Spectroscopic characterization of nickel containing desulfurization sorbents

Characterization of nickel-containing desulfurization sorbents was performed by X-ray photoelectron spectroscopy, scanning electron microscopy/energy-dispersive spectroscopy, thermogravimetric analysis, and atomic absorption analysis, Sorbent pellets were tested with simulated coal-derived hot fuel gas containing H2S, in a bench-scale fixed-bed reactor. Analysis was performed on both the interior and exterior of the sorbent pellets after both sulfidations and regenerations. In the sulfided sorbents, migration of nickel to the grain surface was observed at the exterior of the sorbent pellet. The nickel migration was less significant at the grain surface of the interior of the pellet. Changes in the oxidation state of the nickel were also observed at the outer surface of the pellet. The sulfur concentration was significantly higher at the outer surface of the pellet, indicating diffusional resistance of the fuel gas to the pellet interior.