不同介质下物理法活化制备兰炭基活性炭实验研究
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摘要
以粒径小于6mm的废弃兰炭末为原料,高温下分别用水蒸气和CO2为介质活化制备兰炭基活性炭。采用碘吸附实验、N_2吸附/脱附实验和SEM等手段对成品的孔隙结构进行表征,比较了不同温度下活化介质对成品孔隙形成过程的影响,并分析了活化机理。结果表明:水蒸气活化速率更快,在温度较低时反应就能充分进行。随着活化温度的升高,两种活化介质制备活性炭的碘吸附值先增加后减小,收率均降低;N_2吸附/脱附实验表明,两种吸附等温线均符合I型吸附曲线的特征,成品微孔发达并含有中、大孔,900℃和1 000℃分别是水蒸气和CO_2活化过程的最佳温度,CO_2活化效果更好,成品的微孔比表面积和微孔体积低,平均孔径更大;机理分析表明,随着活化温度上升,先持续发生径向造孔作用,再发生横向扩孔作用,径向活化是活性炭形成发达微孔的主要控制过程。
Blue coke-based activated carbon(BAC)was prepared using disused blue coke powder less than 6 mm as raw materials by activation with steam and CO_2 at high temperature.The pore structure of BAC sample was characterized by iodine adsorbed,cryogenic N_2 adsorption techniques and scanning electron microscopy(SEM)and the influence of activation medium on formation process of pore was compared.Moreover,the activation mechanism was also tentatively postulated.The results show that the activation rate of steam is faster than that of CO_2 because it can be fully carried out at low temperatures.The iodine adsorption value of BACs activated by steam and CO_2 increases firstly and then decreases,and the yields all reduce.The N_2 adsorptiondesorption isotherms revealed that the BACs exhibit type I adsorption isotherms and the material structure consists of microporous and mesoporous.The optimal temperatures of steam and CO_2 activation are 900℃and 1 000℃respectively.Compared to steam,although the CO_2 activation is more effective,the specific surface area and volume of the micropore are lower,and the average pore size is larger.Mechanism analysis shows that with the increase of activation temperature,radial hole-making function occurs firstly and then transverse hole-enlarging occurs.In addition,in order to form a large amount of microporous,the radial activation is the main controlling process.
Blue coke-based activated carbon(BAC)was prepared using disused blue coke powder less than 6 mm as raw materials by activation with steam and CO_2 at high temperature.The pore structure of BAC sample was characterized by iodine adsorbed,cryogenic N_2 adsorption techniques and scanning electron microscopy(SEM)and the influence of activation medium on formation process of pore was compared.Moreover,the activation mechanism was also tentatively postulated.The results show that the activation rate of steam is faster than that of CO_2 because it can be fully carried out at low temperatures.The iodine adsorption value of BACs activated by steam and CO_2 increases firstly and then decreases,and the yields all reduce.The N_2 adsorptiondesorption isotherms revealed that the BACs exhibit type I adsorption isotherms and the material structure consists of microporous and mesoporous.The optimal temperatures of steam and CO_2 activation are 900℃and 1 000℃respectively.Compared to steam,although the CO_2 activation is more effective,the specific surface area and volume of the micropore are lower,and the average pore size is larger.Mechanism analysis shows that with the increase of activation temperature,radial hole-making function occurs firstly and then transverse hole-enlarging occurs.In addition,in order to form a large amount of microporous,the radial activation is the main controlling process.
引文
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[14]汪岸,骆仲泱,方梦祥,等.煤热解沥青炭化程度对KOH活化制备活性炭孔隙结构的影响[J].浙江大学学报(工学版),2018,52(8):1551-1557.WANG An,LUO Zhongyang,FANG Mengxiang,et al.Influence of Carbonization Degree of Coal Pyrolytic Pitch on the Pore Structure of Carbon Activated with KOH[J].Journal of Zhejiang University(Engineering Science),2018,52(8):1551-1557.
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[17]张利波,彭金辉,杨坤彬,等.微波辐射烟秆CO2活化制取活性炭及孔结构表征[J].化学工程,2007,35(5):67-70.ZHANG Libo,PENG Jinhui,YANG Kunbin,et al.Preparation and Characterization of Activated Carbons from Tobacco Stems with CO2 Activation by Microwave Irradiation[J].Chemical Engineering,2007,35(5):67-70.
[18]VALENYE NABAIS J,CARROTT P,RIBEIRO CARROTT M L,et al.Influence of Preparation Conditions in the Textural and Chemical Properties of Activated Carbons from a Novel Biomass Precursor:the Coffee Endocarp[J].Bioresource Technology,2008,99(15):7224-7231.
[19]RODRIGUEZ-REINOSO F,MOLINA-SABIO M,GONZLEZ M T.The Use of Steam and CO2as Activating Agents in the Preparation of Activated Carbons[J].Carbon,1995,33(1):15-23.
[2]宋永辉,马巧娜,李欣,等.活化温度对兰炭基活性炭结构与性能的影响[J].材料导报,2016,30(2):34-37.SONG Yonghui,MA Qiaona,LI Xin,et al.The Influence of Activation Temperature on Structure and Properties of Semicoke-based Activated Carbon[J].Materials Review,2016,30(2):34-37.
[3]宋永辉,张蕾,蒋绪,等.兰炭末水蒸气活化制备活性炭过程中反应温度的影响[J].煤炭转化,2017,40(5):56-62.SONG Yonghui,ZHANG Lei,JIANG Xu,et al.Effects of Reaction Temperature on Activated Carbon by Steam Activation from Blue-coke Powder[J].Coal Conversion,2017,40(5):56-62.
[4]宋永辉,汤洁莉.煤化工工艺学[M].北京:化学工业出版社,2017:364.SONG Yonghui,TANG Jieli.Coal Chemical Technology[M].Beijing:Chemical Industry Press,2017:364.
[5]马留可,詹福如.活性炭对水中亚甲基蓝的吸附性能研究[J].化学工程,2016,44(1):28-32.MA Liuke,ZHAN Furu.Adsorption Properties of Methylene Blue from Wastewater by Activated Carbon[J].Chemical Engineer(China),2016,44(1):28-32.
[6]杨森,韩洋,李阳,等.活化工艺对煤基活性炭结构及电容性能的影响[J].煤炭转化,2018,41(2):57-66.YANG Sen,HAN Yang,LI Yang,et al.Effect of Activated Technology on Structure and Capacitance Performance of Coalbased Activated Carbon[J].Coal Conversion,2018,41(2):57-66.
[7]赵旺,张双全,刘闯.糖液脱色颗粒活性炭的制备及其孔隙结构[J].煤炭转化,2016,39(1):71-75.ZHANG Wang,ZHANG Shuangquan,LIU Chuang.Preparation and Pore Structure of Granular Activated Carbon for Sugar Decolorizing[J].Coal Conversion,2016,39(1):71-75.
[8]ROMN S,GONZLEZ J F,GONZLEZ-GARCIA C M,et al.Control of Pore Development During CO2and Steam Activation of Olive Stones[J].Fuel Processing Technology,2008,89(8):715-720.
[9]TIAN Yuhong,LAN Xinzhe,SONG Yonghui,et al.Preparation and Characterization of Formed Activated Carbon from Fine Blue-coke[J].International Journal of Energy Research,2015,39(13):1800-1806.
[10]杨洪楠.兰炭制备活性炭的方法研究[D].马鞍山:安徽工业大学,2015.YANG Hongnan.Study on Methods of Semi-coke Preparation of Activated Carbon[D].Maanshan:Anhui University of Technology,2015.
[11]吴鹏,滕济林,张旭辉.兰炭活性焦的制备及应用性能研究[J].煤炭技术,2017,36(11):333-335.WU Peng,TENG Jilin,ZHANG Xuhui.Preparation and Application Properties Research on Activated Coke Based on Semicoke[J].Coal Technology,2017,36(11):333-335.
[12]JANKOWSKA H,SWIATKOWSKI A,CHOMA J.Active Carbon[M].New York:Ellis Horwood,1991.
[13]CHOMAA J,OSUCHOWSKIB L,MARSZEWSKIC M,et al.Developing Microporosity in Kevlar○R-derived Carbon Fibers by CO2 Activation for CO2 Adsorption[J].Journal of CO2 Utilization,2016,16:7-22.
[14]汪岸,骆仲泱,方梦祥,等.煤热解沥青炭化程度对KOH活化制备活性炭孔隙结构的影响[J].浙江大学学报(工学版),2018,52(8):1551-1557.WANG An,LUO Zhongyang,FANG Mengxiang,et al.Influence of Carbonization Degree of Coal Pyrolytic Pitch on the Pore Structure of Carbon Activated with KOH[J].Journal of Zhejiang University(Engineering Science),2018,52(8):1551-1557.
[15]ARENAS E,CHEJNE F.The Effect of the Activating Agent and Temperature on the Porosity Development of Physically Activated Coal Chars[J].Carbon,2004,42(12/13):2451-2455.
[16]刘长波,兰新哲,田宇红,等.炭化温度对兰炭基成型活性炭性能的影响[J].煤炭转化,2012,35(1):69-72.LIU Changbo,LAN Xinzhe,TIAN Yuhong,et al.Influence of Carbonization Temperature on the Performance of Formed Activated Carbon Based on Blue-coke[J].Coal Conversion,2012,35(1):69-72.
[17]张利波,彭金辉,杨坤彬,等.微波辐射烟秆CO2活化制取活性炭及孔结构表征[J].化学工程,2007,35(5):67-70.ZHANG Libo,PENG Jinhui,YANG Kunbin,et al.Preparation and Characterization of Activated Carbons from Tobacco Stems with CO2 Activation by Microwave Irradiation[J].Chemical Engineering,2007,35(5):67-70.
[18]VALENYE NABAIS J,CARROTT P,RIBEIRO CARROTT M L,et al.Influence of Preparation Conditions in the Textural and Chemical Properties of Activated Carbons from a Novel Biomass Precursor:the Coffee Endocarp[J].Bioresource Technology,2008,99(15):7224-7231.
[19]RODRIGUEZ-REINOSO F,MOLINA-SABIO M,GONZLEZ M T.The Use of Steam and CO2as Activating Agents in the Preparation of Activated Carbons[J].Carbon,1995,33(1):15-23.