Barbara Ernst

Modelling of methane dry reforming over Ni/Al2O3 catalyst in a fixed-bed catalytic reactor

AbstractThe dry reforming of CH4 in a fixed-bed catalytic reactor for the production of hydrogen at different temperatures over supported Ni catalyst has been studied. In the simulation of the reactor, a one-dimensional heterogeneous model is applied. Temperature and concentration gradients are accounted for in the axial direction only. The reactor model for the dry reforming of methane used the Richardson and Paripatyadar kinetics and the Snoeck et al. kinetics for the coke-deposition and gasification reactions. The effect of using different temperatures on the performance of the reactor was analyzed. The amounts of each species consumed or/and produced were calculated and compared with the experimental determined ones. It was shown that the Richardson and Paripatyadar–Snoeck et al. kinetics gave a good fit and accurately predicted the experimental observed profiles from the fixed bed reactor, and thus the degree of conversion of CH4 and CO2.

Methane Dry Reforming over Ni-Co/Al2O3: Kinetic Modelling in a Catalytic Fixed-bed Reactor

Abstract The dry reforming of CH4 was investigated in a catalytic fixed-bed reactor to produce hydrogen at different temperatures over supported bimetallic Ni-Co catalyst. The reactor model for the dry reforming of methane used a set of kinetic models: The Zhang et al model for the dry reforming of methane (DRM); the Richardson-Paripatyadar model for the reverse water gas shift (RWGS); and the Snoeck et al kinetics for the coke-deposition and gasification reactions. The effect of temperatures on the performance of the reactor was studied. The amount of each species consumed or/and produced were calculated and compared with the experimental determined ones. It was showed that the set of kinetic model used in this work gave a good fit and accurately predict the experimental observed profiles from the fixed bed reactor. It was found that reaction-4 and reaction-5 could be neglected which could explain the fact that this catalyst coked rapidly comparatively with other catalyst. The use of large amount of Ni-Co will lead to carbon deposition and so to the catalyst deactivation.

Thin palladium layer deposited on ceramic materials: application in hydrogen transport and catalytic membrane process

The objective of this work was to develop a thin, highly permeable, composite inorganic membrane based on palladium supported on a porous ceramic for high temperature hydrogen separation. The palladium layer (1-2 µm thick) was deposited by electroless plating on an asymmetric tubular alumina support. High temperature hydrogen permeation tests were done showing interesting hydrogen permselectivity properties with a H2/N2 separation factor at 60 (400°C) with a trans-membrane pressure difference of 1 bar. The transport of the hydrogen through the Pd membrane is mixed, solution-diffusion through the metal bulk and surface diffusion/Knudsen diffusion through the pores/defects of the film. As predicted, the membrane reactor for the dry reforming of methane shifts the equilibrium of the reaction in the direction of a higher hydrogen production. An enhancement of the methane conversion of 18% was observed in the membrane reactor configuration due to the selective removal of the hydrogen during the reaction as well as a limitation of side reactions.

Computational fluid dynamics study of the dry reforming of methane over Ni/Al 2 O 3 catalyst in a membrane reactor. Coke deposition

This work investigates the dry reforming of CH4 as an important process for the conversion of greenhouse gases to synthesis gas. The mixture of methane and CO2 is readily available in the greenhouse gas which makes realization of dry reforming of methane process more convenient. The paper is an attempt to numerically analyse by computational fluid dynamics (CFD) the coking and gasification mechanisms in the lab-scale membrane module with a fixed-bed supported nickel catalyst (Ni/Al2O3). The concentrations and molar fluxes obtained by the simulation are compared with the experimental profiles to validate the CFD model. It was found that working in a catalytic fixed-bed membrane reactor, in the case of the dry reforming of methane and under specific conditions, was not critical, from the point of view of catalyst deactivation.

Modelling of the Membrane Permeability Effect on the H2 Production Using CFD Method

Abstract Autothermal reforming of CH4 in a membrane catalytic microreactor for the production of hydrogen at different temperatures over supported Ni catalysts has been studied. A three-dimensional mathematical model was developed using a computational fluid dynamics (CFD) technique. The effect of using different membranes on the performance of the micro-reactor was analysed. The amounts of hydrogen produced and separated in each case, under the same operating conditions, were compared. It was proven that using the porous membrane (Ni–Al2O3) could be an economic solution for the production and separation of hydrogen in membrane reactors.