蔗渣水解液酸催化制备糠醛及其萃取分离

Acid-catalyzed preparation of furfural from bagasse pre-hydrolysate and its extractive separation

首先,蔗渣在高温下通过酸性水解制备了水解液和水解渣;然后,水解液经深度酸解制备了糠醛,并以有机溶剂萃取分离了水相中的糠醛;水解渣经硫酸盐蒸煮制备了浆料纤维。采用FTIR、XRD、SEM、TG对蔗渣及水解渣进行了表征,利用UV-Vis吸收光谱对水解液中的木糖及深度酸解液中的糠醛进行了定量检测。对蔗渣预水解条件、糠醛的有机溶剂萃取条件进行了考察。结果表明,在反应温度160℃、液固比(mL∶g)为6∶1、浓硫酸用量为0.176%(以绝干蔗渣质量计,下同)的条件下,预水解反应3 h后,水解液中木糖质量浓度最高(41.72 g/L);水解液在170℃下深度酸解90 min,深度酸解液中糠醛质量浓度最高可达15.91 g/L,糠醛收率最高为59.60%。以V(1,2-二氯乙烷)∶V(正丁醇)=9∶1的混合溶剂萃取深度酸解液中糠醛(有机相与水相体积比为2∶1),糠醛分配系数最高为7.62,糠醛的萃取率可达93.53%。浆料中α-纤维素质量分数高达93.41%,纤维长径比为29.9,细小纤维占比34.7%。

Bagasse hydrolytic liquid and residue were obtained through high temperature acid hydrolysis.Furfural was then prepared from deep acidolysis of bagasse hydrolytic liquid,and purified by organic solvent extraction,while pulp fiber was synthesized via sulfate cooking of bagasse hydrolytic residue.Bagasse and its hydrolysis residue were characterized by FTIR,XRD,SEM and TG.Xylose in hydrolysis solution and furfural in deep acid solution were quantitatively analyzed by UV-Vis absorption spectrum.The pre-hydrolysis conditions of bagasse and the organic solvent extraction conditions for furfural were investigated.The results showed that under the conditions of 160℃,liquid-solid ratio(mL∶g)6∶1,concentrated sulfuric acid 0.176%(based on the mass of bagasse,the same below),the mass concentration of xylose(41.72 g/L)in the hydrolysate reached the highest after 3 h of prehydrolysis reaction.The furfural mass concentration in the hydrolysate was up to 15.91 g/L and the furfural yield was up to 59.60%after deep acidolysis at 170℃for 90 min.When the furfural in deep acid solution was extracted by mixed solvent of V(1,2-dichloroethane)∶V(n-butanol)=9∶1(the volume ratio of organic phase to aqueous phase was 2∶1),the partition coefficient of furfural was up to 7.62,and the extraction rate of furfural was up to 93.53%.α-Cellulose mass fraction in pulp was as high as 93.41%,and the length to diameter ratio of fiber was 29.9,and fine fibers accounted for 34.7%.