Effect of electrochemical reaction on steam adsorption during methane reforming on a Ni-GDC anode

Abstract

The influence of steam on the internal reforming reaction in solid oxide fuel cells is under debate based on previously reported results. Therefore, appropriate kinetic models that accurately describe the methane reforming behaviour in solid oxide fuel cells under various operating conditions are required. The objective of this study is to find the appropriate kinetic model to describe the effect of current density on steam adsorption behaviour. The Langmuir-Hinshelwood model considers the associative methane adsorption and the dissociative steam adsorption. The formation of catalyst-hydroxide complexes is directly influenced by the steam concentration and current drawn via the non-faradaic electrochemical modification of the catalysis effect. The steam adsorption constant appeared to significantly drop when a current was produced. Of the current densities investigated, the models seemed to provide a more accurate description of reforming rates at a 600 A/m2 current density relative to open-circuit and 1000 A/m2 conditions. The models are used to predict the reaction rate in the fuel cell channel where the in-situ measurement is not practical.