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从麦草碱法制浆黑液中提取木质素,精制后,以苯乙酮为木质素的模型化合物,对催化剂组成及溶剂进行了考察.在此基础上,以NaBH4/I2为催化剂,无水乙醇为溶剂,对木质素进行加氢还原裂解反应研究.考察了温度和时间对木质素催化加氢效果的影响,采用红外光谱(FTIR)、元素分析及凝胶渗透色谱分析(GPC),表征木质素反应前后结构的变化.凝胶渗透色谱分析表明,加氢还原后木质素的分子量明显降低.采用自动电位滴定法测定反应前后木质素中总羟基含量,反应后木质素中总羟基含量为10.19%.得到了NaBH4/I2催化木质素加氢还原反应的最优条件:以1,2-二氯乙烷和乙醇(2∶1,v/v)作溶剂,m(NaBH4)∶m(I2)=1∶1,温度175℃,反应时间15 h.
The lignin was extracted from wheat straw alkaline pulping black liquor, and then refined with acetophenone as lignin, the composition and solvent of the catalyst were investigated.On the basis of NaBH4 / I2 as catalyst, Ethanol was used as solvent to study the effect of temperature and time on the catalytic hydrogenation of lignin. FTIR, elemental analysis and gel permeation chromatography (GPC) The changes of structure before and after lignin reaction gel permeation chromatography analysis showed that the molecular weight of lignin decreased significantly after hydrogenation.Using potentiometric titration to determine the total hydroxyl content of lignin before and after reaction, the total hydroxyl content of lignin after reaction was 10.19% .The optimum conditions for the hydrogenation of lignin by NaBH4 / I2 were obtained: the molar ratio of m (NaBH4): m (2: 1, v / v) I2) = 1: 1, temperature 175 ℃, reaction time 15 h.