Rapid catalyst deactivation caused by severe coking and active-phase reconstruction fundamentally hinders the application of high-pressure dry reforming of methane (DRM). To address this challenge, we developed a robust strontium-promoted, defect-rich N-doped carbon-supported cobalt catalyst (Co-Sr/CN). The catalysts were systematically evaluated under variable-pressure conditions (0.5-1.4 MPa) and a rigorous high-pressure "ultimate lifetime test" (780 ^oC, 1.1 MPa), combined with surface and in-situ mechanistic characterizations. The optimized Co-3Sr/CN catalyst significantly shortened the reaction induction period, achieving stable CH₄ and CO₂ conversions of 75.5% and 84.8%, respectively, at 0.5 MPa. Mechanistic studies, including in-situ DRIFTS and CO₂-TPSR, revealed that Sr promotion enriches oxygen-vacancy sites and strengthens the surface oxygen cycle, thereby accelerating intermediate CO₂ activation and oxygen-assisted carbon removal. Consequently, Co-3Sr/CN extended the high-pressure lifetime to 1046 h, vastly outperforming the unpromoted Co/C catalyst (482 h). However, post-reaction analyses revealed that both catalysts ultimately succumbed to catastrophic coking and aggregation. These findings demonstrate that while Sr-mediated oxygen cycles effectively delay deactivation, runaway carbon accumulation dictates late-stage failure in pressurized DRM, providing crucial insights for future industrial catalyst design.
 

Pressurized dry reforming of methane; Surface oxygen cycling; Extreme lifetime evaluation; Coking