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摘要: 采用不同H2O2含量的芬顿溶液对碱木质素进行预处理,并结合快速热解,探究轻质生物油中含甲氧基化合物含量的变化规律,同时研究了芬顿溶液对木质素结构的影响规律。结果表明,轻质生物油中含甲氧基团的酚类化合物峰面积从AL(未处理碱木质素)的7.3×109下降至13-FML(H2O2含量为13 mL/g芬顿溶液预处理碱木质素)的5.2×109,减少了0.29倍。而含甲基团和乙基团的酚类化合物峰面积从AL的3.9×109上升到13-FML的7.2×109,增加了0.85倍。同时,轻质生物油产率从22.4%提高到28.7%。通过FT-IR、1H NMR和13C NMR分析发现,芬顿预处理使木质素凝缩性结构单元减少,甲氧基含量降低,为后续快速热解产生低甲氧基含量的生物油提供了有利条件。Abstract: A Fenton solution with different H2O2 concentrations was used to pretreat an alkali lignin (AL), and combined with fast pyrolysis, the change in the content of phenolic compounds containing methoxy group in light bio-oil was explored, also, the influence of the Fenton solution on the structure of the alkali lignin was also studied. The results show that the peak area of phenolic compounds containing methoxy groups in light bio-oil decreases from 7.3×109 with AL (untreated alkali lignin) to 5.2×109 with 13-FML (pretreated alkali lignin with Fenton solution at a concentration of 13 mL/g H2O2), decreasing by about 29%. While the peak area of phenolic compounds containing methyl groups and ethyl groups increases from 3.9×109 with AL to 7.2×109 with 13-FML, increasing by about 1.85 times. At the same time, the yield of light bio-oil increases from 22.4% to 28.7%. Through FT-IR, 1H NMR and 13C NMR analysis, it is found that Fenton pretreatment can destroy the condensational structural units of lignin and reduce the content of methoxy, thus providing favorable conditions for subsequent fast pyrolysis to produce bio-oil with low methoxy content.
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Key words:
- lignin /
- fenton pretreatment /
- fast pyrolysis /
- methoxy removal
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表 1 轻质生物油的GM-MS分析
Table 1 GM-MS analysis of light bio-oil
Time Compounds Peak area of compounds /×109 AL 3-FML 5-FML 9-FML 13-FML 15-FML Phenol methoxy groups 15.1 phenol, 2-methoxy- 1.9 1.6 1.3 1.0 0.9 0.9 16.6 phenol, 2-methoxy-3-methyl- 0.3 0.2 0.2 0.4 0.3 0.2 17.3 phenol, 2-methoxy-4-methyl- 0.6 0.8 0.8 0.7 0.7 0.7 19.2 phenol, 4-ethyl-2-methoxy- 0.8 0.8 0.8 0.7 0.7 0.6 20.4 2-methoxy-4-vinylphenol 1.5 1.1 1.0 1.0 1.0 1.0 21.5 phenol, 2, 6-dimethoxy- 1.2 0.7 0.7 0.6 0.5 0.5 21.7 3-methoxy-5-methylphenol 0.1 0.3 0.3 0.4 0.5 0.4 23.7 phenol, 4-methoxy-3-(methoxymethyl)- 0.9 0.7 0.7 0.6 0.6 0.5 Total 7.3 6.2 5.8 5.4 5.2 4.8 Phenol methyl groups and phenol ethyl groups 15.0 phenol, 2-methyl- 0.6 0.5 0.5 0.7 0.9 0.8 15.7 phenol, 4-methyl- 0.8 1.2 1.2 1.5 2.0 1.9 16.8 phenol, 2, 4-dimethyl- 0.3 0.5 0.4 0.7 0.9 0.7 17.6 phenol, 4-ethyl- 1.6 1.6 1.5 1.8 2.2 1.9 18.4 phenol, 3-ethyl-5-methyl- 0.3 0.4 0.4 0.6 0.7 0.3 20.6 2-pllylphenol 0.3 0.3 0.3 0.4 0.5 0.3 Total 3.9 4.5 4.3 5.7 7.2 5.9 Acid 6.7 acetic acid 0.2 0.3 0.3 0.4 0.5 0.6 Phenol 14.0 phenol 1.2 1.3 1.6 2.0 2.3 2.2 Others Total 4.9 3.6 3.7 4.6 4.8 4.7 -
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