Effect of Arsenic and Selenium on Nickel in SOFC Anode Materials

Abstract

The effect of arsenic and selenium in coal gasification gas on nickel in SOFC anode materials was investigated using a commercial thermodynamic equilibrium calculation software, batch reactor, and digital microscope. The thermodynamic equilibrium simulations of 0.5CO, 0.2H₂, 0.04CO₂, 0.26N₂, 0.2H₂O, 10Ni, and arsenic and/or selenium were carried out to result in forming NiAs as solid-phase species under the conditions more than 10 ppm arsenic, the equivalent amount of NiAs as solid-phase species and AsSe as gas-phase species under the conditions of 10-1000 ppm arsenic and selenium, and Ni₇Se₈ as solid-phase species under the conditions more than 1% selenium. The impedance of nickel wire with arsenic and selenium from 500 to 900 °C in the batch reactor was measured under simulated coal gasification gas (H₂/N₂ = 30/70 vol%) by a digital multi-meter to result in increasing the impedance with > 0.05 g arsenic and > 0.05 g selenium due to nickel corrosion. The reaction of nickel plate with arsenic and/or selenium to 900 °C in the batch reactor and digital microscope was performed under simulated coal gasification gas (CO/CO₂/N₂/H₂ = 50.0/4.00/26.0/20.0 vol%) to result in the corrosion on the surface of nickel plate due to forming Ni₅As₂ and pumping nickel by arsenic.