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oxidative coupling of methane in a fixed bed reactor over perovskite catalyst:A simulation study using experimental kinetic model

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Journal of Natural Gas Chemistry 2008年第1期17卷 8-16页

作者： Nakisa Yaghobi Mir Hamid Reza Ghoreishy Iran Polymer and Petrochemical Institute P.O.Box14965/115TehranIran

The oxidative coupling of methane （OCM） to ethylene over a perovskite titanate catalyst in a fixed bed reactor was studied experimentally and numerically. The two-dimensional steady state model accounted for separate energy equations for the gas and solid phases coupled with an experimental kinetic model. A lumped kinetic model containing four main species CH4, O2, COx （CO2, CO）, and C2 （C2H4 and C2H6） was used with a plug flow reactor model as well. The results from the model agreed with the experimental data. The model was used to analyze the influence of temperature and feed gas composition on the conversion and selectivity of the reactor performance. The analytical results indicate that the conversion decreases, whereas, C2 selectivity increases by increasing gas hourly space velocity （GHSV） and the methane conversion also decreases by increasing the methane to oxygen ratio.

关键词： oxidative coupling of methane simulation kinetics fixed bed catalytic reactor ethylene

From fundamentals to chemical engineering on oxidative coupling of methane for ethylene production:A review

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Carbon Resources Conversion 2022年第1期5卷 1-14页

作者： Jiao Liu Junrong Yue Mei Lv Fang Wang Yanbin Cui Zhanguo Zhang Guangwen Xu Institute of Process Engineering Chinese Academy of SciencesBeijing 100190China Institute of Industrial Chemistry and Energy Technology Shenyang University of Chemical TechnologyShenyang 110142LiaoningChina School of Ecology and Environment Beijing Technology and Business UniversityBeijing 100048China

A comprehensive overview is presented to summarize the research works since 1982 on oxidative coupling of methane(OCM),a complex reaction network combining heterogeneous and homogeneous reaction steps.Fundamentals on reaction mechanisms and thermodynamics have revealed that the OCM process is highly exothermic and its C2+selectivity and yield is critical in evaluating its commercial viability.Catalytic strategies have been put to enhance C2+selectivity,improve C2+yield and lower reaction temperature.The catalyst MnNa2WO4/SiO2 enables methane activation at a temperature of 800◦C and simultaneously a high C2+selectivity of 70–80%,while the nanowire and La2O3-based catalysts enable to lower the reaction temperature to 200–300◦C and 500◦C,respectively.Reaction engineering aspects have also been dealt in many investigations in order to make the process technically feasible.Particularly,research works on reaction kinetics,reactor selection and reactor operating mode choice have been addressed.Intermediate cooling and distributed oxygen feed have been integrated into a multi-stage adiabatic fixed-bed reactor system to suppress the side oxidation reactions and improve the performance of the catalysts towards CH4 conversion and C2+yield.This review paper proposes employing a circulating reactor system coupled with catalyst fine particles but having little internal diffusion resistance to maximize one-pass C2+selectivity and yield of the OCM reaction and evaluate its industrial application potential.

关键词： oxidative coupling of methane methane C2+ Ethylene OCM Reactor

oxidative coupling of methane over Lithium Doped (Mn+W)/SiO_2 Catalysts

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Journal of Natural Gas Chemistry 2007年第2期16卷 121-129页

作者： A. Malekzadeh A. Khodadadi A. K. Dalai M. Abedini School of Chemistry Damghan University of Basic SciencesDamghanIran College of Chemical Engineering University of TehranTehranIran Department of Chemical Engineering University of SaskatchewanResearch Annex105 Maintenance RoadSaskatoonSK S7N 5C5Canada College of Chemistry University of TehranTehranIran

Modification and performance of Li induced silica phase transition of （Mn＋W）/SiO2 catalyst, under reaction conditions of oxidative coupling of methane （OCM）, have been investigated employing textural characterizations and redox studies. Stability and precrystalline form of fresh Li induced silica phase transition catalyst depend on the Li loading. A catalyst, with high lithium loading, destabilizes on OCM stream. This destabilization is not due to Li evaporation at OCM reaction conditions, α-cristobalite is proposed to be an intermediate in the crystallization of amorphous silica into quartz in the Li-induced silica phase transition process. However, the type of crystalline structure was found to be unimportant with regard to the formation of a selective catalyst. Metal-metal interactions of Li-Mn, Li-W and Mn-W, which are affected during silica phase crystallization, are found to be critical parameters of the trimetallic catalyst and were studied by TPR. Role of lithium in Li doped （Mn＋W）/SiO2 catalyst is described as a moderator of the Mn-W interaction by involving W in silica phase transition. These interactions help in the improvement of transition metal redox properties, especially that of Mn, in favor of OCM selectivity.

关键词： oxidative coupling of methane silica phase transition lithium intermetallic interaction redox properties

oxidative coupling of methane over La-promoted CaO catalysts:Influence of precursors and catalyst preparation method

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Journal of Natural Gas Chemistry 2010年第1期19卷 25-30页

作者： Vilas H. Rane Sopan T. Chaudhari Vasant R. Choudhary Chemical Engineering and Process Development Division National Chemical LaboratoryPune India

The oxidative coupling of methane to C2 hydrocarbons has been studied over a series of La-promoted CaO （La/Ca = 0.05） catalysts, prepared using different precursor salts for CaO and La2O3 （viz. acetates, carbonates, nitrates and hydroxides） and catalyst preparation methods （viz. physical mixing of precursors, co-precipitation using ammonium carbonate/sodium carbonate as a precipitating agent）, under different reaction conditions （temperature： 700-850 ℃, CH4/O2 ratio： 4.0 and 8.0, and GHSV： 51360 cm^3·g^-1·h^- 1）. The surface area and surface basicity/base strength distribution of the catalysts have also been investigated. The surface properties and catalytic activity/selectivity of the La-promoted CaO catalysts vary from catalyst to catalyst depending on the catalyst precursors used and catalyst preparation method. The basicity/base strength distribution is strongly influenced by the precursors （for CaO and La2O3） and catalyst preparation method. Basicity （total and strong basic sites measured in terms of CO2 chemisorbed at 50℃ and 500 ℃, respectively） observed for the catalyst prepared by co-precipitation method is higher than that of the catalysts prepared by physical mixing method. The catalysts prepared by the nitrates of La- and Ca- and co- precipitated by the solution of sodium carbonate and ammonium carbonate exhibit different catalytic performance in OCM. The finding that no direct relationship between the surface basicity and catalytic activity/selectivity in OCM exists indicates that basicity is not solely responsible for obtaining high selectivity to C2 hydrocarbons.

关键词： oxidative coupling of methane La-promoted CaO catalysts basicity distribution

oxidative coupling of methane over BaCl_2-TiO_2-SnO_2 catalyst

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Journal of Natural Gas Chemistry 2012年第1期21卷 49-55页

作者： Zhonglai Wang Guojun Zou Xu Luo Hua Liu Runxiong Gao Lingjun Chou Xiaolai Wang State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000GansuChina Graduate University of the Chinese Academy of Sciences Beijing 10039China

The performance of BaC12-TiO2-SnO2 composite catalysts in oxidative coupling of methane reaction has been investigated. A series of BaC12-TiO2, BaC1E-SnO2, TiO2-SnO2, and BaC12-TiO2-SnO2 catalysts were prepared, and characterized by BET, XRD, XPS, CO2-TPD and H2-TPR, respectively. The synergistic effect among BaC12, SnO2 and TiO2 compositions enhances the catalytic performance. The best C2 selectivity and ethylene yield are obtained on the catalyst with the equal molar amount of the three compositions （BaC12 ： TiO2 ： SnO2 molar ratio of 1 ： 1 ： 1）. The optimal reaction conditions are as follows： 800 ℃, 44 mL.min-1 for methane, 22 mL.min-1 for oxygen and a space velocity of 5000 mL-h-1 .g-1, and the C2H4 yield over the catalyst is 20.1% with the CH4 conversion of 43.8% and C2 selectivity of 53.3%.

关键词： oxidative coupling of methane BaC12-TiO2-SnO2 catalyst synergistic effect Na2WO4-Mn/SiO2 catalyst

oxidative coupling of methane in a dual-bed reactor comprising of particle/cordierite monolithic catalysts

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Journal of Natural Gas Chemistry 2010年第6期19卷 600-604页

作者： Deng Pan Shengfu Ji Wenhua Wang Chengyue Li State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijng 100029 China

A dual-bed reactor was constructed comprising of a 5%Na2WO4-2%Mn/SiO2 particle catalyst and a 4%Ce-5%Na2WO4-2%Mn/SiO2 /cordierite monolithic catalyst.The reaction performance of the oxidative coupling of methane （OCM） over the dual-bed reactor system was evaluated.The effects of the bed height and operation mode,as well as the reaction parameters such as reaction temperature,CH4/O2 ratio and flowrate of feed gas,on the catalytic performance were investigated.The results indicated that the suggested dual-bed reactor exhibited a good performance for the OCM reaction when the feed gases firstly passed through the particle catalyst bed and then to the monolithic catalyst bed.A CH4 conversion of 38.2% and a C2H4 selectivity of 43.3% could be obtained using the dual-bed reactor with a particle catalyst bed height of 10 mm and a monolithic catalyst bed height of 50 mm.Both the CH4 conversion and C2H4 selectivity have increased by 2.5% and 12.8%,respectively,as compared with the 5%Na2WO4-2%Mn/SiO2 particle catalyst in a conventional single-bed reactor and by 12.9% and 23.0%,respectively,as compared with the 4%Ce-5%Na2WO4-2%Mn/SiO2 /cordierite monolithic catalyst in a single-bed reactor.The catalytic performance of the OCM in the dual-bed reactor system has been improved remarkably.

关键词： oxidative coupling of methane dual-bed reactor monolithic catalysts

Numerical simulation of packed-bed reactor for oxidative coupling of methane

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Journal of Energy Chemistry 2015年第1期24卷 23-30页

作者： Zhao Zhang Ziqi Guo Shengfu Ji State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology

A three-dimensional geometric model of the oxidative coupling of methane （OCM） packed-bed reactor loaded with Na2WO4-Mn/SiO2 partic- ulate catalyst was set up, and an improved Stansch kinetic model was established to calculate the OCM reactions using the computational fluid dynamics method and Fluent software. The simulation conditions were completely the same with the experimental conditions that the volume velocity of the reactant was 80 mL/min under standard state, the ratio of CH4/O2 was 3, the temperature and pressure were 800 ℃ and 1 atm, respectively. The contour of the characteristics parameters in the catalyst bed was analyzed, such as the species mass fractions, temperature, the heat flux on side wall surface, pressure, fluid density and velocity. The results showed that the calculated values matched well with the experimental values on the conversion of CH4 and the selectivity to products （C2H6, C2H4, CO2, CO） in the reactor outlet with an error range of 4-2%. The mass fractions of CH4 and O2 decreased from 0.6 and 0.4 in the catalyst bed inlet to 0.436 and 0.142 in the outlet, where the mass fractions of C2H6, C2H4, CO and CO2 were 0.035, 0.061, 0.032 and 0.106, respectively. Due to the existence of laminar boundary layer, the contours of each component bent upwards in the vicinity of the boundary layer. This OCM reaction was volume increase reaction and the total moles of products were greater than those of reactants. The flow field in the catalyst bed maintained constant temperature and pressure. The fluid density decreased gradually from 2.28 kg/m3 in the inlet of the catalyst bed to 2.22 kg/m3 in the outlet of the catalyst bed, while the velocity increased from 0.108 m/s to 0.115 m/s.

关键词： oxidative coupling of methane packed-bed reactor computational fluid dynamics numerical simulation

Techno-economic evaluation of a biogas-based oxidative coupling of methane process for ethylene production

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Frontiers of Chemical Science and Engineering 2018年第4期12卷 598-618页

作者： Alberto T.Penteado Mijin Kim Hamid R.Godini Erik Esche Jens-Uwe Repke Process Dynamics and Operations Group Technische Universitat BerlinD-10623 BerlinGermany

This contribution is a preliminary techno-economic assessment of a biogas-based oxidative coupling of methane (OCM) process. Biogas is frequently utilized as a renewable energy source within small scale combined heat and power plants or as a natural gas substitute. The activation of methane also enables its utilization as a feedstock to produce chemicals. In this sense, the OCM process allows for the direct conversion of methane into ethylene, which is a major building block for the chemical and polymer industries. Biogas resulting from the anaerobic digestion of vinasse, a liquid effluent from bioethanol industry, is treated for contaminant removal and its methane content is converted into ethylene, which is then purified as the main product. The biogas cleaning process is assessed based on literature data, while an experimentally validated simulation model is used to assess the OCM process. A techno-economic evaluation is then performed through a Monte Carlo simulation, wherein uncertain parameters take random values between reasonable bounds. The net present value results positive in 74% of the cases, indicating that the project is profitable under a wide range of scenarios. Some performance improvement opportunities have been identified and highlighted to guide future studies in the topic.

关键词： biogas conversion ethylene production oxidative coupling of methane feasibility study

Active oxygen center in oxidative coupling of methane on La_(2)O_(3) catalyst

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Journal of Energy Chemistry 2021年第9期30卷 649-659页

作者： Xiaohong Zhou Yaoqi Pang Zebang Liu Evgeny I.Vovk Alexander Pvan Bavel Shenggang Li Yong Yang School of Physical Science and Technology Shanghai Tech UniversityShanghai 201210China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China Shell Technology Centre Amsterdam P.O.Box 380001030 BN AmsterdamNetherlands CAS Key Laboratory of Low-Carbon Conversion Science and Engineering Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201210China

La_(2)O_(3) catalyzed oxidative coupling of methane(OCM) is a promising process that converts methane directly to valuable C_(2)(ethylene and ethane) products. Our online MS transient study results indicate that pristine surface without carbonate species demonstrates a higher selectivity to C_(2) products, and a lower light-off temperature as well. Further study is focused on carbonate-free La_(2)O_(3) catalyst surface for identification of active oxygen species associated with such products behavior. XPS reveals unique oxygen species with O 1 s binding energy of 531.5 e V correlated with OCM catalytic activity and carbonates removal. However, indicated thermal stability of this species is much higher than the surface peroxide or superoxide structures proposed by earlier computation models. Motivated by experimental results,DFT calculations reveal a new more stable peroxide structure, formed at the subsurface hexacoordinate lattice oxygen sites, with energy 2.18 e V lower than the previous models. The new model of subsurface peroxide provides a perspective for understanding of methyl radicals formation and C_(2) products selectivity in OCM over La_(2)O_(3) catalyst.

关键词： In-situ XPS Online MS DFT oxidative coupling of methane High C_(2)selectivity Active oxygen center La_(2)O_(3)catalyst