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 )03-0225-05Science Technology and Engineering⑨2016 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。結果表明:隨著(zhù)升溫速率的增加,揮發(fā)分析出階段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);且較高的升溫速率不利于氣相產(chǎn)物的析出。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，相比堿金屬鹽的加入量而言,最終熱解固體產(chǎn)物略有增加;同時(shí)堿金屬鹽的添加對氣相產(chǎn)物的析出有明顯抑制作用。與其他兩種堿金屬鹽相比，碳酸鈣的加入對600~700 C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)素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"1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'1。 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)能源的充放機理的研究還較少,本實(shí)驗采用TGFTIR聯(lián)用分利用,熱裂解是重要的技術(shù)手段之- -。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5。而熱重傅里葉紅外光譜聯(lián)用技術(shù)(TGFT-1實(shí)驗IR)不僅可獲得物質(zhì)熱分解的失重與溫度關(guān)系，還可實(shí)時(shí)檢測物質(zhì)熱分解氣相產(chǎn)物的組成，因而越來(lái)1.1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SigmaAldrich公司提供的高純等領(lǐng)域度脫堿木質(zhì)素。將原料破碎篩分0.1 mm以下,以針對木質(zhì)素的熱解,已有大量文獻進(jìn)行了研究，消除熱解試驗中粒徑對熱擴散的影響。在60 C帶姚燕等91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16 h,用密封袋封好，于5 C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10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)一一步證明 了木質(zhì)Na2C03、CaCO3和K2C03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 analysis of lignin and cellulose工業(yè)分析/WAD%元素分析/WAD%樣品MAaVaFCCaHNoSa木質(zhì)素 。10.4518. 3339.8131.4145.654.30_19. 62.920. 081.2 實(shí)驗儀器與方法實(shí)驗主要采用熱重差熱綜合熱分析儀(瑞士生產(chǎn)的METTLER TGA/STD 1)和紅外光譜儀(美國生2015年9月17日收到226科學(xué)技術(shù)與工程16卷到900C,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50 mL/min,試樣質(zhì)量在15 mg左右。析出規律將木質(zhì)素按照不同升溫速率(5 C/min、10 C/2結果 與討論min、20 C/min. .40 C/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10C/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DTC曲線(xiàn)具有- -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5C/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,熱解起段可以看出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00第一階段 第二階段 第三階段t .00000面與坩堝間的溫度梯度增大，木質(zhì)素熱解過(guò)程產(chǎn)生8C0.0001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)g 60[V/^升高,從而測得的揮發(fā)分初始析出溫度和峰溫均向-0.00022 40高溫側移動(dòng)。TG曲線(xiàn)0000100. DTG曲線(xiàn)-0.0004一5 Cmin-!90-+ 10 'Cmin-!一20 C min-!02004006008001000+ 40 C-min-!1/查70圖1木質(zhì)素熱解TG和DTG曲線(xiàn)60Fig. 1 TG-DTG curves of lignin pyrolysis50圖2顯示了木質(zhì)素熱解過(guò)程氣體產(chǎn)物的FTIR，4020400600800 1 000三維譜圖。由圖2可以看出木質(zhì)素在不同熱解階段1/C(a) TG曲線(xiàn)析出的物質(zhì)有很大不同。木質(zhì)素初次揮發(fā)階段0.0000(200 ~550 C )的熱解產(chǎn)物成分較為復雜,主要氣體產(chǎn)物為H2O、CH4、CO和CO2等輕質(zhì)氣體。木質(zhì)素-00000t。-0.000 6與苯環(huán)連接的甲氧基發(fā)生裂解,可生成CO和CH,已-.000 8- 5'C-min-!等小分子氣體;木質(zhì)素部分末端官能團和側鏈,如末日-0.000 0- 10 Cmin-!-0.001 2端的一-OH 鍵、- C00H 鍵和苯基C- -C 的斷裂,析-0.001 4+40 Cmin!出少量烴類(lèi)氣體產(chǎn)物和大量含氧化合物,如水、CO-0.0016200400 600和CO2等[21。當熱解溫度繼續升高,在深度熱解階(b) DTG曲線(xiàn)段(550 ~900 C)，析出的主要氣體為CO ,此外繼續圖3不同升溫速率下木質(zhì)素熱解曲線(xiàn)析出少量CO2。這是因為芳香族化合物到650 C左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 diferent heating rates醚鍵等斷裂131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COCO2和CH1 0020290.015吸光度曲線(xiàn)見(jiàn)圖4。由圖可以看出,CO和CO2的起始析出溫度較低且相近,在200 C氣體就開(kāi)始析出，HO00.. 0.010 :均有一大一小兩個(gè)峰，同時(shí)還存在肩峰，但二者析出0005峰形差異較大。CO2 在300 C時(shí)大量析出,而C0.起始析出溫度較高。CH4的析出在300~750 C溫度區間完成，有兩個(gè)主要生成峰和肩峰。隨升溫速4000 3500 3000 2500 2000 1500 1000率的增加,氣體的析出溫度及峰值溫度均向高溫方Wavenumbers/cm圖2木質(zhì)素熱解 氣體產(chǎn)物的FTIR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2270.030- : A-5 Cmin-1.，00006| + 5 C-min-!005 (- ←5 C-min-!4- 10C-min-!-+10Cmin0.04-一10Cmin20 C-min-!00440 C/min-I0.0340 cminr003-百0015-, 0.02-5 0010-001o 0.0050.000.0001002003004005006007008009000100200300400500600700 800 900(a)CO(b)CO,(e)CH,圖4不同升溫速率氣相產(chǎn)物的吸 光度隨溫度變化Fig4 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100-一lignin :(CO、CO2和CH)的析出規律,圖5為木質(zhì)素在不9(lignin+CaCO,+ - lignin+Na,CO,80-同升溫速率下熱解過(guò)程中氣相產(chǎn)物的累計產(chǎn)率。lignin+K.CO,s 70-由圖可明顯看出,木質(zhì)素熱解氣相產(chǎn)物的累積產(chǎn)60率發(fā)生了明顯變化，隨升溫速率的增大,累積產(chǎn)率50減小，可見(jiàn)，較高的升溫速率對氣體產(chǎn)物的析出40-不利。0400 6008001 000zZ0 5 Cmin-'(細) TG曲線(xiàn)888 10C-min-!3 20 C-min40 Cmin-0.000 1? -0.0002g -00030 Ilignin. lignin+CaCO,-0.0004 t- + lignin+Na,CO,+ - lignin+K.Co,-0.0005 tCOCH,200300 1000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)Fig. 6 TG DTG curves of lignin pyrolysis loaded2.3不同催化劑下木質(zhì)素熱解特性及氣體產(chǎn)物析alkali 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H4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300C就出現了較強的CH,析出峰，而堿金度較低時(shí)( <600 C),堿金屬鹽的加入對木質(zhì)素屬鹽的加入明顯降低了CH4的析出峰，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CH4的產(chǎn)生。對CO和CO2氣體,添重--般都是在低于600C發(fā)生的,因此，堿金屬鹽加碳酸鈣的木質(zhì)素熱解在650 C出現尖銳的氣體析的添加對木質(zhì)素主反應區影響較小。但相比較堿出峰,鈣鹽中的礦物質(zhì)在較高溫度下有利于CO和金屬鹽的加人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 C)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)素熱解產(chǎn)生的CO、CO2和CH4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)率均較小，雖然鈣鹽促進(jìn)了某個(gè)溫度段CO和CO2的生成,但最終生成總量與木質(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228科學(xué)技術(shù)與工程16卷0.025lignin+CaCO.0.016 FTignin干lignin+CaCo.0.020. lignin- lignin+K ,Co, |。lignin+Na.CO, Alienin+K colignin+CaCO,豈0.015來(lái)0.015lignin+ Na,CO,0.0080.010十lignin+K.Co,0.0005. 0.005古0.0040.000010203040506070809002040608/min1/min(a)CO(b)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 C0 、CO2 and CH, release rules of lignin pyrolysis loaded alkali metal saltzZa ligninbiomass pyrolysis. 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China)[ Abstract] In order to investigate the progressive collapse mechanism of the high -rise reinforced concrete framestructure under blast loading ，the progressive collapse of the high rise reinforced concrete frame structure under ex -ternal explosion load were simulated using the ANSYS /LS DYNA sofware. 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 contras -ted. The results show: multi -scale modeling method can effctively simulate the process of frame structure responseunder blast loading. The target column damage is serious under blast loading，and the target column loss of bearingcapacity. The adjacent structure is damaged because internal force redistribution 。At last, the progressive collapseis happened. The scope of collapse is signifcantly different when the explosives are located in different location[ Key words ] blasthigh- rise buildingsframe structureprogressive collapse :nonlinear analysis(上接第228頁(yè))TG FTIR Experimental Study on Lignin PyrolysisCHE De- yong, SUN Ya-ping, SUN Yan-xue(School of Energy and Power Engineering , Northeast Dianli University ,Jilin 132012,P. R. China)[ Abstract] Thermogravimetric analysis Fourier transform infrared spectromerer (TG-TIR ) was applied to analy-sis 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 heatingrate, 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 C0 andCO2 formation in entire temperature range. Compared to the other salt , the Ca salt has advantage on the product ofCO and CO2 in the temperature range of 600~ 700 C.[ Key words] igninpyrolysisalkali metal saltsgas products