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Hydrogen is an energy carrier of the future need. It could be produced from different sources and used for power generation or as a transport fuel which mainly in association with fuel cells. The primary challenge for hydrogen production is reducing the cost of production technologies to make the resulting hydrogen cost competitive with conventional fuels. Thermocatalytic decomposition (TCD) of methane is one of the most advantageous processes, which will meet the future demand, hence an attractive route for CO free environment. The present study deals with the production of hydrogen with 30 wt% of Ni impregnated in commercially available activated carbon and carbon black catalysts (samples coded as Ni/AC and Ni/CB, respectively). These combined catalysts were not attempted by previous studies. Pure form of hydrogen is produced at 850 °C and volume hourly space velocity (VHSV) of 1.62 L/h g on the activity of both the catalysts. The analysis (X-ray diffraction (XRD)) of the catalysts reveals moderately crystalline peaks of Ni, which might be responsible for the increase in catalytic life along with formation of carbon fibers. The activity of carbon black is sustainable for a longer time compared to that of activated carbon which has been confirmed by life time studies (850 °C and 54 sccm of methane). [ABSTRACT FROM AUTHOR]

Abstract: Chemical kinetics of hydrogen production from the thermocatalytic decomposition (TCD) of methane at the early reaction stage and the steady state is modeled in this study. Numerical simulations are also carried out to figure out the detailed reaction phenomena in a catalyst bed which is packed with activated carbon. The effects of reaction (wall) temperature, catalyst mass, and reactant flow rate on the performance of methane TCD are evaluated. The predictions suggest that the CH4 conversion is linearly proportional to the reaction temperature at the early stage; the reaction is more sensitive to the reaction temperature at the steady state. Hydrogen formation from the reaction is also affected by the flow rate to a certain extent. In contrast, the performance of methane TCD is relatively insensitive to the catalyst mass, regardless of which reaction stage is. When the temperature distribution, reaction rate, and H2 concentration in the catalyst bed are examined, two-dimensional contours of reaction rate are exhibited, whereas the isothermal and concentration contours are almost one-dimensional. The simulated results are able to aid in recognizing the reaction behavior in the reactor, thereby providing more detailed information to experimental measurements and practical design of reactor. [Copyright &y& Elsevier]

Abstract: Hydrogen has been produced by decomposing methane thermocatalytically at 1123 K in the presence of activated carbon supported Pd catalysts (Samples coded as Pd5 and Pd10 respectively) procured from SRL Chemicals, India. The studies indicated that the Pd10 catalyst has higher catalytic activity and life for methane decomposition reaction at 1123 K and volume hourly space velocity (VHSV) of 1.62 L/hr∙g. An average methane conversion of 50 mol % has been obtained for Pd10 catalyst at the above reaction conditions. SEM and TEM-EDXA images of Pd10 catalyst after methane decomposition showed formation of carbon nanofibers. XRD of the above catalyst revealed, moderately crystalline peaks of Pd which may be responsible for the increase in the catalytic life and the formation of carbon nanofibers. [Copyright &y& Elsevier]

A fluidized bed reactor made of quartz with 0.055 m i.d. and 0.65 m in height was employed for the thermocatalytic decomposition of methane to produce CO2 free hydrogen. The fluidized bed reactor was proposed in order to overcome the reactor plugging problem due to carbon deposition, which was resulted in the shut-down of the fixed bed reactor system. Several kinds of activated carbons were employed as the catalyst to examine the reaction activity. The experimental results in this study were compared with that of fixed bed reactor. The reaction rate and deactivation of carbon catalyst were similar to that of lab scale fixed bed reactor system. The deactivation due to carbon deposition was verified with the SEM images of fresh and used carbon catalysts. The effects of gas velocity, reaction temperature and particle size on the reaction rates were also investigated. From the experimental results of this study, the optimum operating conditions for fluidized bed were also determined. [Copyright &y& Elsevier]