廢聚對苯二甲酸乙二醇酯的高溫醇解研究

研究與開(kāi)發(fā)合成纖維工業(yè),2014,37(1):9CHINA SYNTHETIC. FIBER INDUSTRY廢聚對苯二甲酸乙二醇酯的高溫醇解研究俞昊,黃芳,馮淑芹,梅鋒(1.東華大學(xué)材料學(xué)院,上海201620;2.江蘇盛虹化纖集團,江蘇吳江215200)摘要:通過(guò)高溫高壓醇解法對廢聚對苯二甲酸乙二醇酯(PET)在催化劑金屬醋酸鹽作用下,進(jìn)行乙二醇醇解得到對苯二甲酸乙二醇酯(BHET),研究了廢PET高溫醇解的影響因素及工藝條件。結果表明:在高溫醇解反應中,乙二醇與廢PT的質(zhì)量比和反應壓力為主要影響因素反應溫度和解聚時(shí)間為次要影響因素;BHET收率隨反應時(shí)間的延長(cháng)溫度與壓力的升高、乙二醇與廢PET的質(zhì)量比加大催化劑的用量增大而增加,而二甘醇含量(除質(zhì)量比因素)及醇解產(chǎn)物的熔點(diǎn)則隨其相應降低;最佳醇解反應條件為壓力04MPa、乙二醇與廢PET質(zhì)量比0.5:1.0、反應溫度250℃、反應時(shí)間4h,BHET收率達82%。關(guān)鍵詞:聚對苯二甲酸乙二醇酯回收采用高溫高壓醇解反應正交實(shí)驗中圖分類(lèi)號:TQ3234·1文獻標識碼:A文章編號:1001-0041(2014)01-000-04聚酯(PET)廣泛用于塑料制品,同時(shí)其廢棄虹集團中鱸科技發(fā)展股份有限公司產(chǎn);乙二醇、苯物帶來(lái)了環(huán)境污染,PET的回收日益受到各界重酚、四氯乙烷、四甘醇二甲醚、活性炭:分析純,國視。但是,再生料由于其純度以及結構性能的改藥集團化學(xué)試劑有限公司產(chǎn);醋酸鋅:分析純,上變,目前主要是短纖維的開(kāi)發(fā),導致其應用受到限海達瑞精細化工有限公司產(chǎn);乙二醇銻:分析純制每年回收的PET僅占產(chǎn)量的37%。目前江蘇鴻聲化工廠(chǎng)產(chǎn),甲醇:分析純,上?；瘜W(xué)試劑PET瓶片的回收工業(yè)化生產(chǎn)方法主要有水公司產(chǎn)。解23、甲醇醇解‘”和乙二醇醇解°8。其中1.2儀器與設備PET水解法的主要缺點(diǎn)是高溫、高壓及解聚時(shí)間氣相色譜儀: Agilent7890A,安捷倫科技公司較長(cháng)、對苯二甲酸(TPA)的提純成本高”;甲制;高溫高壓醇解設備:PET聚合釜,江蘇盛虹集醇醇解法的產(chǎn)物存在反應溫度高壓力大、PET分團中鱸科技發(fā)展股份有限公司制,有效容積為70解不完全成本高等缺點(diǎn)"“;乙二醇醇解法主L壓力0-0.5MPa,攪拌速率0-100ymin,溫度要是用乙二醇的降解),二甘醇的醇解,丙一0~450℃;常壓醇解設備:自制玻璃釜反應裝置。醇的醇解),乙二醇超聲波降解,其降解時(shí)間降低獲得(BHET)產(chǎn)品純度較高,成本相對較1.3廢PET的乙二醇醇解方法低,因此,廣泛用于工業(yè)生產(chǎn)1。廢PET解聚反應在高壓反應釜中進(jìn)行。首為了引入工業(yè)化的PET降解工藝,擴大其應先干燥廢PET除去水分及其他揮發(fā)性物質(zhì);而后在反應釜中加入一定量的乙二醇廢PET及催化以便深入了解和控制醇解程度。PET醇解反應所劑密封后開(kāi)始加熱,控制升溫速率5-10℃/用的催化劑一般有鈦酸酯類(lèi)、醋酸鹽類(lèi)和稀土氧min,記錄加熱過(guò)程中溫度與壓力的變化情況,當化物等。目前關(guān)于PET醇解反應中催化劑的作加熱到設定溫度時(shí)開(kāi)始記錄時(shí)間,在維持恒溫的用機理尚未達成統一的認識。作者研究了金屬醋情況下使解聚反應進(jìn)行1,2,3,4,5,6h?？芍虚g酸鹽催化劑對醇解產(chǎn)物BHET的收率及產(chǎn)物性質(zhì)取樣反應結束后對解聚產(chǎn)物進(jìn)行分析。反應溫的影響以及壓力、溫度、時(shí)間物料配比對乙二醇度為0-270℃,反應壓力為0-0.5MPa解聚產(chǎn)物性質(zhì)BHET收率的影響優(yōu)化PE降解14分析與測試工藝BHET收率(y):在反應結束后,將反應產(chǎn)物調節溫度至130~140℃,將醇解產(chǎn)物快速熱過(guò)1實(shí)驗收稿日期:2013-06-18;修改稿收到日期:20131227。1.1原料作者簡(jiǎn)介:俞昊(1973-),男博士副教授從事材料改性及廢PET:特性黏數([η])0.65dLg,江蘇盛成型、功能高分子等領(lǐng)域的研究。 E-mail: yuh@ dhu. edu,cn10合成纖維工業(yè)2014年第37卷濾得到有色不溶物試樣A。然后對濾液進(jìn)行減受能力能源消耗、連續業(yè)化生產(chǎn)的可能性及經(jīng)壓蒸餾回收乙二醇。將減壓蒸餾后的液體(常溫濟性等原因,有必要對各個(gè)因子對PT乙二醇解下為固體)溶入溶劑中,加熱后熱過(guò)濾,得到不溶的影響再進(jìn)行探討。物B。再向濾液中加人一定量的活性炭脫色,熱表2廢PETr的乙二醇解正交實(shí)驗結果過(guò)濾得無(wú)色透明濾液,自然冷卻結晶,過(guò)濾,得晶Tab 2 Orthogonal experimental results of體C,在60℃下干燥ethylene glycol alcoholysis of PET wastey=m/m3×100%序號壓力/MPa溫度/℃時(shí)間/hmEc:mrry,%式中:m。為晶體C質(zhì)量;m3為BHET理論值。0.3:120.8:1[η]:采用烏氏黏度計法(GBT141900.23421.3:12008)進(jìn)行測試。77二甘醇(DEG)含量:用氣相色譜法測定PET4567891.3:12乙二醇醇解產(chǎn)物的二甘醇含量。端羧基:采用0.1mo/L的KOH-乙醇標準溶0.225030.8:10.31.8:1液,10g/L的酚酞指示液,PET醇解物溶于二甲苯1.3:1與乙醇的混合溶液(體積比為2:1),用堿式滴定10.30.8:1管進(jìn)行端羧基測定。120.30.3:10.40.8:141427229750.3:12結果與討論0.42500.8:12.1催化劑對廢PET醇解反應的影響16從表1可知,在反應3h內,醇解物可形成透M,50.7561.7560.2549.75M.0065.2564.2564明均勻溶液,催化劑含量增加,BHET的y增加,M173.2568.0069,2571.00當用量達1000μg/g時(shí),BHET的y可達86%。Ma76.7569.7571.0079.50表1催化劑用量對醇解產(chǎn)物性質(zhì)的影響26.008.0010.9029.75Tab 1 Effect of catalyst amount on2. 2. 2 mEG: mpEtphysical index of alcoholysates從表3可以看出,BHET的y隨著(zhù)mBc:mrr出用里2"*(,狀態(tài)的增大而增加,當mc:mrr從0.3:I增大至0s91.7821025800.640溶解5:1,增加幅度大,而隨著(zhù)配比的繼續增加,BHET702·451341400.051溶解的y增加較緩。醇解物熔點(diǎn)、[η]均隨著(zhù)配比降792.7811314.520.052溶解1000862.199714.360.046溶解低,但副產(chǎn)物二甘醇量卻增多。綜合考慮后續實(shí)注:反應溫度為250℃,反應壓力為04MP,反應時(shí)間為3驗間題以及經(jīng)濟效益,mne:mn為0.5:1h,mrc:mpr為0.5表3r對醇解反應的影響Tab 3 Effect of meG: mpeT2.2PET醇解反應的影響因素on alcoholysis reaction2.2.1醇解反應的正交實(shí)驗端羧基(mol·t-l)(dLg-1)以PET醇解產(chǎn)物BHET的y為實(shí)驗指標,選894.17357定4個(gè)影響因素:反應壓力,反應溫度,反應時(shí)間l:1119mc:mmr。選用用量為500g/g金屬醋酸鹽催08:193.54111.0.030.5:1化劑進(jìn)行正交實(shí)驗結果如表2所示。R值衡量0.052670.5913719.80.055不同因子的重要性,表明在PET的醇解反應中注:反應溫度250℃,反應壓力為04MPa,反應時(shí)間3h,催各因素的影響力由大到小依次為mrc:mr、反化劑用量500μ/go應壓力、反應時(shí)間、反應溫度,且物料配比及壓力2.2.3反應壓力占主要作用。從BHET的y看,最佳反應條件為從表4可以看出,在0.1MPa壓力以上反應乙二醇與PEI質(zhì)量比為1.8:1,壓力為0.43h,即可完全溶解。隨著(zhù)壓力的增加,BHET的yMPa,溫度為260℃,時(shí)間為2h?？紤]到設備承大幅度的增加,醇解聚產(chǎn)物的平均熔點(diǎn)端羧基與I期俞昊等廢聚對苯二甲酸乙二醇酯的高溫醇解研究[η]降低。由此說(shuō)明壓力的增大有利于醇解反應2.2.5反應溫度對PET乙二醇解反應的影響的進(jìn)行。這是由于高壓態(tài)的乙二醇分子間的作用從表5可見(jiàn),隨著(zhù)溫度的升高,BHET的y增力消失,其熱運動(dòng)速率增大,同時(shí)又由于其密度隨.多,到260℃時(shí)BHET的y可以達到82%;解聚產(chǎn)壓力的增大而增大,增加了與PET分子碰撞的幾物的平均熔點(diǎn)與[η]則相應下降。這些充分地率。另外,高壓態(tài)的乙二醇對PET有較高的溶解說(shuō)明了溫度的升高有助于醇解效率的提高。同時(shí)性,也提高了醇解反應程度。溫度的升高也導致副產(chǎn)物二甘醇量的減少。這主表4反應壓力對PET醇解產(chǎn)物的性質(zhì)的影響要由于溫度的升高導致DEG的醚鍵的不穩定性Tab 4 Effect of reaction pressure on physical增強,從而二甘醇的量得到減少。由于DEG量的index of PEt alcoholysates減少有利于后續的聚合與紡絲,因此高壓下的壓力y,"mc,熔點(diǎn),端羧基、]1、溶解情況PET乙二醇解反應宜250-260℃下進(jìn)行)(0364.1721623.350.096基本溶解表5反應溫度對PET醇解產(chǎn)物性質(zhì)的影響0.10564.1014516.020.081均勻透明Tab. 5 Erect of reaction temperature on0.20703.5414315.790.064均勻透明physical index of PET alcoholysates0.35752.7811915.100.059均勻透明溫度/DEc,熔點(diǎn)/端羧基′[n]/0.40792.7811314.520.052均勻透明℃(mod·t-)(dL·g-)044852.7810913.020.046均勻透明16527.040.083注:反應溫度250℃,反應時(shí)間為3h,mc:mpr為0.5:115.46催化劑用量為500w/g2502.781130.0521.011.02醇解產(chǎn)物中二甘醇含量也是控制乙二醇解聚性注:mgc:mr為0.5:1,催化劑用量t500g/g,反應壓力0.的控制質(zhì)量指標。過(guò)量二甘醇的存在會(huì )降低PET4MPa,反應溫度230-260℃,反應時(shí)間3h的熱氧化穩定性。隨著(zhù)壓力的增加,醇解物中DEG含量減少,有利于后續的再生PET聚合及紡3結論絲。因而PET的乙二醇解反應宜在0.35~0.44a.壓力時(shí)間、物料配比和溫度對PET的解MPa下進(jìn)行聚反應影響由大到小依次為:配比,壓力溫度,時(shí)2.24反應時(shí)間間,其中物料配比及壓力為主要影響因素,時(shí)間和從圖1可以看出,PET的醇解產(chǎn)物中BHET溫度為次要影響因素。的y隨著(zhù)時(shí)間的延長(cháng)而增多,在反應時(shí)間4h時(shí)b.BHET和y隨反應時(shí)間的延長(cháng),溫度和壓BHET的y達到了82%。這說(shuō)明時(shí)間對PET的解的升高、乙二醇與回收PET的質(zhì)量配比的加聚是起著(zhù)重要作用。在反應時(shí)間小于2h,BHE大、催化劑的用量增大而增加,而DEG含量(除質(zhì)的y大幅度增加而反應時(shí)間大于2h,BHET的y量比因素)及醇解產(chǎn)物的平均熔點(diǎn)、[7]則隨其增加較緩慢。PET的乙二醇解反應時(shí)間需大于2相應降低。h,較適宜的時(shí)間為4hc.根據后續的研究發(fā)現,醇解產(chǎn)物的平均熔點(diǎn)、DEG含量對再聚合及紡絲工藝有影響。因而,在確定最佳回收PET的乙二醇醇解工藝時(shí)應考慮多種因素,如醇解產(chǎn)物的性質(zhì)、設備承受能力、能源消耗、經(jīng)濟效益等。因此,確定最佳PET的乙二醇醇解反應條件為:壓力0.4MPa,mEc:mmr為0.5:1,溫度250℃,反應時(shí)間為4h,BHET的y達82%。時(shí)間h參考文獻圖1反應時(shí)間對PET醇解反應的影響[1] Coelho T M, Castro R, Gobbo JJ A. 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The molecular weight distribution [18] Pingale N D, Shukla SR, Microwave assisted ecofriendly recy.and oligomers of sodium hydroxide hydrolyzed poly( ethylenecling of poly (ethylene terephthalate)bottle waste[J].Eurterephthalate)[J]. J Appl Polym Sci, 1992, 45(5): 797-804Polym J,2008,44(12):4151-4156[10 Yoshioka T, Ota M, Okuwaki A. Conversion of a used poly(eth. [19] Suh D J, Park 00, Yoon K H. The properties of unsaturatedylene terephthalate )bottle into oxalic acid and terephthalic acidpolyester based on the glycolyzed poly ethylene terephthalate)idation in alkaline solutions at elevated twith various glycol compositions[ J]. Polymer, 2000, 41(2):[門(mén)]. Ind Eng Chem Res,2003,42(4):675-679Study on high-temperature alcoholysis of PEt wasteYu Hao, Huang Fang, Feng Shuqin, Mei Feng(1. College of Materials Science and EngiShanghai 201620; 2. Shenghong Chemical Fiber Group, Wujiang 215200)Abstract: Polyethylene terephthalate( PET)waste was exposed to high-temperature high-pressure ethylene glycol alcoholysis inpressence of metal acetate catalyst to produce ethylene terephthalate( BHET). The influential factors on the high-temperature alnolysis of PET waste and the process conditions were studied. The results showed that the mass ratio of ethylene glycol and PETwaste and the reaction pressure were the primary influential factors and the reaction temperature and depolymerization time werethe secondary factors on the high-temperature alcoholysis; and the BHEt yield was increased with the increase of reaction timetemperature, pressure, ethylene glycol-and-PET waste mass ratio and catalyst amount, but the amount of diethylene glycol(except the mass ratio) and the melting point of alcoholysates were decreased. The BHET yield reached 82% when the alcoholysisconditions were optimized as followed pressure 0. 4 MPa, ethylene glycol-and-PET waste mass ratio 0. 5: 1.0, temperature 250℃ and time4h.Key words: polyethylene terephthalate; recovery and utilization; high-temperature high-pressure; alcoholysis orthogonal ex-