Copper promotion of chromium-doped iron oxide water-gas shift catalysts under industrially relevant conditions

Copper promotion of chromium-doped iron oxide prepared via co-precipitation for high-temperature water–gas shift (WGS) catalysis is investigated. Low-temperature Mössbauer spectra demonstrate that copper doping delays hematite (?-Fe2O3) formation in the fresh catalyst, favoring small crystallites ferrihydrite (Fe5HO8?4 H2O). Catalysts are treated under industrial WGS conditions at 360 °C (activity evaluation) and 450 (ageing) 2 25 bar. show chromium incorporated octahedral sites active magnetite (Fe3O4) phase, resulting a partially oxidized structure. did not affect bulk structure activated which points to presence separate phase. Near-ambient pressure XPS shows metallic state. discharged catalysts evidenced reaction elevated resulted surface reduction Fe3+ Fe2+. enhances CO conversion conditions.