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Methane Steam (methane + steam)

Distribution by Scientific Domains
Chemistry100%

Terms modified by Methane Steam

  • methane steam reforming
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    Selected Abstracts

    A C1 microkinetic model for methane conversion to syngas on Rh/Al2O3

    AICHE JOURNAL, Issue 4 2009
    Matteo Maestri
    Abstract A microkinetic model capable of describing multiple processes related to the conversion of natural gas to syngas and hydrogen on Rh is derived. The parameters of microkinetic models are subject to (intrinsic) uncertainty arising from estimation. It is shown that intrinsic uncertainty could markedly affect even qualitative model predictions (e.g., the rate-determining step). In order to render kinetic models predictive, we propose a hierarchical, data-driven methodology, where microkinetic model analysis is combined with a comprehensive, kinetically relevant set of nearly isothermal experimental data. The new, thermodynamically consistent model is capable of predicting several processes, including methane steam and dry reforming, catalytic partial oxidation, H2 and CO rich combustion, water-gas shift and its reverse at different temperatures, space velocities, compositions and reactant dilutions, using the measured Rh dispersion as an input. Comparison with other microkinetic models is undertaken. Finally, an uncertainty analysis assesses the effect of intrinsic uncertainty and catalyst heterogeneity on the overall model predictions. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    Design of a thermally balanced membrane reformer for hydrogen production

    AICHE JOURNAL, Issue 10 2008
    David S. A. Simakov
    Abstract Hydrogen production by autothermal methane steam reforming in a catalytic fixed bed membrane reactor has been analyzed and simulated. The two-compartment reactor indirectly couples the endothermic steam reforming with methane oxidation, while hydrogen is separated by a permselective Pd membrane. Simulations of the reactor, using published kinetics, map the acceptable domain of operation and the optimal set of operating parameters. The simulations exhibit slow-moving thermal fronts and the steady-state operation domains bounded by stationary fronts, separating domains of upstream and downstream-moving fronts. Front velocity depends on thermal coupling and hydrogen separation. An analytical approximation for the thermal front velocity in a thermally balanced reactor has been developed. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source]

    Estimating limit conversion for methane steam reforming in a palladium membrane reactor using countercurrent sweep gas

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010
    S. Hara
    Abstract Generally speaking, conversion increases with increasing reactor length to approach a certain value: so-called limit conversion. Limit conversion for a membrane reactor with a cocurrent sweep gas has been studied extensively. However, characteristics of limit conversion for the countercurrent, which are examined in this study, remain unclear. First, conversions of MRs with different reactor lengths were calculated using a conventional mode of integrating differential equations. Results confirmed that limit conversion is not always 100%, even for the countercurrent. Long MRs were found to have a pseudo-constant state inside, characterized by an extremely low apparent reaction rate and permeation rate. Secondly, a novel approach to estimate limit conversion was developed: reaction equilibrium constants and hydrogen partial pressure balance between both sides were applied not for the end of the reactor but for the pseudo-constant state. This new approach suggests that limit conversion for the countercurrent depends on the reaction temperature, feed-side and permeation-side pressures, feed-gas composition, and the sweep rate. It is fundamentally independent of reaction kinetic equations and hydrogen permeation-rate properties. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

    Novel nickel-based catalyst for low temperature hydrogen production from methane steam reforming in membrane reformer

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010
    Yazhong Chen
    Abstract Hydrogen production from various hydrocarbon fuels, particularly biomass-derived fuels, has attracted worldwide attention due to its potential for application to fuel cells, a device which converts chemical energy into electricity efficiently and cleanly. However, current technology, such as natural gas steam reforming, could not meet the specific requirements of hydrogen for fuel cells. Therefore, novel processes are intensively investigated, aiming to develop economic and efficient ones for the specific purpose. An important direction is the integrated membrane reformer for one-step high-purity hydrogen production. However, for the commercial realization of this technology, there are still some difficulties to overcome. By comparison with previous investigations with a similar membrane, this work showed that catalyst also played an important role in determining membrane reformer performance. We proposed that when thickness of membrane was several micrometers, the permeance of membrane became less important than the kinetics of catalyst, due to the fact that under such conditions, hydrogen permeation rate was faster than the kinetics of steam reforming reaction when commercial catalyst was applied, but further evidence is indispensable. In this initial work, we focused on developing efficient nickel catalyst for low temperature steam reforming. Nickel-based catalyst was developed by deposition,coprecipitation and used as pre-reduced, showing high performance for methane steam reforming at low temperatures and good durability, which may find practical application for the integrated membrane reforming process. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]