纤维素在炭化和活化过程中的结构变化  

Structural evolution of cellulose during carbonization and activation

作　　者：朱琼琼[1,2] 周花蕾[1,2] 李文军[1,2] 常志东[1,2] 孙长艳[1,2] 

机构地区：[1]北京科技大学化学与生物工程学院,北京100083 [2]北京科技大学功能分子与晶态材料科学与应用北京市重点实验室,北京100083

出　　处：《北京科技大学学报》2014年第11期1545-1551,共7页Journal of University of Science and Technology Beijing

基　　金：中国石油科技创新基金资助项目(2012D-5006-0208);中央高校基本科研业务费资助项目(FRF-BR-13-008;FPR-SD-13-002B);北京科技大学冶金研究基金资助项目(YJ2012-008);国家自然科学基金资助项目(21271022);中国石油天然气股份有限公司资助项目(2011B-1303)

摘　　要：以纤维素为原料,通过在氮气氛下炭化和水蒸气活化得到纤维素基炭。采用热分析、傅里叶红外光谱、X 射线衍射及低温 N2吸附测试手段研究了纤维素的炭化和活化过程以及过程中炭微晶结构和比表面积的变化。纤维素分子结构中的C—OH、C—O—C、C—H 等基团在280~380℃之间大量分解,380℃后少量裂解产生的小分子碎片或基团持续分解,同时碳元素发生结构重排,形成石墨微晶。炭化温度是影响纤维素基活性炭微晶结构及孔结构的关键因素,随炭化温度的升高,石墨微晶尺寸变大,孔结构得到发育,但活性炭的比表面积则呈先增加后下降趋势,当炭化温度为600℃时所得活性炭比表面积最大；炭化时间对炭微晶结构及比表面积的影响不显著；随着活化时间的延长,先是炭结构中的非微晶碳被氧化,比表面积及总孔容积变大,然后微晶碳被氧化,微晶结构被破坏,炭中部分微孔变成中孔或大孔,导致比表面积及总孔容积变小,当微晶间的非微晶碳被充分氧化而又不破坏原微晶结构时得到的炭孔隙最丰富。Carbon samples were prepared from cellulose by carbonization under the nitrogen atmosphere and water steam activa-tion. Their structure and specific surface area during carbonation and activation processes were studied by thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and nitrogen adsorption at low temperature. The results show that groups in the cellulose molecular structure like C—OH, C—O—C and C—H are mostly pyrolyzed completely between 280 - 380 ℃ . A few frag-ments or surface groups produced during pyrolysis decompose continuously above 380 ℃ . Meanwhile, carbon atoms rearrange within the solid sample and form graphite crystallites. Carbonization temperature exerts a crucial influence on the microcrystalline carbon structure and pore structure. With the rise of carbonation temperature, the size of graphite crystallites increases and the pore structure develops, but the specific surface area of the carbon prepared first increases and then decreases, reaching maximum at 600 ℃ . Carbon-ization time has less significant influence on the structures. With increasing activation time, non-crystalline carbon is oxidized, the spe-cific surface area and total pore volume of the carbon sample increase simultaneously. However, a longer activation time causes that the original crystalline carbon structure is destroyed, the specific surface area and total pore volume of the carbon sample decrease. The po-rosity is mostly abundant when non-crystalline carbon is fully oxidized and the original crystalline carbon structure is not destroyed.

关 键 词：纤维素 炭化 活化 微晶 比表面积 

分 类 号：TQ424.1[化学工程]