| This thesis constitutes the first step in the design and construction of a high- temperature and high-pressure channel flow cell (HT-CFC) for electrochemical studies under hydrothermal conditions. The system would allow to investigate at a fundamental level the interaction between new materials and media conditions such those found in modern power plants, industrial processes, and geochemistry.;A first CFC prototype was constructed based on the evaluation of different room temperature cell designs, and the performance of the cell was studied using the oxidation of ferrocyanide in 0.1M KCl as reference system under room temperature conditions. A numerical simulation software, COMSOL Multiphysics, was used to analyze the experimental results, as well as to evaluate other cell/electrode configurations that could perform better under hydrothermal conditions.;At the same time, the thermal stability of hydroquinone (H2Q) and 1,4-benzoquinone (BQ), a redox couple that it could be used to extend the evaluation of the CFC to higher temperatures and pressures was also investigated using UV-visible spectroscopy up to 250°C at 70 bar. These studies confirmed H2Q is stable in hot compressed water (pH ∼ 2) up to at least 250°C at 70 bar, but BQ, the oxidation production of H2Q, decomposes at temperatures lower than 100°C with the formation H2Q and other non-absorbing products. Based on these results, the oxidation of H 2Q to BQ in acid media could fulfill the stability requirements for the evaluation of a future HT-CFC provided that BQ be removed from the cell before it undergoes decomposition.;Keywords: Hydrodynamic electrodes, channel flow cell, UV-visible spectroscopy, hydrothermal systems, hydroquinone, 1,4-benzoquinone, COMSOL Multiphysics, numerical simulations. |
