Enhanced oxygen-release/storage properties of Pd-loaded Sr₃Fe₂O_7−δ

Abstract

This study proves that a small amount of Pd loading (1 wt%) on SrFeO can dramatically enhance the oxygen-storage properties of SrFeO. The topotactic oxygen intake and release between SrFeO and SrFeO takes place in response to gas switching between an O flow and H flow, regardless of the presence or absence of Pd loading. The effect of Pd loading is significant for the oxygen-release process under H atmosphere; that is, highly dispersed Pd metal nanoparticles sized less than 1 nm formed on Pd/SrFeO to promote H dissociation, resulting in the improvement of the oxygen-release temperature and rate. Pd/SrFeO with a layered perovskite structure has a higher oxygen-release property at lower temperature than Pd/SrFeO with a perovskite phase without the layered structure. These facts indicate that the surface reaction as well as the crystal structure are responsible for the oxide ion mobility in perovskite structure, and also provide guidelines for designing novel oxygen-storage materials.

Effect of catalyst preparation and storage on chemical looping epoxidation of ethylene

“…S6). The catalytic influence of a noble metal on redox of perovskite was noted by Beppu et al [27], when the impregnation of 1 wt% of Pd onto Sr3Fe2O7 significantly enhanced its oxygen release and storage. The results in Fig.…”

Mechanistic Analysis of Oxygen Vacancy Formation and Ionic Transport in Sr3Fe2O7−δ

“…To satisfy such strict requirements, reasonably good structural stability and proper ionic conductivity must be balanced because a higher structural stability could reduce the mobility of oxygen ions and vice versa. Many perovskite-related materials have been explored in previous research. − Among them, the family of Ruddlesden–Popper A n +1 B n C 3 n +1 oxides has been studied for use in ionic-conducting applications, such as SOFCs and oxygen-storage materials, operating at intermediate or high temperatures (300–900 °C). − In particular, Sr 3 Fe 2 O 7−δ , which contains no rare-earth elements, has recently been found to exhibit high structural stability and high oxygen-ion conductivity. , Beppu et al revealed that Sr 3 Fe 2 O 7−δ shows higher performance in the oxygen storage capacity and the rate of oxygen release and storage, compared with the conventional Pt/Ce 2 Zr 2 O 8 used in three way catalysts . It is also experimentally shown that Sr 3 Fe 2 O 7−δ is more sustainable under H 2 reductive conditions than perovskite SrFeO 3−δ .…”

Striking Oxygen-Release/Storage Properties of Fe-Site-Substituted Sr3Fe2O7−δ

“…Recently, we have reported that Sr 3 Fe 2 O 7−δ , with a layered perovskite-type structure, exhibits topotactic oxygen-storage/release behaviors and has higher structural stability under severe reductive condition than SrFeO 3−δ . , The space group ( I 4/ mmm ) of Sr 3 Fe 2 O 6.75 is identical to that of Sr 3 Fe 2 O 6 obtained through the release of lattice oxygen. Only oxygen ions at the apical position between bilayers of FeO 6 in Sr 3 Fe 2 O 6.75 are topotactically eliminated by reduction with H 2 (Figure ) because the oxygen vacancy site at the apical position is more stable than that at the equatorial position in Sr 3 Fe 2 O 6.75 .…”

“…X-ray absorption fine structure (XAFS) spectra at the Fe, Mn, Co, and Ni K-edges were measured at the BL11S2 beam line of the Aichi Synchrotron Radiation Center (AichiSR); these spectra were recorded in transmission mode at room temperature using a Si(111) double-crystal monochromator. Time-resolved in situ energy-dispersive XAFS (DXAFS) spectra at the Sr K-edge were measured with a polychromator in transmission mode at the BL28B2 beam line of SPring-8, as described in our previous reports. , Each sample (30 mg) was pressed into a pellet and placed in a batch-type in situ cell. The sample was pretreated with pure H 2 at 873 K for 15 min and then with pure O 2 under the same conditions.…”