稻草秸秆超低酸水解及水解产物分析

用0.05%(w)的稀硫酸对湖北省稻草秸秆进行水解,考察了混合原料中固体含量和搅拌转速对稻草秸秆水解的影响。实验结果表明,最佳秸秆颗粒的质量浓度为0.050 0 g/mL,最佳转速为700 r/min。研究了稻草秸秆在160～210℃内的水解趋势。研究结果表明,160℃时,稻草秸秆水解得到的还原糖含量随水解的进行呈单峰趋势;在170～200℃时呈双峰趋势;当温度达到210℃时又呈现单峰趋势,这与稻草秸秆中纤维素和半纤维素水解得到的两个还原糖峰随水解的进行呈现叠加和分离有关。表征固体残渣并分析水解产物组成的结果显示,水解后半纤维素大部分水解,木质素的结构在一定程度上被破坏,纤维素的聚合度急剧降低但结晶度仍较高;水解产物主要为纤维三糖、纤维二糖、葡萄糖、木糖、丙酮醛和未知混合物。

Hydrolysis of Rice Straw with Extremely Dilute Acid and Products Analysis

The hydrolysis of rice straw with extremely dilute sulfuric acid(0.05%(w)) was conducted.It was found that the optimal solid content and stirring speed for the rice straw hydrolysis were 0.050 0 g/mL and 700 r/min,respectively.The change of the hydrolysis with time was investigated in the temperature range of 160-210 ℃.The results indicated that,in the hydrolysis,there was a single-peak of reducing sugar content at 160 ℃,in the temperature range of 170-200 ℃ there was a double-peak,and a single-peak reappeared at 210 ℃.The reason was that the reducing sugar concentration from the hydrolysis of hemicellulose and cellulose showed two peaks,and the peaks superimposed or separated as the hydrolysis temperature changed.The hydrolysis products and solid residues were characterized by means of FTIR and HPLC.The results showed that,most of hemicellulose hydrolyzed and disappeared,the structure of the lignin was destroyed to a certain extent,the polymerization degree of the cellulose decreased greatly but its crystallinity was still high.The main hydrolysis products were cellotriose,cellobiose,glucose,xylose,methylglyoxal and some unknown compounds.