玉米秸秆不同部位的组成及其对预处理的影响

Varied local compositions of corn stover and their effects on pretreatment

不同玉米秸秆部位的成分组成及分布对预处理和酶解影响显著。研究表明:韧皮部与髓芯的成分相近,但叶子的差异较大,其木聚糖和总糖的质量分数最高,分别为29.48%和66.15%,而木质素的质量分数最低,因而叶子更容易预处理。玉米秸秆在稀酸预处理过程中可回收96.9%葡聚糖和50.0%～70.0%木聚糖,其中50.0%～60.0%木聚糖水解成木糖溶出;不同部位的木聚糖损失率与初始的木聚糖含量正相关;经稀酸预处理后,叶子中葡聚糖的质量分数最高,达72.40%,叶子和髓芯易于被纤维素酶水解生成葡萄糖,而韧皮部困难。不同部位的酶解得率与自身的葡聚糖含量正相关,与酸不溶木质素含量负相关,同时受原料的物理结构、葡聚糖和木质素大分子的化学组成等影响。

The variation in corn stover fraction composition affect markedly on the downstream steps of pretreatment and enzyme hydrolysis as the main materials for fuel ethanol production.Results showed that by view of the composition,corn bast was similar to pitch and leaf changed.Compared with bast and pitch,the xylan content in leaf reached the highest value of 29.48% and its total polysaccharides accounted for 66.15%.Meanwhile its lignin content was lowest.Based on its composition,leaf pretreatment would be easier than other two fractions.96.9% of glucan and 50.0% to 70.0% of xylan were recovered during dilute sulfuric acid pretreatment,in which 50.0% to 60.0% of xylan was hydrolyzed into xylose and solved in the stream.The xylan loss ratio seemed to be positive,related to the initial xylan content in various corn stover fractions.After dilute sulfuric acid pretreatment,the glucan content of leaf could reach the highest value of 72.40% in three corn stover fractions,and the leaf and the pitch were much easier than bast on cellulase hydrolysis glucan to glucose.According to the yield of glucan to glucose from cellulase hydrolysis of various dilute acid pretreated corn stover fractions,it seemed to be positively related to glucan content and negatively related to lignin content in pretreated residues,respectively,and influence of their physical structure of materials and chemical composition of glucan and lignin in pretreated residues were involved.