Statistical Method of Deducting Activation Energies for the Steam Methane Reforming Reactions

In this paper, a method of deducting activation energies for heterogeneous reactions of steam methane reforming is presented. The essence of the method lies in iterative evaluation of kinetic parameters, namely activation energies of reactions, for a given reactor. The novelty of the method lies in utilizing a statistical approach to reduce computational effort of numerical simulation. The method produces multivariable correlations between activation energies and operational parameters of the process: pressure, temperature, steam-to-methane ratio, residence time, and catalyst properties. These correlations can be used for numerical simulations of steam methane reforming to yield methane conversion rate, spatial and temporal distribution of reaction products, temperature and pressure within the reactor. An average computational effort is equal to a batch of 18 ([Formula: see text]) simulations for [Formula: see text] variables. The method was demonstrated by evaluating two-variable correlations of activation energies with pressure and temperature. The developed numerical model was validated against adopted experimental data.

Methane Pyrolysis in Molten Potassium Chloride: An Experimental and Economic Analysis

Although steam methane reforming (CH4 + 2H2O → 4H2 + CO2) is the most commercialized process for producing hydrogen from methane, more than 10 kg of carbon dioxide is emitted to produce 1 kg of hydrogen. Methane pyrolysis (CH4 → 2H2 + C) has attracted much attention as an alternative to steam methane reforming because the co-product of hydrogen is solid carbon. In this study, the simultaneous production of hydrogen and separable solid carbon from methane was experimentally achieved in a bubble column filled with molten potassium chloride. The melt acted as a carbon-separating agent and as a pyrolytic catalyst, and enabled 40 h of continuous running without catalytic deactivation with an apparent activation energy of 277 kJ/mole. The resultant solid was purified by water washing or acid washing, or heating at high temperature to remove salt residues from the carbon. Heating the solid product at 1200 °C produced the highest purity carbon (97.2 at%). The economic feasibility of methane pyrolysis was evaluated by varying key parameters, that is, melt loss, melt price, and carbon revenue. Given a potassium chloride loss of <0.1 kg of salt per kg of produced carbon, the carbon revenue was calculated to be USD > 0.45 per kg of produced carbon. In this case, methane pyrolysis using molten potassium chloride may be comparable to steam methane reforming with carbon capture storage.

Study of steam methane reforming in plasma generated by nanosecond surface gas discharge

The paper represents the results of the experimental study of steam methane reforming under the action of spark discharge on water surface. Values of conversion rate and output of reaction products at methane pressures of 1 to 5 atm were obtained, and specific energy consumption of reforming process was determined. Pulse generator with a voltage amplitude up to 200 kV and a pulse duration of 15 ns was used to power the discharge. Although an increase in pressure decreases both the methane conversion rate and the energy deposition into the gas mixture, the conversion efficiency and specific energy consumption remain the same. The obtained minimum value of specific energy consumption for steam methane reforming amounted to 10 eV/molecule.