Construção de um eletrolisador para captura de metano e produção de hidrogênio: uma investigação aplicada e fundamental

Abstract

There is a great demand for mitigating gases that contribute to the greenhouse effect and for producing sustainable H2, which can be used for fuel and in various industrial processes. Electrochemical technologies are an alternative to couple-catalyzed reaction processes to produce H2 or mitigate the increasing atmospheric concentrations of CH4 (or CO2). Although some effort has already been made on synthesizing newly applied nanomaterials, majority of the work demonstrate the activity of these materials, although they not apply them in scenarios close to real ones. In this work, we built a flow electrolyzer, equipped with simple materials capable of converting methane and producing H2. Half-cell investigations show that 316L stainless steel electrode promotes water reduction to H2 at -1.2 V. In contrast, Ni foam electrodes electro-oxidize CH4 starting at 0.4 V, suggesting an open circuit voltage of -1.6 V. Measurements for anodic reaction indicate that the surface oxides of the Ni surface participate in the reaction, while the metallic phase is inactive. These reactions were coupled in a 3D-printed electrolyzer and equipped with the respective electrodes. The equipment fed by KOH pH13 at the cathode and the same solution, but saturated with CH4 at the anode, showed constant production of H2 for a duration of 50 minutes. Although we still must identify the products of the anodic reaction, the electrochemical measurements combined with the H2 production study show that the unprecedented electrolyzer built into this work can be a simple alternative and easy to operate in flow for converting a greenhouse gas with simultaneous production of a gas of interest to the both energetic and industrial sectors.