共查询到20条相似文献,搜索用时 0 毫秒
1.
Torsten Kolb Thorsten Kroker Jan H. Voigt Karl-Heinz Gericke 《Plasma Chemistry and Plasma Processing》2012,32(6):1139-1155
The influence of water on the plasma assisted conversion of methane and carbon dioxide in a dielectric barrier discharge (DBD) plug flow reactor was studied. The plasma at atmospheric pressure was ignited by a power supply at a frequency of 13.56?MHz. Product formation was studied at a power range between 35 and 70?W. The concentrations of the three gases were altered and diluted with helium to 3?%. FTIR spectroscopy and mass spectroscopy were applied to analyze the inlet and the product streams. The main product of this process are hydrogen, carbon monoxide and ethane. Ethene, ethine, methanol and formaldehyde are generated beside the main products in this DBD in lower concentrations. The conversion of methane, the ratio of the synthesis gas components (n(H2):n(CO)), and the yield of oxygenated hydrocarbons and hydrogen increases by adding water. The total consumed energy reaches lower values for small amounts of water. Additional water does not influence the generated amount of C2 hydrocarbons and of CO, but decreases the carbon dioxide conversion. 相似文献
2.
甲烷二氧化碳转化制备富含一氧化碳合成气 总被引:9,自引:1,他引:9
研究了甲烷二氧化碳转化反应的热力学特性,计算了反应平衡常数及平衡组成,分析和确定了抑制积碳的生成条件,采用固定床流动和脉冲反应装置研究了Ni/Al_2O_3催化剂对甲烷二氧化碳转化的催化性能。 相似文献
3.
在常温常压条件下 ,利用电晕放电 ,使 CH4 - CO2 混合气转化生成合成气 .结果表明 ,该过程中 CH4 和 CO2 的转化率与反应体系能量密度、原料气配比和流速等有关 .在 0 .1MPa气压 ,能量密度为 10 50 k J/ mol(反应体系温度低于 50 0 K) ,n( CH4 )∶ n( CO2 ) =1∶ 2条件下 CH4 和 CO2 的转化率分别超过 60 %和 50 % ,超出了热力学平衡转化率的限制 .通过调配原料的配比 ,可以得到不同 n( H2 ) / n( CO)比值的产物 .对该体系的反应机理进行了探讨 . 相似文献
4.
L. V. Galaktionova L. A. Arkatova L. N. Kurina E. I. Gorbunova V. N. Belousova Yu. S. Naiborodenko N. G. Kasatskii N. N. Golobokov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(2):206-210
Systems based on iron and aluminum were studied in methane conversion with carbon dioxide. The systems were prepared by the method of self-propagating high-temperature synthesis. Massive iron did not exhibit noticeable catalytic activity in methane conversion with carbon dioxide. The deactivation of iron-containing intermetallic compounds was shown to occur because of the formation of the FeC and FeO phases, which screened the active centers of the catalyst surface. The suggestion was made that the active center of the dissociative adsorption of methane was the γ-Fe phase, which existed at the working temperature of methane conversion with carbon dioxide. 相似文献
5.
MethaneutilizationhasbeendrawingconsiderableattentionrecentlyduetothelargeamountofnatUralgasavailabletobeupgradedandtheworldwidedemandforlow-costtransportationfuelsl'2.Amongthemanyconversionroutes,partialoxidationofmethane(POM)tosyngasprovedanewwayforthepotentialalternativetotoday'sindustrialsteamreformingprocesses.HoweveT,althoughveryactivecatalystsforthePOMtosyngashavebeenreported,large-scaleplantshavenotyetbeenconstructed.AIargeadiabatictemperatUreriseatthefrontoftheco-bedeasilycausesre… 相似文献
6.
Valentin Goujard Jean-Michel Tatibouët Catherine Batiot-Dupeyrat 《Plasma Chemistry and Plasma Processing》2011,31(2):315-325
The carbon dioxide reforming of methane to synthesis gas was investigated in a dielectric barrier discharge reactor at room
temperature. The influence of dilution of reactants by helium was studied. We showed that, at a fixed contact time, the conversions
of CH4 and CO2 increase when the amount of helium in the gas mixture increases. This result is attributed to the “penning ionization” phenomenon,
which corresponds to an energy transfer from excited He to molecules in ground state (CH4, CO2). The selectivity to products is affected by the dilution factor. As soon as helium is present in a large amount the formation
of products resulting from recombination of methyl radicals (such as C2, C3 and C4) is less favourable due to the lowest probability of collisions to proceed. A kinetic model is proposed based on the assumption
that the reactant molecules CH4 or CO2 are attacked by active species produced by the plasma discharges, and the production of this active species are function
of the plasma power. This model which takes into account the dilution by helium fits particularly well the experimental data
we obtained. 相似文献
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8.
Liu Chang-Jun Xue Bingzhang Eliasson Baldur He Fei Li Yang Xu Gen-Hui 《Plasma Chemistry and Plasma Processing》2001,21(3):301-310
Experimental investigation has been conducted to convert methane into higher hydrocarbons in the presence of carbon dioxide within dielectric-barrier discharge (DBD) plasmas. The objectives of cofeed of carbon dioxide are to inhibit carbon deposit and to increase methane conversion. The products from this plasma methane conversion include: (1) syngas (H2+CO), (2) gaseous hydrocarbons containing ethylene, acetylene, and propylene, (3) liquid hydrocarbons, (4) plasma-polymerized film, and (5) oxygenates. The selectivity of products is subject to the DBD plasma-reactive conditions and catalyst applied. The liquid hydrocarbons produced by this way are highly branched, which represents a better fuel production. 相似文献
9.
Influence of Helium on the Conversion of Methane and Carbon dioxide in a Dielectric Barrier Discharge 总被引:1,自引:0,他引:1
We have studied the production of synthesis gas and other hydrocarbons in a dielectric barrier discharge using mixtures of
helium, methane and carbon dioxide. It was found that helium has a significant influence on the discharge, decreasing the
breakdown voltage and increasing the rate of conversion of CH4 and CO2. However it also decreases the selectivities and the range of stable operating conditions for the discharge. The main products
obtained were H2, CO, C2H6 and C3H8 but traces of other hydrocarbon, carbon deposition and the formation of condensable products were also detected. The rate
of conversion and conversion abilities were obtained by fitting the conversion results to a model. 相似文献
10.
Pengju Yang Hangyu Zhuzhang Ruirui Wang Wei Lin Xinchen Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(4):1146-1149
Photosynthetic conversion of CO2 into fuel and chemicals is a promising but challenging technology. The bottleneck of this reaction lies in the activation of CO2, owing to the chemical inertness of linear CO2. Herein, we present a defect‐engineering methodology to construct CO2 activation sites by implanting carbon vacancies (CVs) in the melon polymer (MP) matrix. Positron annihilation spectroscopy confirmed the location and density of the CVs in the MP skeleton. In situ diffuse reflectance infrared Fourier transform spectroscopy and a DFT study revealed that the CVs can function as active sites for CO2 activation while stabilizing COOH* intermediates, thereby boosting the reaction kinetics. As a result, the modified MP‐TAP‐CVs displayed a 45‐fold improvement in CO2‐to‐CO activity over the pristine MP. The apparent quantum efficiency of the MP‐TAP‐CVs was 4.8 % at 420 nm. This study sheds new light on the design of high‐efficiency polymer semiconductors for CO2 conversion. 相似文献
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Dr. Yucheng Yuan Yuhan Zhang Dr. Haoyi Li Muchun Fei Dr. Hongna Zhang John Santoro Prof. Dunwei Wang 《Angewandte Chemie (International ed. in English)》2023,62(27):e202305568
Direct synthesis of CH3COOH from CH4 and CO2 is an appealing approach for the utilization of two potent greenhouse gases that are notoriously difficult to activate. In this Communication, we report an integrated route to enable this reaction. Recognizing the thermodynamic stability of CO2, our strategy sought to first activate CO2 to produce CO (through electrochemical CO2 reduction) and O2 (through water oxidation), followed by oxidative CH4 carbonylation catalyzed by Rh single atom catalysts supported on zeolite. The net result was CH4 carboxylation with 100 % atom economy. CH3COOH was obtained at a high selectivity (>80 %) and good yield (ca. 3.2 mmol g−1cat in 3 h). Isotope labelling experiments confirmed that CH3COOH is produced through the coupling of CH4 and CO2. This work represents the first successful integration of CO/O2 production with oxidative carbonylation reaction. The result is expected to inspire more carboxylation reactions utilizing preactivated CO2 that take advantage of both products from the reduction and oxidation processes, thus achieving high atom efficiency in the synthesis. 相似文献
13.
Yuan Yang Bin Yang Yan‐Xia Zhao Li‐Xue Jiang Zi‐Yu Li Yi Ren Hong‐Guang Xu Wei‐Jun Zheng Sheng‐Gui He 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17447-17452
Direct conversion of methane with carbon dioxide to value‐added chemicals is attractive but extremely challenging because of the thermodynamic stability and kinetic inertness of both molecules. Herein, the first dinuclear cluster species, RhVO3?, has been designed to mediate the co‐conversion of CH4 and CO2 to oxygenated products, CH3OH and CH2O, in the temperature range of 393–600 K. The resulting cluster ions RhVO3CO? after CH3OH formation can further desorb the [CO] unit to regenerate the RhVO3? cluster, leading to the successful establishment of a catalytic cycle for methanol production from CH4 and CO2 (CH4+CO2→CH3OH+CO). The exceptional activity of Rh‐V dinuclear oxide cluster (RhVO3?) identified herein provides a new mechanism for co‐conversion of two very stable molecules CH4 and CO2. 相似文献
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Thorsten Kroker Torsten Kolb Andreas Schenk Krzysztof Krawczyk Michal M?otek Karl-Heinz Gericke 《Plasma Chemistry and Plasma Processing》2012,32(3):565-582
The catalytic conversion of methane and carbon dioxide was studied in a fluidized bed reactor supported by a 13.56?Hz driven coaxial DBD-reactor. Palladium or cupper catalyst which are covered on Al2O3 particles were used. The goal was to test whether biogas can be used for the production of synthesis gas. The influences of discharge power, catalysts and temperature of the catalyst bed on the product yield were studied. The starting material and product stream was analyzed by quadrupole mass spectrometry and infrared spectroscopy. H2/CO ratios can be adjusted in a range between 0.65 (without a catalyst) and 1.75 (using a copper catalyst). The process is highly selective for hydrogen production (up to 83%, using a Palladium catalyst). A copper catalyst increases the H2/CO ratio can from 1.04 to 1.16 and the palladium catalyst from 1.11 to 1.43 by heating the catalyst to a temperature of 250°C. 相似文献
16.
Su Cheun Oh Emily Schulman Junyan Zhang Jiufeng Fan Ying Pan Jianqiang Meng Dongxia Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7157-7160
Direct non‐oxidative methane conversion (DNMC) has been recognized as a single‐step technology that directly converts methane into olefins and higher hydrocarbons. High reaction temperature and low catalyst durability, resulting from the endothermic reaction and coke deposition, are two main challenges. We show that a millisecond catalytic wall reactor enables stable methane conversion, C2+ selectivity, coke yield, and long‐term durability. These effects originate from initiation of the DNMC on a reactor wall and maintenance of the reaction by gas‐phase chemistry within the reactor compartment. The results obtained under various temperatures and gas flow rates form a basis for optimizing the process towards lighter C2 or heavier aromatic products. A process simulation was done by Aspen Plus to understand the practical implications of this reactor in DNMC. High carbon and thermal efficiencies and low cost of the reactor materials are realized, indicating the technoeconomic viability of this DNMC technology. 相似文献
17.
Firsova A. A. Tyulenin Yu. P. Khomenko T. I. Korchak V. N. Krylov O. V. 《Kinetics and Catalysis》2003,44(6):819-826
Cobalt- and iron-containing catalysts supported on MgO, ZrO2, -, -, and -Al2O3 were synthesized and studied in the CO2 reforming of methane. The CoO/-Al2O3 systems are the most active and stable. The dependence of the catalytic activity and the degree of reduction on the amount of supported CoO was studied. In the active catalysts, CoO is weakly bound to the support and can readily be reduced to metal cobalt. Coke formed in the course of the reaction does not affect the activity of the CoO/-Al2O3 catalyst. 相似文献
18.
The authors recently developed a high-frequency pulsed plasma process for methane conversion to acetylene and hydrogen using a co-axial cylindrical (CAC) type of reactor. The energy efficiency represented by methane conversion rate per unit input energy has been improved so that such a pulsed plasma has potential for commercial acetylene production. A pulsed plasma consists of a pulsed corona discharge and a pulsed spark discharge. Most of energy is injected over the duration of the pulsed spark discharge. Methane conversion using this kind of pulsed plasma is a kind of pyrolysis enhanced by the pulsed spark discharge. In this study, a point-to-point (PTP) type of reactor that can produce a discharge channel over the duration of a pulse discharge was used for the pulsed plasma conversion of methane. The energy efficiency and carbon formation on electrodes have been improved. The influences of pulse frequency and pulse voltage on methane conversion rate and product selectivity were investigated. The features of methane conversion using PTP and CAC reactors were discussed. 相似文献
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A novel plasma-catalyst converter (NPCC) was engineered in applying the carbon capture utilization technology for the destruction of carbon dioxide (CO2), which is a cause of global warming and is generated from the combustion of fossil fuels. The NPCC has an orifice-type baffle to improve an amount of gas feed with the higher CO2 destruction for a stationary point sources application . To examine its ability for the CO2 destruction, the performance analysis was conducted on the effects of methane additive, nozzle injection velocity, total gas feed, and catalyst type. The product gas from the NPCC was combustible components like CO, H2, CH4, THCs. The CO2 destruction and the CH4 conversion at a 1.29 CH4/CO2 ratio were 37 and 47 %, respectively, and the energy decomposition efficiency was 0.0036 L/min W. The nickel oxide catalyst among other catalysts showed the most effectiveness for the CO2 destruction and CH4 conversion at a lower temperature. The carbon-black produced without the catalytic bed has carbon nanoparticles with diverse shapes, such as spherical carbon particles and carbon nanotubes; and its high conductivity and specific surface area were suitable for special electronic materials, fuel cells, and nanocomponents. 相似文献