The use of strontium ferrite perovskite as an oxygen carrier in the chemical looping epoxidation of ethylene

Controlling lattice oxygen activity of oxygen carrier materials by design: a review and perspective

“…For example, Gabra et al compared the performance of Ag catalysts supported on SrFeO 3 and Sr 3 Fe 2 O 7 (n = 2) for chemical looping epoxidation (CLE) of ethylene and found that the structures of the R-P phases influenced the oxygen release and uptake, which ultimately resulted in different ethylene oxide (EO) yields and selectivities during CLE. 30 Reportedly, a 1 : 1 mixture of SrFeO 3 and Sr 3 Fe 2 O 7 gave optimal CLE performance in terms of EO yield, EO selectivity and cyclic stability.…”

“…[17][18][19] Likewise, the chemical looping approach has been adopted for a variety of applications, including the ODH of propane and ethyl benzene, 20,21 selective oxidation of methane to methanol, 22,23 oxidative coupling of methane (OCM), [24][25][26] and the epoxidation of ethylene to ethylene oxide. [27][28][29][30] Lastly, reactions in chemical looping systems take place much closer to equilibria than those in conventional reactors, meaning that chemical looping systems generally exhibit higher exergy efficiency. 31,32 The aforementioned advantages have made chemical looping technologies increasingly popular amongst reaction engineers in recent years.…”

“…In these ternary oxides, the A sites are often occupied by nonredox active cations, while the transition metal cations occupy the coordinatively well-defined B sites (as oppose to the near-random site occupancies in solid solution mixtures). Examples of such ternary oxide oxygen carriers include NaFe x Al 1−x O 2 , 55 SrFeO 3 and its derivatives, [61][62][63][64] Ca 2 Fe 2 O 5 and its derivatives, [65][66][67] Fe-doped hexaaluminates, [68][69][70] 30,71,72 etc. (the list is non-exhaustive), as depicted in Fig.…”

Selective formation of propan-1-ol from propylene via a chemical looping approach

“…The ratio of the perovskite phase, SrFeO 3 , to Ruddlesden-Popper phase, Sr 3 Fe 2 O 7 , was found to strongly influence the rate of release of oxygen from the SrFeO 3 support 22 . Catalysts for chemical looping epoxidation of ethylene have been found to give stable performance over 33 cycles 23 , producing EO at 67% selectivity, with 19% conversion of ethylene.…”

“…The complete combustion reaction can be partially suppressed by the addition of chloride species, either on the surface of the catalyst or in the feed gas [7][8][9][10][11] , but at the penalty of decreased propylene conversion. Studies on chemical looping for selective oxidation of ethylene 19,22,23 have used Ag deposited on a non-stoichiometric oxide, strontium ferrite, SrFeO &14 , with perovskite structure, demonstrating chemical looping epoxidation of ethylene to ethylene oxide (EO). Strontium ferrite was chosen as a suitable oxygen carrier for selective oxidation reactions, as SrFeO &14 undergoes reversible oxygen release at relatively low temperatures (<300°C) 19,24 , and can be produced inexpensively via solidstate methods 25 .…”