| 摘要: |
| 【目的】研究亚/超临界乙醇自由基对玉米秸秆纤维素液化的作用机理。【方法】利用间歇高压反应釜，在反应温度200～320 ℃、反应时间30 min条件下，对比研究亚/超临界乙醇液化和热裂解下反应温度对玉米秸秆纤维素产物收率的影响，并利用气相色谱 质谱联用仪(GC/MS)和傅里叶红外光谱法(FT-IR)分别对产物中重油和轻油的组成、原料和固体残渣特性等进行分析。【结果】1)与热裂解相比，当反应温度为320 ℃时，玉米秸秆纤维素在亚/超临界乙醇作用下，重油产物收率由5.0%上升至13.8%，固体残渣收率由29.7%下降至17.8%，乙醇自由基促进了玉米秸秆纤维素液化，同时抑制了残渣的生成。2)玉米秸秆纤维素在亚/超临界乙醇液化中的重油产物主要由酮类(相对含量为54.2%)、酯类(相对含量为26.5%)以及少量的醇类和酚类等物质组成，未检测出呋喃类物质。3)亚/超-临界乙醇液化玉米秸秆纤维素的轻油产物中，酸类物质主要为C8化合物，而在亚/超临界乙醇液化条件下生成的轻油产物中，酸类以C2～C4化合物为主。【结论】1)乙醇自由基促进了玉米秸秆纤维素液化中间产物葡聚糖内的C-C、C-O和-OH等键进一步断裂，从而抑制了呋喃类物质的形成。2)亚/超临界乙醇液化玉米秸秆纤维素生成了多种自由基，自由基之间(中间产物自由基之间、中间产物自由基与乙醇自由基之间等)发生缩合反应，从而生成了碳原子数相对较多的酸类物质，同时自由基之间相互作用也抑制了产物的二次反应。 |
| 关键词: 亚/超临界乙醇 液化 热裂解 玉米秸秆纤维素 反应机理 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目(21176097)；广东省科技计划项目(2009B050700037) |
|
| Liquefaction of cornstalk cellulose in sub/super-critical ethanol |
|
TAO Hong-xiu,XIE Xin-an,ZHENG Chao-yang,et al
|
| Abstract: |
| 【Objective】The liquefaction mechanism of cornstalk cellulose in sub/super-critical ethanol was investigated.【Method】Cornstalk cellulose pyrolysis and liquefaction in sub/super-critical ethanol were studied in an autoclave at temperature of 200-320 ℃ for 30 min.The effects of temperature on products of pyrolysis and liquefaction in ethanol were studied.The liquid products and solid residues were analyzed using gas chromatograph with mass selective detector (GC/MS) and Fourier transform infrared (FT-IR),respectively.【Result】1) Compared with pyrolysis,the yield of heavy oil (HO) was increased from 5.0% to 13.8%,and the yield of residues (RE) was decreased from 29.7% to 17.8% when temperature was 320 ℃.The sub/super-critical ethanol promoted cellulose liquefaction and inhibited residue production.2) The HO products from liquefaction of cellulose were composed of ketones (54.2%),esters (26.5%),and small amount of alcohols and phenols,but furans were not detected.3) Carboxylic acids from cellulose liquefaction were consisted of C8 compounds, while carboxylic acids from pyrolysis of cellulose were mainly composed of C2-C4.【Conclusion】1) Sub/super-critical ethanol free radicals promoted bonds cracking,such as C-C,C-O and -OH.2) Many free radicals including intermediate free radicals and sub/super-critical ethanol free radicals produced in sub/super-critical ethanol reacted with each other to form large molecular acids,and the interactions inhibited the formation of secondary products. |
| Key words: sub/super-critical ethanol liquefaction pyrolysis cornstalk cellulose reaction mechanism |
