Valorização do H2S para a produção de hidrogénio verde usando condutores cerâmicos protónicos

The main goal of this proposal is to engineer a membrane electrode assembly (MEA) that directly decomposes hydrogen sulfide (H2S) into sulfur and hydrogen, at anode and cathode chamber, respectively. The strategy will make use of ceramic materials for each MEA component, namely, anode, electrolyte and cathode that will be designed in parallel. For this reason, the development of the different membrane components will be based on the study of different ceramic membranes by A.C. impedance spectroscopy complimented by gas chromatography that will assess the effect of variation of properties on cell performance and gas phase products. The main challenge is related to the presence of sulfur in the gas feedstock stream which can poisoning the electrocatalyst materials. To overcome these, novel concepts/materials will be investigated. Therefore, the specific objectives comprise for: a) Electrolyte, sulfurization of the perovskite oxide powders of BaZr1-xCexO3 and Ba(Zr1-xCex)0.9Y0.1O3-d (BCZY) and Ruddlesden-popper (RP) oxide materials (e.g., Ba3ZrO4, BaxZrO7) will be investigated, particularly, its chemical stability in H2S environments, its conductivity and transport properties will be assessed under operation conditions. b) the anode side, transition metal sulfides (TMSs), namely, ternary metal sulfides with a formula AB2S4 (where A was selected from Mo, Cr, Ni, Fe, Co, and Cu, and B was selected from V, Cr, and Mo) demonstrate to be active for H2S decomposition. Thus, ternary TMSs will be explored as anode for PCFC, in this regard their electrocatalytic activity will be assessed modifying the conditions of temperature and gas phase. Moreover, the characterization of physical and chemical properties of the proposed materials will be evaluated. c) the cathode side, a nickel based cerment material will be used. Nickel is a recognized electrocatalyst for H2 production and it’s also abundant, affordable and a viable option to be employ for large scale production. Therefore, nickel will be used and its capacity to produce H2 will be evaluated by modified working conditions or through new engineering design such as the use of nanotechnology. d) the construction of a demonstration prototype for proof of concept based on the peak performing materials obtained in the previous tasks. The electrocatalytic performance of the MEA will be evaluated by combination of gas chromatography and impedance spectroscopy as a function of electrochemical hydrogen pumping and temperature.