Reports: UR1053614-UR10: Supercritically Functionalized Nonstructures for Methane Reforming

Alevtina Smirnova, PhD, South Dakota School of Mines and Technology

PART I: Functionalization of the SOFC anodes using organometallic precursors in supercritical carbon dioxide

During Year IV of the ACS PRF project the study was focused on functionalization of the SOFC anode substrates deposited on the surface of the YSZ electrolytes with Ru nanoparticles using the Ru-based organometallic precursor dissolved in supercritical carbon dioxide.

In order to functionalize the anode with ruthenium nanoparticles for improved internal reforming, SOFC half-cells were placed in the 0.5L supercritical vessel. A metal mesh pouch with 0.1g of organometallic ruthenium compound bis(1,1,1-trifluoro-2,4-pentanedionato)(1,5-cyclooctadiene)ruthenium(II) was also paced in the same vessel. Before liquid carbon dioxide was introduced to the system, the temperature and pressure were adjusted to 80oC and 3000psi. During this process, the organometallic precursor dissolved in supercritical carbon dioxide (scCO2) has been deposited within the structure of the NiO/YSZ composite anode. Due to absence of mass transport limitations and relatively high solubility of the organometallic precursor, it took about 2-3 hours to complete the process. Comparison of the original NiO/YSZ composite anode and the NiO/YSZ anode exposed to scCO2 with dissolved Ru organometallic precursor flowed by sintering indicate that this process resulted in the targeted value of 1-2 wt. % of Ru within the NiO/YSZ anode composite.

The results of the morphological characterization indicate that the NiO/YSZ anode structure is composed of irregular grains ranging from 0.5 to 5 μm. The SEM-energy-dispersive X-ray spectroscopy (EDS) chemical analysis confirms that chemical composition of NiO/YSZ corresponds to about 53wt. % Ni, 16.2 wt. % Zr. and 2.6 wt. % Y, the rest is oxygen which is present in both NiO and YSZ oxides.

Part II. Manufacturing of the setup for SOFC button cell testing In Year IV an attempt has been made to modify and improve the existing setup for the button cell SOFC testing. This mechanical engineering approach was important for this and future projects since it allows to change the SOFCs faster and provide a better control of the contact resistances between the current collector and the electrodes.