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文章编号: 1007⁃8827(2017)05⁃0451⁃09热解自活化法制备生物质基微孔型活性炭孙 康1,2, 冷昌宇1, 蒋剑春1,2, 卜 权3, 林冠峰4, 卢辛成1, 朱光真1(1.中国林业科学研究院林产化学工业研究所,江苏南京210042;2.中国林业科学研究院林业新技术研究所,北京100091;3.江苏大学农业装备工程学院,江苏大学,江苏镇江212013;4.福建农林大学金山学院,福建福州350002)摘 要: 提出热解自活化制备生物质基活性炭的新方法,制备过程不添加任何活化剂㊂将生物质原料置于可密闭反应器,在高温高压条件下进行热解自活化反应㊂结果表明,椰子壳是热解自活化制备微孔型活性炭的最佳原料,选择活化温度900℃并保持6h ,制备出了具有网络状发达微孔结构的活性炭,微孔率高达87.8%,比表面积1194.4m 2/g ,总孔容积0.528cm 3/g ,碘吸附值1280mg /g ,亚甲基蓝吸附值315mg /g ㊂同时,作为电化学储能电极材料,比电容可达258F /g ,而且阻抗小,3000次充电循环后比电容仍能保持97.2%㊂热解自活化机理研究表明,生物质热解过程中产生的水蒸气㊁二氧化碳和反应器内的空气形成了良好的活化气氛,密闭反应器内形成的自生压力促进了水蒸气/二氧化碳与固体炭的活化反应速度,明显提高了微孔率㊂为了验证热解自活化法对其他生物质原料的适用性,还选择了杏核㊁核桃壳和松木屑作为原料进行热解自活化实验,并制得了高吸附力的活性炭样品㊂因此,热解自活化是一种无污染㊁清洁方便㊁产品得率高的新型活化方法,可产生良好的经济和环境效益㊂关键词: 生物质;微孔活性炭;热解自活化;电极材料;机理分析中图分类号: TQ 127.1+1文献标识码: A基金项目:林业公益性行业专项(201404610);国家自然基金(31400510).通讯作者:蒋剑春,研究员.E⁃mail :bio⁃energy @作者简介:孙 康,博士,副研究员.E⁃mail :sunkang 0226@Microporous activated carbons from coconut shells produced by self⁃activation using the pyrolysis gases produced from them ,that have an excellent electric double layer performanceSUN Kang 1,2, LENG Chang⁃yu 1, JIANG Jian⁃chun 1,2, BU Quan 3, LIN Guan⁃feng 4, LU Xin⁃cheng 1, ZHU Guang⁃zhen 1(1.Institute of Chemical Industry of Forest Products,Chinese Academy of Forestry,Nanjing 210042,China;2.Research Institute of Forestry New Technology of Forestry,Chinese Academy of Forestry,Beijing 100091,China;3.School of Agricultural Equipment Engineering,Jiangsu University,Zhenjiang 212013,China;4.Jinshan College of Fujian Agriculture and Forestry University,Fuzhou 350002,China)Abstract : Coconut shell⁃based activated carbons were prepared by self⁃activation using the pyrolysis gases generated from them.The process was carried out at high temperatures in a closed reactor filled with coconut shell under a high pressure that was generated by pyrolysis gases.Results indicate that the activated carbon prepared at 900℃for 6h has a specific surface area ,total pore volume ,micropore percentage ,iodine adsorption capacity and methylene blue adsorption capacity of 1194.4m 2/g ,0.528cm 3/g ,87.8%,1280mg /g and 315mg /g ,respectively.When used as the electrode material of electrochemical capacitors this activated carbon exhibits a specific capacitance of 258F /g ,a high capacitance retention rate of 97.2%after 3000charge /discharge cycles and a small imped⁃ance.The water vapor and carbon dioxide generated by the pyrolysis of the coconut shell in the closed reactor act as activating agents and also increase the pressure of the reaction system.This is favorable for the activation of the formed char.This self⁃activation meth⁃od was also used to prepare activated carbons with high adsorption capacities for iodine and methylene blue from almond stones ,pecan shells and slash pine sawdust ,indicating that it is a very simple ,efficient ,environmentally friendly and economical method for the preparation of biomass⁃based activated carbons for supercapacitor electrode materials and adsorption.Keywords : Biomass ;Microspores activated carbon ;Self⁃activation pyrolysis ;Electrode material ;Mechanism analysis Received date :2017⁃04⁃06; Revised date :2017⁃08⁃09Foundation item :State Forestry Public Benefit Research Sector (201404610);Natural Science Foundation of China (31400510).Corresponding author :JIANG Jian⁃chun ,Professor.E⁃mail :bio⁃energy @第32卷 第5期2017年10月新 型 炭 材 料NEW CARBON MATERIALSVol.32 No.5Oct.2017Author introduction:SUN Kang,Ph.D,Research Associate.E⁃mai:sunkang0226@English edition available online ScienceDirect(http:∕∕∕science∕journal∕18725805). DOI:10.1016/S1872⁃5805(17)60134⁃31 IntroductionBiomass is the most abundant reserves of renew⁃able organic resources on the Earth,which is cheap and easy available.Because it is rich in cellulose, semi cellulose,lignin,and low in inorganic impuri⁃ties,biomass is the particularly promising raw material for preparation of activated carbons(ACs).For exam⁃ple,a wide variety of biomass materials,including lig⁃nin,walnut and coconut shells,coffee beans,fire⁃wood,bamboo,rice husk,animal bones,animal feather,fungi,tea leaves,cocoon,dead leaves,ba⁃nana peel and sugarcane bagasse,have been used as the raw materials for the preparation of ACs.ACs are prepared mainly by physical and chemi⁃cal activation.The physical activation of carbonized biomass consumes about5tons of water vapor or car⁃bon dioxide per ton of feed,and a large amount of heat is required to heat water or carbon dioxide.This process is complex and the yield is lower than10%[1]. The chemical activation of biomass with H3PO4[2], ZnCl2[3],or KOH[4]consumes chemical weight4⁃6 times as much as feed.Moreover,the ACs prepared by chemical activation have a high content of metal impurities generally above3000mg/kg,which can block some pores of ACs,leading to a high self⁃dis⁃charge of AC electrode and a short cycle life of super⁃capacitors.In order to remove those chemical impuri⁃ties from ACs,a large amount of deionized water is needed to wash the ACs after chemical activation,gen⁃erating a large quantity of waste water.What is more, gas pollutants are also released during the chemical ac⁃tivation.In order to reduce pollutants,a kind of environ⁃ment friendly activation method is urgently needed to activate carbons.In the present study,a self⁃activation with pyrolysis gases(PSAM)was first employed to prepare microporous activated carbon using biomass as feed without aid of any physical or chemical agent. The activation was carried out in a covered reactor,in which a gas mixture from biomass pyrolysis was used as activation agents to create micropores in the biochar under an autogenerated pressure that can accelerate the activation rate[5,6].In this method,the air enclosed in the reactor and the oxygen adsorbed by the biomass feed can also act as activation agents[7].Supercapacitors(SCs),also known as electro⁃chemical capacitors,have recently gained much atten⁃tion owing to its high power density and long cycle life[8,9].On the basis of the charge storage mecha⁃nisms,supercapacitors have two categories,electrical double layer capacitors(EDLCs)and pseudocapaci⁃tor[10⁃11].The capacitance for EDLC originates from pure electrostatic charge separation at the interface be⁃tween electrode and electrolytes,which requires elec⁃trode materials with a large specific surface area and well⁃developed pores[12].Up to now,a variety of car⁃bon⁃based materials such as ACs,carbon aerogels, carbon nanotubes,carbon nanofibers,and graphene have been utilized as the electrode materials for EDLCs[13⁃15].Among them,ACs are considered as one of the most attractive candidates for EDLCs because of its large surface area,developed microporous struc⁃ture,excellent chemical stability and low cost.[16⁃18] In this study,the EDLC capacitance of ACs pre⁃pared by the self⁃activation of biomass with pyrolysis gases as the electrode of EDLCs was determined.The effects of reaction conditions including the moisture content,reaction time and reaction temperature on the properties of the ACs were investigated.The activation mechanism of this method was analyzed.2 Experimental2.1 PreparationCoconut shell,almond stone,pecan shell and slash pine sawdust were selected as feeds,and the AC samples prepared with these feeds were labeled as CSAC,ASAC,PSAC,SPAC,respectively.The ele⁃mental and proximate analysis of the feeds are summa⁃rized in Table.1.A stainless steel autoclave was used to maintain autogenerated pressure in the self⁃activation as shown Fig.1.The raw materials were pre⁃crushed to smaller than1mm,washed with deionized water and dried under150℃for2h.Then,they were put into the autoclave reactor,keeping their volume not exceed 1/3of the reactor volume.Then the reactor was sealed and put in a quartz tube furnace.The temperature was increased to700⁃1000℃at a heating rate of5℃/ min.The samples were held at the targeted tempera⁃ture for2⁃8h.Finally,the products were collected from the reactor after it was cooled to room tempera⁃ture.During the activation,a large number of pyroly⁃sis gases were generated,which can generate certain autogenerated pressure under high temperature.So the reactor was always kept sealed during the activation.㊃254㊃ 新 型 炭 材 料第32卷Table1 Elemental and proximate analysis of feeds.SampleElementC carbon H hydrogen O oxygen N nitrgen S sulfur*ProximateMoisture Ash Volatile Fixed carbonCoconut49.146.3742.470.130.7113.260.7677.7021.54 Almond stone48.767.5243.680.480.5611.052.1177.3220.57 Pecan shell48.656.6944.110.420.1310.161.5878.6319.79 Slash pine sawdust47.66.4545.400.550.217.893.4276.1120.47 Note:*ash,volatile and fixed carbon based on dry feed.Fig.1 Schematic diagram of the self⁃activation devicewith pyrolysis gases(1:furnace,2:resistance wire,3:thermocouple,4:pressure gauge,5:stainless steel autoclave reactor,6:electric heating rod). 2.2 CharacterizationsNitrogen adsorption isotherm was measured by a Micromeritics ASAP2020absorption analyzer at77K. Before analysis,the samples were degassed at200℃for24h.The surface area was calculated according to the Brunauer⁃Emmett⁃Teller(B.E.T)method.Pore size distribution was calculated based on the density function theory(DFT)method from nitrogen adsorp⁃tion data by assuming a slit pore geometry.Scanning electron microscopic(SEM)analysis was conducted by a S⁃3400⁃SEM(Toshiba).Before observation,E⁃1010ion⁃covered plane was used to spray metal on ma⁃terials.Transmission electron microscopic(TEM)in⁃vestigations were performed on a FEI Tecnai G2T20 microscope operated at200kV.XRD analysis was per⁃formed with a PANalytical X’Pert Pro MPD diffrak⁃tometer using Cu Ka⁃Radiation(40kV,40mA). Scanning resolution was0.02⁃2h and1s per step. Thermo⁃gravimetric analysis(TG)was carried out by a DSC⁃TG STA409(Netzsch,German).1g sam⁃ple,under the protection of the nitrogen flow,was put into the DSC/⁃TG and the temperature was raised to 900℃with a heating rate of10℃/min and main⁃tained for10min.The composition of pyrolysis gases was analyzed by GC/MS of a QMS403C(NETZSCH Company,Germany).With a heating rate of10K/ min,an outlet temperature of220℃,the ion current intensity of mass⁃to⁃charge ratios for the pyrolysis ga⁃ses were continuously detected.The gas composition was inferred according to characteristic peaks of vari⁃ous substances.The gaseous components were qualita⁃tively determined by comparing with a relevant stand⁃ard gas,and quantitatively determined using a single point external standard.2.3 Electrode preparation and electrochemical measurementsThe EDLC performance of all samples was evalu⁃ated at room temperature using a double electrode sys⁃tem.The working electrodes were prepared by mixing 85wt%microporous carbon,10wt%carbon⁃black, and5wt%polytetrafluoroethylene,and rolling into a thin film.After being pressed,the film was cut into disks of11mm in diameter with an approximate mass load of6mg/cm2.1M H2SO4was used as an electro⁃lyte.Galvanostatic charge⁃discharge(GCD)experi⁃ments were conducted with a VMP3B⁃2x2,Bio⁃Logic electrochemical workstation.The specific capacitance of the electrode material was derived according toC=2I(d V/d t)m(1) where I is the current(A),d V/d t is the slope of dis⁃charge curve(V㊃s-1),and m is the mass(g)of the active material in each electrode.3 Results and discussion3.1 N2adsorptionPyrolysis/self⁃activation temperature and holding time had a great impact on the pore structures of CSACs.As shown in Fig.2,the three adsorption iso⁃therms exhibited curves closed to a TypeⅠisotherm ac⁃cording to the IUPAC classification.The N2uptake in⁃creased sharply at low relative pressures(p/p0)from0 to0.1,but leveled off at the high relative pressures from0.1to0.99,which implied that CSACs had a de⁃veloped microporous structure.The three adsorption i⁃sotherms up⁃shifted gradually as the activation temper⁃ature increased from800to1000℃,indicating that their total pore volume increased gradually.The sam⁃ple prepared at900℃had no obvious hysteretic loop in the adsorption⁃desorption isotherm,indicating it had only a small number of mesopores.When the activa⁃tion temperature was increased to1000℃,the iso⁃therms showed an obvious hysteresis loop,which indi⁃cated that there was a moderate number of mesopores. It revealed that partial micropore walls collapsed under a high activation temperature,leading to a decrease of the microporosity and an increase of the mesoporosity.㊃354㊃第5期SUN Kang et al:Microporous activated carbons from coconut shells produced by Fig.2 N2adsorption isotherms of CSACs prepared atdifferent activation temperatures▲:1000℃;□:900℃;◆:800℃adsorption Fig.3represents the N2adsorption isotherms of the CSACs prepared at different activation times.All the samples gave a TypeⅠisotherm according to the IUPAC classification.The curves up⁃shifted gradually with the activation time.It was obviously observed that the lowest isotherm was achieved at an activation time of2h.This demonstrated that the total pore vol⁃ume was the smallest because the activation had not been performed insufficiently.When the activation time was increased to6h,N2adsorption volume in⁃creased rapidly at the relative pressures below0.2,but leveled off at the relative pressures from0.2to0.99. But the hysteresis loop is not clear,indicated that few meso⁃and macro⁃pores existed in the activated carbon. When the activation time was increased further to8h, an obvious hysteresis loop was observed,suggesting that some of the micropores were widened with the generation of mesopores and the decrease of micropore percentage.Fig.3 N2adsorption isotherms of CSACsprepared at different activation times△:8h;●:6h;□:4h;▲:2h3.2 Specific surface area and pore structureTable2summarizes the pore characteristics of the CSACs.The specific surface area and total pore vol⁃ume increased with the activation temperature and acti⁃vation time.The ratio of micropores reached87.80% at900℃,but decreased slightly with the temperature up to1000℃.The average pore diameter was in⁃creased with the activation temperature.The effect of activation time on the pore structure is the same as that of the activation temperature.This phenomenon is due to the fact that which micropores were generated first⁃ly,and developed to mesopores and macropores with the proceeding of the self⁃activation.Under high tem⁃perature,partial micropores were enlarged while new micropores were generated.When the widening speed of micropores exceeded the generation speed of new micropores,the number of mesopores and macropores increased while the number of micropores decreased. Hence,the activated carbon with a high microporosity (HMAC)could be prepared by controlling the activa⁃tion temperature and activation time carefully in the self⁃activation with pyrolysis gases.Table2 Characteristics of pore structure of CSACs.Temp.a(℃)Time(h)S b B.E.T(m2㊃g-1)V c t(cm3㊃g-1)V c micro(cm3㊃g-1)R d micro(%)V c meso(cm3㊃g-1)R d meso(%)D e(nm)80068030.3450.29786.100.0319.201.98 900611940.5280.44687.800.07113.402.02 1000611490.5580.40572.500.11821.202.12 90027170.3340.29187.100.0289.101.94 90049420.5690.44978.900.08915.602.05 900810870.6070.42870.500.13622.502.14 Note:a:Activation temperature;b:Specific surface area calculated by Brunauer⁃Emmett⁃Teller method;c:Total,micro⁃and meso⁃pore volume from N2adsorption;d:Ratio of micropore and mesopore;e:Average pore size.㊃454㊃ 新 型 炭 材 料第32卷3.3 EDLC performanceThe CSAC with the highest micropore ratio pre⁃pared in this work was selected as the electrode materi⁃al of EDLC.The cyclic voltammograms and the effect of scanning speed on specific capacitance are shown in Fig.4.EDLC performance of the CSAC was evaluated with atwo⁃electrode system using1M H2SO4as the e⁃lectrolyte.According to the equation(1),the specific capacitance of the CSAC was calculated as258F/g. As shown in Fig.3⁃a,the capacitance is higher at a lower scanning speed,which indicated that the CSAC had rich micropores.The cyclic voltammetry curve can still maintain the rectangular shape,even at a very high scanning speed of600mV/s,which shows that the CSAC has a much better capacitance performance.Fig.4 Effect of cyclic voltammograms(CV)and scanning speed on specific capacitance,(a)CV measurements of the CSAC electrode at different scan rates;(b)specific capacitance calculated from the CV measurements at various scan rates The electrochemical impedance spectra(EIS)of the CSAC is shown in Fig.5.The plot exhibited a semicircle in the high⁃frequency region and a straight line in the low⁃frequency region[19].The small semi⁃circle in the high⁃frequency region indicates a very low charge transfer resistance.This is due to its pore struc⁃ture,in which the micropores were internally connect⁃ed with each other.The interconnected pore structure facilitated the rapid diffusion of electrolyte ions into the micropores of the electrode material.In addition, the plot showed a vertical line to the imaginary axis in the low⁃frequency region,suggesting that the CSAC had a good capacitive behavior[20].Fig.5 Nyquist plot for the CSAC electrode Fig.6shows the cyclic performance of the CSAC. It can be seen that the CSAC had a long charge⁃dis⁃charge cycle life,since its discharge capacitance was kept at97.2%of the maximum discharge capacity af⁃ter3000cycles.That is due to the self⁃activation method proposed in this paper that does not use any chemical agents,avoiding contamination of the materi⁃als,which can keep clear of pore channels.Therefore, the CSAC prepared by self⁃activation is suitable for the electrode material of EDLCs.Fig.6 The cycling performance of the CSACat a current density of1A㊃g-13.4 Mechanism of activation3.4.1 Micropores created by pyrolysis gasesFig.7shows the TG⁃DTG curve of coconut shell. At the temperature below200℃,a small amount weight loss is related to dehydration of coconut shell. The main weight loss of70%took place in the most intense pyrolysis temperature between200and500℃, which was accompanied by releasing a large number of pyrolysis gases from coconut shell.The semi⁃cellulose that is the most unstable part of the woody materials decomposed between225and325℃,the cellulose be⁃㊃554㊃第5期SUN Kang et al:Microporous activated carbons from coconut shells produced by tween300and375℃,and the lignin between250and 500℃[21].As the pyrolysis temperature was elevated from500to1000℃,all the pyrolysis gases were re⁃leased and about30wt%solid char was left.Fig.7 TG⁃DTG curves of coconut shell The components of the gas mixture produced at different pyrolysis temperatures from coconut shell were detected by mass spectrometry.It can be seen from the peaks in Fig.8that the pyrolysis gases are mainly H2O(m/z=17,18),CO2(m/z=44)and CH4/C2H6(m/z=12,16).The CO2and H2O,a large portion of gases,are good activation agents,which e⁃volved above300℃.The results indicated that the ex⁃cellent activation atmosphere could be generated in the covered reactor,which can activate the char to create micropores in the self⁃activation[22⁃27].Fig.8 GC/MS curves of the pyrolysis gases of coconut shellm/z:1,18;2,44;3,17;4,16;5,12. Fig.9illustrates the mechanism of pore formation in the self⁃activation with pyrolysis gases,which in⁃clude two steps.As shown in Fig.9⁃(a),the first step happened in the temperature range of200⁃500℃, in which a large volume of pyrolysis gases escaping from coconut shell generates channel.Fig.8⁃(b)ex⁃hibits the second step happened in the high temperature range of800⁃1000℃,during which a high pressure is produced in the sealed reactor.The pyrolysis gases were forced into the channel of solid char under the au⁃togenerated pressure and created micropores by gasifi⁃cation reactions with carbon.At the same time,the high pressure can also promote the gasification reaction rate[28]to develop micropores in the self⁃activation with pyrolysis gases.Fig.9 An illustration of self⁃activation mechanism that creates micropores(a)channel formed by escaping pyrolysis gases between200and500℃and(b)microproes created by pyrolysis gases in the solid char at800⁃1000℃.3.4.2 The self⁃activation promoted by autogenerated pressureIn order to measure the autogenerated pressure in the sealed system,a high⁃temperature⁃proof pressure gauge was installed at the top of the tube furnace.The system pressure was recorded when temperature was increased to600,700,800,900and1000℃at a heating rate of10℃/min.Pressure gauge read was a constant value when the temperature was kept un⁃changed.Fig.10exhibits the relationship of autogener⁃ated pressure and temperature in the sealed reactor.It can be seen that the autogenerated pressure increased with the temperature because the pyrolysis gases were expanded to increase pressure in the sealed reactor un⁃der a high temperature.㊃654㊃ 新 型 炭 材 料第32卷Fig.10 Relationship of autogenerated pressure and temperature. 3.4.3 Carbon crystallite and its evolutionFig.11exhibits the XRD patterns of the CSAC and natural graphite.The XRD diffraction pattern of the CSAC showed two peaks at23°and44°,which corresponded to graphite pared with the XRD pattern of natural graphite,the diffraction peaks of the CSAC slightly shifted to the small diffrac⁃tion angle direction,indicating that the d⁃space of car⁃bon layer of the CSAC is larger than that of natural graphite.The d⁃space of the CSAC was calculated to be0.42nm,which is larger than0.34nm of the ideal graphite.Because the carbon microcrystallite derived from biomass is disorder and instable,it becomes or⁃dered under high temperature and high pressure.The carbon layer tends to be regular,making mesopore shrink to form new micropores,which leads to the in⁃crease of microporosity and electric conductivity[29].Fig.11 XRD patterns of the CSAC and natural graphite. Fig.12shows the TEM image of the CSAC pre⁃pared with the self⁃activation with pyrolysis gases at 900℃.Fig.12(a)shows a TEM picture of channel and pore of the CSAC.The sample has a very novel pore structure like a tree root,which is shown in sup⁃porting information in Fig.8.The channel formed by escaping pyrolysis gases and the micropores generated by gas activation were significant,and both type con⁃nected with each other.The interconnected porosity is in favor of the electrolyte ion access to the huge inter⁃nal area of the CSAC,which is very important for the electrode materials of supercapacitors.Fig.12 TEM images of the CSAC prepared by the self⁃activation at900℃.㊃754㊃第5期SUN Kang et al:Microporous activated carbons from coconut shells produced by Fig.12(b)is a high resolution TEM picture, showing rich micropores and surface of the CSAC. Fig.12(c)shows the image of the yellow region1of Fig.12(b),which further revealed that the CSAC had a highly porous structure with a large percentage of micropores.Fig.12(d)shows the image of the yellow region2of Fig.12(b),indicating that the surface of the CASC was covered obviously with a graphite layer about24graphene sheets.This indicated that coconut shell could be transformed into the graphite like struc⁃ture under high temperature and pressure,a which is in consistent with the analysis results from XRD.The im⁃provement of the conductivity of the CSAC by the graphite like structure is surely beneficial to improve the electrochemical performance of supercapacitors[30].3.5 Applicability of the self⁃activation method in other raw materialsIn order to determine the applicability of the self⁃activation with pyrolysis gases in the other raw materi⁃als,almond stone,pecan shell and slash pine sawdust were also selected as feeds to prepare ACs with an acti⁃vation temperature900℃and a holding time6h.The yield and adsorption properties are given and compared as shown in Table3.It was observed from Table2that ACs can all be prepared with the self⁃activation with pyrolysis gases from the selected three feeds.The sam⁃ples had good adsorption capacities for iodine and methylene blue of972⁃1200mg㊃g-1and180⁃315mg㊃g-1,respectively.Besides,the coconut shell was obvi⁃ously the best among them.Table3 Results of activated carbons prepared by the self⁃activation with pyrolysis gases.Feed Temperature/℃Time/h Yield/%MB capacity(mg㊃g-1)I2capacity(mg㊃g-1) Coconut shell900613.83151280Almond stone900612.41801119Pecan shell900612.5255972 Slash pine sawdust90065.72401028 Note:MB capacity:methylene blue adsorption capacity.I2capacity:iodine adsorption capacity.4 ConclusionsThe self⁃activation with pyrolysis gaes was firstly developed to prepare high microporous biomass⁃based ACs without using any activation agent.The obtained coconut shell based activated carbon showed a micro⁃pore ratio of87.7%and a specific capacitance of258 F/g.Because the micropore structure was formed as a conductive network,the activated carbon had a very small impedance and kept97.2%of initial capacitance after3000charge/discharge cycles.The high tempera⁃ture and autogenerated pressure made it possible to transform disordered carbon to graphite structure on the surface of coconut shell activated carbon,which im⁃proved the conductivity of the material.While no chemical agent was used,the activated carbon was pure and suitable for the electrode of super capacitor. The almond stone,walnut shell and slash pine sawdust were also selected as feeds to verify the effectiveness of the self⁃activation with pyrolysis gases,and results indicated that the prepared activated carbons showed a good adsorption capacity for iodine and methylene blue.This work reveals the activation mechanism of the self⁃activation with pyrolysis gases,which will contribute to the development of a very simple,effi⁃cient,environmental friendly and economical process for the preparation of biomass⁃based ACs for super ca⁃pacitor electrode materials and adsorption materials.References[1] Qiang L,Yin W,Jian Y,et al.Preparation and characterizationof activated carbons from spirit lees by physical activation[J].Carbon,2012,55(1):376.[2] Jagtoyen M,Derbyshire F.Activated carbons from yellow andwhite oak by H3PO4activation[J].Carbon,1998,36(7⁃8): 1085⁃1097.[3] Caturla F,Molina⁃Sabio M,Rodríguez⁃Reinoso F.Preparation ofactivated carbon by chemical activation with ZnCl2[J].Carbon, 1991,29(7):999⁃1007.[4] Elmouwahidi A,Zapata⁃Benabithe Z,Carrasco⁃Marín F,et al.Activated carbons from KOH⁃activation of argan(Argania spinosa )seed shells as supercapacitor electrodes[J].Bioresource Tech⁃nology,2012,111(1):185⁃190.[5] Pol S V,Pol V G,Gedanken A.Reactions under autogeneratedpressure at elevated temperature(RAPET)of various alkoxides:formation of metals/metal oxides⁃carbon core⁃hell structures[J].Chemistry,2004,10(18):4467⁃473.[6] Gershi H,Gedanken A,Keppner H,et al.One⁃step synthesis ofprolate spheroidal⁃shaped carbon produced by the thermolysis of octene under its autogenerated pressure[J].Carbon,2011,49(4): 1067⁃1074.[7] Man S T,Antal M J.Preparation of activated carbons from maca⁃damia nut shell and coconut shell by air activation[J].Industrial &Engineering Chemistry Research,1999,38(11):4268⁃4276.[8] Qu W H,Xu Y Y,Lu A H.Converting biowaste corncob residueinto high value added porous carbon for supercapacitor electrodes [J].Bioresource Technology,2015,189:285⁃291. 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江西农业学报 2009,21(3):96～98Acta Agriculturae J iangxi甘蔗渣制取活性炭的试验研究严兴,赵玲3,尹平河,周铁海 收稿日期:2008-12-19基金项目:广东省自然科学基金重点项目(04105835)。
作者简介:严兴(1982-),男,湖南人,硕士研究生,主要从事固体废弃物资源化和难降解废水处理的研究。
3通讯作者:赵玲。
(暨南大学环境工程系,广东广州510632)摘 要:以甘蔗渣为原料,以ZnCl 2为活化剂,采用先活化再炭化的方法制取生物活性炭。
通过比较得率和碘值,得到了制取活性炭的优化条件:活化剂ZnCl 2浓度为2.0mol/L,活化剂与甘蔗渣的质量比为5∶1,活化时间为24h,炭化温度为500℃,炭化时间为50m in,以N 2作为保护气,流量为2.5L /m in 。
在上述条件下制得的活性炭的碘值为510mg/g,得率为35.4%,比表面积为653m 2/g,平均孔径为2.4n m,孔体积为7.1×10-2c m 3/g 。
关键词:活性炭;甘蔗渣;活化炭化;XRD;SE M;BET中图分类号:X705 文献标识码:A 文章编号:1001-8581(2009)03-0096-03Exper im en t a l Study on M ak i n g of Acti va ted Charcoa l fro m Baga sseY AN Xing,Z HAO L ing 3,YIN Ping -he,Z HOU Tie -hai(Depart m ent of Envir on mental Engineering,J i ’nan University,Guangzhou 510632,China )Abstract:U sing ZnCl 2as activat or,the activated carbon was made fr o m bagasse by the method of firstly activati on and then car 2bonizati on .Thr ough the co mparis on of obtaining rate and i odine -value of the made activated charcoal,the op ti m u m conditi ons f or making activated carbon were obtained as f oll o ws:activat or ZnCl 2concentrati on was at 2.0mol/L,the quality rati o of the activat or t o bagasse was 5∶1,the activati on ti m e was 24h,the carbonizati on te mperature was at 500℃,the carbonizati on ti m e was 50m in and the current capacity of the p r otective N 2was 2.5L /m in .Under the above op ti m ized conditi ons,the i odine -value of made activated car 2bon was 510mg/g,the obtaining rate was 35.4%.Key words:Activated charcoal;Bagasse;Activati on and carbonizati on;XRD;SE M;BET 甘蔗渣是各种制糖基地的主要副产物,来源丰富。
甘蔗渣制取活性炭的试验研究
严兴;赵玲;尹平河;周铁海
【期刊名称】《江西农业学报》
【年(卷),期】2009(021)003
【摘要】以甘蔗渣为原料,以ZnCl2为活化剂,采用先活化再炭化的方法制取生物活性炭.通过比较得率和碘值,得到了制取活性炭的优化条件:活化剂ZnCl2浓度为2.0 mol/L,活化剂与甘蔗渣的质量比为5∶1,活化时间为24 h,炭化温度为500 ℃,炭化时间为50 min,以N2作为保护气,流量为2.5 L/min.在上述条件下制得的活性炭的碘值为510 mg/g,得率为35.4%,比表面积为653 m2/g,平均孔径为2.4 nm,孔体积为7.1×10-2 cm3/g.
【总页数】4页(P96-98,114)
【作者】严兴;赵玲;尹平河;周铁海
【作者单位】暨南大学,环境工程系,广东,广州,510632;暨南大学,环境工程系,广东,广州,510632;暨南大学,环境工程系,广东,广州,510632;暨南大学,环境工程系,广东,广州,510632
【正文语种】中文
【中图分类】X705
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生物质热解制备活性炭性能实验报告一、实验背景活性炭作为一种具有优良吸附性能的多孔材料，在环境保护、化工、医药等领域有着广泛的应用。
传统的活性炭制备方法通常依赖于化石资源，不仅成本较高，而且对环境造成一定压力。
生物质作为一种可再生资源，通过热解技术制备活性炭具有潜在的优势和应用前景。
二、实验目的本实验旨在研究生物质热解制备活性炭的性能，包括比表面积、孔隙结构、吸附性能等，为优化制备工艺和提高活性炭质量提供依据。
三、实验材料与设备（一）实验材料选取了玉米秸秆、稻壳、木屑等常见的生物质作为原料。
（二）实验设备1、热解炉：用于生物质的热解反应。
2、气体分析仪：用于分析热解过程中产生的气体成分。
3、比表面积及孔径分析仪：用于测定活性炭的比表面积和孔隙结构。
4、吸附实验装置：包括吸附柱、恒温振荡器等，用于评估活性炭的吸附性能。
四、实验方法（一）生物质预处理将收集到的生物质原料进行粉碎、筛选，得到粒度均匀的样品，然后在 105℃下干燥至恒重。
（二）热解过程将预处理后的生物质样品放入热解炉中，在氮气氛围下以一定的升温速率加热至设定温度，并保持一定时间进行热解反应。
热解产物经过冷却、收集，得到生物质炭。
（三）活化处理将生物质炭与活化剂（如氯化锌、磷酸等）按照一定比例混合，在一定温度下进行活化处理，以增加活性炭的孔隙结构和比表面积。
（四）性能测试1、比表面积和孔隙结构分析：采用氮气吸附法，使用比表面积及孔径分析仪测定活性炭的比表面积、孔径分布等参数。
2、吸附性能测试：选择亚甲基蓝作为吸附质，通过吸附实验装置测定活性炭对亚甲基蓝的吸附量和吸附速率。
五、实验结果与分析（一）比表面积和孔隙结构不同生物质原料制备的活性炭比表面积和孔隙结构存在差异。
其中，以玉米秸秆为原料制备的活性炭比表面积较大，孔隙结构较为发达。
活化剂的种类和用量对活性炭的孔隙结构也有显著影响。
适量增加活化剂的用量可以提高活性炭的比表面积和孔隙体积，但过量使用可能导致孔隙过度扩张，降低活性炭的机械强度。
生物质热解制备活性炭的工艺优化研究随着环境污染问题日益严重，低碳经济的发展逐渐成为了人们的共同愿望。
而生物质热解制备活性炭技术作为一种环保、可持续的资源利用方式，广受关注。
然而，该技术的不断发展与完善也需要科学家们的不懈努力。
在研究生物质热解制备活性炭的过程中，工艺优化显得尤为重要，本文将探讨生物质热解制备活性炭的工艺优化研究。
一、生物质热解技术生物质热解技术是通过高温蒸气处理生物质物质，使其分解成炭质和非炭质两部分。
其中，非炭质部分包括水和气体，可在后续进行处理中再次利用。
炭质部分则可以进一步加工制备成活性炭。
二、活性炭的制备方式活性炭是一种多孔性、高比表面积的炭质材料。
生物质热解技术是活性炭制备的常用方式之一。
在该技术中，生物质被加热至一定温度下，产生的热量和物质经过反应后，生成炭质。
生物质的种类和裂解温度会直接影响生物质热解制备活性炭的孔隙结构、化学性质和表面形貌等。
三、工艺优化研究生物质热解制备活性炭的过程中，工艺控制和参数优化是制备高质量活性炭的保证。
首先需要考虑的是生物质的种类，因为生物质的种类会直接影响制备出的活性炭的孔隙结构和比表面积。
例如，纤维素质材料易于形成纤维状结构，因而制备成的活性炭内含有较多的微孔和介孔；而木质材料在高温下易于产生聚合，因而制备活性炭的孔隙结构以大孔为主。
其次，要考虑热解温度和时间参数。
温度的选择要根据生物质的种类、成型材料的密度和热传导率等因素综合考虑。
热解时间则应根据热解温度和设备规格等因素来进行调整。
一般来说，高温热解时间短可以生成大量的孔洞，而低温热解时间长则能够生成更多的微孔和介孔。
同时，也需要考虑溶剂和处理方式的选择，这些因素都会影响活性炭质量和性能。
四、优化后的生物质热解制备活性炭的性能通过对工艺参数和溶剂等因素的优化，制备出的活性炭质量和性能都得到了很大提升。
研究表明，优化后的活性炭表面积和孔隙度都有较大提升，吸附能力也得到了明显提升。
此外，其在电化学性能、吸热性和催化性能等方面也有很好的表现。
专利名称：一种活性炭催化热解甘蔗渣制备4‑乙基苯酚的方法专利类型：发明专利
发明人：陆强,叶小宁,王昕,郭浩强,周民星,董长青,杨勇平
申请号：CN201710127516.6
申请日：20170306
公开号：CN106946658A
公开日：
20170714
专利内容由知识产权出版社提供
摘要：本发明属于生物质能的利用领域，具体涉及一种活性炭催化热解甘蔗渣制备4‑乙基苯酚的方法。
本发明是以甘蔗渣为原料，活性炭为催化剂，所述活性炭由生物质通过水蒸气活化法制备获得；将甘蔗渣与上述活性炭机械混合后在氢气氛围下于240～410℃下进行催化热解，对热解气进行冷凝后即可得到富含4‑乙基苯酚的液体产物；4‑乙基苯酚的产率及其在液体产物中的纯度都较高。
此外，本发明的方法以来源广泛的甘蔗渣为原料，以价格低廉的活性炭为催化剂，能够显著降低4‑乙基苯酚的生产成本。
申请人：华北电力大学
地址：102206 北京市昌平区回龙观镇北农路2号华北电力大学
国籍：CN
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