Pd/C催化下碱木质素与环己烯的还原反应

以钯/炭(Pd/C)为催化剂,以环己烯为氢给予体与麦秆碱木质素进行还原反应,分析了不同因素对反应过程的影响,通过正交实验优化了反应参数,用化学法对反应前后碱木质素官能团进行了定量测定,实验结果表明,最佳的Pd/C催化、环己烯还原法活化碱木质素的反应条件为:pH值10,催化剂质量分数7%,反应时间1.5h,碱木质素与环己烯质量比1:4.1,反应后碱木质素的总羟基含量为13.45%,增加了104.72%;羧基含量为1.60%,降低了39.39%;羰基2.96%,降低了50.99%.凝胶渗透色谱(GPC)分析表明,对于反应前后的碱木质素,其相对分子质量主要在1000～10000之间,所占比例分别为63.23%、84.66%,经Pd/C催化还原后碱木质素的多分散系数变小.

Deoxidation of Alkali Ligain and Cyclohexene Catalysed by Pd/ C

In this paper straw alkali lignin was deoxidized by cyclohexene in the present of Pd/C catalyst.Several effects were analyzed in detail and parameters of deoxidation reaction were optimized by orthogonal experiments.The function groups of alkali lignin were determined by chemical methods.The results obtained indicated that the optimum conditions of deoxidation reaction of alkali lignin and cyclohexene catalysed by Pd/C were as follows: pH=10,catalyst concentration of 7%,reaction time of 1.5h,the ratio of cyclohexene to alkali lignin was 1: 4.1(by weight).Total hydroxyl of alkali lignin after activation was 13.45%,with an increase of 104.72%,content of carboxyl was 1.60%,and the carbonyl was 2.96%,decreased by 39.39% and 50.99% respectively.The molecular weight of alkali lignin was mainly distributed between 1000 and 10000 by GPC analysis.In the range of 10000 to 1000,the proportions of alkali lignin and activated alkali lignin were 63.23% and 84.66% respectively,indicating the polydispersity of alkali lignin was decreased after the deoxidation reaction catalysed by Pd/C catalyst.