Effect of the Reduction Temperature on the Activity and Selectivity of Titania-Supported Iridium Nanoparticles for Methylcyclopentane Reaction

The catalytic performance of Ir/TiO₂ reduced at low (573 K, LTR) and high temperature (773 K, HTR) was studied in the methylcyclopentane (MCP) reaction at atmospheric pressure in a flow system. Ir/Al₂O₃ was used as the reference catalyst. Catalysts were prepared by deposition–precipitation with urea and characterized by ICP, H₂-TPR, HAADF-STEM, Cs-STEM, and DRIFTS. For LTR samples, the activity follows the order Ir/TiO₂ > Ir/Al₂O₃, and at low conversion and temperature, ring opening (RO) of MCP is selective (2MP/3MP = 2.7; n-H/3MP = 0.05) with SRO = 100%. As the reaction temperature increased, C₁–C₅ products appeared but Ir/TiO₂ was still more selective to RO products than Ir/Al₂O₃. Ir/TiO₂ HTR was significantly less active, with SRO = 100% and a product distribution approaching a nonselective behavior with n-H/3MP = 1. This was not observed in the case of Ir/Al₂O₃ HTR. The structure of Ir/TiO₂ HTR included nanoparticles, clusters of few atoms, and isolated iridium atoms. The results were analyzed in light of the metal–support interaction (SMSI) effect.