亚/超临界乙醇中羟基和氢自由基作用下的纤维素液化行为  

Effects of hydroxyl and hydrogen free radicals on the liquefaction of cellulose in sub/supercritical ethanol

作　　者：黎巍[1] 解新安[1] 汤成正[1] 李雁[1] 李璐[1] 王娅莉[1] 魏星[1] 樊荻 

机构地区：[1]华南农业大学食品学院,广东广州510642

出　　处：《燃料化学学报》2016年第4期415-421,共7页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(21576107;21176097);广东省科技计划项目(2014A010106024)资助~~

摘　　要：以水杨酸为羟基自由基(HO·)捕捉剂、四氯化碳为氢自由基(H·)捕捉剂,采用间歇高压反应釜对玉米秸秆纤维素在亚/超临界乙醇中的液化行为进行了研究,通过考察自由基捕捉剂用量、反应温度和反应时间对纤维素液化行为的影响,研究亚/超临界乙醇产生的HO·和H·自由基对纤维素的液化作用。结果表明,随着水杨酸用量增加(0-4mL),HO·浓度升高,生物油收率由29.3%提高至47.9%,固体残渣收率从26.7%降低至24.3%;反应温度从250℃升高至320℃,HO·活性随之增强,生物油收率由35.9%升高至58.2%,固体残渣收率由51.8%降低至20.4%;随着四氯化碳用量由0增加为2mL时,H·浓度降低,生物油收率由24.7%降低至20.7%,固体残渣收率由54.1%增加至59.1%;反应时间从0到30min,液化作用不断增强,生物油收率从8.7%升高至28.5%,固体残渣收率由86.3%下降至60.9%;30min之后,四氯化碳对H·活性的抑制加强,导致液化作用减弱,生物油收率有所下降。实验结果表明,乙醇在亚/超临界状态下能够产生HO·和H·,且HO·和H·浓度和活性与反应条件相关,对纤维素液化产物的收率及其分布具有明显的影响。With salicylic acid as hydroxyl radical（ HO·） trap and carbon tetrachloride as hydrogen radical（ H·） trap,the effects of HO· and H· radicals on the liquefaction of cornstalk cellulose in sub /supercritical ethanol was investigated in an autoclave. The results indicated that the concentration of HO· radical increases with the increase of salicylic acid amount added in the feed from 0 to 4 m L; meanwhile,the bio-oil yield is increased from 29.3% to 47.9%,whereas the residue yield is decreased from 26.7% to 24.3%. The activity of HO· increases with the increase of reaction temperature from 250 to 320 ℃; meanwhile,the bio-oil yield is increased from 35.9% to 58.2%,whereas the residue yield is reduced from 51.8% to 20.4%. On the other hand,the concentration of H· radical decreases with the increase of carbon tetrachloride from 0 to 2 m L; meanwhile,the bio-oil yield is decreased from 24.7% to 20.7%,whereas the residue yield is increased from 54.1% to 59.1%.The liquefaction of cellulose is enhanced within 30 min due to the increase of H· activity; after that,the bio-oil yield begins to decline due to the inhibition of H· activity by CCl4. Current results proved that ethanol can produce HO· and H· radicals under sub / supercritical state; the concentration and activity of HO· and H·radicals are dependent on the reaction conditions,which may determine the product yield and distribution for the liquefaction of cellulose in sub / supercritical ethanol.

关 键 词：纤维素 液化 亚/超临界乙醇 自由基 自由基捕捉剂 

分 类 号：TK6[动力工程及工程热物理—生物能]