Outstanding Methane Oxidation Performance of Palladium‐Embedded Ceria Catalysts Prepared by a One‐Step Dry Ball‐Milling Method

Danielis, Maila; Colussi, Sara; Leitenburg, Carla de; Soler, Lluís; Llorca, Jordi; Trovarelli, Alessandro

doi:10.1002/anie.201805929

Cited by 130 publications

(132 citation statements)

References 35 publications

(14 reference statements)

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“…However,m echanochemical activation has not only been used to prepare catalytic materials with properties that match those of heterogeneous catalysts made by conventional methods (e.g.s ol-gel method, co-precipitation, wetness impregnation, etc. ): [25] In numerous cases,b all milling has proven fundamental in designing and improving the interface of solid catalysts, [26] boosting their catalytic and redox behavior, [27] increasing their dispersion on the catalyst matrix surface, [28] enriching the mesoporosity of the solid material, [29] and tempering the thermal conditions required for the heterogeneous catalyst to perform. [26] Although the large majority of the catalysts synthesized by mechanochemistry have been tested in experiments with controlled microreactors,s uch as fixed-bed catalytic reactors, [24] there have been reports where the catalytic activity of the solid materials for reactions at the interface of solid-gas systems was assessed under the application of am echanical force.B elow,w ew ill discuss some of these recent examples,a lthough this is not acomprehensive list.…”

Section: Mechanosynthesis and Use Of Heterogeneous Catalysts With Balmentioning

confidence: 99%

Mechanochemistry of Gaseous Reactants

2019

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In recent years, the application of mechanical energy to chemical systems has repeatedly proven beneficial to facilitate chemical transformations in various areas in chemistry. Today, a systematic body of evidence indicates that mechanochemistry holds great promise to become a game‐changer in chemical synthesis. Not only does mechanochemistry permit access to products that are inaccessible by established means (e.g. purely thermal activation), mechanochemical reactions often outperform their solution‐based counterparts in terms of sustainability. Most mechanochemical reactions carried out by ball milling techniques involve transformations of solids and liquids, but the number of mechanochemical reactions with gaseous reactants is increasing. The aim of this Minireview is to provide an overview of recent chemical reactions involving gaseous samples by ball milling techniques and to highlight advances in ball milling technology for the safe handling of gaseous reagents. Examples of reactions proceeding at the interface of solid–/liquid–/gas–gas systems that led to significant improvements in reactivity or selectivity will also be highlighted.

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Section: Mechanosynthesis and Use Of Heterogeneous Catalysts With Balmentioning

confidence: 99%

Mechanochemistry of Gaseous Reactants

2019

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“…It is not surprising that the quest for effective low‐temperature methane oxidation catalysts has focused mainly on systems involving precious metals, such as platinum and palladium . Metal oxide–supported PdO catalysts are generally considered to represent the state of the art for methane combustion catalysts . Recent research in this field has focused on improving activity at low temperatures, reducing the required loading of metal and improving the thermal and hydrothermal stability of PdO catalysts .…”

Section: Introductionmentioning

confidence: 99%

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

Dai

Kumar

Zhu

et al. 2019

Adv Funct Materials

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Bowtie-shaped NiCo 2 O 4 nanostructures are prepared using a hydrothermal method. Variation of the synthesis parameters, including reaction time, additives, and calcination temperature, allows an understanding of the origin of the bowtie-shaped structure to be developed. Methane oxidation experiments performed using temperature-programed oxidation (TPO) show that the new materials, which do not contain precious metals, have excellent activity for low-temperature methane combustion, with 100% conversion at ≈410 °C (gas hourly space velocity (GHSV): 90 000 mL (STP) g −1 h −1 ). The structure-activity relationships of the bowtie-shaped nanostructures are explored. The relatively low exhaust temperature in NGVs means that the activation of methane, which has the strongest CH bond of any hydrocarbon, is challenging from a chemical perspective. It is not surprising that the quest for effective lowtemperature methane oxidation catalysts has focused mainly on systems involving precious metals, such as platinum and palladium. [11][12][13][14][15] Metal oxidesupported PdO catalysts are generally considered to represent the state of the art for methane combustion catalysts. [16][17][18][19][20] Recent research in this field has focused on improving activity at low temperatures, [21,22] reducing the required loading of metal [23,24] and improving the thermal and hydrothermal stability of PdO catalysts. [25][26][27][28][29][30] Exciting recent advances include the development of core-shell Pd@CeO 2 catalysts with high activity and thermal stability, demonstrating complete conversion to CO 2 below 400 °C (gas hourly space velocity (GHSV) = 200 000 mL g −1 h −1 ). [21] Pd@ZrO 2 /Si-Al 2 O 3 catalysts that are stable in the presence of high concentrations of water vapor have also been proposed recently. [25] NiO@PdO/Al 2 O 3 catalysts that show good activity and stability with only 0.2 wt% Pd loading have been prepared [23] as well as Pd-based bimetallic nanocrystalline catalysts, in which the promotional effects of different transition metals have been examined. [26] Although Pd-based catalysts show excellent activity, the high price and low abundance of palladium are limiting factors to practical application, [31] and both the hydrothermal stability and SO 2 tolerance for these catalysts need to be improved. For this reason, the development of alternative catalysts based on non-noble metals is attractive. [32] These include single metal oxide-based catalysts (CuO, [33] Co 3 O 4 , [34] and MnO 2 [35] ), perovskite, [36,37] spinel, [38,39] and hexaaluminate [40] catalysts. Among these, Co 3 O 4 exhibits good activity for methane combustion attributed to a spinel-type structure with variable Co oxidation states and a high density of oxygen vacancies on the surface. [41] Additionally, the specific exposed facets and morphology of Co 3 O 4 plays an important role in the catalysis. [42,43] Materials with exposed (110) planes show enhanced catalytic activity for methane oxidation compared with those only exposing (100) or (111) face...

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“…and its inherent existence of the stable Ce 3+ /Ce 4+ redox pair could cause strong interactions with either noble metal or transition metal ions. [41][42][43][44] The larger amount of interfaces the hybrids have, the more active they should be if it follows a reaction mechanism related to defect or lattice oxygen. [45,46] Pd/ Co 3 O 4 came into our field of vision again arising from a new discovery from our recent experiments on CeO 2 as the catalytic assistant.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance Ultrathin Co₃O₄ Nanosheet Supported PdO/CeO₂ Catalysts for Methane Combustion

Liu

Feng

et al. 2019

Advanced Energy Materials

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As one of the most important noble metals, Pd species including Pd 0 and PdO x based catalysts have exhibited excellent catalytic activity toward methane combustion at relatively low temperatures. [2,3] During manufacturing applications the active Pd species were usually loaded on metal oxides (MO x ) supports via the traditional deposition precipitation [4,5] or impregnation [6,7] methods in which good Pd dispersion could result in ideal initial catalytic activity. However, these strategies brought an obvious drawback that the as-obtained Pd nanocatalysts with overexposed active centers often exhibited unsatisfied thermal stability caused by sintering. To solve this problem, kinds of Pd@MO x core(yolk)@shell nanostructures [8][9][10] and Pd-metal alloys [11][12][13] have been successfully investigated to improve anti-sintering ability of Pd despite the catalytic active centers might be partially blocked, so it seems hard to reconcile activity and stability. Moreover, most of the Pd@MO x core@shell nanostructures and Pd-metal alloys are prepared by toxic and complex organic routes that limit mass production for application.From a widely accepted viewpoint of catalysts design, there should be enough exposed active centers and highly dispersed Pd species as catalytic sites, strong coupling between Pd and MO x to produce effective synergistic effects, [14,15] and welldefined MO x nanostructures as supports to get large specific surface areas and rational pore distributions. [16][17][18][19][20] Obviously, the properties of MO x supports greatly determined the final performance of Pd catalysts. [21,22] 2D nanosheets (NSs) have been considered as good supports to anchor Pd, which are of large aspect ratios and high specific surface areas. [23][24][25] Such 2D material supported hybrid nanocatalysts have been successfully used in photocatalysis [26] and electocatalysis, [27,28] showing potential applications for renewable energy production and environment remediation. [29,30] However here comes a new question that these reported ultrathin 2D NSs are mainly based on carbon materials, [31,32] metal chalcogenide, [33] and transition metal hydroxides [34,35] that are hard to survive from calcination caused by thermal decomposition and meanwhile transformed into oxides. As a result, the initial 2D nanostructures were thoroughly damaged into heavily aggregated nanoparticles (NPs), leading to bad catalytic performance during heterogeneous catalysts.For years we have been focusing on preparation of noble metal or MO x catalysts with well-defined nanostructures via nonorganic routes, especially for those CeO 2 encapsulated ones. [36][37][38][39][40] CeO 2 is of excellent oxygen storage/release capacity, Efficient utilization of methane via catalytic complete combustion is a very important pathway to realize energy efficiency and pollution reduction. From the viewpoint of structural design, herein a green water-phase route is developed to prepare ultrathin Co(OH) 2 nanosheet supported Pd catalysts. As a platform, the as-obtained...

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Outstanding Methane Oxidation Performance of Palladium‐Embedded Ceria Catalysts Prepared by a One‐Step Dry Ball‐Milling Method

Cited by 130 publications

References 35 publications

Mechanochemistry of Gaseous Reactants

Mechanochemistry of Gaseous Reactants

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

High‐Performance Ultrathin Co₃O₄ Nanosheet Supported PdO/CeO₂ Catalysts for Methane Combustion

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Outstanding Methane Oxidation Performance of Palladium‐Embedded Ceria Catalysts Prepared by a One‐Step Dry Ball‐Milling Method

Cited by 130 publications

References 35 publications

Mechanochemistry of Gaseous Reactants

Mechanochemistry of Gaseous Reactants

Bowtie‐Shaped NiCo2O4 Catalysts for Low‐Temperature Methane Combustion

High‐Performance Ultrathin Co3O4 Nanosheet Supported PdO/CeO2 Catalysts for Methane Combustion

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Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

High‐Performance Ultrathin Co₃O₄ Nanosheet Supported PdO/CeO₂ Catalysts for Methane Combustion