 Da	适用于木材生物质，低成本，水溶性好	含硫/灰分多及缩聚程度高
有机溶剂木质素	有机溶液萃取，温度在90~210℃	3000~4500 Da	不含硫，可溶于碱性溶液，木质素结构改变小	有机溶液需要回收，且成本高，难溶于水
热解木质素	高温加热	300~600 Da	处理时间短，不含硫	温度高，消耗能量大
酶解木质素	酶或者真菌处理	4500~9500 Da	不含硫	处理时间长

方法		优势	局限
热处理法	热解	反应迅速，易于操作	产物选择性低，反应条件苛刻，易积炭
热处理法	气化	简单，反应迅速	能耗大，产生焦油
化学处理法	酸催化	有效断裂各种键，低成本	环境污染，具有腐蚀性
	碱催化	有效断裂各种键，低成本	环境污染，可能导致再聚合
	金属催化	高选择性	低转化率，价格贵
	离子液体催化	可调整反应，适应性好	难以分离产物
生物处理法		无毒害，成本低	反应速率慢，效率低
微波辅助解聚		可精确控制操作，避免表面发热	高能耗

方法		优势	局限
热处理法	热解	反应迅速，易于操作	产物选择性低，反应条件苛刻，易积炭
热处理法	气化	简单，反应迅速	能耗大，产生焦油
化学处理法	酸催化	有效断裂各种键，低成本	环境污染，具有腐蚀性
	碱催化	有效断裂各种键，低成本	环境污染，可能导致再聚合
	金属催化	高选择性	低转化率，价格贵
	离子液体催化	可调整反应，适应性好	难以分离产物
生物处理法		无毒害，成本低	反应速率慢，效率低
微波辅助解聚		可精确控制操作，避免表面发热	高能耗

氧化剂	优点	缺点
氧气，过氧化氢	反应温和易控制，低成本，环保，反应条件易控制	需较长反应时间和较高温度
空气	成本低，环保，可控性高	反应时间长，氧化性能相对低
硝基苯	氧化性好，使用简单	有毒，安全风险高，危害环境
氯氧化物	高效氧化性能，漂白效果好	环境污染，废物难处理
臭氧	高效氧化性能，快速反应，氧化副产物为氧气	设备成本高，高浓度下刺激性强