共查询到19条相似文献,搜索用时 109 毫秒
1.
《天然气化学杂志》1995,(3)
CO adsorption and oxidation over Cu2MnOx catalyst from room temperature to 373 K were studied by in situ IR with and without oxygen The results indicate that CO is easier to be oxidi/ed on Cu2MnOx surface at low temperature. The optimum temperature and the ratio of carbon monoxide to oxygen for CO oxidation were studied. Besides CO, the IR absorption bands of CO2 and carbonate group were also observed and used for qualitative catalyst structure analysis. 相似文献
2.
XIE Mao-Song WANG Xue-Lin XU Gui-Fen WANG Lin-Shang TAO Long-XiangDalian Institute of Chemical Physics Academia Sinaca Datum Liaomig 《天然气化学杂志》1995,(2)
The temperature of the catalyst bed in the oxidative coupling ofmethane would rise and be higher than the wall temperature when the amountof catalyst, the space velocity and the ratio of oxygen to methane wereincreased. Various aspects of the catalytic technology including the thickness ofthe catalyst bed, the mode of catalyst charge, the ratio of CH_4 to O_2 and thespece velocity were studied. An optimum temperature of the catalyst bed forhigher methane conversion and C_2 selectivity was investigated. It was foundthat the burning of methane in the gas phase to form CO occurred at certaintemperatures with some ratios of oxygen to methane. Additionally, the effectof adding water to the reaction feed gas was studied. 相似文献
3.
甲烷在Rh/SiO2催化剂表面解离的红外光谱研究 总被引:1,自引:0,他引:1
FT-IR spectroscopy is employed to investigate the methane dissociation and methane partial oxidation over the Rh/SiO2 catalyst. When CH4 is adsorbed onto the catalyst surface, it dissociates into adsorbed CHx (x=1~3) and atomic hydrogen on Rh surface. Atomic hydrogen can diffuse from Rh surface to SiO2 surface where a proton exchange reaction of H with the surface Si-OH occurs, or it reacts with the lattice oxygen of SiO2 to form new Si-OH. 相似文献
4.
CHAOZi-Sheng* ZHOU Xiao- PingWAN Hui-Lin TSAI Khi-RuiDepartment of Clie-mudry Xiamen University Xiamen Fujian 《天然气化学杂志》1995,(2)
The oxidative coupling of methane(OCM)over ThO_2/CaF_2 catalystwas investigated.The catalyst was found to be active and selective for OCMreaction.At 1153 K,the C_2~ yield was 19.9% with 61.7% C_2~ selectivityand 32.1% CH_4 conversion.XRD results indicated that F~-(?)O~(2-)exchangehappened between ThO_2 and CaF_2 phases.XPS and Raman results suggestedthat the active oxygen species were generated and suitable for OCM reactionover the catalyst. 相似文献
5.
Octávio R. Macedo Neto 《天然气化学杂志》2006,15(1):21-27
Auto-thermal reforming of methane, combining partial oxidation and reforming of methane with CO2 or steam, was carried out with Pt/Al2O3, Pt/ZrO2 and Pt/CeO2 catalysts, in a temperature range of 300-900℃. The auto-thermal reforming occurs in two simultaneous stages, namely, total combustion of methane and reforming of the unconverted methane with steam and CO2, with the O2 conversion of 100% starting from 450 ℃. For combination with CO2 reforming, the Pt/CeO2 catalyst showed the lowest initial activity at 800 ℃, and the highest stability over 40 h on-stream. This catalyst also presented the best performance for the reaction with steam at 800 ℃. The higher resistance to coke formation of the catalyst supported on ceria is due to the metal-support interactions and the higher mobility of oxygen in the oxide lattice. 相似文献
6.
WU Jin-Gang LI Shu-BenState Key Laboratory of Oxo Synthesis Selective Oxidation Lanzhou Institute of Chemical Physics Academia Sinica Lanzhou Gansu 《天然气化学杂志》1995,(3)
The oxidative coupling of methane over Mn2O3-Na2WO4/SiO2 catalyst has been investigated in the absence of dilute gas. 16.4% of C2 yield and 80.4% of the selectivity to C2 hydrocarbons were obtained at CH4/O2 = 8.5/1.5. The effect of flow rate on the selectivity to C2 hydrocarbons and CH4 conversion was different under the reaction condition of different ratio of CH4 to oxygen. The flow rate had a more remarkable effect on the selectivity at the lower ratio of methane to oxygen. The addition of steam into the reaction gas can increase C2 yield to some extent, but that of HC1 decrease the selectivity to C2 hydrocarbons. 相似文献
7.
《天然气化学杂志》1993,(2)
On the basis of the characterization of typical catalysts by activityevaluation,TPR,XRD and TEM,the effects of nickel content and promoterssuch as MgO,La_2O_3,and MnO_2 were discussed.Formation of MgNiO_2 by thecombination of promoter MgO with NiO increases the catalyst stability.Promot-er La_2O_3 is found well-distributed on the catalyst surface in the form of La_2O_3without any interaction with uther components.With physically scattering ef-fect,La_2O_3 can prohibit active component Ni from sintreing at high temperatureand then improve its thermal stability.It also affects the catalyst activity andreducibility.Introduction of La_2O_3 decreases the content of small Ni crystallite,and is helpful to the prohibition of carbon deposition.A new Ni-based town gasmethanation catalyst of low Ni content with high activity and high carbon depo-sition resistance is successfully developed in the laboratory. 相似文献
8.
《天然气化学杂志》1992,(2)
Microreactor-chromatography and XRD technique have been used to investigate the proper-ties of Ni/Al_2O_3 catalyst impregnated with rare earth oxides for the steam reforming of methane.Theresults of the study have shown that the stability of catalytic activity and the ability of resistance to ox-idation of high temperature steam are improved. 相似文献
9.
Mn-Na2WO4/SiO2催化剂表面活性中心结构的DFT研究 总被引:1,自引:0,他引:1
Mn Na2WO4/SiO2 is one of the best catalysts for oxidative coupling of methane.To investigate the nature of active centers and the reaction mechanism,the structure of possible metal sites formed by tungsten and manganese over the silica surface were studied using molecular simulation method and ab initio DFT calculations.Silica support exists in the catalyst as 岐瞔ristobalite and its (111) face exposes preferentially to the surface.The calculated results show that tungsten interacts with the silica surface by three or one bridge oxygen atoms to form tetrahedral [WO4],and manganese interacts with single bridge oxygen to form dispersed [MnO4] or exists as oxide clusters.The nature of the molecular orbitals and the electronic structure suggest that the tetrahedral [WO4] site with single bridge oxygen is the most probable active center responsible for methane activation. 相似文献
10.
N. A. S. Amin Sriraj Ammasi 《天然气化学杂志》2006,15(3):191-202
A dual-bed catalytic system is proposed for the direct conversion of methane to liquid hydrocarbons. In this system, methane is converted in the first stage to oxidative coupling of methane (OCM) products by selective catalytic oxidation with oxygen over La-supported MgO catalyst. The second bed, comprising of the HZSM-5 zeolite catalyst, is used for the oligomerization of OCM light hydrocarbon products to liquid hydrocarbons. The effects of temperature (650-800℃), methane to oxygen ratio (4 10), and SiO2/Al2O3 ratio of the HZSM-5 zeolite catalyst on the process are studied. At higher reaction temperatures, there is considerable dealumination of HZSM-5, and thus its catalytic performance is reduced. The acidity of HZSM-5 in the second bed is responsible for the oligomerization reaction that leads to the formation of liquid hydrocarbons. The activities of the oligomerization sites were unequivocally affected by the SiO2/Al2O3 ratio. The relation between the acidity and the activity of HZSM-5 is studied by means of TPD-NH:j techniques. The rise in oxygen concentration is not beneficial for the C5 selectivity, where the combustion reaction of intermediate hydrocarbon products that leads to the formation of carbon oxide (CO CO2) products is more dominant than the oligomerization reaction. The dual-bed catalytie system is highly potential for directly converting methane to liquid fuels. 相似文献
11.
IntroductionInthcsclcctivcoxidationofalkanes.suchas'theoxidativccouplingofmcthanc(0CM)andthcoxidativcdch}'drogenationofcthanc(0DE)t0prcparccth}'lene.bothoxidcionsofthelatticeandtheox}'genspeciesovercataIystsuffocepla}'animportantrole.Althoughcxtcnsivcinvcstigationshavcbeengivcntothecharactcrizationofox}'gcnspccicsandthcreactionofox}'gcnspecicsx`ithalkanes,itisstilldifficulttosayt`hichoncsofox}'gcnspcciesarcthcactivcspecicsinthcactivation0falkancs.bccauscthenaturcofcatal}'stsandthecxperimcntc… 相似文献
12.
A new K-Fe-MnO/Si-2 catalyst has been developed for CO2 hydrogenation, which exhibits a fascinating reaction activity and light olefin selectivity for CO2 hydrogenation. Over the catalyst, it is observed that olefin selectivity increases apparently with reaction temperature and/or GHSV, while decreases when reaction pressure is up. Furthermore, the catalyst exhibits a better stability for CO2 hydrogenation. However, coke deposited on catalyst surface is formed at the beginning of the reaction period and then reached a stable state during CO2 hydrogenation. Generally, the K-Fe-MnO/Si-2 catalyst can be regenerated for CO2 hydrogenation, the same selectivity of C2=-C4=alkenes is regained without any decrease in catalyst activity with time on stream. 相似文献
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14.
Fe—Silicalite—2催化剂表面CO2加氢反应性能的研究 总被引:3,自引:0,他引:3
研究了Fe/Silicalite-2催化剂CO2加氢低碳烯烃反应性能,利用CO2-TPD,CO2/H2-TPSR和CO/H2-TPSR表征手段,考察了铁含量及MnO助剂对Fe/Silicalite-2催化剂CO2吸附脱附及加氢反应性能的影响,表明随铁含量增加可提高催化剂对CO2的吸附能力,有利于提高CO2加氢反应的转化率。 相似文献
15.
本工作用浸渍法和沉淀法制得了两种负载型非晶态催化剂Ru-B/TiO2「w(Ru)=5%」。X射线衍射和差动热分析实验结果证实了Ru以非晶态形式存在,这两种非晶态催化剂在温和条件下对苯和环己烯均具有很高的催化加氢活性并对CS2也有良好的抗毒性能,在90℃,0.22MPa条件下,苯在这两种非晶态催化剂上加氢生成环己烷的转化率分别为99.4%和91.0%;当环己烯中CS2的含量为2.5%时环己烯在这两种催化剂上的加氢转化率分别为100%和31.3%。 相似文献
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lntroductionTio2islargelyemploycdincatalystprcparationductoitsreducibilityandStrongilltCodionwiththesupportcdcomponcntsl1].Hotvever,somedraWbacksofTiO2,suchaslowsurfacearea,poormechanicalstrengthandunstableanataSestruCtureathightettiperature,makeitsindustrialutiliZaionnearlyimpossible.Accordinly,thcY-AlO3-Tio2supportisdeveloPedformakinbeStuseoftheadvantagndbyPaSsbethedisadVantagsl2-].ThcreisnoncwcompoundformedbetWeeny-Al2O3andTiO2,Iinstedd,TiO2isuniformlydisperscdonthesurfaceofy-Al2… 相似文献
18.
IntroductionConsiderableattelltionisno\vbeillgpaidtotheCO7refonningof.etha..llto]forseveralreasonst(l)withthedevelopmentofindustrics.moreandnlorcCOZIsabettedintotheatmosphere,leadingto"greenhouseeffect",whichhasbroughtaboutgreatilltcreslallovertheworld.Th… 相似文献
19.
MgCl_2晶型对丙烯聚合MgCl_2载体催化剂活性的影响张明辉,肖世镜中国科学院化学研究所,北京,10080)关键词丙烯聚合、MgCl2、载体催化剂近年来,有关MgCI。载体催化剂的研究报道和综述文章不少,但涉及载体晶型对催化剂结构性能的影响却少见.... 相似文献