木質(zhì)素熱解的熱重紅外分析儀實(shí)驗研究

第16卷第3期2016年1月科學(xué)技術(shù)與工程Vol 16 No. 3 Jan. 20161671-1815(2016)03-0225-0Science Technology and EngineeC 2016 Sci. Tech engrg化學(xué)工業(yè)木質(zhì)素熱解的熱重紅外分析儀實(shí)驗研究車(chē)德勇孫亞萍孫艷雪(東北電力大學(xué)能源與動(dòng)力工程學(xué)院,吉林132012)摘要利用熱重紅外分析儀( TG-FTIR)對木質(zhì)素進(jìn)行熱重分析及主要氣相產(chǎn)物分析;并探討了升溫速率和堿金屬鹽對木質(zhì)素熱解過(guò)程的影響規律。結果表眀:隨著(zhù)升溫速率的增加,揮發(fā)分析岀階段DTG曲線(xiàn)的峰型變寬,熱解起始溫度、最大失重峰溫均向高溫側移動(dòng);且較髙的升溫速率不利于氣相產(chǎn)物的析岀。添加碳酸鈉、碳酸鈣和碳酸鉀對木質(zhì)素熱解主反應區反應速率的影響較小,相比堿金屬鹽的加λ量而言,最終熱解固體產(chǎn)物略有増加;同時(shí)堿金屬鹽的添加對氣相產(chǎn)物的析岀有明顯抑制作用。與其他兩種堿金屬鹽相比,碳酸鈣的加入對600~700℃溫度區間內木質(zhì)素熱解產(chǎn)生的CO和CO2產(chǎn)量有一定的促進(jìn)作用關(guān)鍵詞木質(zhì)熱解堿金屬鹽氣相產(chǎn)物中圖法分類(lèi)號TQ351.635文獻標志碼B化石燃料的迅速消耗導致全球能源危機,而生素熱解的分段特征。潭洪等"對木質(zhì)素熱解過(guò)程物質(zhì)作為潔凈能源和高附加值化學(xué)品的原料受到廣中的焦油產(chǎn)物進(jìn)行考察,得到焦油產(chǎn)物的生成機理。泛關(guān)注。生物質(zhì)具有儲量豐富、對環(huán)境污染小目前,關(guān)于木質(zhì)素熱解過(guò)程中氣體產(chǎn)物的釋低溫室效應等優(yōu)點(diǎn)。然而,要實(shí)現生物質(zhì)能源的充放機理的硏究還較少,本實(shí)驗采用TG-TIR聯(lián)用分利用,熱裂解是重要的技術(shù)手段之一。作為生物技術(shù),對木質(zhì)素的熱解過(guò)程及主要氣相產(chǎn)物進(jìn)行質(zhì)三組分之一的木質(zhì)素雖然含量不高,但熱解過(guò)程分析,并深入探討了升溫速率、堿金屬鹽等因素對相對復雜,且可能與生物質(zhì)其余組分有相互作用,所木質(zhì)素熱解失重特性及主要氣相產(chǎn)物的釋放規律以對木質(zhì)素熱解過(guò)程及其產(chǎn)物析出的研究具有重要的影響。意義。而熱重傅里葉紅外光譜聯(lián)用技術(shù)(TGTIR)不僅可獲得物質(zhì)熱分解的失重與溫度關(guān)系,還1實(shí)驗可實(shí)時(shí)檢測物質(zhì)熱分解氣相產(chǎn)物的組成,因而越來(lái)1實(shí)驗樣品越受到研究者的重視,廣泛應用于化工、能源、材料實(shí)驗用原料為 Sigma Aldrich公司提供的高純等領(lǐng)域°8度脫堿木質(zhì)素。將原料破碎篩分0.1mm以下,以針對木質(zhì)素的熱解,已有大量文獻進(jìn)行了硏究,消除熱解試驗中粒徑對熱擴散的影響。在60℃帶姚燕等”利用熱重紅外聯(lián)用儀對木質(zhì)素熱解失重通風(fēng)的烘箱中烘干16h,用密封袋封好,于5℃冰箱過(guò)程及析出氣體進(jìn)行研究,分析得到木質(zhì)素熱解過(guò)中保存待用。樣品的元素分析、工業(yè)分析見(jiàn)表1程的活化能等。程輝等研究了木質(zhì)素熱解過(guò)程為考察堿金屬對木質(zhì)素熱解特性的影響,將樣品與中產(chǎn)物半焦官能團的演化規律,進(jìn)一步證明了木質(zhì)Na2CO3、CaCO3和K2CO3物理?yè)交?摻混比為5%。表1木質(zhì)素的元素分析和工業(yè)分析Table 1 Proximate and ultimate analf lignin and cellul工業(yè)分析/WAD%元素分析/WAD%vad18.3345.65中國煤化工1.2CNMHG實(shí)驗主要釆用熱重差熱綜合熱分析儀(瑞土生2015年9月17日收到產(chǎn)的 METTLER TGA/STD1)和紅外光譜儀(美國生第一作者簡(jiǎn)介:車(chē)德勇(1975-),女,教授,博士。研究方向:生物質(zhì)產(chǎn)的 NICOLET IS10)。采用程序升溫,分別采用5氣化技術(shù)及煤的潔凈利用技術(shù)。 E-mail: chedeyongy@16310、20、40℃/min的升溫速率將木質(zhì)素從50℃升溫科學(xué)技術(shù)與工程16卷到900℃,采用高純N2作為保護氣體,流量設置為2.2不同升溫速率下木質(zhì)素熱解特性及氣體產(chǎn)物50m/min,試樣質(zhì)量在15mg左右析出規律2結果與討論將木質(zhì)素按照不同升溫速率(5℃/min、10℃/min、20℃/min、40℃/min)進(jìn)行熱解實(shí)驗,得到的2.1木質(zhì)素熱解特性及氣體產(chǎn)物析出規律TG曲線(xiàn)和DTG曲線(xiàn)。圖1為木質(zhì)素在10℃/min升溫速率下單獨熱由圖3可知,不同升溫速率下,木質(zhì)素熱裂解的解的TG和DTG曲線(xiàn)。由圖可以看出木質(zhì)素熱解大TG和DTG曲線(xiàn)具有一致的演化趨勢。升溫速率為致分為三個(gè)失重階段,脫除自由水階段、揮發(fā)分析出5℃/min時(shí),熱解的主失重區內DTG曲線(xiàn)的峰型不階段和深度熱裂解階段,其三個(gè)階段失重率分別為明顯,特別是在熱解后期。隨升溫速率的增加,在揮6%、36%、12%,總失重為54%。在揮發(fā)分析出階發(fā)分析出階段DTG曲線(xiàn)的峰型也隨之變寬,熱解起段可以看岀DTG曲線(xiàn)呈現不對稱(chēng)的肩峰和拖尾,說(shuō)始溫度、最大失重峰溫均向高溫側移動(dòng),這是因為升明此過(guò)程是多個(gè)反應綜合的復合反應。溫速率的增加引起木質(zhì)素試樣內外之間、試樣外表0.0000面與坩堝間的溫度梯度增大,木質(zhì)素熱解過(guò)程產(chǎn)生-0.0001的氣相產(chǎn)物擴散至外面時(shí),反應室的實(shí)際溫度已經(jīng)升高,從而測得的揮發(fā)分初始析出溫度和峰溫均向G曲線(xiàn)100035高溫側移動(dòng)DTG曲線(xiàn)20℃min1圖1木質(zhì)素熱解TG和DTG曲線(xiàn)Fig. 1 TG-DTG curves of lignin pyrolysis圖2顯示了木質(zhì)素熱解過(guò)程氣體產(chǎn)物的FTIR三維譜圖。由圖2可以看出木質(zhì)素在不同熱解階段析出的物質(zhì)有很大不同。木質(zhì)素初次揮發(fā)階段a)TG曲線(xiàn)0.0000(200~550℃)的熱解產(chǎn)物成分較為復雜,主要氣體0.0002產(chǎn)物為H2O、CH4、CO和CO2等輕質(zhì)氣體。木質(zhì)素00004與苯環(huán)連接的甲氧基發(fā)生裂解,可生成CO和CH40.0006等小分子氣體;木質(zhì)素部分末端官能團和側鏈,如末-000100.00120℃min端的—OH鍵、COOH鍵和苯基C-C的斷裂,析0.0014出少量烴類(lèi)氣體產(chǎn)物和大量含氧化合物,如水、CO0.00168001000和CO2等。當熱解溫度繼續升高,在深度熱解階(b)DTG曲線(xiàn)段(550~900℃),析出的主要氣體為CO,此外繼續析出少量CO2。這是因為芳香族化合物到650℃左圖3不同升溫速率下木質(zhì)素熱解曲線(xiàn)Fig 3 TG -DTG curves of lignin pyrolysis右時(shí)基本熱解完全,析出大量CO,苯丙烷基團間的at different heating rates醚鍵等斷裂和揮發(fā)分的二次裂解反應而生成木質(zhì)素在不同升溫速率下熱解CO、CO2和CH0015吸光度曲線(xiàn)見(jiàn)圖4。由圖可以看出,CO和CO2的起始析岀溫度較低且相近,在200℃氣體就開(kāi)始析出均有一大一小兩個(gè)峰,同時(shí)還存在肩峰,但二者析出峰形中國煤化x℃時(shí)大量析出,而CO起CNMH折出在300-750℃溫度區同門(mén)工姦王成峰和肩峰。隨升溫速4000350030002500200015001000率的增加,氣體的析出溫度及峰值溫度均向高溫方圖2木質(zhì)素熱解氣體產(chǎn)物的FTR三維譜圖向移動(dòng),這一現象與升溫速率對TG、DTG曲線(xiàn)影響Fig 2 Three dimensional spectra ( FTIR)規律一致。主要是因為升溫速率過(guò)快,傳熱及析出of gas product on lignin pyrol的氣體產(chǎn)物不能及時(shí)擴散出去。3期車(chē)德勇,等:木質(zhì)素熱解的熱重紅外分析儀實(shí)驗研究5℃0.015CANAA200300400500600100200300400500600700800900(b)co.()CH4圖4不同升溫速率氣相產(chǎn)物的吸光度隨溫度變化Fig, 4 CO, CO2 and CH4 release rules of lignin pyrolysis at different heating rates為深入分析木質(zhì)素熱解過(guò)程中主要氣體產(chǎn)物lignin(CO、CO2和CH4)的析出規律,圖5為木質(zhì)素在不lignin+CacO,b lignin+Na, CO同升溫速率下熱解過(guò)程中氣相產(chǎn)物的累計產(chǎn)率。由圖可明顯看出,木質(zhì)素熱解氣相產(chǎn)物的累積產(chǎn)率發(fā)生了明顯變化,隨升溫速率的增大,累積產(chǎn)率減小,可見(jiàn),較高的升溫速率對氣體產(chǎn)物的析出80000不利l000zz5℃min1(a)TG曲線(xiàn)區10℃min-1E20℃min140℃min0.00010.0002-0.0003ligninlignin+ CacO,0.0005圖5不同升溫速率氣相產(chǎn)物的累積產(chǎn)率b)DTG曲線(xiàn)Fig. 5 The accumulation yield of gas productat different heating rates圖6添加堿金屬鹽的木質(zhì)素熱解TG和DTG曲線(xiàn)2.3不同催化劑下木質(zhì)素熱解特性及氣體產(chǎn)物析Fig 6 TG -DTG curves of lignin pyrolysis loadedali metal salt出規律圖6為添加三種堿金屬鹽和木質(zhì)素物理?yè)交霤H初始析出溫度較低,含量較高的甲氧基的存在后和木質(zhì)素的熱解失重圖。從圖中可以看出:溫使其在300℃就出現了較強的CH析出峰,而堿金度較低時(shí)(<600℃),堿金屬鹽的加入對木質(zhì)素屬鹽的加入明顯降低了CH4的析岀峰,說(shuō)明堿金屬的熱解沒(méi)有明顯影響,由于木質(zhì)素的主要熱解失鹽加入不利于CH1的產(chǎn)生。對CO和CO2氣體,添重一般都是在低于600℃發(fā)生的,因此,堿金屬鹽加碳酸鈣的木質(zhì)素熱解在650℃岀現尖銳的氣體析出峰,鈣鹽中的礦物質(zhì)在較高溫度下有利于CO和的添加對木質(zhì)素主反應區影響較小。但相比較堿金屬鹽的加入量而言最終熱解固體產(chǎn)物略有增CO2的生成。加。當熱解溫度較高時(shí)(>600℃)時(shí),三種堿金如圖8可知,添加碳酸鈉和碳酸鉀后的木質(zhì)屬鹽的添加使得木質(zhì)素的熱解速率明顯高于木質(zhì)中國煤化工H氣體的最終累積素單獨熱解時(shí)的速率,這說(shuō)明堿金屬鹽對木質(zhì)素產(chǎn)CNMHG了某個(gè)溫度段CO和瑕玲生懇量與木質(zhì)素單獨熱解的高溫裂解速率有一定的促進(jìn)作用,文獻[14]也相比明顯減少。比較而言碳酸鈉和碳酸鉀對木得到了相同的結論質(zhì)素熱解氣相產(chǎn)物CO、CO2和CH4的析出抑制圖7為添加堿金屬鹽后木質(zhì)素熱解氣相產(chǎn)物的作用明顯析出規律。由圖7可以看出,木質(zhì)素單獨熱解時(shí)科學(xué)技術(shù)與工程16卷00254 lignin+CaCO0016ignin+ Cacolignin+Na co, + lig← lignin+CaCO0012F- lignin+Na, co, A- lignin+K CO,0.015F+lignin+Na, C含0010lignin+K, CO0.00000000102030405060708090010203040506070809t/min(a) cob)co(c)CH圖7不同催化劑氣相產(chǎn)物的吸光度隨溫度變化Fig. 7 CO, CO2 and CH, release rules of lignin pyrolysis loaded alkali metal saltz ligninbiomass pyrolysis, Fuel, 2001: 80(5): 1765--1786w8 lignin+ CacO,E lignin+Na cO4 Yang H P, Yan R, Chen H P, et al. 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A TG-FTIR study on catalytic pyrolysis of加,揮發(fā)分析出階段DTG曲線(xiàn)的峰型隨之變寬;熱coal. Journal of Fuel Chemistry and Technology 2006: 34(6): 650-654解起始溫度、最大失重峰溫均向高溫側移動(dòng),氣體產(chǎn)樹(shù)榮,鄭赟,等.基于熱紅聯(lián)用分析的木質(zhì)素熱裂解動(dòng)力學(xué)研究,燃料科學(xué)與技術(shù),2007;1(13):50-55物的累積產(chǎn)率逐漸減小,表明較高的升溫速率不利Yao Yan, Wang Shurong, Zheng Yun, et al. Kinetic research of lignin于氣相產(chǎn)物的析出。pyrolysis by TGA-FTIR analysis. Journal of Combustion Science and堿金屬鹽K2CO3、Na2CO3和CaCO3的加入使木Technology,2007;1(13):50-55質(zhì)素殘余焦炭產(chǎn)量略有增加,并且對氣相產(chǎn)物的析10程解,余劍,構琴,等,本質(zhì)素慢速熱解機理,化工學(xué)報出尤其對CH4的生成有明顯的抑制作用。鈉鹽的Cheng Hui, Yu Jian, Yao Meiqin, et al. Mechanism analysis of li加入提高了熱解主反應區木質(zhì)素的熱解速率slow pyrolysis CIESC Journal, 2013: 64(5): 1757-1765K2CO3的加入對木質(zhì)素的高溫裂解速率有一定的促11潭洪,王樹(shù)榮,駱仲泱,等.木質(zhì)素快速熱裂解試驗研究浙江進(jìn)作用。鈣鹽促進(jìn)了600~700℃溫度區間CO和大學(xué)學(xué)報(工學(xué)版),2005:39(5):710-714CO2的生成。比較而言碳酸鈉和碳酸鉀對木質(zhì)素熱Tan Hong, Wang Shurong, Luo Zhongyang, et al. Experimental studyof lignin flash pyrolysis. Journal of Zhejiang University( Engineering解氣相產(chǎn)物CO、CO2和CH4的析出抑制作用明顯enee),2005;39(5):710-71參考文獻12 Zhang M, Resende FL P, Moutsoglou A, et al. Pyrolysis of lignin extractedfrom prairie cordgrass, aspen, and Kraft lignin by Py -GC/MS and TGA/張紀莊.生物質(zhì)能利用方式的分析比較.新能源及工藝,2003;2Al- Pyrolysis,2012;27(64):2中國煤化工(12):23-25ProdZhang Jizhuang Comparison analysis on mode of biomass energy utiCNMH+Fuel Processinon. Energy Engineering, 2003: 2(12): 23-25Technology,2001;70(1):9-262 Bu Q, Lei H W, Zacher A H, et al. A review of14 Kowalski T, Ludwig C, Wokaun A, et al. Qualitative evaluation of alcenation of ligninkali release during the pyrolysis of biomass. Energy and Fuels, 2007;Technology, 2012: 124 470-3 Bassilakis R, Carangerlo R M, Wojtowicz M A, TG-FTIR analysis of(下轉第238頁(yè))科學(xué)技術(shù)與工程16卷ulations. Engineering Structure, 2010; 32(10): 3180-319210 Malvar L. Review of static and dynamic properties of steel reinfor9 Bischoff P H, Perry S H. Compressive behavior of concrete at highcing bars. ACI Materials Journal, 1998: 95(5): 609-616stain rate. Materials and Structures, 1991; 24(144): 425--450Progressive Collapse mechanism Analysis of High-rise Reinforced ConcreteFrame Structure under blast loadingTiAN Li. fu Xie-eiSchool of Civil Engineering, Tianjin University, Key Laboratory of Coast Civil Structure Safety of Ministryf Education, Tianjin University", Tianjin 300072, P. R. China[Abstract] In order to investigate the progressive collapse mechanism of the high +ise reinforced concrete frametructure under blast loading, the progressive collapse of the high -rise reinforced concrete frame structure under external explosion load were simulated using the ANSYS/LS-DYNA software. The multi-scale model of the structurewas set up and verified. The frame structure damage was respectively analyzed and collapsed when the explosives inangle column and side column. The process and degree of collapse of the building at the above cases were contrasted. The results show: multi-scale modeling method can effectively simulate the process of frame structure responseolumn damage is serious under blast loading and the target column loss of beacapacity. The adjacent structure is damaged because internal force redistributeive collapseis happened. The scope of collapse is significantly different when the explosives are located in different locationI Key words blast high-rise buildings frame structure progressive collapseonlinear analysi(上接第228頁(yè))TG-FTIR Experimental Study on Lignin PyrolysisCHE De-yong, SuN Ya-ping, SUN Yan-xueSchool of Energy and Power Engineering, Northeast Dianli University, Jilin 132012, P. R. China)L Abstract] Thermogravimetric analysis -Fourier transform infrared spectrometer(TG-FTIR )was applied to analsis the thermogravimetric and main gas products of alkali lignin pyrolysis. The heatIng rate and loaded alkali metalsalts how to influence lignin pyrolysis processes were studied. The results show that: with the increasing of heatinrate, the dtg curves of volatility phase become wider, the onset temperature and the maximum weight peak temperature move to the higher temperature side. The slow heating rate is of great benefit to gas products. It is foundthat the Na, Ca and K salts additive have a promoting effect on the formation of char, but they get the less co andCO2 formation in entire temperature range. Compared to the中國煤化工 antage on the product ofCO and CO2 in the temperature range of 600-700 CCNMHGI Key wordsIgnnalkali metal saltsducTs