CeO<sub>2</sub>-Grafted Mn–Fe Oxide Composites as Alternative Oxygen-Storage Materials for Three-Way Catalysts: Laboratory and Chassis Dynamometer Tests

Machida, Masato; Ueno, Mana; Omura, Takeshi; Kurusu, Sae; Hinokuma, Satoshi; Nanba, Tetsuya; Shinozaki, Osamu; Furutani, Hirohide

doi:10.1021/acs.iecr.6b04468

Cited by 17 publications

(11 citation statements)

References 41 publications

(64 reference statements)

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“…The proposed mechanism requires fast O-transport, which would have been assured by very mobile oxygen vacancies in CeO2. Similar phase cooperation has been observed between CeO2 and: CuMnO2 [25], Mn2O3, MnxFe1-xOy (both in [26]); CuO [27,28], La2O2SO4 [29] and tungstophosphoric acid HPW [30].…”

Section: Discussionsupporting

confidence: 76%

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High selectivity epoxidation of ethylene in chemical looping setup

Marek

Gabra

Dennis

et al. 2020

Applied Catalysis B: Environmental

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We describe the remarkable performance of a new catalyst for the chemical looping (CL-) epoxidation of ethylene, performed at atmospheric pressure and without any promoters added to either the catalyst or the feed gas. To undertake the CL-epoxidation of ethylene, silver was used as the catalyst, supported on either the perovskite SrFeO3 or Ce-modified SrFeO3. Here, the oxygen for the reaction is supplied to the silver catalyst from the active solid support, not from the gas stream. When the support has been reduced and depleted of oxygen, it is regenerated in a separate step with air, which makes the process cyclic and closes a chemical loop. Thus, there is no need to co-feed gaseous oxygen along with the ethylene feed, an important improvement in safety. Two methods were used to synthesise Ce-modified materials, employing either (i) the mechanical mixing of powdered CeO2 and the solid precursors of the perovskite, or (ii) the impregnation of a solution of cerium nitrate into solid particles of SrFeO3. In both cases, the materials were calcined to produce a mixture of CeO2 and SrFeO3. Both CeO2-SrFeO3 materials surpassed the unmodified SrFeO3 for CL-epoxidation. For the CeO2-SrFeO3 prepared by mechanical mixing, the production of ethylene oxide was stable over 15 cycles, giving 60% selectivity at 10% conversion of C2H4. In contrast, the material prepared by impregnation gave up to 85% selectivity but only in the first cycle of reduction, with the performance degrading over subsequent cycles. The reported results are better than the 50% selectivity achieved for the classical epoxidation using pure silver as the catalyst and feeds of gaseous ethylene and oxygen, without reaction promoters.

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Section: Discussionsupporting

confidence: 76%

“…Ethylene oxide (EO), is an important chemical commodity, with an annual production (2016) of about 26 Mte [1]. Industrially, ethylene oxide is produced by the epoxidation of ethylene, where gaseous streams of ethylene and pure O2 are passed through a bed of catalyst, usually silver supported on alumina.…”

Section: Introductionmentioning

confidence: 99%

High selectivity epoxidation of ethylene in chemical looping setup

Marek

Gabra

Dennis

et al. 2020

Applied Catalysis B: Environmental

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“…In a redox-involved context, Machida at Kumamoto University found that surface CeO 2 could act as a gateway for oxygen storage in and release from various oxides acting as an oxygen reservoir, such as Fe 2 O 3 or La 2 O 2 SO 4 . [141][142][143] Although the abovementioned strategy for catalyst selectivity optimization has been shown to be effective, we note that it still represents a rather simplified view of the redox catalyst. It would be desirable, from both scientific and engineering standpoints, to determine the active sites and elementary reaction pathways of the chemical looping reactions, but such tasks can be daunting due to the highly dynamic nature of chemical looping reactions.…”

Section: View Article Onlinementioning

confidence: 99%

Chemical looping beyond combustion – a perspective

Zhu

Imtiaz

Donat

et al. 2020

Energy Environ. Sci.

349

179

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“…[4][5][6][7][8][9] Although catalysts that contain these non-noble metal components have recently been intensively studied, practical systems still need large amounts of PGMs, such as Pd, Rh, and Pt in order to meet the very strict regulations for controlling exhaust gas emissions. [10][11][12][13] Modern commercial three-way catalysts generally consist of Pd-and Rh-based catalysts, 14,15 and therefore, the design and development of effective catalytic supports is necessary in order to maximize the activity of PGMs, especially Pd and Rh. Among various candidates for TWC supports, La-loaded Al 2 O 3 (La/Al 2 O 3 ) is one of the most wellknown and used industrial supports.…”

Section: Introductionmentioning

confidence: 99%

Promotional Effect of La in the Three-Way Catalysis of La-Loaded Al₂O₃-Supported Pd Catalysts (Pd/La/Al₂O₃)

et al. 2019

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La-loaded Al 2 O 3 (La/Al 2 O 3 ) is a practical support for three-way catalysis (TWC) reactions. Although it has been reported that the addition of La to Al 2 O 3 results in improved thermal stability to retain high specific surface areas, its effect on the catalytic reduction of NO x (DeNO x ) has not been studied systematically. Herein, we describe the role of La in La/Al 2 O 3 -supported Pd catalysts (Pd/La/Al 2 O 3 ) for TWC reactions. For that purpose, we employed various in situ spectroscopic studies, including IR, XAFS, and near-ambient-pressure XPS (NAP-XPS), in combination with DFT calculations. The obtained results revealed that Pd 0 species supported on La/Al 2 O 3 are more electron deficient compared to those on pristine Al 2 O 3 without La (Pd/Al 2 O 3 ). Kinetic studies using powdered catalysts revealed that the addition of La suppresses the poisoning effect by CO during the DeNO x reactions.In addition to the catalytic tests with powdered catalysts, monolithic honeycomb forms of the catalysts were prepared and employed for TWC reactions, which showed that Pd/La/Al 2 O 3 exhibits higher DeNO x activity than Pd/Al 2 O 3 . In this study, we also reexamined the effective loading amount of La, which has traditionally been ~3-5 wt% of La for TWC processes in order to retain the high specific surface area of the La/Al 2 O 3 supports. Our investigations showed that an increased La loading (15 wt%) is even more effective for the DeNO x reactions tested in this study due to the higher reactivity toward NO and the greater suppression of the poisoning effect of CO. The developed catalyst Pd/La(15)/Al 2 O 3 has also been tested in a commercial vehicle and been evaluated on a practical driving mode test cycle (LA-4; city cycle of US Federal and California), where it showed a better catalytic performance than the conventionally used Pd/La(3-5)/Al 2 O 3 catalysts. Our study suggests that the loading amount of La in Pd/La/Al 2 O 3 catalysts needs to be adjusted depending on the application systems, considering not only the support stability (surface areas) but also the promotional effect in the TWC process.

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CeO₂-Grafted Mn–Fe Oxide Composites as Alternative Oxygen-Storage Materials for Three-Way Catalysts: Laboratory and Chassis Dynamometer Tests

Cited by 17 publications

References 41 publications

High selectivity epoxidation of ethylene in chemical looping setup

High selectivity epoxidation of ethylene in chemical looping setup

Chemical looping beyond combustion – a perspective

Promotional Effect of La in the Three-Way Catalysis of La-Loaded Al₂O₃-Supported Pd Catalysts (Pd/La/Al₂O₃)

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CeO2-Grafted Mn–Fe Oxide Composites as Alternative Oxygen-Storage Materials for Three-Way Catalysts: Laboratory and Chassis Dynamometer Tests

Cited by 17 publications

References 41 publications

High selectivity epoxidation of ethylene in chemical looping setup

High selectivity epoxidation of ethylene in chemical looping setup

Chemical looping beyond combustion – a perspective

Promotional Effect of La in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3)

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CeO₂-Grafted Mn–Fe Oxide Composites as Alternative Oxygen-Storage Materials for Three-Way Catalysts: Laboratory and Chassis Dynamometer Tests

Promotional Effect of La in the Three-Way Catalysis of La-Loaded Al₂O₃-Supported Pd Catalysts (Pd/La/Al₂O₃)