Atypical stability of exsolved Ni-Fe alloy nanoparticles on double layered perovskite for CO2 dry reforming of methane

Yao, Xueli; Cheng, Qingpeng; Yerrayya, Attada; Ould‐Chikh, Samy; Ramírez, Adrián; Bai, Xueqin; Mohamed, Hend Omar; Li, Guanxing; Shterk, Genrikh; Zheng, Lirong; Gascón, Jorge; Han, Yu; Bakr, Osman M.; Castaño, Pedro

doi:10.1016/j.apcatb.2023.122479

Cited by 28 publications

(22 citation statements)

References 75 publications

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“…Examples of studies using ∼2−4 wt % active metal resulted in conversions ranging between 45% and 80% CH 4 and 70%−93% CO 2 ; however, deactivation, mainly due to coke formation, was always observed. 28,39,50,51 Our system, doped with only 0.4 wt % Ir, showed conversions of 82% CH 4 and 86% CO 2 , without any coke deposition. Therefore, the use of a very dilute amount of Ir proved to be more effective than using Ni alone or combining Ni with another noble metal.…”

Section: ■ Conclusionmentioning

confidence: 88%

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO₂ Reforming of Methane

Calì,

Saini,

Kerherve

et al. 2023

ACS Appl. Nano Mater.

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The reforming reactions of greenhouse gases require catalysts with high reactivity, coking resistance, and structural stability for efficient and durable use. Among the possible strategies, exsolution has been shown to demonstrate the requirements needed to produce appropriate catalysts for the dry reforming of methane, the conversion of which strongly depends on the choice of active species, its interaction with the support, and the catalyst size and dispersion properties. Here, we exploit the exsolution approach, known to produce stable and highly active nanoparticle-supported catalysts, to develop iridium-nanoparticle-decorated perovskites and apply them as catalysts for the dry reforming of methane. By studying the effect of several parameters, we tune the degree of exsolution, and consequently the catalytic activity, thereby identifying the most efficient sample, 0.5 atomic % Ir-BaTiO 3 , which showed 82% and 86% conversion of CO 2 and CH 4 , respectively. By comparison with standard impregnated catalysts (e.g., Ir/Al 2 O 3 ), we benchmark the activity and stability of our exsolved systems. We find almost identical conversion and syngas rates of formation but observe no carbon deposition for the exsolved samples after catalytic testing; such deposition was significant for the traditionally prepared impregnated Ir/Al 2 O 3 , with almost 30 mg C /g sample measured, compared to 0 mg C /g sample detected for the exsolved system. These findings highlight the possibility of achieving in a single step the mutual interaction of the parameters enhancing the catalytic efficiency, leading to a promising pathway for the design of catalysts for reforming reactions.

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Section: ■ Conclusionmentioning

confidence: 88%

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO₂ Reforming of Methane

Calì,

Saini,

Kerherve

et al. 2023

ACS Appl. Nano Mater.

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“…This assumption is wrong in some conditions where the conversion is greater than 10%. The H 2 /CO ratio of the catalysts (Figure S10) was all lower than one, mainly due to the existence of the reverse water gas shift reaction, 20 which is one of the main side reactions under DRM conditions. Moreover, the H 2 /CO ratio reached a stable status at the end of the test except for the R350 catalyst (Figure S10a), which was continuously decreasing.…”

Section: Catalyst Propertiesmentioning

confidence: 98%

“…Specifically, the changes of representative intermediates along with the time are shown in Figure 9 panels c and d. The DRIFTS bands ascribed to CO 2 (g) 18,20 from 2250 to 2450 cm −1 and surface −OH groups 34,51 from 3500 to 3700 cm −1 are shown after being exposed to CO 2 . No bands assigned to carbonate species were detected, reported to be common intermediates for CO 2 adsorption.…”

Section: Effect Of Other Pretreatment Conditionsmentioning

confidence: 99%

“…Nickel-based catalysts have a low price, high availability, and comparable activity. 6 Many methodologies have been applied to improve the coking and sintering resistance of the Ni-based catalyst, including the selection of the support 9−11 and promoters, 12−14 the application of bimetallic Ni catalyst, 15−20 strengthening the metal support interactions, 11,21,22 catalysts like core/yolk shell, 12,23 sandwiched catalyst, 24,25 perovskite, 20,26 and others. Among them, creating a strong metal support interaction (SMSI) between the Ni and the support has been reported to be an effective strategy to improve the thermal and the coke resistance by its unique geometric and electronic properties in DRM.…”

Section: Introductionmentioning

confidence: 99%

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Engineering the TiO_x Overlayer on Ni Catalyst to Balance Conversion and Stability for Methane Dry-CO₂ Reforming

Bai,

Yao,

Cheng

et al. 2023

ACS Sustainable Chem. Eng.

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Ni-supported catalyst is a viable system to convert methane and carbon dioxide into syngas through methane dry reforming, with the main drawbacks of its fast deactivation being sintering and coking. Here, we developed methods to engineer a TiO x overlayer on Ni/TiO 2 catalysts to shield the catalyst against sintering and coking while preserving the Ni accessibility and, thus, conversion. These methods involved altering TiO 2 crystal phases, pretreatment, and reaction conditions in the reforming stage. Through characterization, testing, and operando spectroscopy, we found that the TiO x overlayer with incomplete Ni coverage maintained a balanced conversion and stability by quenching the sintering and coking. Conversely, thick or nonexistent overlayers led to lower conversions or faster deactivation. The formation of TiO x overlayer increased the CO 2 activation capacity and oxygen mobility and protected Ni from sintering by its shield function. At the same time, the reaction pathways remained unchanged despite the TiO x overlayer with different morphologies.

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“…Dry reforming of methane (DRM) is a process that converts two greenhouse gases, methane (CH 4 ) and carbon dioxide (CO 2 ), into syngas, an important intermediate used in well-established routes for the synthesis of various chemicals and fuels. – Metallic nickel (Ni), mainly in the form of nanoparticles, has been extensively studied to catalyze the DRM because of its high C–H activation ability and low cost. ,– However, due to the low Tammann temperature of Ni (581 °C), Ni nanoparticles are prone to sintering at the operating temperatures of DRM, which are typically high (>600 °C) to facilitate the highly endothermic reaction (Δ H 298K ° = 247 kJ mol –1 ); moreover, metallic Ni nanoparticles display close proximity between active sites, which favors successive C–H bond cleavage and subsequent C–C coupling, leading to severe coke formation and thus limited catalyst lifetime. – Strategies employed to mitigate coke formation on Ni catalysts encompass alloying Ni with Mo, carbon doping into the support, and coating with boron nitride …”

Section: Introductionmentioning

confidence: 99%

Highly Efficient and Stable Methane Dry Reforming Enabled by a Single-Site Cationic Ni Catalyst

Cheng,

Yao,

et al. 2023

J. Am. Chem. Soc.

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Zeolite-supported nickel (Ni) catalysts have been extensively studied for the dry reforming of methane (DRM). It is generally believed that prior to or during the reaction, Ni is reduced to a metallic state to act as the catalytic site. Here, we employed a ligand-protected synthesis method to achieve a high degree of Ni incorporation into the framework of the MFI zeolite. The incorporated Ni species retained their cationic nature during the DRM reaction carried out at 600 °C, exhibiting higher apparent catalytic activity and significantly greater catalytic stability in comparison to supported metallic Ni particles at the same loading. From theoretical and experimental evidence, we conclude that the incorporation of Ni into the zeolite framework leads to the formation of metal−oxygen (Ni δ+ −O (2−ξ)− ) pairs, which serve as catalytic active sites, promoting the dissociation of C−H bonds in CH 4 through a mechanism distinct from that of metallic Ni. The conversion of CH 4 on cationic Ni single sites follows the CH x oxidation pathway, which is characterized by the rapid transformation of partial cracking intermediates CH x *, effectively inhibiting coke formation. The presence of the CH x oxidation pathway was experimentally validated by identifying the reaction intermediates. These new mechanistic insights elucidate the exceptional performance of the developed Ni-MFI catalyst and offer guidance for designing more efficient and stable Ni-based DRM catalysts.

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Atypical stability of exsolved Ni-Fe alloy nanoparticles on double layered perovskite for CO2 dry reforming of methane

Cited by 28 publications

References 75 publications

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO₂ Reforming of Methane

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO₂ Reforming of Methane

Engineering the TiO_x Overlayer on Ni Catalyst to Balance Conversion and Stability for Methane Dry-CO₂ Reforming

Highly Efficient and Stable Methane Dry Reforming Enabled by a Single-Site Cationic Ni Catalyst

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Atypical stability of exsolved Ni-Fe alloy nanoparticles on double layered perovskite for CO2 dry reforming of methane

Cited by 28 publications

References 75 publications

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO2 Reforming of Methane

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO2 Reforming of Methane

Engineering the TiOx Overlayer on Ni Catalyst to Balance Conversion and Stability for Methane Dry-CO2 Reforming

Highly Efficient and Stable Methane Dry Reforming Enabled by a Single-Site Cationic Ni Catalyst

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Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO₂ Reforming of Methane

Enhanced Stability of Iridium Nanocatalysts via Exsolution for the CO₂ Reforming of Methane

Engineering the TiO_x Overlayer on Ni Catalyst to Balance Conversion and Stability for Methane Dry-CO₂ Reforming