scholarly journals Kinetic Study of Nonequilibrium Plasma-Assisted Methane Steam Reforming

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Hongtao Zheng ◽  
Qian Liu
Keyword(s):  
Reaction Mechanism ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Reaction Path ◽  
Nonequilibrium Plasma ◽  
Operating Conditions ◽  
Methane Steam Reforming ◽  
Molar Ratio ◽  
Flux Analysis ◽  
Methane Steam

To develop a detailed reaction mechanism for plasma-assisted methane steam reforming, a comprehensive numerical and experimental study of effect laws on methane conversion and products yield is performed at different steam to methane molar ratio (S/C), residence time s, and reaction temperatures. A CHEMKIN-PRO software with sensitivity analysis module and path flux analysis module was used for simulations. A set of comparisons show that the developed reaction mechanism can accurately predict methane conversion and the trend of products yield in different operating conditions. Using the developed reaction mechanism in plasma-assisted kinetic model, the reaction path flux analysis was carried out. The result shows that CH3recombination is the limiting reaction for CO production and O is the critical species for CO production. Adding 40 wt.% Ni/SiO2in discharge region has significantly promoted the yield of H2, CO, or CO2in dielectric packed bed (DPB) reactor. Plasma catalytic hybrid reforming experiment verifies the reaction path flux analysis tentatively.

Methane Steam Reforming Over NiO/CexZryO2-Sil-1 Catalyst Prepared by In-Situ Self-Assembly

2019 ◽  
Vol 19 (11) ◽  
pp. 7416-7420
Author(s):  
Ning Wei ◽  
Jia Zhang ◽  
Hexiang Zhong ◽  
Liwei Pan ◽  
Zeyu Wang ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Steam Reforming ◽  
Self Assembly ◽  
Methane Conversion ◽  
High Surface ◽  
Synthesis Method ◽  
Methane Steam Reforming ◽  
Molar Ratio ◽  
Methane Steam

NiO/CexZryO2-Sil-1 catalysts were prepared using an In-Situ self-assembly approach by coupling silicalite-1 and CexZryO2. This one-step synthesis method utilized the high surface area and hydrothermal stability of silicalite-1 and the good oxidation-reduction ability of the CexZryO2, and hence offered high synthesis efficiency. The catalyst structure was examined by N2-physisorption, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. All the results showed that silicalite-1 was well-encapsulated by NiO/Ce0.5Zr0.5O2. Furthermore, the effect of the Ce/Zr molar ratio on the performance of the catalysts was investigated in detail. The catalysts were subjected to methane steam reforming at high temperatures to evaluate their catalytic performance. The result showed that the NiO/Ce0.5Zr0.5O2-Sil-1 catalyst exhibited the best performance and its methane conversion efficiency reached up to 99.5%. Even after 16 h of continuous stability test, this catalyst could retain a methane conversion efficiency of 97.8%.

scholarly journals Sensitivity analysis and optimization of a membrane reactor for hydrogen production through methane steam reforming

2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Igor Nardi Caxiano ◽  
Lizandro De Sousa Santos ◽  
Diego Martinez Prata
Keyword(s):  
Hydrogen Production ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Membrane Reactor ◽  
Packed Bed ◽  
Operating Conditions ◽  
Methane Steam Reforming ◽  
Maximum Efficiency ◽  
Promising Alternative ◽  
Methane Steam

Hydrogen is one of most studied sources for clean power generation in the near future. Nowadays, hydrogen is mainly produced through methane steam reforming in packed bed reactors, with a promising alternative to this technology being the implementation of hydrogen-selective membrane reactors. This work compares the isothermal mathematical models of both designs by assessing the effects of multiple design variables on methane conversion, while also providing recommended operating conditions for maximum efficiency of the membrane reactor over the packed bed technology. Additionally, an optimization study is carried by dividing the reactor length in isothermal segments to achieve higher efficiency. Results showed that the membrane technology considerably increases hydrogen production, with temperature being the most influential variable on methane conversion. While the temperature profile optimization provided similar conversions compared to the isothermal models, the membrane reactor’s efficiency was increased, further justifying its implementation.

Transport Mechanism of Methane Steam Reforming on Fixed Bed Catalyst Heated by High Temperature Helium for Hydrogen Production: A CFD Investigation

2017 ◽  
Author(s):  
Feng Wang ◽  
Jing Zhou ◽  
Qiang Wen
Keyword(s):  
High Temperature ◽  
Hydrogen Production ◽  
Production Rate ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Methane Steam Reforming ◽  
Inlet Temperature ◽  
Hydrogen Production Rate ◽  
Inlet Velocity ◽  
Methane Steam

Performance of methane steam reforming reactor heated by helium for hydrogen production has been studied by numerical method. Results show with the increasing of reactant gas inlet velocity, temperature in the reactor drops, leading to the decreasing of methane conversion and hydrogen production rate. Methane conversion, hydrogen production and hydrogen production rate rise with the increasing of reactant gas inlet temperature, while the increasing degree of system thermal efficiency reduces. Besides, with helium inlet velocity rising, temperature in the reactor increases and reaction in the reactor becomes more sufficient. Therefore, methane conversion and hydrogen production also increase when helium inlet temperature of rises, but its influence is weaker compared to that of helium inlet velocity. In the process of methane steam reforming heated by high temperature gas cooled reactor (HTGR) for hydrogen production, lower reactant gas inlet velocity, suitable inlet temperature, higher inlet velocity and higher HTGR outlet temperature of helium are preferable.

Ni/x%Nb2O5/Al2O3 Catalysts Prepared via Coprecipitation-Wet Impregnation Method for Methane Steam Reforming

2020 ◽  
Vol 9 (1) ◽  
pp. 80-89
Author(s):  
Juliana F. Gonçalves ◽  
Mariana M.V.M. Souza
Keyword(s):  
Steam Reforming ◽  
Methane Conversion ◽  
Coke Formation ◽  
Methane Steam Reforming ◽  
Impregnation Method ◽  
Wet Impregnation ◽  
X Ray ◽  
Methane Steam ◽  
Temperature Programmed ◽  
Wet Impregnation Method

Background: Hydrogen has been considered the energy source of the future and one of the processes for its production is the methane steam reforming. The catalyst used industrially is Ni/Al2O3 and the addition of promoter oxides can be an alternative to improve the performance of this catalyst, which suffers from coke formation and sintering. Objective: Evaluate the role of niobia on catalytic activity and stability. Methods: Ni/x%Nb2O5/Al2O3 (x = 5, 10 and 20) catalysts were synthesized via coprecipitation-wet impregnation method and characterized by X-ray fluorescence (XRF), N2 adsorption-desorption, X-ray diffraction (XRD), temperature- programmed reduction (TPR), temperature-programmed desorption of ammonia (TPD-NH3), etc. Finally, the catalysts were tested for methane steam reforming reaction. Results: All niobia-doped catalysts presented similar values of methane conversion and when comparing with Ni-Al, the addition of niobia slightly improved the methane conversion. In the stability test at 800oC, all doped and non-doped catalysts did not deactivate during the 24 h of reaction. Conclusion: The addition of 10 and 20 wt.% of niobia had a significant promoter effect over Ni/Al2O3 catalyst in terms of activity and stability at 800 oC and the sample with 20 wt.% of niobia presented lower coke formation.

Kinetic Effects of Non-Equilibrium Plasma-Assisted Methane Steam Reforming on Heat Recovery in Chemically Recuperated Gas Turbine

2013 ◽  
Author(s):  
Qian Liu ◽  
Hongtao Zheng ◽  
Fumin Pan ◽  
Gang Pan ◽  
Ren Yang
Keyword(s):  
Kinetic Model ◽  
Reaction Temperature ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Heat Recovery ◽  
Methane Steam Reforming ◽  
Equilibrium Plasma ◽  
Methane Steam ◽  
Kinetic Effects ◽  
Non Equilibrium

Plasma is proposed as a prospective tool for chemical heat recovery process without restriction from reaction temperature. The author designed DBD catalytic reactors and carried out extensive experiments to investigate methane conversion and products yield and analyze the effect laws of steam to methane ratio, resident time and reaction temperature on methane steam reforming (MSR). Based on extensive experimental studies of steam reforming, a detailed reaction mechanism for the plasma-assisted MSR was developed and evaluated by comparison of experimentally derived and numerically predicted conversion and products yield. The comparisons showed the kinetic model well predicted methane conversion and products yield in different operating conditions. By employing the kinetic model and path flux analysis module the kinetic effects of low temperature non-equilibrium plasma assisted CH4 steam reforming on the methane conversion was studied without catalyst. The results showed that CH3 recombination was the limiting reaction for CO production; meantime O was the critical species for CO production. By adding Ni catalyst can reduce methyl recombination and promote hydroxyl into oxygen, which is beneficial to heat recovery. The proposed research ensures the effect laws and characters of MSR by plasma, and contribute to improve the objective products concentration and furthermore the energy efficiency.

CFD Simulation of a Methane Steam Reforming Reactor

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohammad Taghi Sadeghi ◽  
Mazaher Molaei
Keyword(s):  
Skin Temperature ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Cfd Simulation ◽  
Fixed Bed ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Methane Steam Reforming ◽  
Tehran Refinery

An industrial steam reforming reactor producing hydrogen is simulated using the three-dimensional Computational Fluid Dynamics (CFD) technique. The fixed bed reactor is filled with a nickel oxide catalyst. Effects of operating conditions such as temperature and steam to methane ratio on the reformer performance are investigated. Simulation results show that a steam to carbon ratio of more than 4 increases in the ratio does not have a notable influence on methane yield. Moreover, it shows that methane conversion is strongly affected by reactor skin temperature and higher skin temperature leads to an increase in the methane conversion. The results were successfully validated with industrial data obtained from a hydrogen plant at a Tehran refinery.

scholarly journals Catalysts for Methane Steam Reforming Reaction: Evaluation of CeO2 Addition to Alumina-Based Washcoat Slurry Formulation

2020 ◽  
Vol 6 (3) ◽  
pp. 52 ◽  
Author(s):  
Vincenzo Palma ◽  
Eugenio Meloni ◽  
Simona Renda ◽  
Marco Martino
Keyword(s):  
Steam Reforming ◽  
Methane Conversion ◽  
Formation Rate ◽  
Coke Formation ◽  
Methane Steam Reforming ◽  
Mechanical Resistance ◽  
Carbon Formation ◽  
Structured Catalyst ◽  
Methane Steam ◽  
Adherence Test

The effect of the addition of CeO2 to alumina-based washcoat slurry formulation on the methane steam reforming (MSR) reaction was investigated. Five Al2O3-CeO2-based washcoat slurries, differing from each other in the Al2O3/CeO2 ratio (nominal ratio equal to ∞, 0.042, 0.087, 0.250, 0.667) were prepared, dried and calcined; the resulting powders were loaded with nickel as an active metal and the obtained catalysts were tested in MSR reaction. Five cylindrical silicon carbide (SiC) monoliths were washcoated with the prepared slurries and their mechanical resistance was evaluated through the ultrasound adherence test. The activity tests results highlighted the best performance in terms of methane conversion and hydrogen selectivity of the powder catalyst, with the Al2O3/CeO2 percentage nominal ratio equal to 0.042. A structured catalyst was finally prepared by loading a SiC monolith with the most active catalytic formulation and tested in MSR reaction. The performance of the structured catalyst was evaluated in terms of methane conversion and its stability was verified in a time-on-stream test, which allowed for the evaluation of the carbon formation rate; furthermore, its activity was characterized by the estimation of the kinetic parameters. The results highlighted the beneficial effect of ceria addition on the catalytic activity; moreover, compared with data of the literature, the calculated carbon formation rate demonstrated a good resistance of the catalyst to coke formation.

Hydrogen Production by Methane Steam Reforming Over Ru and Cu Supported on Hydrotalcite Precursors

2011 ◽  
Vol 324 ◽  
pp. 453-456 ◽  
Author(s):  
Doris Homsi ◽  
Samer Aouad ◽  
Cedric Gennequin ◽  
Antoine Aboukaïs ◽  
Edmond Abi-Aad
Keyword(s):  
Hydrogen Production ◽  
Cobalt Oxide ◽  
Steam Reforming ◽  
Methane Conversion ◽  
Nitrate Solution ◽  
Methane Steam Reforming ◽  
Cobalt Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Methane Steam

Co6Al2oxide was prepared using the hydrotalcite route. The obtained solid was thermally stabilized at 500°C and then impregnated with 5 wt.% copper or 1 wt.% ruthenium nitrate solution followed by calcination at 500°C under an air flow. X-ray diffraction results showed that the calcination of the impregnated solids led to the formation of various oxides (CuO, RuO2, Co3O4, CoAl2O4, CoAl2O4). The different impregnated and non impregnated solids were tested in the methane steam reforming reaction (MSR). Methane conversion did not exceed 5% at 800°C in the case of the non impregnated solid, whereas the impregnation strongly enhanced the reactivity: ~89% and ~92% conversions were reached at 600°C for Cu and Ru respectively. The good reactivity of ruthenium impregnated catalyst was attributed to the formation of easily reducible ruthenium and cobalt oxide species at the surface of the support. The addition of ruthenium made the reduction of surface and bulk cobalt oxides possible at lower temperatures.

scholarly journals A Study on CO2 Methanation and Steam Methane Reforming over Commercial Ni/Calcium Aluminate Catalysts

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2792 ◽  
Author(s):  
Gabriella Garbarino ◽  
Federico Pugliese ◽  
Tullio Cavattoni ◽  
Guido Busca ◽  
Paola Costamagna
Keyword(s):  
Steam Reforming ◽  
Operating Conditions ◽  
Packed Bed Reactor ◽  
Methane Steam Reforming ◽  
Hydrogen Yield ◽  
Reactor Model ◽  
Co2 Methanation ◽  
Methane Steam ◽  
Reforming Catalysts ◽  
Steam Reforming Catalysts

Three Ni-based natural gas steam reforming catalysts, i.e., commercial JM25-4Q and JM57-4Q, and a laboratory-made catalyst (26% Ni on a 5% SiO2–95% Al2O3), are tested in a laboratory reactor, under carbon dioxide methanation and methane steam reforming operating conditions. The laboratory catalyst is more active in both CO2 methanation (equilibrium is reached at 623 K with 100% selectivity) and methane steam reforming (92% hydrogen yield at 890 K) than the two commercial catalysts, likely due to its higher nickel loading. In any case, commercial steam reforming catalysts also show interesting activity in CO2 methanation, reduced by K-doping. The interpretation of the experimental results is supported by a one-dimensional (1D) pseudo-homogeneous packed-bed reactor model, embedding the Xu and Froment local kinetics, with appropriate kinetic parameters for each catalyst. In particular, the H2O adsorption coefficient adopted for the commercial catalysts is about two orders of magnitude higher than for the laboratory-made catalyst, and this is in line with the expectations, considering that the commercial catalysts have Ca and K added, which may promote water adsorption.

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