Oscillatory behavior of Ni/TiO2 catalyst during partial oxidation of methane: Understanding the role of strong metal-support interaction

The restructuring of a catalyst under working conditions has been recognized as a critical factor that can significantly impact their performance in recent years. In this study, we investigate the behavior of a highly dispersed Ni supported on TiO 2 (P25) catalyst during the partial oxidation of methane (POM) to produce syngas. Our results reveal a distinct oscillation phenomenon in the catalyst's performance over time. The simultaneous oscillations of rapid deactivation and activation are observed, while the catalyst remains active for continuous POM reaction. Comprehensive characterizations suggest that this deactivation is not caused by traditional deactivation mechanisms with coke formation or Ni sintering. The formation of inactive NiTiO 3 results in catalyst deactivation, which is formed between Ni and TiO 2 support in the reductive atmosphere of POM products under high temperature due to strong metal-support interaction (SMSI). The simultaneous presence of oxidative and reductive atmospheres of the reactants and products in the POM reaction leads to the generation or demise of NiTiO 3 . The dynamic change of the Ni active sites during the in-situ reaction leads to the oscillation of the catalytic activity. This study sheds new light on the importance of SMSI in understanding the behavior of catalysts under working conditions.