用无声放电转化甲烷和二氧化碳同时制备合成气与烃

第29卷第1期燃料化学学报Vol 29 No I年2月JOURNAL OF FUEL CHEMISTRY AND TECHNOLOGYFeb.2001Article ll:0253-2409200m-000606CO-GENERATION OF SYNGAS AND HYDROCARBONS FROMMETHANE AND CARBON DIOXIDE USINGDIELECTRIC BARRIER DISCHARGESJIANG Tao, ZHANG Kui, LIU Chang-jun', LI Yang, XU Gen-huiB. Eliasson(1. State Key Laboratory of C1 Chemical Technology Tianjin University Tianjin 300072,China2. ABB Corporate Research Ltd, 5405 Baden, Switzerland)Abstract: Two major greenhouse gases methane and carbon dioxide were converted to syngas and hydrocar-zeolite catalyst at low temperature and atmospheric pressure in a high power dielectric barrier dis-charge reactor. Co-generation of syngas and hydrocarbons was demonstrated in such a reactor Parameters investigated in this study included flow rate of the feed gas the input power and the molar ratio of Ch to COin the feedResults indicated that low flow rate favored the conversion of CH and Co2 while high flow rate led to theproduction of hydrocarbons. Increasing the input power resulted in high conversion of methane and carbondioxide and high productivity of syngas and hydrocarbons. The ratio of CH,/CO, in the feed gas had thesignificant effect on the ratio of H,/CO in syngas. The highest conversion of CHa and CO, was 64 %0o and39%,respectively at a molar ratio of CH /CO 2 of 1/1, a total flow rate of 200 ml/ min and an input powerof 500 W. Soproduced syngas showed an arbitrary composition( H2/CO ratio )with molar ratio of H, /CO varied in the range from o. 7 to 3Key words: carbon dioxide dielectric barrier discharge i greenhouse gases i hydrocarbons i methane syngasCLC number :0646.9 Document code: AIntroductiono far many studies for the synthesis of syngaBoth of methane and carbon dioxide are from methane and carbon dioxide have been congreenhouse gases. Continued excessive emissions ductedof methane and carbon dioxide to the atmosphereThe application of plasma technique inmay lead to the increase in the average globachemical synthesis has attracted much attentiontemperature. The emissions also result in a waste regarding the effective activation of methane andof natural carbon resources. In addition methane carbon dioxide. Syngas production from mixturesis the major component of natural gas which is of methane and carbon dioxide has been successsuggested as an important energy resource in the fully conducted in a dielectric barrier dischargeoming 21 century. Converting greenhouse gases DBD )reactor] and a special GlidArc dischar-to syngas hydrocarbons methanol and other use- ge. Synthesis of methanol from carbon dioxideful chemicals has been a subject of therefare inhydr中国煤化工 discharge was reportvestigation. Especially simultaneous utilization of ed bCNMHGTheir results showedmethane and carbon dioxide is under active studythat the temperature range of the maximum cataReceived date: 2000-08-28Author intrygustaHEJIANG Tao( 1964-), female, Postdoctor make a speciality chemical technology1期姜涛等:用无声放电转化甲烷和二氧化碳同时制备合成气与烃lytic activity was shifted from220℃tol00°inthe simultaneous presence of catalyst and gas dis-MFCSourcecharge. Recently in the process of syngas pro-eel tubeduction, hydrocarbons was formed in the samereactor]. Further investigation was performed byquartz tubeCurrent probeEliasson et al[9] Co-generation of syngas anddischarge gaphigher hydrocarbons was achieved using Nax zeo-V clectrodecold traplite as catalyst in a DBD reactor. In anotherstudy, conversion of methane in a corona dis- Figure 1 Configuration of DBD reactor and experimental setupcharge was carried out. The products contained CThe feed gas( CH4 and CO,) is introducedhydrocarbons trace Ca hydrocarbons and syngasinto the reactor via mass flow controllers. TheIn this paper simultaneous synthesis of syn-product stream is then introduced into an on-linegas and hydrocarbons from methane and carbongas chromatograph through a heated line to avoiddioxide over zeolite a promoted by DBd is investipossible condensation. The GC applied in this exgated at low temperature and atmospheric presperiment is a mTI( Microsensor Technology IncM200H) dual-module micro GC. A Poraplot Q1 Experimentalcolumn (8 m x0.32 mm i.d.) and a molecularThe experimental setup is schematically il- sieve 5 A Plot column( 10 m x 0.32 mm i d.lustrated in figure 1. Theappere Isare used to detect the exhaust gases with a thermala cylindrical dielectric barrier discharge reactor, conductivity detector( TCD ) The Poraplot Q colwhich is consisted of an outer steel tube of 54 mm umn can separate CO2, CH3 OH, H2O and hydroi.d. an inserted quartz tube of 52 mm o.d. and carbons and the molecular sieve 5 A Plot columna metallic brush. The metallic brush presses aor H,,O2, N,, CHa and CO. In ordermetal foil against the inner surface of the quartz to establish a mass balance of C, H and O eletube and serves as the HV electrode. The outer ments nitrogen is chosen as a reference gassteel tube serves as the ground electrode. Anan- which is added to the product stream at the exit ofnular discharge gap of I mm width and 310 mm the reactorlength is formed, in which the discharge is main2 Results and discussiontained. A high voltage generator( Arcotec corona2.1 Effect of feed flow rate Experimentsgenerator CG 20 working at about 30 kHz is ap- were conducted by varying the total flow rate ofplied to feed 50 W to 1 000 W into the discharge the feed while keeping a constant molar ratio ofreactor. The power supplied is measured by elecCHA/CO2 of 1/1, a pressure of 1 bar an inputtronically integrating the product of voltage andcurrent. An oscilloscope LeCroy Model LC ifo Gr of 500 W and a constant wall temperature of334A) is used to record the voltage- Lissajous diTYH中国煤化工CN MHGeffect of flow rate onagrams. In addition, the temperature of thethe conversion of CHa and co, over zeolite a usground electrode can be adjusted by a closed looping dbd. it can be seen that increasing the flowof re-circulating oil from a thermostat in the rangerate reduces the conversion of Ch4 and co2 quick-of ambien耨 rature to400℃C燃料化学学报29卷Flow rate 4 /mL. min20030040)500600low rate q./ml·minFigure 2 Effect of flow rate on experimental resultsly in the range of 200-600 ml/min. The effect of the range of flow rate 200-600 ml/min. The ef-flow rate on product yields is showed in Figure fect of flow rate on selectivity is listed in Table 12b. Increasing the flow rate results in a decrease The product obtained in the catalytic DBD converin CO and H2 yields in the beginning. The yield sion of CHa and CO2 consists of CO, H2 and C2of C2 Ca hydrocarbons does not change signifi- C4 hydrocarbons. It is interesting to note that mostcantly with the increasing flow rate. From results of the product is syngas( CO and H2). The secin Figure 2c one can see variation of flow rate ond abundant product ethane. Onee can seedoes not affect the ratio of H,/co remarkablyhigh flow rate favors the production of hydrocar-H2/CO ratio only changes from 0. 67 to 0. 80 inTable 1 Effect of flow rate on selectivity(Pressure, I bar wall temperature, 150C i catalyst amount, 4 g i CH,/CO, ratio in feed,1/1put power, 500 w)Flow rateSelectivity S。s/%q, /mL min COHCo haCHCs HsCCH OHH, O46.6531.140.235.165.620.180.367.016.290.240.429,472. 2 Effect of input power Input power is one in th中国煤化工 nditions of the exper-of the important parameters in the DBD conversionlmenHCNMHGr, a total flow rate ofof CH4 and CO2. Experiments were performed in 200 ml/min, a molar ratio of CH/CO2 of 1/1 andthe100W~500Wtowall telof150℃better understanding of the effect of input powerFigure 3 and Table 2 show the effect of inputon the cdAvepUR of CH, and CO 2 over zeolite a power on the experimental results over zeolite A in1期姜涛等:用无声放电转化甲烷和二氧化碳同时制备合成气与烃9the range of 100 W-500W. Figure 3a indicates with low H2/CO ratio. The H2/CO ratio of syngasthat the conversion of ch and CO, increases withcan vary in the range 0.6-1. 55. Table 2 showsIncreasIngcanplained that an increasing selectivity to C3 and C4 hydrocarbonsthere might be more active species generated at and a decreasing selectivity to C, hydrocarbon withhigher input power. Therefore the yield of CO, increasing input power. This suggests that the inH2 and hydrocarbons also increases with increascreased input power destroys the light hydrocarboning input power( see Figure 3b ) From the results and then converts them to higher hydrocarbonsin Figure 3c, molar ratio of H2/CO in syngas Higher input power is required to produce more C3quickly decreases with the increasing input power. and C4 hydrocarbonsHigher input power favors the production of syngas100200300400500Powcr P/wP/wFigure 3 Effect of input power on experimental resultsTable 2 Effect of input power on selectivityPressure, I bar wall temperature, 150C i catalyst amount, 4 g CH/CO2 ratio in feed,1/1feed flow rate, 200 ml/ minPowerSelectivity S/%0CH10052.670.89101.4737.320.4510.100.3141.4333.840.357.76中国煤化工8.6731.145,16CNMHG2.3 Effect of molar ratio of CH/CO, The 3/1. The total flow rate was maintained at 200 ml/effect of feed composition was studied by varying min, input power at 500 W, wall temperature atthe molarS#EcTE CH,/CO2 in the range of 1/1150C and pressure at 1 bar燃料化学学报29卷Figure 4 and Table 3 show the effect of CH,/ CO2. According to Figure 4c, the molar ratio ofCO2 ratio on the conversion of Cha and co2 over CH/CO2 has a significant effect on the molar ratiozeolite A in the DBd reactor. It is clear from Fig- of H2/CO. The molar ratio of H2/CO increasesure 4a that the conversion of both CHa and CO2 rapidly from 0. 7 to 3. 1 when the molar ratio ofdecrease slowly with the increase of molar ratio of CH4/CO2 in the feed increases froml/l to 3/1CH/CO,. High conversion can be obtained at lowThe compsyngas can be adjusted bymolar ratio of CH/CO2. The conversion of CH changing the molar ratio of CH/CO, in the feedand CO2 is 64 %o and 39 at a molar ratio of From the results in Table 3 one can see that highCH4/CO2 of 1/1, respectively. Figure 4b indicates molar ratio of CH,/CO2 results in high selectivitythat the yield of H2 and C2-C4 hydrocarbons inc- to hydrocarbonsseases with the increasing molar ratio of CH/Malar ratm oICILAOMolar ratio ofCH/COMolar ratio of CH/cO.Figure 4 Effect of molar ratio of CH/CO, on experimental resultsTable Effect of molar ratio of CH,/CO,on selectivityPressure, I bar wall temperature, 150C i catalyst amount, 4g input power, 500 wfeed flow rate 200 ml/minC,H,C HeCHsCH OHH,O46.6531.140.235.1601R9.172/126.910.364.51中国煤化工3/119.4960.62CNMHG4.173 Conclusionsover zeolite A in a dielectric barrier discharge reThe conversion of CH and CO, to syngas actor at low temperature and atmospheric pres-and hydroa tbi was experimentally investigated sure. It is demonstrated that co-generation of syn1期姜涛等:用无声放电转化甲烷和二氧化碳同时制备合成气与烃gas and hydrocarbons can be realized by using di- CH/CO2. Flow rate of the feed molar ratio ofelectric barrierdischarge promoted catalysis. High CH/CO, and the input power has significant ef-conversion of CHa and CO2 can be achieved. Syn- fect on the plasma conversion of CHa and cogas composition mainly depends on the ratio ofReverences1 Hibert C, Motret 0, Pellerin S et al. Spectroscopic characterization of CH4+CO2 plasma excited by a dielectricbarrier discharge at atmospheric pressurd J ]. Plasma Chem and Plasma Process, 1997,17 4): 393-407[2] Lesueur H, Czemichowski A, Chapelle J. Electrically assisted partial oxidation of methane[ J ] Hydrogen Ergy,1994,19:139144[ 3] Eliasson B, Simon FG, Egli W. Hydrogenation of CO2 in a silent discharge[ A ] Penetrante B M and SchultheiSE. NATO ASI Series, V. G34, Part B, Non-thermal plasma techniques for pollution control[ C I. Berlin: Springer- Verlag, 1993. 321-337[4] Eliasson B, Kogelschatz U, Killer E et al. Hydrogenation of carbon dioxide and oxidation of methane in an electric discharge[ A ]. Proc of 11th World Hydrogen Energy Conf. Hydrogen'96 )L C ]. Germany: Stuttgart, 19963:2449-2459[5] Bill A, Eliasson B, Kogelschatz U et al. Comparison of CO2 hydrogenation in a catalytic reactor and in a dielec-tric-barrier discharge[ J ] Stud Surface Sci Catal, 1998,114: 541-544[ 6] Bill A, Wokaun A, Eliasson B et al. Greenhouse Gas Chemistry[ J ]. Energy Convers Mgmt, 1997, 38( Sup-pl):S415-S422[7] Eliasson B, Kogelschatz U, Xue B et al. Hydrogenation of carbon dioxide to methanol with discharge-activatedcatalyst[ J ] Ind Eng Chem Res, 1998, 37: 3350-3357[8] Zhou L M, Xue B, Kogelschatz U et al. Non-equilibrium plasma reforming of greenhouse gases to synthesis gas[J1. Energy& Fuels,1998,1x6):1191-1199[9] Eliasson B, Liu C J, Kogelschatz U. Direct conversion of methane and carbon dioxide to higher hydrocarbons usircatalytic dielectric-barrier discharges with zeolites[J]. Ind Eng Chem Res 2000, 395): 1221-1227用无声放电转化甲烷和二氧化碳同时制备合成气与烃姜涛,张悝,刘昌俊',李阳,许根慧',B. Eliasson2,U. Kogelschatz1.天津大学一碳化工国家重点实验室,天津300:2. ABB Corporate Research Lid.,,5405 Baden, Switzerland)摘要∶在低温常压条件下研究了在无声放电反应器中以A型分子筛为催化剂从甲烷和二氧化碳合成烃和合成气实现了在无声放电反应器中同时合成烃和合成气。实验在原料气流量200~600ml/min原料气甲烷和二氧化碳摩尔比11~31及输入功率100~500W的范围内进行。研究结果表明低原料气流量有利于甲烷和二氧化碳的转化而高原料气流量有利于烃的生成源料气甲烷和二氧化碳摩尔比对制得合成气的H/CO摩尔比的影响最显著押烷和二氧化碳转化率及合成气和烃的产率均随输入功率的增加而提高。而所硏究的范围內当原料气流量为20m/rin、甲烷和二氧化碳摩尔比为I、输λ功率为5w时烷和二氧化碳转化率达到最高值分别为64%和39%。以此法制备的合成气的H/CO摩尔比可以在很宽的范围内变化本研究合成气H,/CO摩尔比的变化范围是0.7~3.1。中国煤化工关键词:二氧化碳;甲烷;无声放电;温室气体;烃;合成气CNMHG中图分类号:0646.9文献标识码:A作者简介葜麴据o-)女黑龙江鹤岗人天津大学博士后北学工艺专业。