Steam Reforming of Methane Over Nickel: Development of a Multi-Step Surface Reaction Mechanism

A detailed multi-step reaction mechanism is developed for modeling steam reforming of methane over nickel-based catalysts. The mechanism also includes partial and total oxidation reactions, water-gas shift reactions, formation of carbon monolayers, and methanation reactions. A method is presented for ensuring thermodynamic consistency in the development of surface reaction mechanisms. The applicability of the mechanism is tested by simulating experimental investigations of SR of methane on a Ni-coated monolithic cordierite catalyst as well as experimental studies from literature. The reactive flow in the channels of the experimentally used monolithic structures is modeled by a two-dimensional flow field analysis of a single monolith channel coupled with the reaction mechanism developed. The gas composition and surface coverage with adsorbed species are calculated as function of the position in the channel. The model developed is able to properly describe steam reforming of methane over the nickel catalysts for wide ranges of temperature and steam/methane ratio.