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

Abstract

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 Mn 3 O 4 spinel catalysts (Mn x Cr 3−x O 4 ) were prepared through MOF-74 as precursors and tested for propane total oxidation . Due to the synergy between Cr and Mn, Mn x Cr 3−x O 4 with rich surface-active Mn 4+ , notable low-temperature reducibility and excellent oxygen migration capability displays notable catalytic activity for propane oxidation. The constructed Mn 2.70 Cr 0.30 O 4 exhibited superior propane catalytic activity and notable thermal stability. The T 90 of Mn 2.70 Cr 0.30 O 4 is 264 ℃ under humid condition, that 51 ℃ lower than that of Mn 3 O 4 . 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. • Cr was successfully doped at B position of Mn 3 O 4 spinel via MOF-74 as precursor. • Cr-dopant enhanced the catalytic performance during propane oxidation. • Cr-dopant promoted the oxygen mobility by forming oxygen vacancy. • Cr-dopant could catalyze propane to propene, reducing initial reaction barrier.