石油化工34PETROCHEMICAL TECHNOLOGY2007年第36卷第4期草酸二甲酯加氫合成乙二醇反應(yīng)的研究張啟云,黃維捷,文峰,肖文德(華東理工大學(xué)化學(xué)工程國(guó)家重點(diǎn)實(shí)驗(yàn)室,上海200237)[摘要]在微型管式反應(yīng)器中采用 CaSio2催化劑在溫度190-210℃、壓力1~3MPa草酸二甲酯(DMo)與氫氣的摩爾比(氫酯比)40-120、DMO空速6.0-25.0mmol/(g·h)的條件下,對(duì)DMo加氫制乙二醇的反應(yīng)進(jìn)行了研究。實(shí)驗(yàn)結(jié)果表明,高溫、高壓、高氫酯比和低DMO空速都能提高DMO的轉(zhuǎn)化率和乙二醇的收率,但同時(shí)也增加了副產(chǎn)物的選擇性。較適合的反應(yīng)條件為:壓力2MPa,溫度205-210℃,氫酯比80~100,DMO空速10.0mmo(g·h)。動(dòng)力學(xué)研究表明,DMo加氫反應(yīng)符合Langmuir- Hinshelwood吸附反應(yīng)動(dòng)力學(xué)模型,表面反應(yīng)為速率控制步驟,氫氣不解離吸附,由此得到了相應(yīng)的動(dòng)力學(xué)方程及參數(shù)。統(tǒng)計(jì)檢驗(yàn)結(jié)果表明該模型對(duì)DMO加氫反應(yīng)高度適定。[關(guān)鍵詞]草酸二甲酯;乙二醇;加氫;銅二氧化硅催化劑;動(dòng)力學(xué)[文章編號(hào)]1000-8144(2000)04-0340-05中圖分類號(hào)]TQ22.162[文獻(xiàn)標(biāo)識(shí)碼]AHydrogenation of Dimethyl Oxalate to Ethylene GlycolZhang Qiyun, Huang Weijie, Wen Feng, Xiao WendeState Key Labotatory of Chemical Engineering, Eest China University of Science and Technology, Shanghai 200237, China)Abstract] Hydrogenation of dimethyl oxalate( DMO)to ethylene glycol( EG)was investigated in atubular microreactor on Cu/SiO, catalyst. Effects of temperature, pressure, mole ratio of H, to DMOand dMO space velocity on reaction were studied in ranges of 190-210 C, 1-3 MPa, 40-120 and6.0-25.0 mmol( g. h), respectively. Both DMO conversion and EG yield increased at highertemperature, higher pressure, larger mole ratio of H, to DMO and lower DMO space velocity, butelectivity to byproduct also increased. The optimized reaction conditions were: pressure 2 MPatemperature 205-210 C, mole ratio of H, to DMO 80-100 and DMO space velocity 10. 0 mmol(g. h). Langmuir-Hinshelwood mechanism model with non-dissociative hydrogen adsorption isremarkably suitable to DMO hydrogenation. Surface reaction is the velocity controlling step. Thekinetic equation was checked by statistic test.Keywords] dimethyl oxalate; ethylene glycol; hydrogenation; copper/silicon dioxide catalyst;kinetics乙二醇(EG),又稱甘醇,主要用于生產(chǎn)聚對(duì)苯行了深入的研究,制備了CuSO2催化劑,并在自制二甲酸乙二醇酯、防凍劑、溶劑等,是一種重要的有三段爐固定床不銹鋼加壓反應(yīng)器中對(duì)該反應(yīng)進(jìn)行了機(jī)化工原料。近年來(lái),世界聚酯生產(chǎn)迅猛發(fā)展,BG研究。但由于該反應(yīng)器管徑較粗(φ20mmx2.5需求與日俱增。生產(chǎn)EG的傳統(tǒng)工藝采用環(huán)氧乙烷mm),催化劑床層中難免會(huì)存在溫度的徑向分布,而直接水合法,該工藝流程長(zhǎng)、設(shè)備多、能耗高,EG且該反應(yīng)器還存在測(cè)溫不準(zhǔn)等缺點(diǎn)。DMO加氫反應(yīng)的生產(chǎn)成本高。為此,人們提出了許多新的合成對(duì)溫度極其敏感,即使很小的溫度偏差都會(huì)對(duì)原料轉(zhuǎn)EG的方法23,其中合成氣經(jīng)草酸二甲酯(DMO)化率及產(chǎn)物組成產(chǎn)生巨大的影響,因此在測(cè)溫不準(zhǔn)的生產(chǎn)EG的工藝“具有很強(qiáng)的競(jìng)爭(zhēng)力,該工藝首先反應(yīng)器中得到的動(dòng)力學(xué)數(shù)據(jù)存在較大的誤差。由CO氣相氧化偶聯(lián)得DMO,DMO再加氫制EG。本工作采用改進(jìn)的反應(yīng)器及溫度控制裝置使用DMO加氫是一個(gè)串聯(lián)反應(yīng),首先DMO加氫生成中間產(chǎn)物乙醇酸甲酯(MG),MG再加氫生成【收稿日期]206-12-061修改稿日期286-01-5.李竹霞等6對(duì)合成氣經(jīng)DMO生產(chǎn)EG工藝進(jìn)人:肖文德電話021-64284電郵 wdxiao@ ecus咖可EG,EG過(guò)度加氫則生成副產(chǎn)物乙醇。作者簡(jiǎn)介]張啟云(1981一),男,浙江省寧波市人,碩士生。聯(lián)系第4期張啟云等.草酸二甲酯加氫合成乙二醇反應(yīng)的研究CuSO2催化劑,考察了DMO加氫反應(yīng)的工藝條件,質(zhì)量流量計(jì)控制流量,進(jìn)入汽化器與汽化的DMo提出了該反應(yīng)的動(dòng)力學(xué)模型,為工業(yè)化應(yīng)用提供參考。溶液充分混合后進(jìn)入反應(yīng)器進(jìn)行反應(yīng)。產(chǎn)物由冰水1實(shí)驗(yàn)部分槽冷卻,液體產(chǎn)物收集后進(jìn)行分析,尾氣經(jīng)皂膜流量計(jì)計(jì)量后放空1.1試劑及儀器無(wú)水甲醇:分析純,上海振興化工一廠;DMO:2結(jié)果與討論分析純,上海旭光化工廠;氫氣氮?dú)?純度99.99%,2.1內(nèi)、外擴(kuò)散對(duì)反應(yīng)的影響上海五鋼氣體公司;Cu/SO2催化劑:自制。DMO為考察DMO加氫反應(yīng)的動(dòng)力學(xué)行為,首先要常溫下為固體,難以控制進(jìn)料,因此將DMO溶于甲排除內(nèi)、外擴(kuò)散對(duì)反應(yīng)的影響。內(nèi)擴(kuò)散的消除可通醇配成DMO質(zhì)量分?jǐn)?shù)13.6%的甲醇溶液(簡(jiǎn)稱過(guò)減小催化劑的粒徑來(lái)實(shí)現(xiàn);外擴(kuò)散的消除則通過(guò)DMO溶液)。提高反應(yīng)物的空速來(lái)實(shí)現(xiàn)。為此,考察了Cu/SiO2產(chǎn)物分析采用惠普上海分析儀器有限公司HP催化劑的粒徑及DMO空速對(duì)DMO轉(zhuǎn)化率的影響6890氣相色譜儀色譜柱為美國(guó)惠普公司 Carbowax-實(shí)驗(yàn)結(jié)果見圖2和表1。由圖2可見,當(dāng)ma/Fk<20M填充柱,檢測(cè)溫度和汽化溫度都為230℃;數(shù)1.5g·h/g(即在DMo空速大于5.6mmol據(jù)處理采用大連化學(xué)物理研究所開發(fā)的 Chrom98(g·h)的高空速區(qū))時(shí),外擴(kuò)散的影響已消除。由(V2.0)色譜數(shù)據(jù)處理系統(tǒng)。表1可見,當(dāng)采用40~80目的Cu/SO2催化劑時(shí),1.2實(shí)驗(yàn)裝置與流程DMO轉(zhuǎn)化率基本上不隨CuSO2催化劑粒徑的變改進(jìn)的反應(yīng)器為微型不銹鋼U形管反應(yīng)器化而變化,說(shuō)明在此粒徑范圍內(nèi)無(wú)內(nèi)擴(kuò)散的影響。(中3.6mm×1mm),反應(yīng)溫度由程序控溫式油浴實(shí)驗(yàn)中選用40~60目的Cu/SO2催化劑,DMO空裝置控制,溫度誤差小于0.1℃,由于反應(yīng)器管徑速大于等于6.0mmo/(g·h)。小,導(dǎo)熱油熱容大,因此可消除催化劑床層中溫度的徑向分布。測(cè)溫?zé)犭娕疾迦氲椒磻?yīng)器的內(nèi)部,可準(zhǔn)確測(cè)量反應(yīng)溫度。實(shí)驗(yàn)裝置見圖1。0406081012141618202.2m. FDNo/g·h·g)圖2ma/Fpo對(duì)DMO加氫反應(yīng)的影響Fig. 2 Effect of men/FpMo on hydrogenation of DMOReaction conditions: 200 C, 2 MPa, n(H,): n( DMO)=80Cw/sio, catalysts 40-60 mesh圖1實(shí)驗(yàn)裝置FDMo: feeding rate of DMO, g/h; mos. mass of Cw SiO, catalyst, g.Fig 1 Schematic diagram of experimental apparatus.Cold trap: 2 Gas-liquid separator; 3 Soap film flowmeter表1cu/SiO2催化劑粒徑對(duì)DMo加氫反應(yīng)的影響4 Stirrer: 5 Reactor: 6 Oil bath: 7 vaporizeTable 1 Effect of Cw/Sio, catalyst particle sizeTI, T2, T3 Thermocoupleon hydrogenation of DMODMO: dimethyl oxalateSelectivity.在反應(yīng)器中裝填1.0g40~60目的Cu/SO2催w/Sio, catalystDMO.glycollate( MG) glycol( EG)化劑,并在反應(yīng)器兩端各裝人1mL20~40目的石20-40meh75.4119.14英砂,防止反應(yīng)器內(nèi)氣體溝流并固定催化劑床層。40-60 mesh79.867.02Cu/Sio2催化劑由氫氣在特定條件下還原活化,然60-80mesh19:90后設(shè)定好反應(yīng)溫度和壓力。DMO溶液由高壓計(jì)量Reaction conditions: 200 C, 2 MPa, DMO space velocity 8.5泵打人汽化器汽化,鋼瓶中的氫氣經(jīng)減壓后由高壓mmo(g·h),n(H2):n(DMo)=80石油化工342PETROCHEMICAL TECHNOLOGY007年第36卷2.2反應(yīng)條件對(duì)DMo加氫反應(yīng)的影響223原料配比的影響2.2.1壓力的影響氫氣與DMO的摩爾比(氫酯比)對(duì)DMO加氫壓力對(duì)DMO加氫反應(yīng)的影響見圖3。由圖3反應(yīng)的影響見圖5。由圖5可看出,氫酯比為40可看出,在1~3MPa內(nèi)隨壓力的升高,DMO轉(zhuǎn)化80時(shí),DMO轉(zhuǎn)化率隨氫酯比的增大而增加,當(dāng)氫酯率和EG選擇性略有增加,MG選擇性略有減小;當(dāng)比大于80后,DMO轉(zhuǎn)化率隨氫酯比的變化已不明壓力高于20MPa時(shí),反應(yīng)基本穩(wěn)定。所以較適宜顯;EG選擇性隨氫酯比的增大明顯增加,但當(dāng)氫酯的壓力為2MPa比大于100后,增幅已不明顯,此時(shí),過(guò)量的氫氣加劇了EG加氫反應(yīng),產(chǎn)物中測(cè)出微量乙醇。所以氫酯比應(yīng)控制在80~100。05101.5202.53.03.5PressureMPa圖3壓力對(duì)DMo加氫反應(yīng)的影響80100120Fig 3 Effect of pressurO hydrogenn(H,): nDMOReaction conditions: 200 C, n(H,): n(DMO)DMO space velocity 18.9 mmol/(g. h),圖5氫酯比對(duì)DMO加氫反應(yīng)的影響Cu/Sio, catalyst 40-60 meshFig 5 Effect of n(H,): n(DMO)on DMO hydrogenation.Conversion of DMO: o Selectivity to MG: 4 Selectivity to EGReaction conditions: 200 C, 2 MPa, DMo space velocity9.5 mmo/(g.h), Cu/Sio, catalyst 40-60 mesh2.2.2溫度的影響I Conversion of DMO: o Selectivity to MG: A Selectivity to溫度對(duì)DMo加氫反應(yīng)的影響見圖4。由圖4可看出,在190-210℃內(nèi),DMO轉(zhuǎn)化率和EG選擇2.2.4DMO空速的影響性隨溫度的升高明顯增加,其中DMO轉(zhuǎn)化率在210由于反應(yīng)中氫氣大大過(guò)量,所以考察DMo空℃時(shí)已接近100%;MG的選擇性隨溫度的升高明速對(duì)DMO加氫反應(yīng)的影響實(shí)驗(yàn)結(jié)果見圖6。由圖顯減小。由此可見,升高溫度對(duì)反應(yīng)有利,但當(dāng)溫度6可看出,DMO轉(zhuǎn)化率和EG選擇性隨DMO空速升到210℃以上時(shí),產(chǎn)物中測(cè)出微量乙醇,說(shuō)明副反的增加而下降,在DMO空速為6.0~15.0mmo應(yīng)開始發(fā)生。所以溫度應(yīng)控制在205~210℃內(nèi)(g·h)時(shí),DMo轉(zhuǎn)化率降幅較緩,大于15.0mmol°(g·h)時(shí),降幅增大;EG選擇性在DMo空速為6.0~20.0mmol/(g·h)時(shí),降幅較大,大于20.0劂*mmov/(g·h)時(shí),降幅變小。由EG空時(shí)收率隨DMO空速的變化可看出,為使反應(yīng)器的生產(chǎn)能力最大化,DMO空速應(yīng)控制在10.0mmol/(g·h)左右。2.3反應(yīng)動(dòng)力學(xué)研究DMO催化加氫為氣固相串聯(lián)反應(yīng)。多相催化反應(yīng)可分為單位吸附反應(yīng)及多位吸附反應(yīng),氫氣在吸附時(shí)又分為解離吸附和不解離吸附酯加氫的步驟根據(jù)不同研究者的結(jié)論也可細(xì)化為解離吸附圖4溫度對(duì)DMo加氫反應(yīng)的影響和非解離吸附2。根據(jù)不同機(jī)理可得到不同的Fig 4 Effect of temperature on DMO hydroge模型,本工作根據(jù)以下4個(gè)判別準(zhǔn)則建立動(dòng)力學(xué)模Reaction conditions: 2 MPa, n(H2):n(DMO)DMO space velocity 9. 5 mmol(g.h)型:(1)反應(yīng)速率常數(shù)和吸附平衡常數(shù)必須大于Cu/sio, catalyst 40-60 mesh.(2)表面反應(yīng)的活化能必須為正值,吸附熱為負(fù)值Conversion of DMO; o Selectivity to MG; Selectivity to EG(3)反應(yīng)速率常數(shù)和吸附平衡常數(shù)分別符合第4期張啟云等.草酸二甲酯加氫合成乙二醇反應(yīng)的研究343Arrhenius方程和van' t Hoff方程;(4)模型與動(dòng)力DMO +*w DMO學(xué)實(shí)驗(yàn)數(shù)據(jù)良好吻合。Mo*+H2*一A*A*+H2MG * +Meoh*MG來(lái)MG+B*+EG+MeOH申2③466789Meoh*= Meoh++其中A為QH4 COCHOHOCH,: B為(H3 OCHOHCH2OH;*為吸附活性位反應(yīng)(4)和反應(yīng)(7)為速率控制步驟,通過(guò)穩(wěn)態(tài)圖6DMo空速對(duì)DMo加氫反應(yīng)的影響近似法進(jìn)行處理可推出:DMReaction conditions: 2 MPa, 205 C, n(H, ): n( DMO)=80,k, KDMoKH PDMoPHCusiO, catalyst 40-60 mesh(I+KHPu +KpMoPoMo +km.pI Couversion of DMO: o Selectivity to MG;Selectivity to EG; v Yield of EGkKwKM(Pm.Pu-PEo結(jié)合動(dòng)力學(xué)數(shù)據(jù)對(duì)模型進(jìn)行了篩選。篩選結(jié)果1+KHPH+ KpMoPomo +KM顯示,在溫度190~205℃、壓力1-3MPa、氫酯比40~120、DMO空速6.0~25.0mmol(g·h)的范由遺傳算法結(jié)合單純形法3,優(yōu)化的不同溫圍內(nèi),對(duì)于DMO加氫反應(yīng)DMO非解離吸附,表面度下的動(dòng)力學(xué)參數(shù)見表2。將表2中的反應(yīng)速率常符Langmuir- Hinshelwood模型(L-H模型),反應(yīng)歷H方程,求得活化能,吸附熱及相應(yīng)的指數(shù)前因程如下:子,見表3和表4。表2不同溫度下DMO加氫反應(yīng)的反應(yīng)速率常數(shù)和吸附平衡常數(shù)計(jì)算值Table 2 Calculated constants of reaction rate and absorption equilibrium for DMO hydrogenation at different temperaturesTemperature/t Reaction rate constant/( mol'8h2on equilibrium constant/MPaK63.5850130798.876347.910387.7220.0091696.906224.771232.126427.710442.1940.0066607,I41100.320184.901I87.873468.670550.0880.0048540.994145.56057,903表3DMO加氫反應(yīng)的活化能和反應(yīng)指數(shù)前因子由模型得到的計(jì)算值的比較見圖7。從圖7可看Table 3 Activation energy and pre-exponential factor出,實(shí)驗(yàn)值和計(jì)算值基本符合。實(shí)驗(yàn)值和計(jì)算值的總相對(duì)平均偏差為144%。Reaction rate constant采用適用于非線性模型的統(tǒng)計(jì)方法對(duì)模型Activation energy/(. mol-l)31.65186.3進(jìn)行了檢驗(yàn)檢驗(yàn)結(jié)果顯示決定性指標(biāo)p2>0.97,Pe- exponential factor/(mot·g-1·b-1)1.337x10°1.499×102統(tǒng)計(jì)量F>10F0m。由此可見,在所研究的壓力溫度、氫酯比和DMO空速的范圍內(nèi),該模型對(duì)DMO轉(zhuǎn)化率及EG和MG選擇性的實(shí)驗(yàn)值和DMO加氫反應(yīng)高度適定。表4DMo加氫反應(yīng)的吸附熱和吸附指數(shù)前因子Table 4 Heat and pre-exponential factor of absorption in DMO hydrogenationAbsorption equilibrium constarHeat of absorption/(. mol -)121.95595.249Pre- exponential factor of absorption/MPa-12.270×10-162.943x10-4.648×10-12.504×105914×10石油化工344PETROCHEMICAL TECHNOLOGY2007年第36卷MG乙醇酸甲酯1,2反應(yīng)序號(hào)1沈景馀.國(guó)外環(huán)氧乙烷/乙二醇技術(shù)進(jìn)展.石油化工,200130(5):404-4092黃衛(wèi)國(guó),賀德華,劉金堯等,非石油路線合成乙二醇方法論述然氣化工,1997,22(5):35-393華強(qiáng),劉定華,馬正飛等.催化水合法合成乙二醇.石油化工,2003,32(4):317~3204 william J B, Charleston w V. Ethylene Glycol by Catalytic Hydro-圖7實(shí)驗(yàn)值和計(jì)算值的比較genation. US Appl Pat, US 4628128. 1986Fig 7 Comparison of the experimental and calculated data.Conversion of DMO: o Selectivity to MG; 4 Selectivity to EG5李竹霞,錢志剛,趙秀閣等,草酸二甲酯加氫CuSO2催化劑前體的研究.華東理工大學(xué)學(xué)報(bào),2004,30(6):613-6173結(jié)論6李竹霞,錢志剛,趙秀閣等. Cu/SiO2催化劑上草酸二甲酯加氫反應(yīng)的研究化學(xué)反應(yīng)工程與工藝,2004,20(2):121~128(1)在微型管式反應(yīng)器中,采用Cu/SiO2催化7 Agarwal A K, Cant w, Wainwright M S,eta. Catalytic Hydro-劑,研究了DMO加氫反應(yīng)。實(shí)驗(yàn)結(jié)果表明,高溫、高 genolysis of Esters: A Comparative Study of the Reactions of壓高氫酯比和低DMO空速都能提高DMo轉(zhuǎn)化率Simple Formates and Acetates over Copper on Silica. J Mol Catal和EG收率,但冋時(shí)也增加了副產(chǎn)物乙醇的選擇性1987,43(1):79-92較適合的反應(yīng)條件為壓力2MPa,溫度205~208 Monti D M, Wainwright M S, Trimm D L. Kinetics ofVapor-Phase Hydrogenolysis of Methyl Formate over Copper on℃,氫酯比80~100,DMoO空速10.0mmo(g·h)。Silica Catalysts, Ind Eng Chem Prod Res Dev, 1985, 24(3):(2)結(jié)合動(dòng)力學(xué)數(shù)據(jù),通過(guò)模型篩選及優(yōu)化,確定DMO加氫反應(yīng)符合L-H模型,表面反應(yīng)為速9 Monti D M, Cant N w, Trimm D L,cta. Hydrogenolysis of率控制步驟,氫不解離吸附,并得到了相應(yīng)的動(dòng)力學(xué)Methyl Formate over Copper on Silica I. Study of Surface Species方程及參數(shù)。統(tǒng)計(jì)檢驗(yàn)表明,在實(shí)驗(yàn)條件范圍內(nèi),該by in Situ Infrared Spectroscopy. J Catal, 1986, 100(1): 17模型對(duì)DMO加氫反應(yīng)高度適定。10 Monti D M, Cant N w. Trimm D L, et al. Hydrogenolysis of符號(hào)說(shuō)明Methyl Formate over Copper on Silica H. Study of the MechanismUsing Labeled Compounds. J Catal, 1986, 100(1): 28-38統(tǒng)計(jì)量11 Santiago M A N, Sanchez-Castillo M A, Cortright R D, e al.FD草酸二甲酯的流量,g/hCatalytic Reduction of Acetic Acid, Methyl Acetate, and EthylK吸附平衡常數(shù),MPa-1Acetate over Silica-Supported Copper. J Catal, 2000, 193(1):K,反應(yīng)平衡常數(shù)MPa16-28反應(yīng)速率常數(shù),moU(g·h12 Thomas D J, Wehrli JT, Wainwright M S, et al. Hydrogenolysis催化劑的質(zhì)量,gof Diethyl Oxalate over Copper-Based Catalysts. Appl Catal, A壓力,MPa1992,86(2):101-114反應(yīng)速率,moU(g·h)13粟塔山編.最優(yōu)化計(jì)算原理與算法程序設(shè)計(jì)長(zhǎng)沙:國(guó)防科技大決定性指標(biāo)學(xué)出版社,2001.90-97下角標(biāo)14王沫然編. MATLAB與科學(xué)計(jì)算.第二版.北京:電子工業(yè)出DMo草酸二甲酯BG·乙二醇15劉建平編.數(shù)理統(tǒng)計(jì)方法與概率論.上海:華東理工大學(xué)出版氫氣社,2000174-180甲醇?xì)g迎投稿、歡迎訂閱、歡迎刊登廣告