麦草碱木质素的过氧化氢氧化氨解 Ⅲ.过渡金属对氧化氨解反应的影响

Oxiammonolysis of Wheat Straw Alkaline Lignin by HydroperoxideⅢ. The Effect of Transitional Metal Ions on Oxiammonolysis Reaction

探讨了过渡金属对麦草碱木质素过氧化氢氧化氨解的影响。结果表明 ,加入Mn2 + 和Cu2 + 导致过氧化氢无效分解 ,使氧化氨解产物的氮含量下降 ;而添加Fe2 + 作催化剂 ,在 5× 1 0 - 6 ～ 2 5× 1 0 - 6 (质量分数 )浓度范围内可有效地促进产物氮含量的提高。当Fe2 + 的添加量为 2 5× 1 0 - 6(质量分数 )时 ,氧化氨解木质素的总氮和有效氮含量分别提高 34 %和39% ,甲氧基含量进一步下降 ,羧基含量增加 ,并且在 50℃时反应时间可缩短至 60min。

The effects of transitional metal ions on the oxiammonolysis of wheat straw alkaline lignin with hydroperoxide were studied. The results show that hydroperoxide is decompouded with the existence of Mn 2+ and Cu 2+ , and as a result, the nitrogen content of oxiammonolysis lignin decreases. However, adding Fe 2+ with a concentration from 5 ×10 -6 to 25 ×10 -6 (mass fraction) in the reaction system, nitrogen content of the product increases obviously. When the concentration of Fe 2+ is 25 ×10 -6 (mass fraction), the total and hydrolyzable nitrogen contents of oxiammonolyzed lignin increase 34% and 39%, respectively. Compared to the contrast sample , methoxyl content of oxiammonolysis lignin is lower, and carboxyl content is higher. The reaction time can be reduced to 60 min when the temperature is 50℃.