High temperature and pressure electrochemical test station

Abstract

An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 °C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells and facilitate different types of electrochemical measurements. Selected examples of materials and electrochemical cells examined in the test station are provided, ranging from the evaluation of the ionic conductivity of liquid electrolytic solutions immobilized in mesoporous ceramic structures, to the electrochemical characterization of high temperature and pressure alkaline electrolysis cells and the use of pseudo-reference electrodes for the separation of each electrode contribution. A future perspective of various electrochemical processes and devices that can be developed with the use of the established test station is provided.

Reversible Hydrogen and Pd Hydride Reference Electrodes with Electrochemically Supplied H2 for High Temperature and Pressure Electrochemistry

“…The autoclave was equipped with additional gas handling components and wire through-puts, and pressurized using N 2 , as described elsewhere. 43 The open circuit potential (OCP) between the PdH T/P and the RHE T/P was continuously measured to calibrate the potential of the PdH with increasing operating temperature and pressure. To test the stability of the PdH RE, electrolysis was performed in 45% (w/w) KOH at 150 °C and 50 bar pressure for 98 h. Two Pt mesh electrodes (2.5 × 2.5 cm 2 ) separated by a ceramic separator 7 were used as anode and cathode.…”

High Temperature Alkaline Electrolysis Cells with Metal Foam Based Gas Diffusion Electrodes

“…The entire system, including a sample holder for simultaneous measurements of four cells, has been described in detail elsewhere. 11 The measurements reported here were carried out at a pressure of 20 bar and temperature of 200 • C. The OE was constantly flushed with a gas mixture of 30% H 2 O (g), 5% O 2 and 65% N 2 while the HE was flushed with pure H 2 . 1 shows a SEM micrograph of the cross section of a FobAEC with two Inconel foam electrodes and the electrolyte matrix.…”

“…The entire system, including a sample holder for simultaneous measurements of four cells, has been described in detail elsewhere. 11 The measurements reported here were carried out at a pressure of 20 bar and temperature of 200…”

High-Pressure Diffusion Control: Na Extraction from NaAlB14

“…Furthermore, since high-pressure synthesis is a completely closed system, it is possible to prevent unexpected chemical reactions based on the inflow of oxygen from outside during macroscopic compositional modulation by anisotropic ion diffusion. Although a number of high-temperature and high-pressure electrochemical cells have been demonstrated in previous studies, − these studies aimed at power generation, and the target pressure was 0.05 GPa or less. In contrast, HPDC focuses on material synthesis.…”