SiO2對改性生物質(zhì)焦理化特性的影響

第30卷第24期農業(yè)工程學(xué)報Vol 30 No 24Transactions of the Chinese Society of Agricultural Engineering259SiO2對改性生物質(zhì)焦理化特性的影響馮燁12,米鐵1,張雄2,楊海平2,王賢華2,張世紅2,陳漢平(1.江漢大學(xué)工業(yè)煙塵污染控制湖北省重點(diǎn)實(shí)驗室,武漢430056;2.華中科技大學(xué)煤燃燒國家重點(diǎn)實(shí)驗室,武漢430074)摘要:為了探索SiO2對改性生物質(zhì)焦理化特性的影響,以稻稈、棉稈、稻殼作為原料,在600℃下熱解制備生物質(zhì)焦;焦樣再經(jīng)不同溫度下NHCO2高溫氣態(tài)改性后獲得對CO2具有高選擇性的富氮生物質(zhì)焦。采用傅立葉紅外光譜分析改性前后生物質(zhì)焦的表面官能團結構,利用ASAP2020自動(dòng)吸附儀測量其常溫變壓下的CO2吸附量并結合ⅹ射線(xiàn)熒光光譜對熱解焦的灰成分進(jìn)行分析,探討不同原料的生物質(zhì)焦改性過(guò)程中,其理化特性的演變。研究表明,生物質(zhì)焦灰分中過(guò)高的SiO2會(huì )阻礙其高溫下CO2的活化作用及NH3的氨化作用;焦樣灰分中的SiO2含量越低,其改性效果越理想。關(guān)鍵詞:生物質(zhì);二氧化硅;物理特性;化學(xué)特性;富氮生物質(zhì)焦;二氧化碳吸附doi:10.3969/iss.1002-6819.2014.24.032中圖分類(lèi)號:TK16文獻標識碼:A文章編號:1002-6819(2014)24-025907馮燁,米鐵,張雄,等.SiO3對改性生物質(zhì)焦理化特性的影響[J].農業(yè)工程學(xué)報,2014,30(24):259—265Feng Ye, Mi Tie, Zhang Xiong, et al. Influence of silica on physicochemical characteristic of modified bio-charsUJITransactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE), 2014, 30(24 ): 259-265(inChinese with english abstract0引言劑,在100℃的溫度下,最高的CO2的吸附量可以達到80mgg。陶賀等采用活性焦用于煙氣脫硫脫硝,大氣中CO2濃度增加是產(chǎn)生溫室效應及全球變脫硫效率高達98%,脫硝效率為70%。樊瑞軍6用椰暖的罪魁禍首,而且CO2排放量依然在以每年1.5%殼作為原材料,制取具有高度貫通的大孔-介孔-微的速度增加。中國承諾將在2020年前將單位GDP孔三連續的含氮整體式炭,通過(guò)調節胺的加入量制二氧化碳排放量在2005年的基礎上削減40%備不同含氮量的多孔炭材料,對塊狀炭進(jìn)行胺化試45%,面臨著(zhù)巨大的CO2減排壓力。在眾多碳減驗,提高炭表面含氮官能團的含量,CO2的靜態(tài)吸排技術(shù)中,CO2的捕獲、利用及封存技術(shù)( carbon附量提高了22%capture, utilization and storage,CCUS)具有非常但是在生物質(zhì)焦的制備過(guò)程中,原料自身的特大的前景凹。cCUs的關(guān)鍵技術(shù)在于CO2的捕集,性對改性后吸附劑的理化特性有很大的影響。林曉現有捕集技術(shù)主要分為吸收法、膜分離法、低溫蒸芬等發(fā)現,不同生物質(zhì)原料制取的焦,表面形貌餾法和吸附法,其中吸附法以其高效、簡(jiǎn)單、低成和孔結構區別很大,表面形貌和孔結構主要跟原料本、低腐蝕等優(yōu)點(diǎn)受到廣泛的關(guān)注。種類(lèi)有關(guān),孔結構對生物質(zhì)焦的吸附性能的影響很吸附劑的吸附特性主要和其孔隙特性其化學(xué)大。樹(shù)童圍使用4種不同生物質(zhì)制焦,并將活化和特性相關(guān)。以農業(yè)廢棄物為原料制備的改性生物質(zhì)改性焦對煙氣中的汞進(jìn)行吸附,研究發(fā)現不同原料焦具有良好的孔隙結構和豐富的含氮官能團,其吸制備的生物質(zhì)焦的吸附效果不同,活化和改性后的附性能強且生產(chǎn)成本低廉,因此倍受?chē)鴥韧庋芯咳私箤奈搅匡@著(zhù)提高。 wigman等凹發(fā)現,灰員的青睞。 Plaza等利用杏殼作為原材料,在800℃分中堿金屬(如K、Na)、Cu等的氧化物和碳酸鹽的高溫下用NH3對其改性,以此來(lái)制備CO2的吸附對水蒸氣的活化具有一定的促進(jìn)作用;且有利于微孔結構的形成。但謝強等發(fā)現,當有大量SiO2、稿日期:201409-17修訂日期:2014-12-14基金項目:國家863計劃課題(212401803);江漢大學(xué)工業(yè)煙坐污AlO3、Fe2O3存在時(shí),活化作用并不明顯;只有經(jīng)染控制湖北省重點(diǎn)實(shí)驗室開(kāi)放課題(HBIK201401),國家自然科學(xué)基氫氟酸處理后,堿金屬的活化作用表現才明顯金項目(51276075)關(guān)于不同的改性條件以及不同的原料種類(lèi)對作者簡(jiǎn)介:馮燁,男,主要從事生物質(zhì)熱解焦脫除大氣污染物研究武漢華中科技大學(xué)煤燃燒國家重點(diǎn)實(shí)驗室,430074生物質(zhì)焦改性及其CO2吸附特性的影響研究已經(jīng)進(jìn)Email:miniye2005@126.com行了很多1,而有關(guān)灰成分,尤其是SO2對高溫※通信作者:張世紅,男,教授,博士生導師,主要從事生物質(zhì)轉化利氣態(tài)改性及C中國煤化及道。因此本和流化床技術(shù)硏究。武漢華中科技大學(xué)煤燃燒國家重點(diǎn)實(shí)驗室430074.Email:shizhang(@hust.edu.cn文基于灰成分CNMHG焦的表面特農業(yè)工程學(xué)報2014年性及其CO2吸附效果,研究灰分中SⅰO2對改性及析如表1所示?；罨蠼箻永砘匦缘挠绊?焦樣制備及改性方法試驗生物質(zhì)焦的制備與改性系統主要在立式爐反應裝置進(jìn)行,該裝置可分為氣體發(fā)生區和改性反應1.1試驗樣品區,氣體發(fā)生區包括鋼瓶氣體及對應的減壓閥和質(zhì)本研究選取典型的農業(yè)廢棄物稻稈、棉稈、稻量流量計,反應區主要由不銹鋼管反應器(內徑殼,經(jīng)研磨及篩選后,獲得粒徑為30~60目的顆38mm,外徑40mm,髙600mm)和程序升溫電爐粒作為生物質(zhì)原料。3種原料的工業(yè)分析和元素分組成。表1生物質(zhì)原料工業(yè)分析與元素分析Table 1 Proximate and ultimate analysis of biomass raw material工業(yè)分析 Proximate analysis/%元素分析 Ultimate analysis/低位熱值揮發(fā)分LHV/MJkg)Fixed Carbon稻稈 Rice straw82125.1037.525920.860.1442.7817.23棉稈 Cotton stalk4.6615.8045.220.3437.7017.77稻殼 Rice husk61835.039.330.550.4714.52注:氧含量由差減法計算得出;ad;空氣干燥基Note: The O content was determined by difference; ad: air-dried basi熱解制焦:生物質(zhì)原料經(jīng)105℃烘焙預處理后應器中取出的固體即為CO2+NH3改性焦。送入固定床,通入N2(400m/min)作為保護氣,1.3焦樣表征及CO2吸附固定床升溫至600℃熱解保持30min得生物質(zhì)原試驗采用傅立葉紅外分析儀(德國 Bruker公焦,原焦樣收集后存放于干燥器中留待后續使用司, VERTEX70)來(lái)對焦樣表面的官能團種類(lèi)及表NH3改性:將生物原焦樣(2g)加入反應器內,面化學(xué)特性進(jìn)行分析?；页煞址治龈鶕鴺薔H3由N2攜帶(400mL/min)經(jīng)NH3通道進(jìn)入反GB/1574,利用美國伊達克斯有限公司 EDAX Inc應系統;啟動(dòng)電爐開(kāi)始程序升溫至預定溫度(400、生產(chǎn)的Ⅹ射線(xiàn)熒光探針(型號為: EAGLEⅢ)和600、800和1000℃)并保持30min,進(jìn)行NH3改美國戴安公司生產(chǎn)的ICS90離子色譜儀測定。CO2性反應。改性結束后關(guān)閉電爐,將氣體切換為純的常溫變壓吸附采用全自動(dòng)吸附儀(美國N2進(jìn)行吹掃冷卻,冷卻后反應器中取出的固體即為 Micromeritics公司,ASAP2020)測定。NH3改性焦。CO2活化:將生物質(zhì)焦(2g)加入反應器后開(kāi)2結果與討論啟CO2,CO2以200mL/min的速率通入反應器,電2.1灰分分析爐程序升溫至設定溫度(800℃)并保持30min進(jìn)表2為棉稈、稻殼和稻稈在600℃的熱解溫度行活化反應?；罨Y束后關(guān)閉電爐,將氣體切換為下制備生物質(zhì)原焦的灰成分分析。由表2可知,稻N2(400m/min)進(jìn)行冷卻,冷卻后反應器中取出殼焦的灰成分中SO2的質(zhì)量分數達到了8747%,的固體即為CO2活化焦稻稈焦中為51.99%,而棉稈焦中只有18.21%。同CO2+NH3活化改性:將生物質(zhì)焦(2g)加入時(shí)參考表1中稻稈和稻殼的灰分比例,約為棉稈的反應器后,重復CO2活化步驟;活化完畢后,直接2~3倍,經(jīng)折算后,采用相同質(zhì)量的原料制備熱解將CO2切換成NH,在相同溫度下進(jìn)行30min的焦,稻殼焦中的SiO2的含量約為棉稈的15倍,而NH3改性。改性結束后重復N2吹掃冷卻,冷卻后反稻稈焦中的SO2的含量約為棉稈的4~5倍。表2600℃熱解焦的灰成分分析Table 2 Ash analysis of pyrolytic biochars obtainted at 600C樣品 SamplegO AlO3 SioP,O5CaoTi0棉稈 Cotton stalk5.8218.217.14170726090.352.76稻稈 Rice straw0.9151.992.497.680.040.87.09稻殼 Cotton husk87470.812.382.2紅外光譜分析紅外光譜儀(FF改性首后的生物質(zhì)焦表面在不同的設定溫度下,分別對3種生物質(zhì)熱解官能團變化中國煤化工圖譜進(jìn)行結焦進(jìn)行高溫氨化(NH3改性),并利用傅里葉變換合分析。CNMHG第24期馮燁等:SiO2對改性生物質(zhì)焦理化特性的影響2.2.1生物質(zhì)原樣的紅外圖譜分析的吸收峰,應該對應著(zhù)C=O;而在波數為3400cm圖1是3種生物質(zhì)原樣的FTIR( Fourier附近出現的一個(gè)強且較寬的吸收峰主要對應OHtransform infrared spectra)圖譜,圖1a、1b和lc分在稻稈和稻殼原樣的紅外圖譜(圖1b和圖lc)中別對應棉稈、稻稈和稻殼。的相同位置,O-H鍵同樣有所體現。以五碳糖和六碳糖為主要成分的纖維素和半纖維素,與木質(zhì)素280}OH脂肪族,芳香族起構成生物質(zhì)三組分,它們之間的連接鍵中也富含酯鍵、醚鍵等含氧官能團1η。此外,位于波數2920cm附近出現的吸收峰,2.65恰好在2850~3000cm的范圍內,通常理解為飽2.55和C-H、CC的伸縮振動(dòng)。而在波數1400~1650cm]范圍之間出現的大量吸收峰,主要表征為木質(zhì)素中的芳香族和脂肪族結構。在3種生物質(zhì)原樣的2.35紅外圖譜中,波數1080cm附近均存在一個(gè)明顯4000350030002500200015001000波數 Wavenumber/cn的吸收峰,且在稻殼的紅外圖譜中最為顯著(zhù),有可棉稈原樣能對應著(zhù)SiO鍵8a. Cotton stalk2.2.2生物質(zhì)熱解焦及其改性(NH3)焦的紅外圖譜分析圖2a是棉稈熱解焦及NH3改性焦的紅外圖譜脂肪族,芳香族可以觀(guān)察到,600℃下熱解制備的原焦除波數Aliphatic, aromatic3400cm處的OH,基本上不含含氧官能團;而H c-c原樣中波數1400~1650cm范圍內的芳香族和脂1等肪族結構,由于木質(zhì)素的分解而基本消失。經(jīng)400℃-NH3改性后,在波數1580cm處出現一個(gè)明顯的吸收峰,這主要是由C=N官能團的伸縮振動(dòng)引400030002000起;同時(shí),在波數1420cm附近也出現一個(gè)吸收波數1峰,該峰主要對應于酰胺官能團NH振動(dòng)。C=Nb.稻稈原樣N-H官能團的出現,表明在400℃改性溫度下,NHb Rice straw3.1中的N元素被有效地引入到焦炭的碳基體結構中然而,隨著(zhù)改性溫度逐漸升高至1000℃C,C=N、脂肪族,芳香族NH的吸收峰逐漸消失,而在1000~1100cm波O-HAliphatic, aromatic段內出現了CNC官能團,應該是不穩定的C=N雙鍵隨著(zhù)溫度的升高趨于向更加穩定的CN單鍵C-H. C-C轉化,高溫(800℃和1000℃)改性焦在指紋區附近出現的吸收峰也印證了這一點(diǎn)相對于圖2a中棉稈焦的官能團變化趨勢,在稻2.5殼焦和稻稈焦的紅外圖譜(圖2b和圖2c)中400010043400cm2附近的OH吸收峰隨著(zhù)溫度的升高而出波數 Wavenumberc.稻殼原樣現明顯的下降,應該是通過(guò)水分的形式脫出焦炭。同時(shí),在圖2b和圖2c中,波數1580cm附近也圖1生物質(zhì)的傅里葉變換紅外圖譜有一些微弱的吸收峰存在,雖然不如圖2a中那么Fig. I Fourier transform infrared spectra of biomass明顯,但同樣隨改性溫度的升高而逐漸消失。這表根據表1中元素分析的結果,棉稈、稻稈和稻明,高溫氨化作用同樣使得N元素以官能團的形式殼的構成元素中,O質(zhì)量分數分別高達37.70%、引入到稻稈和稻殼的改性焦表面,只是引入數量上42.78%和3242%,表明這3種生物質(zhì)均富含含氧官明顯不如棉稈改性焦,可能是灰分中大量存在的能團,而這些官能團主要以羰基、羥基及醚鍵等形SiO2影響了含氮官能團的引入9。然而,與棉桿改式存在。生物質(zhì)的羰基峰值基本都處于波數1650~性效果明顯不中國煤化工中,有一個(gè)177cm2z間,因此,圖1a中波數為1739cm處較強的吸收峰CNMHGcm的波段農業(yè)工程學(xué)報2014年內,且幾乎不受溫度和改性作用的影響;根據特征2.3CO2的常溫變壓吸附峰的出現位置,結合灰分分析的結果,可判定為由我們之前的研究1已知,活化溫度是影響SiO吸收峰。由于SiO單鍵一般不會(huì )與NH2,NHCO2活化的關(guān)鍵因素,經(jīng)CO2活化后的棉稈焦,其等基團發(fā)生反應,而且較大的鍵能使得其難以在改比表面積及微孔孔容隨溫度的變化趨勢為先增大性溫度下斷裂;當SiO2大量存在于生物質(zhì)焦的結構后減小,在800℃時(shí)達到最大值。因此,在制備CO2中,有可能阻礙NH3中游離基團與焦炭的反應,從改性焦和CO2+NH3改性焦時(shí),直接選擇800℃作為而影響高溫氨化作用,減弱改性效果1820。反應溫度。選取3種生物質(zhì)的熱解焦及其800℃改性焦,進(jìn)行CO2的常溫變壓吸附,并根據吸附量的對比分析,探討原料對改性生物質(zhì)焦理化特性的C-H, C-C影響。圖3是棉稈熱解焦及3種不同氣氛下改性焦的C-N..H常溫變壓吸附特性曲線(xiàn)。CO2活化焦的吸附量明顯高于NH3改性焦及原焦的吸附量。這主要因為在室溫條件下,物理吸附占主導作用,吸附性能與比表面積成正相關(guān)性9。800℃時(shí),CO2和焦炭發(fā)生了氣化反應,對焦炭表面造成了熱蝕,使得其表面的孔隙結構進(jìn)一步豐富,從而增強了吸附量的相應提升921CO2+NH3改性焦的吸附量低于CO2改性4000300020001000波數 Wavenumber/cm焦,可能跟高溫氨化作用在焦炭表面引入了含氮官a.棉稈熱解焦及改性(NH3)焦能團有關(guān)?？赡茉谛鹿倌軋F生成過(guò)程中,發(fā)生的化a Pyrolytic and NH, modified Cotton stalk chars學(xué)反應產(chǎn)生了局部高溫,導致焦炭孔窄化和孔關(guān)閉,造成了比表面積的減小,因而吸附能力有所降低。NH3改性焦吸附量是最低的,且低于原焦樣,這也進(jìn)一步證明了CO2氣氛能夠擴大生物質(zhì)焦炭的孔隙結構。而NH3改性引入N元素的過(guò)程中,新的含氮官能團在一定程度上會(huì )對原來(lái)的孔隙結構產(chǎn)生影響,從而導致吸附量的下降從圖3b和圖3c中可以看出,稻殼焦和稻稈焦室溫吸附曲線(xiàn)與棉稈焦并不一致。不同氣氛下制備104000的改性焦,其吸附量比較接近,差值相對于棉稈焦波數 Wavenumber/cm已經(jīng)非常小。由此可見(jiàn),3種不同的改性方法,對b.稻稈熱解焦及改性(NH3)焦b Pyrolytic and NH3 modified rice straw chars稻殼改性焦和稻稈改性焦的孔隙結構影響并不是十分明顯。與棉稈改性焦相比,稻殼改性焦和稻稈O-H圖85改性焦CO2+NH3改性焦的吸附量明顯高于CO2改性焦的吸附量,但是CO2改性焦的吸附量依然高于求一個(gè)未改性的抽解焦樣的賤,這說(shuō)明,在0℃下,CO2對于生物質(zhì)焦的表面起到了一定的活化作用,但由于焦樣內有大量的Si-O鍵的存在,阻礙了大面積CO2的熱腐蝕作用,從而大大降低了CO2高溫氣令態(tài)活化作用9172021由于高溫氣態(tài)活化促進(jìn)了焦樣2表面大量sO鍵的裸露,使得NH1難以形成NH24000300010040NH等自由基負載在焦樣的表面2,從而降低了高波數 Wavenumber/cm溫氣態(tài)下NH3改性作用,減少了因含氮官能團的引c.稻殼熱解焦及改性(NH)焦入而引起孔隙結構惡化的幾率;從而使得800℃C. Pyrolytic and NH3 modified rice husk chars圖2生物質(zhì)熱解焦及其改性焦的傅里葉變換紅外圖譜CO2+NH3改性焦的吸附量高于相同溫度下CO2改Fig 2 Diagram of Fourier transform infrared spectra of性焦的吸附中國煤化工焦和稻稈焦pyrolytic and NH, modified bio-chars800℃時(shí)NH34CNMHG的原焦樣的第24期馮燁等:SiO2對改性生物質(zhì)焦理化特性的影響吸附量相差不明顯。這也說(shuō)明,對于灰成分中SiO2(18.21%)遠低于稻稈(51.99%)和稻殼(87.47%),含量較高的稻殼焦和稻稈焦,800℃NH3高溫氣態(tài)但其高溫CO2活化及高溫NH3改性的效果最明顯。改性作用不大。2)NH3的高溫氣態(tài)改性,可以促使原焦樣的52表面C=N,CN等含氮官能團的引入,提高改性焦■一NH:+CO2800℃NH3800℃對CO2的選擇性吸附。但是當被改性的焦樣中有大▲CO2800℃量的Si-O鍵存在時(shí),對NH3的高溫氣態(tài)改性有定的阻礙作用,會(huì )削弱含氮官能團的引入。3)CO2的高溫氣態(tài)活化,能改善原焦樣的表面結構,從而提高CO2的吸附量。但是當被改性焦樣的灰分中有大量的SiO2時(shí),會(huì )降低高溫下CO2的活化效果[參考文獻500550600650700750800]廖景明.生物質(zhì)活性炭吸附二氧化碳的性能研究門(mén)絕對壓力 Absolutely presssure/mm太陽(yáng)能學(xué)報,2013,34(3):382-387a.棉稈改性焦Liao Jingming. Carbon dixodie adsorption property ofa Modified cotton stalk charsactivated carbon from biomass[J]. 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Preparation and Modification of PorousCarbon for CO2 Adsorption[D]. Dalian: Dalian University一■一CO2+NH3800℃一▲COof Technology, 2013. (in Chinese with English abstract)NH800℃I7]林曉芬,張軍,尹艷山,等.生物質(zhì)焦表面形貌SEM7- Untreatment研究.炭素技術(shù),2011,30(4):27-29Lin Xiaofen, Zhang Jun, Yin Yanshan, et al. Study orsurface of biomass chars by scanning electron絕對壓力 Absolutely presssure/mmmicroscopy[J]. Carbon Techniques, 2011, 30(4): 27-29C.稻稈改性焦(in Chinese with English abstract)[8]樹(shù)童.生物質(zhì)焦改性及其對煙氣中汞吸附特性的實(shí)驗圖3棉稈、稻殼和稻稈改性焦室溫吸附量分析研究[D].南京:南京師范大學(xué),2012.Fig3 Adsorption capacities of modified chars of cotton stalk, [9] Wigmans T, Tromp P, Moulijn J. On the interpretation ofrice husk and rice straw chars at roomreactiveeasurements during potassium catalysedcarbon gasification reactions[J]. Carbon, 1984, 22(3)3結論中國煤化工結構調節:理1)棉稈熱解焦的灰分中SiO2質(zhì)量分數. HCNMH(005,20(2)264農業(yè)工程學(xué)報2014年183-190modification of activated carnon for CO2 adsorption[J]Xie Qiang, Zhang Xianglan, Li Lanting, et al. 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Characterizationpplied Surface Science, 2011, 257(9): 3936-3942of char from rapid pyrolysis of rice husk]. Fuel13]李通,羅仕忠,吳永永,等.活性炭改性及其對processing technology, 2008, 89(11): 1096-1105CO2CH4吸附性能的研究門(mén)J煤炭學(xué)報,2011,19] Zhang Xiong, Zhang Shihong, Yang Haiping,etal36(12):2012-2017Influence of NHy/CO2 Modification on the CharacteristicLi Tong, Luo Shizhong, Wu Yongyong, et al. Study of theof Biochar and the co 2 Capture[J]. BioEnergy Research,modifying of activated carbon and its adsorption2013,6:1147-1153properties of CO2/CH, mixture[J] Journal of China Coal [20] Capon A, Maggs F Compensation effect in the activationSociety, 2011, 36(12): 2012-2017.(in Chinese withof fibrous chars prepared from viscose[J]. Carbon, 1983English abstract)21(1):75-8014】魏浩然.三種生物質(zhì)基活性炭的制備及其對CO2的吸[2 Molina- Sabio m, Gonzalez m, Rodriguez- Reinoso h,etal附研究D.北京:清華大學(xué),201Effectide activation in theWei Haoran. The Preparation of Three Biomass-derivedicropore size distribution of activated carbon[J]. Carbon,Activated Carbons and Their CO2 Sorption[D]. Beijin1996,34(4):505-509Tsinghua University,2013. Gin Chinese with- nglish[22]張軍,解強,李蘭亭.煤質(zhì)活性炭脫灰工藝的研究進(jìn)abstract)展.煤化工,2007,35(2):20-2315]高峰,王媛,李存梅,等.活性炭表面改性及其對Zhang jun, Xie Qiang, Li Lanting, et al. Progress inCO2吸附性能的影響門(mén)J新型炭材料,2014,29(2)demineralization of coal- based activated carbon[j]. CoalChemical Industry, 2007, 35(2): 20-23. (in Chinese withGao Feng, Wang Yuan, Li Cunmei, et al. SurfaceEnglish abstract)Influence of silica on physicochemical characteristic of modifiedbio-charsFeng Ye2, Mi Tie, Zhang Xiong Yang Haiping 2, Wang Xianhua, Zhang Shihong", Chen Hanping(1. Hubei Key Laboratory of Indstrial Fume and Dust Pollution, Jianghan University, Wuhan 430056, China2. State Key Laboratory of Coal Combustion, Huazhong University of Science& Technology, Wuhan 430074, China)Abstract: To study the effect of SiO2 on the physicochemical characteristic of modified biochar, bio-chars wereobtained at 600C in a vertical furnace from a pyrolysis of rice straw, cotton stalk, and rice husk. Bio-chars wereactivated at different temperatures(400, 600, 800, and 1 000C)in a gaseous NH3 and/or CO2 atmosphere. Thevariation of chemical properties, the CO2 adsorption capacities, and the physicochemical properties linked with anSh analysis of different raw chars and modified chars were investigated. An X-ray fluorescence (EARGE IllEDAX Inc. and an ion chromatograph (ICS-90, Dionex) were used according to the national standard ofGB/T1574 to analyze the ash composition of pyrolytic biochars. The content of Sioz in rice husk char (87. 47%0)was the highest among the studied samples, followed by rice straw and cotton stalk chars, which were 51.99%o and18.21%, respectively. However, according to the proximate analysis of biomass raw materials, the proportion ofash in rice straw and rice husk was about 2-3 times of that of cotton stalk, therefore the amount of Sio retainedin rice husk and rice straw was nearly 15 times and 4-5 times of that in cotton stalk, respectively. The productieand modification of biomass chars were carried out in a self-designed vertical furnace reaction system whichincluded two parts: A gas generating zone and a modification reaction zone The modification reaction zonemainly consisted of a stainless steel reactor (inner diameter 38 mm, outer中國煤化工ht 600 mm)and a temperature programmed furnaceCNMHG第24期馮燁等:SiO2對改性生物質(zhì)焦理化特性的影響A Fourier transform infrared spectrum analyzer (VErTEX70, Bruker) was used to analyze the variation ofchemical properties and surface functional groups of biochars before and after NH3 modification at differenttemperatures. And the Fourier transform infrared spectra of the corresponding biomass raw materials linked with aroximate and ultimate analysis were also presented to compare with that of chars and modified chars. The resultsshowed that in the NH3 atmosphere, a certain amount of nitrogen had been introduced onto the surface of charsbut the amount of N-containing functional groups that was introduced into rice straw chars or rice husk chars wereobviously lower than that of cotton stalk chars which may be caused by the large amount of SiO2 that remainedthe ash of rice straw and rice husk. The bond energy of Si-O was considerable high, which usually cracks above1 400C and is very difficult to react with the free radical groups such like -NH2 and -NH under an NHatmosphere. Since there is a large amount of Si-O function group on the surface of rice straw or rice husk chars, itill hinder the reactions between-NH2, -NH and other radical groups and chars, which will reduce the totalmodification efficiency of pyrolytic chars. The COz adsorption capacities of biochars before and aftermodification were investigated by an automatic adsorption instrument(ASAP2020, Micromeritics)at roomtemperature. Experimental results showed that the positive influence of CO2 on pore structure evolution and theintroduction of N-containing function groups into char structure may be weakened by sio2, Bio-chars derivedfrom cotton stalk which were modified under a CO2 atmosphere showed the best CO2 adsorption capacities amongall the modification methods and different feedstock. It indicated that modified bio-chars with lower SiO, contentshowed better CO2 adsorption performanceKey words: biomass; silica; physical properties; chemical properties; nitrogen-rich bio-char; CO2 adsorption《農業(yè)工程學(xué)報》位列 Google學(xué)術(shù)搜索高被引中文期刊第10名Google學(xué)術(shù)是一個(gè)可以免費搜索學(xué)術(shù)文章的網(wǎng)年間發(fā)表的h篇文章每篇至少都被引用過(guò)h次的最絡(luò )應用。該項索引包括了世界上絕大部分出版的學(xué)大值);出版物的h5中位數,是指出版物的h5指術(shù)期刊,可以從一個(gè)位置搜索眾多學(xué)科和資料來(lái)源:數所涵蓋的所有文章獲得的引用次數的中位值。h5來(lái)自學(xué)術(shù)著(zhù)作出版商、專(zhuān)業(yè)性社團、預印本、各大指數和h5中位數越高說(shuō)明期刊論文的影響力越大。學(xué)及其他學(xué)術(shù)組織的經(jīng)同行評議的論文、圖書(shū)的摘Google學(xué)術(shù)搜索評出的h5指數前100名高被要和全文。它可幫助科研工作者在整個(gè)學(xué)術(shù)領(lǐng)域中引期刊中,《農業(yè)工程學(xué)報》的h5指數位列第10確定相關(guān)性最強的研究,因而被廣大科研工作者廣名,為37,h5中位數為43。 Google學(xué)術(shù)搜索評出泛應用和認可。期刊h5指數是其推出的一個(gè)評價(jià)期的前20名高被引期刊見(jiàn)表1。相關(guān)鏈接刊論文高被引程度的指標,h5指數是指在過(guò)去整整htp:/cholargoogle.com.cn/citations?view_op=topv5年中所發(fā)表文章的h指數(h指數指在2002013 enues&hl=zhCN&vq=zh表 Google學(xué)術(shù)搜索評出高被引中文期刊-h5指數排名前20名期刊排名出版物h5指數h5中位數排名出版物h5指數h5中位數經(jīng)濟研究中國電機工程學(xué)報2中華醫院感染學(xué)雜志中國社會(huì )科學(xué)中華護理雜志9744實(shí)驗室研究與探索電力系統自動(dòng)化新華月報會(huì )計研究6電網(wǎng)技術(shù)中國感染與化療雜志新華文摘金融研究8管理世界中國高等教育地理學(xué)報837電力中國煤化工44農業(yè)工程學(xué)報3CNMHG