KOH原位活化对木质素基泡沫炭的结构性能调控
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摘要
在碱性条件下,木质素可部分替代苯酚与甲醛反应制备木质素基酚醛树脂,酚醛树脂经物理发泡,高温碳化工艺生成木质素基泡沫炭。为达到调控木质素基泡孔炭的泡孔结构,改善其孔径分布比例的目的,选用600℃碳化后的泡沫炭(CF-600℃)作为活化基体,利用化学试剂KOH对泡沫炭进行原位活化。研究结果表明:纯碱木质素可以部分取代苯酚,与甲醛发生缩合反应生成酚醛树脂;酚醛树脂基泡沫在450℃时有最大分解速率2.04%/min,炭收率为54.36%; 600℃碳化后的泡沫炭(CF-600℃)、900℃碳化后的泡沫炭(CF-900℃)与KOH原位活化后的泡沫炭(CF-KOH)呈玻璃网状结构,泡孔由50～300μm的泡孔及孔壁组成; 3种泡沫炭皆为无定型炭,非石墨化的炭质结构; KOH原位活化后的泡沫炭(CF-KOH)微孔比例下降,中孔比例上升,比表面积可达1 094.14 m~2/g;且3种泡沫炭的表观密度在0.10～0.15 g/cm~3之间,压缩强度最高可达0.35 MPa。
As one of natural multi-phenol polymers,lignin has chemical structure similar to polyphenols. In addition,phenol could be partially replaced by lignin under alkaline conditions,and might be reacted with formaldehyde to form the lignin-based phenolic resin. At the same time,the phenolic foam was obtained by physical foaming,which processed the lignin-based carbon foam at high carbonization temperatures. To adjust the cell structure of lignin-based carbon foam and improve its distribution ratio of pore size,the carbonized carbon foam produced at 600 ℃( CF-600 ℃)was selected as the activated matrix,and the chemical reagent KOH was applied to regulate the carbon foam. The results showed that phenol could be partially replaced by pure alkali lignin,and the phenolic resin was prepared from phenol with formaldehyde. The developed lignin based phenolic resin has good thermal stability. The maximum carbon residue could be 54.36% when the maximum decomposition rate was 2.04%/min at 450 ℃. Three types of carbon foams,i.e. CF-600 ℃ carbonized at 600 ℃,CF-900 ℃ carbonized at 900 ℃ and CF-KOH produced by the in situ regulation,were all in glass reticular structures with the sizes of bubble hole and wall pore between 50-300 μm. Compared with the carbon foam carbonized at 600 ℃( CF-600 ℃),the pore structure of the in situ regulation of carbon foam( CF-KOH) was mostly damaged,and the surface became rougher under high temperatures. The three types of carbon foams were mainly amorphous carbon,and their crystals were non-graphitized carbon structure. In the meantime,this study also found a small amount of sodium chloride crystal existed in carbonization of the carbon foam of CF-600 ℃. After activation,the in situ regulation of the carbon foam of CF-KOH was changed,which not only altered the ratio of micropores,but also increased the proportion of mesoporous,resulting in a specific surface area of1 094.14 m~2/g. Moreover,the apparent densities of carbon foams were between 0.10 and 0.15 g/cm~3,and the compression strength could reach up to 0.35 MPa.
As one of natural multi-phenol polymers,lignin has chemical structure similar to polyphenols. In addition,phenol could be partially replaced by lignin under alkaline conditions,and might be reacted with formaldehyde to form the lignin-based phenolic resin. At the same time,the phenolic foam was obtained by physical foaming,which processed the lignin-based carbon foam at high carbonization temperatures. To adjust the cell structure of lignin-based carbon foam and improve its distribution ratio of pore size,the carbonized carbon foam produced at 600 ℃( CF-600 ℃)was selected as the activated matrix,and the chemical reagent KOH was applied to regulate the carbon foam. The results showed that phenol could be partially replaced by pure alkali lignin,and the phenolic resin was prepared from phenol with formaldehyde. The developed lignin based phenolic resin has good thermal stability. The maximum carbon residue could be 54.36% when the maximum decomposition rate was 2.04%/min at 450 ℃. Three types of carbon foams,i.e. CF-600 ℃ carbonized at 600 ℃,CF-900 ℃ carbonized at 900 ℃ and CF-KOH produced by the in situ regulation,were all in glass reticular structures with the sizes of bubble hole and wall pore between 50-300 μm. Compared with the carbon foam carbonized at 600 ℃( CF-600 ℃),the pore structure of the in situ regulation of carbon foam( CF-KOH) was mostly damaged,and the surface became rougher under high temperatures. The three types of carbon foams were mainly amorphous carbon,and their crystals were non-graphitized carbon structure. In the meantime,this study also found a small amount of sodium chloride crystal existed in carbonization of the carbon foam of CF-600 ℃. After activation,the in situ regulation of the carbon foam of CF-KOH was changed,which not only altered the ratio of micropores,but also increased the proportion of mesoporous,resulting in a specific surface area of1 094.14 m~2/g. Moreover,the apparent densities of carbon foams were between 0.10 and 0.15 g/cm~3,and the compression strength could reach up to 0.35 MPa.
引文
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[11]王颢玉,徐国忠,董梦环,等.镜质组变质程度对泡沫炭孔结构和抗压强度的影响[J].炭素技术,2017,36(3):29-33.DOI:10.14078/j.cnki.1001-3741.2017.03.007.WANG H Y,XU G Z,DONG M H,et al.Influence of metamorphism of vitrinite on pore structure and compressive strength of carbon foam[J].Carbon Techniques,2017,36(3):29-33.
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[13]张坤,王高煊,王晓俊,等.玉米秸秆木质素的提取工艺优化及表征[J].食品科学,2015,36(6):58-62.DOI:10.7506/spkx1002-6630-201506011.ZHANG K,WANG G X,WANG X J,et al.Extraction and characterization of lignin from cornstover[J].Food Science,2015,36(6):58-62.
[14]万永坤,刘守庆,赵建蓉,等.核桃壳粉液化产物大孔泡沫炭的制备研究[J].西南林业大学学报,2017,37(3):192-198.DOI:10.11929/j.issn.2095-1914.2017.03.031.WAN Y K,LIU S Q,ZHAO J R,et al.The preparation of carbon foam with macropores structure from the phenolated walnut shell powder[J].Journal of Southwest Forestry University,2017,37(3):192-198.
[15]李雪梅,刘守庆,黄元波,等.高强度酚醛树脂泡沫炭的制备研究[J].林产化学与工业,2016,36(5):53-60.DOI:10.3969/j.issn.0253-2417.2016.05.008.LI X M,LIU S Q,HUANG Y B,et al.Preparation ofcarbon foams with high compressive strength derived from phenolic resin[J].Chemistry and Industry of Forest Products,2016,36(5):53-60.
[16]NARASIMMAN R,PRABHAKARAN K.Preparation of carbon foams with enhanced oxidation resistance by foaming molten sucrose using a boric acid blowing agent[J].Carbon,2013,55:305-312.DOI:10.1016/j.carbon.2012.12.068.
[17]LIN Q L,ZHENG M Z,QIN T,et al.Preparation of solid carbon spheres by pyrolysis of allyl COPNA-BMI resin[J].Journal of Analytical and Applied Pyrolysis,2010,89(1):112-116.DOI:10.1016/j.jaap.2010.06.005.
[18]WOO S W,DOKKO K,NAKANO H,et al.Preparation of three dimensionally orderedmacroporous carbon with mesoporous walls for electric double-layer capacitors[J].Journal of Materials Chemistry,2008,18(14):1674.DOI:10.1039/b717996k.
[19]WANG H,DA H H,JI S,et al.Selenium-functionalized carbon as a support for platinum nanoparticles with improved electrochemical properties for the oxygen reduction reaction and CO tolerance[J].Journal of the Electrochemical Society,2013,160(4):H266-H270.DOI:10.1149/2.014306jes.
[20]PAUL R,ZEMLYANOV D,VOEVODIN A A,et al.Methanol wetting enthalpy on few-layer graphene decorated hierarchical carbon foam for cooling applications[J].Thin Solid Films,2014,572:169-175.DOI:10.1016/j.tsf.2014.08.020.
[21]INAGAKI,MICHIO.Carbon materials science and engineering:from fundamentals to applications[M].Beijing:Tsinghua University Press,2006:92-120.
[22]SULAYMON A H.Increasing the adsorption surface area of activated carbon[J].Journal of Engineering,2008(3):2700-2717.
[23]孙忠鹏.多级孔FeAlPO-5分子筛的合成及在羟基化反应中的应用[D].兰州:兰州理工大学,2013.SUN Z P.Ionothermal synthesis of hierarchical FeAlPO-5molecular sieves and their catalytic application on phenol hydroxylation[D].Lanzhou:Lanzhou University of Technology,2013.
[24]吴优.落叶松基泡沫炭的制备与结构调控研究[D].哈尔滨:东北林业大学,2014.WU Y.Preparation and porous structure control of carbon foams from larch sawdust[D].Harbin:Northeast Forestry University,2014.
[2]赵鑫,李伟,刘守新,等.泡沫炭的制备及应用[J].林产化学与工业,2012,32(3):117-125.ZHAO X,LI W,LIU S X,et al.Preparation and apllication of carbon foam[J].Chemistry and Industty of Forest Products,2012,32(3):117-125.
[3]WOODWARD R T,FAM D W H,ANTHONY D B,et al.Hierarchically porous carbon foams frompickering high internal phase emulsions[J].Carbon,2016,101:253-260.DOI:10.1016/j.carbon.2016.02.002.
[4]CHEN J Z,XU J L,ZHOU S,et al.Nitrogen-doped hierarchically porous carbon foam:a free-standing electrode and mechanical support for high-performance supercapacitors[J].Nano Energy,2016,25:193-202.DOI:10.1016/j.nanoen.2016.04.037.
[5]DING X H,CHEN S S,LIU J,et al.Synthesis of carbon molecular sieve microspheres via amino phenolic resin as precursor formed from in-situ reaction composite micelles[J].Journal of Porous Materials,2018,25(5):1373-1380.DOI:10.1007/s10934-017-0549-0.
[6]龚青,詹亮,张永正,等.酚醛树脂基泡沫炭的发泡行为及其孔结构控制[J].新型炭材料,2016,31(4):445-450.GONG Q,ZHAN L,ZHANG Y Z,et al.Effects of heating rate on the foaming behavior and pore structure of carbon foams derived from phenol-formaldehyde resin[J].New Carbon Materials,2016,31(4):445-450.
[7]SHAFIZADEH J E,GUIONNET S,TILLMAN M S,et al.Synthesis and characterization of phenolic resole resins for composite applications[J].Journal of Applied Polymer Science,1999,73(4):505-514.DOI:10.1002/(SICI)1097-4628(19990725)73:4<505::AID-APP6>3.0.CO;2-l.
[8]缪正调,杨海艳,史正军,等.水热环境下的核桃壳木质素提取及结构表征[J].林业工程学报,2016,1(6):108-113.DOI:10.13360/j.issn.2096-1359.2016.06.018.MIAO Z D,YANG H Y,SHI Z J,et al.Isolation and characterization of lignin fractions from hydrothermal pretreated walnut shell[J].Journal of Forestry Engineering,2016,1(6):108-113.
[9]CHUNG H,WASHBURN N R.Chemistry of lignin-based materials[J].Green Materials,2013,1(3):137-160.DOI:10.1680/gmat.12.00009.
[10]李忠正.可再生生物质资源:木质素的研究[J].南京林业大学学报(自然科学版),2012,36(1):1-7.DOI:10.3969/j.issn.1000-2006.2012.01.001.LI Z Z.Research on renewable biomass resource:lignin[J].Journal of Nanjing Forestry University(Natural Sciences Edition),2012,36(1):1-7.
[11]王颢玉,徐国忠,董梦环,等.镜质组变质程度对泡沫炭孔结构和抗压强度的影响[J].炭素技术,2017,36(3):29-33.DOI:10.14078/j.cnki.1001-3741.2017.03.007.WANG H Y,XU G Z,DONG M H,et al.Influence of metamorphism of vitrinite on pore structure and compressive strength of carbon foam[J].Carbon Techniques,2017,36(3):29-33.
[12]徐强,孙倩倩,赵新坤,等.工业碱木质素羟甲基化改性研究[J].林业工程学报,2017,2(3):90-96.DOI:10.13360/j.issn.2096-1359.2017.03.015.XU Q,SUN Q Q,ZHAO X K,et al.Study on hydroxymethylation of industrial lignin[J].China Forestry Science and Technology,2017,2(3):90-96.
[13]张坤,王高煊,王晓俊,等.玉米秸秆木质素的提取工艺优化及表征[J].食品科学,2015,36(6):58-62.DOI:10.7506/spkx1002-6630-201506011.ZHANG K,WANG G X,WANG X J,et al.Extraction and characterization of lignin from cornstover[J].Food Science,2015,36(6):58-62.
[14]万永坤,刘守庆,赵建蓉,等.核桃壳粉液化产物大孔泡沫炭的制备研究[J].西南林业大学学报,2017,37(3):192-198.DOI:10.11929/j.issn.2095-1914.2017.03.031.WAN Y K,LIU S Q,ZHAO J R,et al.The preparation of carbon foam with macropores structure from the phenolated walnut shell powder[J].Journal of Southwest Forestry University,2017,37(3):192-198.
[15]李雪梅,刘守庆,黄元波,等.高强度酚醛树脂泡沫炭的制备研究[J].林产化学与工业,2016,36(5):53-60.DOI:10.3969/j.issn.0253-2417.2016.05.008.LI X M,LIU S Q,HUANG Y B,et al.Preparation ofcarbon foams with high compressive strength derived from phenolic resin[J].Chemistry and Industry of Forest Products,2016,36(5):53-60.
[16]NARASIMMAN R,PRABHAKARAN K.Preparation of carbon foams with enhanced oxidation resistance by foaming molten sucrose using a boric acid blowing agent[J].Carbon,2013,55:305-312.DOI:10.1016/j.carbon.2012.12.068.
[17]LIN Q L,ZHENG M Z,QIN T,et al.Preparation of solid carbon spheres by pyrolysis of allyl COPNA-BMI resin[J].Journal of Analytical and Applied Pyrolysis,2010,89(1):112-116.DOI:10.1016/j.jaap.2010.06.005.
[18]WOO S W,DOKKO K,NAKANO H,et al.Preparation of three dimensionally orderedmacroporous carbon with mesoporous walls for electric double-layer capacitors[J].Journal of Materials Chemistry,2008,18(14):1674.DOI:10.1039/b717996k.
[19]WANG H,DA H H,JI S,et al.Selenium-functionalized carbon as a support for platinum nanoparticles with improved electrochemical properties for the oxygen reduction reaction and CO tolerance[J].Journal of the Electrochemical Society,2013,160(4):H266-H270.DOI:10.1149/2.014306jes.
[20]PAUL R,ZEMLYANOV D,VOEVODIN A A,et al.Methanol wetting enthalpy on few-layer graphene decorated hierarchical carbon foam for cooling applications[J].Thin Solid Films,2014,572:169-175.DOI:10.1016/j.tsf.2014.08.020.
[21]INAGAKI,MICHIO.Carbon materials science and engineering:from fundamentals to applications[M].Beijing:Tsinghua University Press,2006:92-120.
[22]SULAYMON A H.Increasing the adsorption surface area of activated carbon[J].Journal of Engineering,2008(3):2700-2717.
[23]孙忠鹏.多级孔FeAlPO-5分子筛的合成及在羟基化反应中的应用[D].兰州:兰州理工大学,2013.SUN Z P.Ionothermal synthesis of hierarchical FeAlPO-5molecular sieves and their catalytic application on phenol hydroxylation[D].Lanzhou:Lanzhou University of Technology,2013.
[24]吴优.落叶松基泡沫炭的制备与结构调控研究[D].哈尔滨:东北林业大学,2014.WU Y.Preparation and porous structure control of carbon foams from larch sawdust[D].Harbin:Northeast Forestry University,2014.