Mass Spectrometry of SOFC Fuel Mixtures Containing Phosphine

Abstract

Phosphine (PH 3 ) is present at ppm concentrations in coal syngas, a potential fuel source for solid oxide fuel cells (SOFCs). A mass spectrometer is used to monitor fuel mixtures of hydrogen and phosphine after exposure to two environments. In the first environment, the gas mixtures are passed through a heated zone in a tube furnace. In the second environment, the gas mixtures are passed across the anodes of operating SOFCs, both electrolyte-and anode-supported. Phosphine appears to react with residual oxygen in dry hydrogen at intermediate temperatures (400-600 • C) but is stable above 600 • C. Phosphine reacts with water in wet hydrogen mixtures and with a Ni/YSZ anode at temperatures above 400 • C. Evidence is presented for deposition of non-volatile contaminants following prolonged phosphine exposure. The contaminants react with dry hydrogen to generate PH 3 at 800 • C. Mass spectra of the anode exhaust of an electrolyte-supported SOFC show that a few torr of water, either present initially or electrochemically generated by fuel oxidation, is sufficient to suppress the phosphine signal. At all gas compositions and currents, no new mass signals were detected in the mass range of 45-100, suggesting that HPO, HPO 2 and HPO 3 are not products of phosphine reaction or electrochemical oxidation.

Recent development and applications of differential electrochemical mass spectrometry in emerging energy conversion and storage solutions

“…This work suggests the difficulty of electrochemical H 3 P oxidation and underscores the importance of impurity removal in the feedstock. 286 4.6.2 Reactions at the cathode. The ORR occurs at the cathode of fuel cells.…”

“…This work suggests the difficulty of electrochemical H 3 P oxidation and underscores the importance of impurity removal in the feedstock. 286…”

Assessing Sulfur-Induced Degradation Mechanisms in SOFCs with Chronocoulometry and Operando Optical Imaging

“…A primary challenge limiting the ability of SOFCs to operate with logistics fuels is their susceptibility to electrode degradation by contaminants. Species such as chlorine, sulfur, and phosphorous have all been implicated in mechanisms that deactivate SOFC anodes, and specific conditions including temperature, duration of exposure, and contaminant concentration determine whether or not degradation is irreversible (2)(3)(4)(5)(6)(7)(8)(9). Most studies of contaminant-induced degradation in SOFCs rely on results from electrochemical measurements and/or comparisons of anode microstructure acquired ex situ before and after operation (5,10).…”

Utilization of Bio-Syngas in Solid Oxide Fuel Cell Stacks: Effect of Hydrocarbon Reforming

“…[8][9][10][11] Therefore, a system of coupling a gasifier producing bio-syngas and SOFCs has been suggested by many authors with their simulation works, [12][13][14][15] tested with simulated syngas [16][17][18][19][20] and with actual bio-syngas. [21][22][23] A system using actual bio-syngas needs an additional reformer for cleaning the bio-syngas because it includes impurities such as tars, [16][17][18][19][20] sulfur, [24][25][26] and phosphorus 27,28 causing significant mechanical and electrochemical degradation. This additional reformer makes the system more complex and expensive.…”