CO Hydrogenation: Exploring Iridium as a Promoter for Supported Cobalt Catalysts by TPR-EXAFS/XANES and Reaction Testing

Abstract  

The price of iridium currently trends at about half the cost of platinum, the latter being a typical reduction promoter for Co/Al₂O₃ Fischer–Tropsch (FT) synthesis catalysts in gas-to-liquids (GTL) technology. In the current contribution, both fixed-bed catalytic FT and TPR-EXAFS/XANES experiments were carried out over 0.1% iridium-doped 25% Co/Al₂O₃ catalysts in order to (1) assess the effectiveness of Ir as a promoter of cobalt oxide reduction and (2) evaluate the effectiveness of the incipient wetness impregnation (IWI) technique for adding the Ir precursor by comparing a catalyst prepared by IWI to one prepared by atomic layer deposition (ALD). Ir was demonstrated to be an effective promoter for facilitating the second step of cobalt oxide reduction, CoO to Co⁰, and the IWI method was found to be superior to ALD.