Vol 30 No. 2第30卷第2期大學(xué)學(xué)報(bào)(理學(xué)版Mar.2003203年3月Journal of Zhe jlang University( Science Edition)合成氣一步法制二甲醚的動(dòng)力學(xué)研究江大好,費(fèi)金華,張一平,鄭小明(浙江大學(xué)催化研究所,浙淅江杭州310028)摘要:采用國(guó)定床積分反應(yīng)器,研究了用浸漬法制備的CuO-ZnO/Y- zeolite雙功能催化劑上CO加氫直接合成二甲醚的反應(yīng)動(dòng)力學(xué),按一氧化碳加氨先合成甲醇,再由甲醇脫水生成二甲醚兩步串聯(lián)的反應(yīng)機(jī)理,分別建立了動(dòng)力學(xué)襪型,并對(duì)該催化劑上甲酵合威及咿醇脫水的機(jī)理作了探討.模型的計(jì)算值和實(shí)驗(yàn)值能較好吻合·兩步反應(yīng)的表觀活化能分別為27.98kJ/mol和30,62kJ/mol關(guān)鬟詞:合成氣;二甲醚;動(dòng)力學(xué);催化劑中圖分類號(hào):TE665.62文獻(xiàn)標(biāo)識(shí)碼:A文章編號(hào):1008-9497(2003)02-167-0JIANG Da-hao, FEI Jin-hua, ZHANG Yi-ping, ZHENG Xiao-ming (Institute of Catalysis, Zhejiang UniversityStudy on the kinetics of dimethyl ether one-step synthesis from syngas. Journal of Zhe jiang University(ScienceEdition),2003,30(2):167~172Abstract: The kinetics for one-step synthesis of dimethyl ether from syngas over CuO-ZnO/Y-zeolite catalysts wasstudied in a fixed-bed reactor. Assuming the reaction includes two steps: methanol synthesis from syngas is thefirst step and followed by methanol dehydration to produce dimethyl ether, The reaction mechanism models wereestablished and the reaction mechanisms of methanol synthesis and methanol dehydration over the bi-functionalcatalyst were discussed in this paper. The data calculated by the mechanism models are consistent with theexperiments and the apparent activation energies of the two steps are 27. 98 kJ/mol and 30. 62 kJ/ mol,Key words: syngas: dimethyl ether; kinetics; catalyst二甲醚作為氟里昂的優(yōu)良替代品已廣泛應(yīng)用于各類氣霧劑的生產(chǎn)中,而且由于全球范圍內(nèi)對(duì)氟里1實(shí)驗(yàn)部分昂使用的限制,預(yù)計(jì)今后氣霧推進(jìn)劑對(duì)二甲醚的需求還將穩(wěn)步增長(zhǎng)(,作為一種可替代民用燃料和柴1.1實(shí)驗(yàn)裝置及流程油的潔凈能源,燃料級(jí)二甲醚極具市場(chǎng)潛力和開發(fā)實(shí)驗(yàn)在MRCS8004高壓微反色譜系統(tǒng)上進(jìn)行前景31.除了可用作氣霧劑和燃料外,二甲醚還是實(shí)驗(yàn)裝置及流程如圖1所示凈化后的H2,CO由質(zhì)種重要的化工原料和有機(jī)合成中間體.近年量流量控制器控制流量(控制精度為±1%),按所需來(lái),合成氣一步法制二甲醚成為國(guó)內(nèi)外的研究熱點(diǎn),的比例,經(jīng)混合器混勻后進(jìn)入反應(yīng)器進(jìn)行反應(yīng),反應(yīng)而其關(guān)鍵是選擇合適的催化劑-10我們采用浸漬器為不銹鋼管,內(nèi)徑q8mm,中心插有熱電偶套管法備的Cu基雙功能系列催化劑,具有很好的活系統(tǒng)壓力由反應(yīng)器出口處的背壓閥調(diào)節(jié).反應(yīng)器溫性、選擇性和穩(wěn)定性,適合于工業(yè)應(yīng)用10;其動(dòng)力度用智能控溫儀控制(控制精度為土0.5C),催化學(xué)研究,對(duì)該催化劑上二甲醚合成機(jī)理的研究以及劑床層溫度用K型熱電偶測(cè)量,電位差計(jì)校正,反工業(yè)催化反應(yīng)器的設(shè)計(jì)都具有重要的意義應(yīng)后的尾氣組成由HP5890-I型氣相色譜儀在線分中國(guó)煤化工收稿日期:2002-11-28.基金項(xiàng)目:浙江省自然科學(xué)基金資助項(xiàng)目(ZD9903YHCNMHG作者簡(jiǎn)介:江大好(1973-),男,碩士研究生,主要從事有機(jī)懂化方面的研究浙江大學(xué)學(xué)報(bào)(理學(xué)版)第30卷析,熱導(dǎo)池檢測(cè)器檢測(cè)5、圖1實(shí)驗(yàn)裝置及流程圖1原料氣鋼瓶,2減壓器3—?dú)怏w凈化管(裝有脫氧劑和干燥劑),4-穩(wěn)壓閥5一截止閥,6一壓力計(jì),7一質(zhì)量流量控制器8一單向閥,9-混合器.10恒溫锎塊,ll一控溫?zé)犭?12一測(cè)溫?zé)犭姾?13一三迺閥,14-背壓閥,15-六通閥1.2動(dòng)力學(xué)實(shí)驗(yàn)驗(yàn)結(jié)果如表1所示,當(dāng)催化劑的粒度小于20目以催化劑與等體積同粒度的石英砂混合均勻后,后,CO的轉(zhuǎn)化率和主要產(chǎn)物的選擇性基本保持不裝在反應(yīng)管的恒溫段,催化劑床層及上下填料的總變,說明內(nèi)擴(kuò)散影響已可排除.改變催化劑的裝量并高度與催化劑的粒度之比大于100,催化劑床層中保持接觸時(shí)間相同,即改變?cè)蠚獾木€速度,CO的氣體處于平推流空白實(shí)驗(yàn)表明反應(yīng)器本身及反應(yīng)轉(zhuǎn)化率和二甲醚等主要產(chǎn)物的選擇性也基本相同管的填料石英砂對(duì)反應(yīng)沒有催化作用.(見表2).該結(jié)果說明,空速大于1000h-后,外擴(kuò)在275C,2.0MPa,1500h,H2/CO=3:2散的影響也被排除的反應(yīng)條件下,對(duì)幾種粒度的催化劑進(jìn)行了評(píng)價(jià),實(shí)表1催化劑顆粒大小對(duì)CO轉(zhuǎn)化率以及主要產(chǎn)物選擇性的影響Table 1 Effect of the catalyst particle sizes on the conversion rate of CO and selectivity of the main productsParticle sizeConversion rateSelectivity/mol(mesh)of co/ molDMEMethanolCO 220~4061.483.7259.1160~8061.82Reaction conditions: T'-275CiP=2.0 MPa: GHSV-1500 h-i H2/CO-3 :2表2氣體線速度對(duì)CO轉(zhuǎn)化率以及主要產(chǎn)物選擇性的影響Table 2 Effect of the linear velocity of gas on the conversion rate of CO and selectivityof the main prodVolume of the filled Conversion rateSelectivity/ mol28.252.54動(dòng)力學(xué)實(shí)驗(yàn)的反應(yīng)條件為溫度255-285C,個(gè)條生下系少洲取2個(gè)以b的亞行樣根據(jù)色譜儀壓刀2.0MPa,空速1000~3000h-,H2/CO=的中國(guó)煤化工,可以求算尾氣中3:2.催化劑用量1.7g(約2ml),粒度20~40目各CNMHG結(jié)果見表3動(dòng)力學(xué)實(shí)驗(yàn)數(shù)據(jù)的采集在催化劑活性穩(wěn)定期內(nèi),每2期江大好,等:合成氣一步法制二甲醚的動(dòng)力學(xué)研究169表3動(dòng)力學(xué)實(shí)驗(yàn)的結(jié)果Table 3 Results of kinetics experimentGHSVConstitution of tail ga/MP282.030000.35610.56670.02740.01630.03160.000625000.34440.56080.03520.01630.04020000.5:450.04590.01280.05500.001000.53820,06530.0,001510000.24570.51210070.01370.920.00272.00000.34080.56010.03750.25000.32420,54960.04800.01710.05610.001320000.30210.53950.063101530.07280.00170.08890.0380000.21410.495712240.01460.13810.0044112.030000.32270.55170.05000.01320.05450.001625000.30340.54290.06310.01190.06990.0200.27790.52920.07980.01250.08850,0028.015000.23950.51190.10580.01440.11170.00412.010000.18740.48850.13950.01230.14440.00660.30780.54790,06120,00880.06380.00230.28630.53820.07660.00900.0770.003120000.26080.52540.09360.01020.09150.00405582.015000.22440.50560.11840.01110.11580.00572.010000,17060.48050.15640.01120.1390.0093結(jié)合尹秋響、李紹芬等對(duì)銅基催化劑上合成2數(shù)據(jù)處理和討論氣制甲醇的研究結(jié)果,對(duì)CO加氫合成甲醇提出如下的反應(yīng)機(jī)理2.1動(dòng)力學(xué)模型的建立CO+“O“,合成氣一步法制二甲醚是一個(gè)復(fù)雜的反應(yīng)體系、其中包含6種化合物、3種元素.根據(jù)相律,體系H2+☆一=H2☆的獨(dú)立反應(yīng)數(shù)為31.為了建立動(dòng)力學(xué)模型,對(duì)反應(yīng)H2O+☆一H2O☆,過程作如下的簡(jiǎn)化或假設(shè):bcdeCOx+H2☆H2CO*十☆,(1)合成氣制二甲醚是一串聯(lián)反應(yīng):CO加氫合H2CO*+H2☆一CHOH*+☆(f)成甲醇,甲醇脫水生成二甲醚,還同時(shí)存在變換反CHOH*一CH3OH+(g)應(yīng).即以下3個(gè)反應(yīng)為獨(dú)立反應(yīng):分別以(e)和()為最終速率控制步驟,根據(jù)催CO+2H2=CH3OH,(1)化劑均勻表面反應(yīng)理論,可以推導(dǎo)出合成甲醇的22CH,OH=CH3 OCH3+H, O速率方CO+H, O=CO2+H(3)如以(e)控制步驟,則:(2)水煤氣變換反應(yīng)處于平衡狀態(tài)213k,PoPH(1-B1)(3)雙功能催化劑上,甲醇合成活性中心有兩(1+Copco+ Kco,pe1+KH, PH, +KH, ok種,一種吸附CO,CO2,CH2OH,另一種吸附H2,如以(f)控制步驟,則H2O14-;甲醇脫水中心的吸附物種為CH3OH(也k pcoP, (1-P可能解離吸附),H2O,DME;其中,產(chǎn)物CH3OH,20+M(1+CopCo+Kco, Pco, )(1+DME都容易脫附,對(duì)各自正反應(yīng)沒有阻礙作用中國(guó)煤化工21,甲醇脫水的速4)吸附物種的表面反應(yīng)為反應(yīng)速率控制步驟.率CNMHG反應(yīng)物吸附和產(chǎn)物脫附處于平衡狀態(tài)17浙江大學(xué)學(xué)報(bào)(理學(xué)版第30卷表4甲醇脫水的待選模型及動(dòng)力學(xué)速率方程Table 4 The mechanism models and rate equations which can be selected for methanol dehydration動(dòng)力學(xué)速率方程機(jī)理模型以分子形式吸附解離吸附L. angmir-Hinshelwoodk:p(1-2)1+Kmp+kHopRideal-Eleyk2p(1-A2)k2pM3(1-2)rn-1KMpw+KH,PH, o(1+K3p+KHPu…)22.2參數(shù)估值和模型篩選KHo=5.89×10exp(-40197.22/RT)采用 Levenberg-Marquart法2)分別對(duì)以上的甲醇脫水速率方程為模型進(jìn)行參數(shù)回歸,發(fā)現(xiàn)若甲醇合成以(e)為控制步k2?P(1-B2)驟,拜醇脫水按解離吸附的LH機(jī)理進(jìn)行,則實(shí)驗(yàn)rn(1+KM數(shù)據(jù)與相應(yīng)的動(dòng)力學(xué)方程達(dá)到最好的符合,即甲醇式中,k2=1.19×10exp(-30620.13/RT);合成速率方程為KM=32.17exp(4287/RT);k,PeoPL(1-月)KHo=6.96×10exp(103744/RT)D-M(1+Kenpo+ Kco, Pcv2 (1+KM, PH, +KH, p,o式中,k1=13875.38exp(-27984.68/RT);表5是r2+M,rp實(shí)驗(yàn)值和計(jì)算值的比較.除少數(shù)點(diǎn)外,2-y的相對(duì)誤差都在±5%以內(nèi),而r相對(duì)K=0.09Xp(10162.90/RT);誤差的最大值也僅為-12.15%可見所建立的動(dòng)力KCo,=2.42×10exp(58762.16/RT);學(xué)模型能很好地關(guān)聯(lián)本次動(dòng)力學(xué)實(shí)驗(yàn)的數(shù)據(jù)K比=2.8×10exp(25069.94/RT)表5r2+M,r實(shí)驗(yàn)值和計(jì)算值的比較Table 5 Comparison of r2D+M and ro data between experimental and calculated valuesID/mmol /(gcat. h)序號(hào)r2D,M/mmol /(gcat. h)實(shí)驗(yàn)值計(jì)算值誤差/%實(shí)驗(yàn)值算值誤差/%25.062.711.4821.8321.660.77418.313.601011.575.0529.626414.3914.4027.7313.8023.4819.3117.976.90ll.661131.4415.2116.0914.1524.1917.3116.991.8710.1011.016827.8727.401.7013.6412.8411.2815.4615.590.83V山中國(guó)煤化工0.76CNMHG23反應(yīng)機(jī)理的探討據(jù)話此,我們認(rèn)為CuU∠nU/Y- zeolite雙功能催化以上兩方程成功地關(guān)聯(lián)了本次動(dòng)力學(xué)實(shí)驗(yàn)的數(shù)劑上甲醚合成的化學(xué)機(jī)理如下:CO、CO2在銅中心第。2期江大好,等:合成氣一步法制二甲醛的動(dòng)力學(xué)研究上吸附,吸附的CO與吸附在ZnO上的H2逐步反Kp,,KP,-反應(yīng)(1),(2)的平衡常數(shù)應(yīng),最終形成甲醇甲醇再在Y-分子篩酸中心的作KP,1=22.70+8.975×103”-7.694ln7+3.920用下解離吸附,形成的甲氧基相互作用生成二甲醚,10-7+5.123×10-72-3.114×10-7:11二臼醚脫附后,分子篩表面氧、氫自由基結(jié)合生成Kp,2=-9.39+3.205×103/T+0.836n7+2.353水.其中甲氧基之間的反應(yīng)為速率控制步驟103T-1.874×10-672+5.160×10-1073:13結(jié)論參考文獻(xiàn)(1)在CuO-znO/ Y-zeolite雙功能催化劑上,合1]常雁紅,韓怡卓,王心葵.二甲醚的生產(chǎn)、應(yīng)用及下游成氣一步合成二甲醚經(jīng)過形成甲醇及甲醇脫水兩個(gè)產(chǎn)品的開發(fā)[J].天然氣化工,2000,25(3):45-54階段,水氣變換反應(yīng)可按平衡反應(yīng)處理CHANG Yan-hong, HAN Yi-zhuo, WANG Xin-kui(2)甲醇合成的速率方程為The production, application and downstream productsdevelopment of dimethyl ether [J]. Natural Gasa:M(1+ Kcopeo+ Keo, Peo, ) (1+KH2 PM, +KH,OPH,0)Chemical Industry, 2000, 25(3): 45-54式中,k1=13875.38xp(-27984.68/RT);[2]葛慶杰,黃友梅李樹本,二甲醚的用處和制備[].石K(=0.09exp(10162,9/RT);油化工K0.=2.42×10exp(58762.16/RT);GE Qing-jie, HUANG You-mei, LI Shu-ben.UsesKH,=2.8×10-exp(25069.94/RTand preparation of dimethyl ether[J]. PetrochemicalTechnology,1997.26(8):560—564KH=5.89×10exp(-40197.22/RT)[3]唐宏青,相宏偉.煤化工工藝技術(shù)評(píng)述與展望L.合成甲醇脫水的速率方程為乙烯和二甲醚[J].燃料化學(xué)學(xué)報(bào),2001,29(2):97k2M(1-B2)(1+K.5pTANG Hong- qing. XIANG Hong-wei. PerspectivesHOPH.oon R&D in coal chemical industry I, synthesis of式中,k2=1,19×10exp(-30620.13/RT);ethene and DME[JJ. Journal of Fuel Chemistry andKM=32.17exp(4287/RT")[4] BROWN D M, BHATT B L. HSIUNG T H, et alKHo=6.96×10"exp(103744/RTNovel technology for synthesis of dimethyl ether from這兩步反應(yīng)的表觀活化能分別為27.98kJ/syngas[J]. Catal Today, 1991. 8(3): 279-304mol和30.62kJ/mol[5 NOJIMA S, IMAI T. Preparation of DME synthesis(3)本動(dòng)力學(xué)研究的結(jié)果為該雙功能催化劑上atalysts[P].JP:02280836,1989-04-21合成氣一步法制二甲醚反應(yīng)機(jī)理的研究提供了十分[6] SOFIANOS A C, SCURRELL MS. Conversion of有益的參考synthesis gas to dimethyl ether over bi-functionalcatalytic systems[J]. Ind Eng Chem Res, 1991.301符號(hào)說明2372-2378.☆—兩種活性吸附位[7]侯昭胤費(fèi)金華,鄭小明,二甲醚的應(yīng)用和生產(chǎn)工藝rao+M—折算結(jié)果相當(dāng)于實(shí)際甲醇生成速率與「J].石油化工,1999,28(1)兩倍二甲醚生成速率之和,單位mmol/(gcat;h);HOU Zhao yin, FEI Jin-hua, ZHENG Xiao-mingThe production technr—二甲醚生成速率,單位mmol/(gcat·h);dimethyl ether[J]. Petrochemical Technology, 1999k1k2一分別為甲醇合成、甲醇脫水的表觀速28(1):59-6率常數(shù);[8]侯昭胤費(fèi)金華,齊共新等.直接合成二甲醚的銅錳K,p,1組分在催化劑上的吸附平衡常數(shù)和催化劑[J.石油化工,2000,29(11):819-822組分分壓;vin. FFI Tin-hma. Q1 Gong-xin, et al.T—反應(yīng)溫度,K;中國(guó)煤化工 r on Cu-Mn catalCNMHG20029(1):819-B1=K,. PcoPK, P2 Kp2Pml:2浙江大學(xué)學(xué)報(bào)(理學(xué)版)第30卷A novel catalyst for DME synthesis from C(infrared spectrum of hydrogen chemisorbed on Zinchydrogenation 1. Activity, structure and surfacOxide[J]. J Catal.1962,1:180-191.proper;ies[J]. Journal of Molecular Catalysis A:[17]尹秋響,李紹芬,廖暉,氣液固相催化合成甲醇本征Chemical,2001.176:195-203.動(dòng)力學(xué)[].化工學(xué)報(bào),1995,46(2):200-205l!侯昭胤,費(fèi)金華,鄭小明.直接合成二甲醚的銅錳催YIN Qiu-xiang, LI Shao-fen. LIAO Hui. Intrinsic化劑及其制備方法[P].CN:98107687.1,1998-08kinetics of gas-liquid-solid phase catalytic synthesisof methanol [J]. Journal of Chemical Industry andHOU Zhao yin, FEl Jin-hua, ZHENG Xiao-mingEngineering(China)The Preparation Method of Cu- Mn Catalyst for[18]雅茹,陶克毅,高峰,等,在HZSM3分子篩上甲醇Dimethyl Ether Direct Synthesis[]. CN: 98107687脫水反應(yīng)動(dòng)力學(xué)研究——在活塞流反應(yīng)器及連續(xù)攪4,1998-08-03.拌槽式反應(yīng)器中穩(wěn)態(tài)反應(yīng)的分析[.高等學(xué)?；瘜W(xué)[1.張海濤曹發(fā)海,劉殿華,等.合成氣直接合成二甲醚學(xué)報(bào),1993,14(2):252-256與甲醇的熱力學(xué)分析[].華東理工大學(xué)學(xué)報(bào),2001ZANG Ya-ru, TAO Ke-yi. GAO Feng. Reaction27(2):198-20kinetics study of methanol dehydration on HZSM-5ZHANG Hai-tao. CAO Fa-hai, LIU Dian-hua. etzeolite- Analysis of steady state reaction in a plugal. Thermodynamic analysis for synthesis offlow reactor [J]. Chemical Journal of Chinesedimethyl ether and methanol from synthesis gas[J]Universities, 1993.14(2):2Journal of East China University of Science and[19]毛麗秋,尹篤林鄭凈植,在改性高嶺土催化劑上甲Technology.2001,27(2):198-201醇脫水生成二甲醚的動(dòng)力學(xué)考察[J].分子催化[12宋維瑞朱炳辰,房鼎業(yè),甲醇合成系統(tǒng)中二氧化碳2000,14(5):379-383.的作用[J].華東化工學(xué)院學(xué)報(bào),1984,(3):267MAO Li-qiu. YIN Du-lin. ZHENG Jing-zhi. Studyon kinetics of methanol dehydration to dimethylSONG Wei-duan, ZHU Bing-chen, FANG Ding-yether on modified kaolin [J]. Journal of MolecularThe effect of carbon dioxide on methanol synthesisCatalysis( China),2000,14(5):379-383.system [JI. Journal of East China Academy of[20]胡惠民,栗同林,甲醇脫水制二甲醚過程的動(dòng)力學(xué)Chemical Industry and Engineering, 1984,(3):267J].天然氣化工,1990,2:17-20HU Hui-min. LI Tong-lin. Kinetics of methanol[13.栗同林,胡惠民,合成氣制甲醇與二甲醚的研究[冂]dehydration to dimethyl ether process [J].Natural天然氣化工,1990,5:12-1Gas Chemical Industry, 1990,2t17-20LI Tong-lin, HU Hui-min. Study on preparation of[21]房鼎業(yè),薛從軍,林荊,等.甲醇在CM-31催化劑上om syngas [J].脫水生成二甲醚的本征動(dòng)力學(xué)[].燃料化學(xué)學(xué)報(bào)Natural Gas Chemical Industry, 1990,5:12-17.1997,25(3):271-276[14. GRAAF G H. WINKELMAN JG M, STAMHUISFANG Ding-ye, XUE Cong-jun, Lin Jing. et alE J. et al. Kinetics of the three phase methanolStudy on intrinsic kinetics of methanol dehydrationsynthesis [J]. Chem Eng Sci,1988.43(8):2161to dimethyl ether on CM-3-1 calalyst[J]. Journal ofFuel Chemistry and Technology, 1997. 25(3):271[15]杜明仙,李永旺,胡惠民,等.CO+H2合成甲醇、二甲醚過程及其動(dòng)力學(xué)研究()動(dòng)力學(xué)模型[J.煤炭轉(zhuǎn)22]謝如彪,非線形數(shù)值分析[M]上海:上海交通大學(xué)化,1993,16(4):68-75出版社,1984DU Ming-xian, LI Yong wang, HU Hui-min, et alXIE Ru-biao. Nonlinear Numerical Analysis [M].Study on the process and kinetics of methanol andShanghai Shanghai Jiaotong University Pressdimethyl ether from CO+H, Part 1. kinetic modelCJ]. Coal Conversion,1993, 16(4):68-75.[16] EISCHENS R P, PLISKIN w A, LOW MJD. The(責(zé)任編輯涂紅)中國(guó)煤化工CNMHG