摘要
采用FT-IR、GPC、^1HNMR、Py-GC-MS等手段，分析了麦草在甲酸水解体系中不同温度、不同时间条件下反应后其固体残渣中木质素的结构。FT-IR分析发现，纯化木质素有羧基存在，表明麦草木质素分子结构在甲酸作用下发生了明显的氧化。Py-GC-MS和^1HNMR分析显示，甲酸不溶木质素以愈刨木基为主，紫丁香基含量略高于对羟苯基。Py-GC-MS及GPC分析发现，甲酸反应体系中随着温度、时间的增加，木质素分子质量会降低，各种木质素型的酚类物质占总木质素的高温分类产物的比例都呈下降趋势，表明该反应体系既能促进木质素α-芳基醚键、β-芳基醚键断裂，使得木质素很快溶解在溶液中，同时也能促进木质素的缩合，但总的趋势是使木质素的分子质量下降。
Dewaxed wheat straw was treated with formic acid （AR, mass concentration is 86.24%） using 0,2 mol/LH2SO4 as catalyst at 65℃ for 4, 6, 8, 10, 12h, and at 50, 55, 60, 65, 70℃ for 10h, in which 24.5, 18.7, 14.5, 12.4, 10.2, 26.0, 21.6, 14.8, 9.8% residues were obtained respectively. Lignins were extracted and purified from the residues .The lignins were characterized by FT-IR, GPC, ^1HNMR, Py-GC-MS. Carboxyl absorption observed in the FT-IR indicated that a remarkable oxidation of the lignin structure occurs during the acid treatment. ^1HNMR, Py-GC-MS analysis indicated that guaiacyl unit is the main structure and the content of syningyl unit is higher than hydroxybenzyl unit. Mw of lignin and lignin unit phenols content of the pyrolysis products from lignin decrease as temperature and time increase. That implies larger time and higher temperature of the acid treatment will accelerate the cleavage of α-aryl, β-aryl ether linkage and condensation of the lignin, but the degree of cleavage is higher than condensation.
出处
《中国造纸学报》
EI
CAS
CSCD
2007年第3期1-4,共4页
Transactions of China Pulp and Paper
基金
本研究得到教育部重大项目培育资金项目资助(750548)。
关键词
麦草
甲酸
水解
木质素
wheat straw
formic acid
hydrolization
lignin
