Manganese‐containing redox catalysts for selective hydrogen combustion under a cyclic redox scheme

Selective hydrogen combustion (SHC) in the presence of light hydrocarbons was demonstrated with a series of Mn‐containing mixed oxide redox catalysts in the context of a chemical looping‐oxidative dehydrogenation scheme. Unpromoted and 20 wt % Na 2 WO 4 ‐promoted Mg 6 MnO 8 , SrMnO 3 , and CaMnO 3 exhibited varying SHC capabilities at temperatures between 550 and 850°C. Reduction temperature of unpromoted redox catalysts increased in the order Mg 6 MnO 8  < SrMnO 3  < CaMnO 3 . Promotion with 20 wt % Na 2 WO 4 resulted in more selective redox catalysts capable of high‐temperature SHC. XPS analysis revealed a correlation between suppression of near‐surface Mn and SHC selectivity. Na 2 WO 4 /CaMnO 3 showed steady SHC performance (89% H 2 conversion, 88% selectivity) at 850°C over 50 redox cycles. In series with a Cr 2 O 3 /Al 2 O 3 ethane dehydrogenation catalyst, Na 2 WO 4 /CaMnO 3 combusted 84% of H 2 produced while limiting CO x yield below 2%. The redox catalysts reported can be suitable for SHC in a cyclic redox scheme for the production of light olefins from alkanes. © 2018 American Institute of Chemical Engineers AIChE J , 64: 3141–3150, 2018