Metal oxide redox chemistry for chemical looping processes

Zeng, Liang; Cheng, Zhuo; Fan, Jonathan A.; Fan, Liang‐Shih; Gong, Jinlong

doi:10.1038/s41570-018-0046-2

Cited by 362 publications

(224 citation statements)

References 127 publications

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“…Among various factors affecting CLAS performance, the metal oxide‐based oxygen carrier, also known as oxygen sorbent, plays the most critical role . For example, CuO and Cu 2 O have been identified as promising oxygen sorbents, owing to their reversible reaction with gaseous oxygen at a suitable oxygen partial pressure range (i.e., 0.01–1 atm) and at below 1000 °C, which has also been demonstrated for chemical‐looping oxygen uncoupling for solid fuel combustion and CO 2 capture .…”

Section: Introductionmentioning

confidence: 99%

A‐ and B‐site Codoped SrFeO₃ Oxygen Sorbents for Enhanced Chemical Looping Air Separation

et al. 2019

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Section: Introductionmentioning

confidence: 99%

A‐ and B‐site Codoped SrFeO₃ Oxygen Sorbents for Enhanced Chemical Looping Air Separation

et al. 2019

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“…In order to perform selective oxidation, an ideal oxygen carrier, therefore, must have an "intermediate" surface M-O bond strength and "intermediate" mobility of lattice O atoms in order to be both selective and active. [108] A weak M-O bond will release O atoms very easily, resulting in reactants undergoing complete oxidation. In contrast, a strong M-O bond implies that the material is a weak oxidant.…”

Section: Dopingmentioning

confidence: 99%

Approaches for Selective Oxidation of Methane to Methanol

et al. 2020

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Methane activation chemistry, despite being widely reported in literature, remains to date a subject of debate. The challenges in this reaction are not limited to methane activation but extend to stabilization of the intermediate species. The low C-H dissociation energy of intermediates vs. reactants leads to CO2 formation. For selective oxidation, nature presents methane monooxygenase as a benchmark. This enzyme selectively consumes methane by breaking it down into methanol. To assemble an active site similar to monooxygenase, the literature reports Cu-ZSM-5, Fe-ZSM-5, and Cu-MOR, using zeolites and systems like CeO2/Cu2O/Cu. However, the trade-off between methane activation and methanol selectivity remains a challenge. Density functional theory (DFT) calculations and spectroscopic studies indicate catalyst reducibility, oxygen mobility, and water as co-feed as primary factors that can assist in enabling higher selectivity. The use of chemical looping can further improve selectivity. However, in all systems, improvements in productivity per cycle are required in order to meet the economical/industrial standards.

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“…It was widely used for electrochemistry, sensors, and solar cells in the previous researches ascribing to its excellent electric conductivity and stability . Then, it becomes more and more attractive as OC in chemical looping process ascribing to its desirable thermodynamic properties, good reactivity as well as good redox properties . In a normative cell of perovskite ABO 3 , lanthanide metal or alkaline earth metal usually occupies the A site combining with 12 oxygen ions to form a face‐centered cubic crystal form occupying the interstitial sites of eight octahedrons.…”

Section: Introductionmentioning

confidence: 99%

“…[16][17][18] Then, it becomes more and more attractive as OC in chemical looping process ascribing to its desirable thermodynamic properties, good reactivity as well as good redox properties. [19][20][21][22] In a normative cell of perovskite ABO 3 , lanthanide metal or alkaline earth metal usually occupies the A site combining with 12 oxygen ions to form a face-centered cubic crystal form occupying the interstitial sites of eight octahedrons. While the transition metal in B site coordinated with six oxygen ions is filling in the center of octahedron.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the relationship between electronic properties and reactivity of 3DOM LaFe _{1 −
x} Co _x O ₃ for methane reforming to produce syngas

Zhao

Chen

et al. 2019

Int J Energy Res

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Summary Chemical looping steam methane reforming (CL‐SMR) provides a promising pathway to reform methane and to jointly generate high‐quality syngas and hydrogen. The key issue is the designing of oxygen carriers (OCs) with high reactivity, good selectivity, and excellent recyclability. The high temperature required for chemical looping reaction also presents challenges in terms of producing stable and anticarbon deposition OCs. Here, we report a three‐dimensional ordered macroporous (3DOM) Co‐Fe doping perovskites as OCs for CL‐SMR, in which the active perovskite phases are equipped with well‐ordered wall skeleton in three dimensions. Multiple of characterization techniques such as H2‐TPR, XRD, SEM, and XPS were used to characterize the physicochemical properties of OCs. Combining with the tests on fixed‐bed reactor, we demonstrated that the 3DOM structures are beneficial to reduce the mass diffusion resistance and to supply more active sites for fuel conversion. The synergetic effects of metal Fe‐Co promote the reactivity by increasing the reaction rate and reducing the reaction temperature. These experiment results are further explored by using the first‐principle calculations. Differences in the atomic charges and electronic densities show that there are more negative oxygen ions in the doping cells. The substitution of Co increased the transition intensity of Co3d‐O2p orbit, and more electrons were excited near Fermi level. These deeper predictions insight into the synergistic mechanism will provide meaningful information for the selecting and designing of oxygen carriers in subsequent study.

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Metal oxide redox chemistry for chemical looping processes

Cited by 362 publications

References 127 publications

A‐ and B‐site Codoped SrFeO₃ Oxygen Sorbents for Enhanced Chemical Looping Air Separation

A‐ and B‐site Codoped SrFeO₃ Oxygen Sorbents for Enhanced Chemical Looping Air Separation

Approaches for Selective Oxidation of Methane to Methanol

Investigation of the relationship between electronic properties and reactivity of 3DOM LaFe _{1 −
x} Co _x O ₃ for methane reforming to produce syngas

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Metal oxide redox chemistry for chemical looping processes

Cited by 362 publications

References 127 publications

A‐ and B‐site Codoped SrFeO3 Oxygen Sorbents for Enhanced Chemical Looping Air Separation

A‐ and B‐site Codoped SrFeO3 Oxygen Sorbents for Enhanced Chemical Looping Air Separation

Approaches for Selective Oxidation of Methane to Methanol

Investigation of the relationship between electronic properties and reactivity of 3DOM LaFe 1 − x Co x O 3 for methane reforming to produce syngas

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Product

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A‐ and B‐site Codoped SrFeO₃ Oxygen Sorbents for Enhanced Chemical Looping Air Separation

A‐ and B‐site Codoped SrFeO₃ Oxygen Sorbents for Enhanced Chemical Looping Air Separation

Investigation of the relationship between electronic properties and reactivity of 3DOM LaFe _{1 −
x} Co _x O ₃ for methane reforming to produce syngas