第42卷第12期燃料化學(xué)學(xué)報(bào)Vol 42 No. 122014年12月Journal of Fuel Chemistry and TechnologyDec.2014文章編號(hào):0253-2409(2014)12-43149乙二醇醇解松木屑反應(yīng)特征及機(jī)理分析房添祥2,侯沛東…,蔣興家2,楊建麗(1.中國(guó)科學(xué)院山西煤炭化學(xué)研究所煤轉(zhuǎn)化國(guó)家重點(diǎn)實(shí)驗(yàn)室,山西太原0300012.中國(guó)科學(xué)院大學(xué),北京100049;3.中科合成油技術(shù)有限公司,北京101407)摘要:利用酸化的乙二醇作溶劑對(duì)松木屑進(jìn)行醇解,探討了溫度和時(shí)間對(duì)醇解轉(zhuǎn)化率的影響。利用熱重分析、紅外光譜分析、掃描電鏡及ⅹ射線衍射考察了醇解殘?jiān)男再|(zhì)。分別利用傅里葉變換紅外光譜及色質(zhì)聯(lián)用分析了正已烷不溶物和可溶物中組分的分布及特征。結(jié)果表明,松木屑轉(zhuǎn)化率在90min、160℃達(dá)到最大值95.3%。松木屑中纖維素?zé)o定形區(qū)的組分和木質(zhì)素發(fā)生了解離,醇解殘?jiān)谋砻娼Y(jié)構(gòu)被破壞;正己烷不溶物是含有羥基、甲氧基及醚鍵等含氧官能團(tuán)的化合物;正己烷可溶物主要由苯二甲酸酯、硬脂酸甲酯、2甲基已酸丙酯、2甲基丙酸、聚乙二醇及未反應(yīng)的乙二醇組成。乙二醇與松木屑解離的羧酸發(fā)生酯化反應(yīng),對(duì)液相產(chǎn)物具有穩(wěn)定作用,促進(jìn)了松木屑的醇解反應(yīng);醇解過程中乙二醇自縮聚生成聚乙二醇,增大了乙二醇的消耗。關(guān)鍵詞:松木屑;醇解;產(chǎn)物;分布;機(jī)理中圖分類號(hào):TK6文獻(xiàn)標(biāo)識(shí)碼:AStudy on alcoholysis of pine sawdust in ethylene glycol and alcoholysis mechanismFANG Tian-xiang", HOU Pei-dong", JIANG Xing jia, YANG Jian-Hi(1. State Key Laboratory of Coal ConversionInstitute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China2. University of Chinese academy of Sciences, Beijing 100049, China; 3. Synfuels China Co., Ltd, Beijing 101407, China)Abstract: The alcoholysis of pine sawdust with acidified ethylene glycol ( EG) as solvent was investigated; theinfluence of reaction temperature and time on the conversion of pine sawdust was examined. The alcoholysisresidual was characterized by thermogravina try (TG ), Fourier transform infrared spectroscopy FT-IRse nning electron microscope($ M)ad X-ray diffraction A RD), whereas the comps ition a p roperties ofh exn e insoluble cm ponents( HIS )and hexane soluble ones HS)were determined by FT-iR and gaschromatography -mass spectrometry(GC-MS). The results showed that the conversion of pinesa wdust reaches amaximum of 95. 3% at 160C after reaction for 90 min. By the alcoholysis, the amorphous components ofcellulose and lignin were decomposed and the surface structure of alcoholysis residual is destructed. The hexaneinsoluble components are composed of compounds with oxygen -bearing functional groups such as hydroxylmethoxy and ether, whereas the hexane soluble components consist of mainly phthalic acid esters, methylstearat, 2-methyl propyl caproate, 2-methyl propionic acid, polyethylene glycol and unreacted EG. Theesterification of EG with carboxylic acid, derived from pine sawdust, can improve the stability of liquid productand promote the alcoholysis of pine sawdust, whereas the self-condensation of EG, forming polyethy lene glycolmay increase the consumption of EGKey words: pine sawdust; alcoholysis; product; composition; mechanism生物質(zhì)具有儲(chǔ)量大、可再生、二氧化碳“零排同溶劑中的轉(zhuǎn)化來提取液體燃料和化學(xué)品2,而放”等特性,隨著化石燃料的日益枯竭和環(huán)境污染產(chǎn)物的收率和分布很大程度上依賴反應(yīng)條件和溶劑的日趨嚴(yán)重,從生物質(zhì)中提取燃料和高值化學(xué)品種類。其中,生物質(zhì)醇解,尤其是多元醇如乙二越來越受到研究者的關(guān)注23。1982年, Bungay醇”,以條件溫和、轉(zhuǎn)化率高等特點(diǎn)應(yīng)用于生物質(zhì)在《 Science)上提岀生物質(zhì)精煉的概念,通過一定的轉(zhuǎn)化。生物質(zhì)醇解是解離和縮聚反應(yīng)共存的一個(gè)過處理過程,將樹木類和農(nóng)業(yè)廢棄物轉(zhuǎn)變?yōu)槿剂虾透叱?醇解過程中各組分的結(jié)構(gòu)變化及降解片段與溶值化學(xué)品。近年來,世界各國(guó)學(xué)者對(duì)生物質(zhì)的利用劑之間的相互作用,影響了生物質(zhì)醇解程度及產(chǎn)物做了大量的硏究,生物質(zhì)熱解制取的生物油組的組成和分布。研究生物質(zhì)醇解,需對(duì)生物質(zhì)醇解成復(fù)雜、有機(jī)酸高、水分高、熱值低;利用生物質(zhì)在不收稿日期:2014修回日期:201445301432燃料化學(xué)學(xué)報(bào)第42卷過程中的作用機(jī)理進(jìn)行深入研究。因此,研究利用1實(shí)驗(yàn)部分乙二醇醇解松木屑,考察了溫和條件下松木屑的液1.1實(shí)驗(yàn)原料化規(guī)律,通過常壓熱重、紅外光譜分析、掃描電鏡等選取松木屑為研究對(duì)象,粉碎至<40目,使用分析手段考察了醇解殘?jiān)男再|(zhì),并利用紅外光譜前在105℃真空干燥24h。松木屑樣品基本性質(zhì)見分析和氣質(zhì)聯(lián)用分別考察了正己烷不溶物和可溶物表1,工業(yè)分析和元素分析分別采用GB/T28731中組分的組成和特征,并獲得乙二醇與松木屑主要2012GB/T28734-2012。組分的醇解機(jī)理。以期為得到穩(wěn)定性好、集中度高所用化學(xué)試劑均為分析純?cè)噭?包括乙二醇、丙及易提取分離的高值化學(xué)品提供理論依據(jù)。酮、正己烷、濃硫酸(98%)等。表1松木屑的工業(yè)分析和元素分析Proximate and ultimate analyses of pine sawdustProximate analyUltimate analyses wdaf/%H0.6612.8653.316.3940.260.020.0by difference1.2醇解反應(yīng)過程別標(biāo)記為AR10min、AR30min、AR60min醇解反應(yīng)裝置為帶有機(jī)械攪拌和冷凝器的三口AR9Omin、AR120mi。其中,“AR醇解溫度或時(shí)燒瓶(250mL)。常規(guī)加料量為10g松木屑、60g間”為不同醇解殘?jiān)臉?biāo)記,與結(jié)果討論部分一致,乙二醇和14g濃硫酸(催化劑)(松木屑:乙二醇用旋轉(zhuǎn)蒸發(fā)的方法除去丙酮可溶物中的丙酮濃硫酸為1:6:0.14)。反應(yīng)物在三口燒瓶中,在連冷卻后加入正己烷,使正己烷不溶物從中析出。索續(xù)攪拌條件下(80~100r/min),以5℃/min的升溫氏萃取正己烷不溶物12h,冷卻、過濾,得到正己烷速率升至反應(yīng)溫度(100、120、160℃)。反應(yīng)至設(shè)定不溶物(黑褐色、黏稠狀)。過濾后,濾液經(jīng)旋轉(zhuǎn)蒸停留時(shí)間(10、30、60、90、120min)時(shí),將三口燒瓶置發(fā)除去正己烷。正己烷可溶物包括醇解液相產(chǎn)物和于冰水混合液中快速冷卻終止反應(yīng)。未反應(yīng)乙二醇,呈微黃色、透明狀,標(biāo)記為HS,置于13醇解固液產(chǎn)物的分離過程低溫、黑暗處保存,待分析。醇解產(chǎn)物的分離過程示意圖見圖1。1.4轉(zhuǎn)化率松木屑醇解轉(zhuǎn)化率(x)定義為松木屑經(jīng)醇解反eaction products應(yīng)減少的質(zhì)量占松木屑投料質(zhì)量的百分?jǐn)?shù),根據(jù)下列公式計(jì)算etone-solidalcoholysis residuesliquid Acetonexn(%)mA×100n-hexane-precipitated phase式中,m:松木屑投料質(zhì)量;mAR:醇解殘?jiān)|(zhì)hexane insoluble partLiquid 2]-yi-hexan1.5樣品分析松木屑及醇解殘?jiān)鼧悠返募t外光譜表征選用BR KER公司Ⅴ ERTEX70紅外光譜儀。采用溴化圖1醇解固液產(chǎn)物分離過程示意圖鉀壓片法(溴化鉀100mg,樣品1mg),分辨率Fign e I Schematic diagram for the separation4 cmsolid-Hiquid mixture from the alcoholysis of pine sawdust醇解產(chǎn)物組分分析,采用 Agilent色質(zhì)聯(lián)用儀在索氏萃取裝置中,用丙酮萃取醇解產(chǎn)物12h。(6890N)。使用 DBWAX(0.32mm×30m將丙酮不溶物,在真空干燥箱中干燥24h,得醇解殘0.5μm)色譜柱,柱溫32℃,進(jìn)樣量0.5μL。氮?dú)庠?AR)。稱重后,保存在干燥器中待用。固定醇為載氣,流量為1.5mL/min。采用EI離子源,電子解反應(yīng)時(shí)間為60min時(shí),不同醇解溫度所得殘?jiān)帜芰?0eV。四級(jí)桿溫度150℃,離子源溫度第12期房添祥等:乙二醇醇解松木屑反應(yīng)特征及機(jī)理分析1433TOLEDO熱分析儀,Al2O3坩堝。常規(guī)加料量為素和木質(zhì)素。松木屑在醇解120℃條件下,醇解時(shí)10mg左右。在氮?dú)膺B續(xù)吹掃下(80m/min),以間從10min延長(zhǎng)到90min,轉(zhuǎn)化率從37.6%增大到10℃/min的升溫速率升至800℃后停止加熱。49.5%,增大了12個(gè)百分點(diǎn);醇解時(shí)間延長(zhǎng)到2結(jié)果與討論120min,松木屑的醇解轉(zhuǎn)化率為44.9%;醇解溫度2.1松木屑的醇解轉(zhuǎn)化率在10℃C和120℃時(shí),松木屑醇解轉(zhuǎn)化率隨醇解時(shí)圖2對(duì)比了醇解時(shí)間及溫度對(duì)醇解松木屑轉(zhuǎn)化間的變化趨勢(shì)與60℃時(shí)醇解類似。在實(shí)驗(yàn)考察條率的影響。件范圍內(nèi),松木屑醇解在90min160C下,轉(zhuǎn)化率最大達(dá)到95.3%。通常認(rèn)為,松木屑醇解反應(yīng)過程100中,存在著松木屑的解離和解離產(chǎn)物的縮聚(副反160℃應(yīng))兩種化學(xué)反應(yīng)。在不同溫度條件下,醇解時(shí)間小于90min,松木屑的解離速率大于解離產(chǎn)物的縮聚速率,醇解時(shí)間延長(zhǎng),則轉(zhuǎn)化率增大。醇解時(shí)間70120℃繼續(xù)延長(zhǎng)松木屑解離生成的小分子化合物縮聚成難被乙二醇醇解的縮聚化合物,從而導(dǎo)致了松木屑醇100℃解轉(zhuǎn)化率降低2.2松木屑醇解產(chǎn)物分析20406C1001202.2.1松木屑及醇解殘?jiān)臒嶂胤治鲞x取松木屑及松木屑在醇解60min、不同溫度圖松木屑醇解轉(zhuǎn)化率及醇解120℃、不同時(shí)間條件下的醇解殘?jiān)?AR時(shí)Figure2 Come rsion of pine sawdust in alcoholysisa t different tempe at res間/溫度,為不同醇解條件下的殘?jiān)?為研究對(duì)象,考察醇解殘?jiān)臒峤馓匦?。圖3為松木屑與醇解殘由圖2可知在相同醇解時(shí)間條件下,隨醇解溫渣的失重曲線和失重速率曲線。由圖3(a)可知,松度升高,轉(zhuǎn)化率明顯增大;在相同醇解溫度條件下,木屑失重起始溫度最高,但失重最多,失重率達(dá)隨醇解時(shí)間的延長(zhǎng),松木屑醇解轉(zhuǎn)化率呈現(xiàn)先增大80%。隨醇解溫度的升高,對(duì)應(yīng)醇解殘?jiān)氖е仄鸷鬁p小的趨勢(shì)。松木屑在醇解10min條件下,在醇始溫度降低,失重率減小;由圖3(6b)可知樣品的失解溫度100-160℃,轉(zhuǎn)化率從26.0%增大到重速率峰溫度也有明顯差別。表2為不同樣品的失78.3%,增大了53個(gè)百分點(diǎn);不同醇解時(shí)間條件下,重速率峰特征溫度(t,;AR120min>AR30min>殘?jiān)氖е厮俾史鍦囟圈?依次為ARl00℃> AR90 min。隨著醇解液化時(shí)間延長(zhǎng),醇解殘?jiān)鼰峤釧R120℃>AR160℃,醇解殘?jiān)氖е厮俾史鍦囟葴囟?350℃時(shí),失重速率峰溫度t2基本不變。醇解t明顯向低溫處偏移,失重速率峰溫度降低到殘?jiān)臒峤馐е厮俾是€出現(xiàn)兩個(gè)失重峰和最大失252℃,失重速率明顯減小;隨著醇解溫度的升高,重速率峰溫偏移,這與醇解殘?jiān)薪M分種類和含量失重速率峰溫度t2依次為AR100℃