Reduction and oxidation behavior of strontium perovskites for chemical looping air separation

Görke, R.H.; Marek, Ewa; Donat, Felix; Scott, Stuart A.

doi:10.1016/j.ijggc.2019.102891

Cited by 28 publications

(37 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Oxygen carriers should maintain similar activity as long as their oxygen reservoir is not severely depleted even if it is overall reduced after each cycle. This will be true only if the net change in oxygen capacity of SrFeO3 in 10 CLE cycles was small, otherwise, the reduction of SrFeO3 should change with conversion [39]. Here, in each cycle, SrFeO3 lost up to 5% of its oxygen capacity (taking SrFeO2.5 as the final stoichiometry, although SrFeO3 can reduce further, to SrO and Fe [11]).…”

Section: Effect Of Calcination Temperature On Catalyst Performancementioning

confidence: 99%

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

Marek

Conde

2021

Chemical Engineering Journal

Self Cite

View full text Add to dashboard Cite

Chemical looping epoxidation (CLE) of ethylene to ethylene oxide (EO) presents an exciting alternative to the incumbent technology of direct epoxidation of ethylene with O2(g). In CLE, the reaction is still catalysed by Ag but oxygen is provided as Olattice from a solid metal oxide, eliminating the need and limitations of using O2(g). Here, the influence of catalyst preparation in CLE is investigated. The Ag catalyst was impregnated on a solid oxide, SrFeO3, which was used as the donor of Olattice in CLE.Temperature programmed reduction in H2 indicated that O-species participating in CLE can be attributed to the removal of the first monolayer of oxygen in SrFeO3. By changing the temperature of calcination in Ag-SrFeO3 preparation, the size of Ag particles was varied, resulting in a simultaneous increase of selectivity for EO (up to 60%) and conversion of C2H4 (up to 10%). Then, an assessment of the effects of impurities (carbonates, hydroxides), which deposit over time on the Ag-SrFeO3 surface, was performed, showing that impurities deteriorate the catalyst performance in CLE. Finally, the doping of the SrFeO3 with Ce to the A-site of the perovskite was carried out, and a substantial improvement of the conversion of C2H4 was achieved, reaching 15%, while maintaining the 60% selectivity for EO.

show abstract

Section: Effect Of Calcination Temperature On Catalyst Performancementioning

confidence: 99%

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

Marek

Conde

2021

Chemical Engineering Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Among the large number of possible non-stoichiometric oxides, strontium and iron-based perovskites have been identified as suitable OCs for low-temperature applications. 19,36,37 For example, Miura et al found that A-site substitution of the SrFeO 3 system by Ca improves the OSC when operating cyclically between 5% O 2 and air, identifying Sr 0.76 Ca 0.24 FeO 3Àd with an OSC of 1.1 wt% at 550 1C as an attractive OC (the OSC of the undoped SrFeO 3Àd was only 0.6 wt%). 28 In addition, substitution of the B-site of SrFeO 3 with Co was investigated by Ikeda et al and they found that the substitution of 85% of Fe with Co allows the release of O 2 at temperatures as low as 300 1C instead of 600 1C for the unsubstituted SrFeO 3Àd .…”

mentioning

confidence: 99%

Structural and thermodynamic study of Ca A- or Co B-site substituted SrFeO_3−δ perovskites for low temperature chemical looping applications

Luongo

Donat

Müller

2020

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Perovskite-structured materials, owing to their chemical-physical properties and tuneable composition, have extended their range of applications to chemical looping processes, in which lattice oxygen provides the oxygen needed for chemical reactions omitting the use of co-fed gaseous oxidants.To optimise their oxygen donating behaviour to the specific application a fundamental understanding of the reduction/oxidation characteristics of perovskite structured oxides and their manipulation through the introduction of dopants is key. In this study, we investigate the structural and oxygen desorption/ sorption properties of Sr 1Àx Ca x FeO 3Àd and SrFe 1Àx Co x O 3Àd (0 r x r 1) to guide the design of more effective oxygen carriers for chemical looping applications at low temperatures (i.e. 400-600 1C).Ca A-or Co B-site substituted SrFeO 3Àd show an increased reducibility, resulting in a higher oxygen capacity at T r 600 1C when compared to the unsubstituted sample. The quantitative assessment of the thermodynamic properties (partial molar enthalpy and entropy of vacancy formation) confirms a reduced enthalpy of vacancy formation upon substitution in this temperature range (i.e. 400-600 1C). Among the examined samples, Sr 0.8 Ca 0.2 FeO 3Àd exhibited the highest oxygen storage capacity (2.15 wt%) at 500 1C, complemented by excellent redox and structural stability over 100 cycles. The thermodynamic assessment, supported by in situ XRD measurements, revealed that the oxygen release occurs with a phase transition perovskite-brownmillerite below 770 1C, while the perovskite structure remains stable above 770 1C.

show abstract

“…The rate of CO 2 production was not constant in the absence of the air cofeed, but followed the O 2 release profile of the OC in an inert atmosphere (Figure S3f, Supporting Information); initially the rate of O 2 release was fast, but then gradually slowed down as the OC became depleted in redox-active lattice oxygen. [21,24,40] Lattice oxygen was consumed also when the ratio of C 2 H 6 /O 2 was high and all of the O 2 from the air cofeed was converted, but not when the conversion of the O 2 from the air cofeed was incomplete (Figure S3d, Supporting Information), pointing to a Mars-van Krevelen-type mechanism that involves the rapid removal and incorporation of oxygen species on the surface of the OC. [8] Since there appears to be a correlation between the rate of O 2 release from the OC (Figure S3f, Supporting Information) and the rate of CO 2 production (Figure S3e, Supporting Information), we made a control experiment in which the rate of O 2 pattern (blue framed area).…”

Section: Origin Of the Overoxidation Of C 2 H 6 To Comentioning

confidence: 99%

Highly Selective Oxidative Dehydrogenation of Ethane to Ethylene via Chemical Looping with Oxygen Uncoupling through Structural Engineering of the Oxygen Carrier

Luongo

Donat

Bork

et al. 2022

Advanced Energy Materials

View full text Add to dashboard Cite

The oxidative dehydrogenation of ethane (ODH) to produce ethylene offers advantages compared to the industry standard steam cracking, but its industrial application is hindered by costly air separation units needed to supply oxygen. A chemical‐looping‐based oxidative dehydrogenation (CL‐ODH) scheme is presented, in which oxygen carriers supply gaseous oxygen in situ, which then reacts with ethane in the presence of a catalyst at a comparatively low temperature (500 °C). A common challenge of chemical looping processes beyond combustion is to suppress the overoxidation of hydrocarbons to COx to enable high product yields. It is demonstrated that the overoxidation of ethane can be eliminated completely through structural engineering of the perovskite oxygen carrier involving alkali‐metal‐based carbonate coatings, while maintaining the materials’ ability to generate oxygen. Through CL‐ODH, higher ethylene selectivity (≈91%) and yields (≈39%) are achieved compared to the conventional ODH scheme without oxygen carrier and cofeeding air/ethane. 18O‐labeling experiments demonstrate that the carbonate layer functions like a diffusion barrier for ethane while being permeable for oxygen. Both the CL‐ODH scheme and the material design strategy can be extended to other catalytic oxidation or dehydrogenation reactions requiring oxygen at different temperatures, offering enormous potential to intensify such processes.

show abstract

Reduction and oxidation behavior of strontium perovskites for chemical looping air separation

Cited by 28 publications

References 38 publications

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

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

Structural and thermodynamic study of Ca A- or Co B-site substituted SrFeO_3−δ perovskites for low temperature chemical looping applications

Highly Selective Oxidative Dehydrogenation of Ethane to Ethylene via Chemical Looping with Oxygen Uncoupling through Structural Engineering of the Oxygen Carrier

Contact Info

Product

Resources

About

Reduction and oxidation behavior of strontium perovskites for chemical looping air separation

Cited by 28 publications

References 38 publications

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

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

Structural and thermodynamic study of Ca A- or Co B-site substituted SrFeO3−δ perovskites for low temperature chemical looping applications

Highly Selective Oxidative Dehydrogenation of Ethane to Ethylene via Chemical Looping with Oxygen Uncoupling through Structural Engineering of the Oxygen Carrier

Contact Info

Product

Resources

About

Structural and thermodynamic study of Ca A- or Co B-site substituted SrFeO_3−δ perovskites for low temperature chemical looping applications