Cr-doping regulates Mn₃O₄ spinel structure for efficient total oxidation of propane: Structural effects and reaction mechanism determination

The exploration of enhancing the low-temperature oxidation performance of catalysts by element doping is desirable but still challenging. Herein, a series of Cr-doping Mn₃O₄ spinel catalysts (Mn_xCr_3−xO₄) were prepared through MOF-74 as precursors and tested for propane total oxidation. Due to the synergy between Cr and Mn, Mn_xCr_3−xO₄ with rich surface-active Mn⁴⁺, notable low-temperature reducibility and excellent oxygen migration capability displays notable catalytic activity for propane oxidation. The constructed Mn_2.70Cr_0.30O₄ exhibited superior propane catalytic activity and notable thermal stability. The T₉₀ of Mn_2.70Cr_0.30O₄ is 264 ℃ under humid condition, that 51 ℃ lower than that of Mn₃O₄. Meanwhile, in-situ spectroscopy and DFT calculations revealed that the addition of Cr can convert propane into propylene in the initial stage thus to reduce the reaction energy barrier. This work provides an element doping strategy to effectively enhance spinel catalysts performance, and can be provided with bright prospect for efficient VOCs catalysts.