As the U.S. Army develops future capabilities for the Next Generation of Combat Vehicles, concerns over increased on-board vehicle power demand have led development efforts to focus on supplemental alternative power technologies. One promising technology that could be implemented to augment on-board vehicle power are Solid Oxide Fuel Cells (SOFCs). Not only are they highly efficient, but they are fuel flexible, which is an important metric for the U.S. Army who operates its ground infrastructure on JP-8 (kerosene-based fuel). However, sulfur, a common SOFC contaminant in naturally sourced fuels, is known to lead to deleterious performance issues at concentrations as low as 10 ppm. JP-8, which is not desulfurized in theater, can contain concentrations of sulfur as high as 3000ppm, would require either an on-board desulfurizer or advanced sulfur tolerant anode catalysts to support their implementation. In this study, a previously reported sulfur tolerant SOFC anode catalyst, La0.7Sr0.3VO3.86-δ (LSV), was further experimentally investigated for its sulfur tolerance at currently targeted SOFC intermediate operating temperatures (400-600°C) in wide range of hydrogen sulfide (30ppm, 300ppm and 10vol%) balance hydrogen gas environments for up to 100 hours. When compared against the industry standard Ni-YSZ anode, LSV was observed to have significantly lower (287x) sulfur adsorption rates, with the lowest rates observed between 600-700°C. This behavior is attributed to its cubic structure at 600-700°C, as higher adsorption rates were observed in the monoclinic/tetragonal at 400-500°C. This study was further supplemented by a theoretical investigation of adsorption on low index LSV surfaces. When compared against Ni-YSZ, which is known to accumulate sulfur from hydrogen sulfide through dissociative adsorption, LSV was observed to accumulate sulfur through weak chemisorption (0.43 eV max) of undissociated molecular hydrogen sulfide. This behavior is attributed to strontium defects, wherein when compared with low index surfaces of LVO3, no adsorption was observed.

Hydrogen atmosphere controlled La0.7Sr0.3VO3.86-δ (LSV) intermediate-temperature solid oxide fuel cell sulfur tolerance explored through experimental and modeling characterization over time

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.