Pd/C催化下麦草碱木质素与氢气的还原反应

以钯/炭(Pd/C)为催化剂,以氢气为还原剂与麦草碱木质素进行反应,分析了不同反应条件对催化效果的影响,用化学法测定了反应前后碱木质素官能团的含量,并与环己烯还原法进行了比较。结果表明,在Pd/C催化剂负载量为3%、用量0.1g/g、氢气流速20mL/min、反应温度363K、反应时间3h的条件下,反应后碱木质素的总羟基、酚羟基、醇羟基含量分别为14.39%、4.21%和10.18%,较反应前分别增加了133.68%、27.96%和264.87%。与环己烯法相比,氢气还原法的催化剂用量明显减少,醇羟基数增加较为显著,酚羟基含量基本一致。氢气还原活化效果明显优于环己烯还原效果。

Hydrogenation of Straw Alkali Lignin Catalysed by Pd/C Catalyst

Deoxidization reaction of straw alkali lignin and hydrogen was investigated in the presence of Pd/C catalyst.Influence of various reaction conditions on catalytic effect was considered.Functional groups of alkali lignin were determined by chemical methods before and after reaction and the deoxidization reactions performed by hydrogen and cyclohexene were compared.The results showed that at the condition of 3% of Pd in Pd/C catalyst,0.1 g of catalyst dosage,a H_2 flow of 20 mL/min,T=363K,reaction time of 3 h,the contents of total hydroxyl,phenolic hydroxyl and alcoholic hydroxyl of alkali lignin after reaction were 14.39%,4.21% and 10.18%,with an increase of 133.68%,27.96% and 264.87% respectively compared with the original alkali lignin.Compared with the reaction using cyclohexene as reducer,the dosage of catalyst was obviously reduced,alcoholic hydroxyl increased and the content of phenolic hydroxyl was almost the same.The deoxidization effect with hydrogen was superior to that with cyclohexene.