Catalytic Oxidation of Methane: Pd and Beyond

Monai, Matteo; Montini, Tiziano; Gorte, Raymond J.; Fornasiero, Paolo

doi:10.1002/ejic.201800326

Cited by 119 publications

(96 citation statements)

References 99 publications

(121 reference statements)

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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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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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“…Methane as the main component of natural gas is playing an increasingly important role in the global energy structure [1,2]. Effective catalytic complete oxidation of CH 4 can improve combustion efficiency and reduce air pollutants, such as CO, NO x , and unburned hydrocarbon [3][4][5][6][7][8]. It has therefore found great applications in modern industry, such as catalytic exhaust converters aimed to reduce methane emission and catalytic gas turbine combustors designed to combust fuel under mild conditions [9,10].…”

Section: Introductionmentioning

confidence: 99%

Pd4S/SiO2: A Sulfur-Tolerant Palladium Catalyst for Catalytic Complete Oxidation of Methane

Yuan

Jiang

et al. 2019

Catalysts

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Sulfur species (e.g. H2S or SO2) are the natural enemies of most metal catalysts, especiallypalladium catalysts. The previously reported methods of improving sulfur-tolerance were toeffectively defer the deactivation of palladium catalysts, but could not prevent PdO and carrierinteraction between sulfur species. In this report, novel sulfur-tolerant SiO2 supported Pd4Scatalysts (5 wt. % Pd loading) were prepared by H2S–H2 aqueous bubble method and applied tocatalytic complete oxidation of methane. The catalysts were characterization by X-ray diffraction,Transmission electron microscopy, X-ray photoelectron Spectroscopy, temperature-programmedoxidation, and temperature-programmed desorption techniques under identical conditions. Thestructural characterization revealed that Pd4S and metallic Pd0 were found on the surface of freshlyprepared catalysts. However, Pd4S remained stable while most of metallic Pd0 was converted toPdO during the oxidation reaction. When coexisting with PdO, Pd4S not only protected PdO fromsulfur poisoning, but also determined the catalytic activity. Moreover, the content of Pd4S could beadjusted by changing H2S concentration of H2S–H2 mixture. When H2S concentration was 7 %, thePd4S/SiO2 catalyst was effective in converting 96% of methane at the 400 °C and also exhibitedlong-term stability in the presence of 200 ppm H2S. A Pd4S/SiO2 catalyst that possesses excellentsulfur-tolerance, oxidation stability, and catalytic activity has been developed for catalyticcomplete oxidation of methane.

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“…Thus, the removal of O 2 through reduction is a new, unique challenge for the capture of CO 2 . Of all metals, palladium (Pd) shows superior activity for catalyzing methane combustion in air at mild temperatures (≈400 °C) . Pd has been extensively studied but not used industrially due to its high cost.…”

Section: Introductionmentioning

confidence: 99%

“…Of all metals, palladium (Pd) shows superior activity for catalyzing methane combustion in air at mild temperatures (%400 C). [25,28] Pd has been extensively studied but not used industrially due to its high cost. For automobile emission remediation, Pd is used in catalytic converters to oxidize hydrocarbons.…”

Section: Introductionmentioning

confidence: 99%

Sequential Oxygen Reduction and Adsorption for Carbon Dioxide Purification for Flue Gas Applications

Kuhn

Chen

et al. 2019

Energy Tech

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Sequestration or utilization of carbon dioxide (CO2) produced from fossil fuels depends on the ability to transform flue gas into purified streams. Recent developments in oxy‐combustion have improved the efficiency of energy generation and carbon capture (>90% CO2). The subsequent removal of oxygen (O2) from this flue gas is critical, but such a process is energy intensive, technologically challenging, and unsolved. Herein, a simulated flue gas stream is purified by the catalytic conversion of oxygen using methane (CH4). The supported palladium (Pd) catalyst selectively reduces oxygen to an effluent gas with 99.7% CO2 and 0.3% O2. Using a higher Pd loading has no impact on the oxygen conversion, whereas feeding excess CH4 decreases the selectivity to CO2. A complete removal of O2 is achieved using a copper‐based oxygen scavenger placed after the Pd catalyst bed, yielding a 100.0% pure CO2 stream.

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Catalytic Oxidation of Methane: Pd and Beyond

Cited by 119 publications

References 99 publications

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

Pd4S/SiO2: A Sulfur-Tolerant Palladium Catalyst for Catalytic Complete Oxidation of Methane

Sequential Oxygen Reduction and Adsorption for Carbon Dioxide Purification for Flue Gas Applications

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Catalytic Oxidation of Methane: Pd and Beyond

Cited by 119 publications

References 99 publications

Bowtie‐Shaped NiCo2O4 Catalysts for Low‐Temperature Methane Combustion

Bowtie‐Shaped NiCo2O4 Catalysts for Low‐Temperature Methane Combustion

Pd4S/SiO2: A Sulfur-Tolerant Palladium Catalyst for Catalytic Complete Oxidation of Methane

Sequential Oxygen Reduction and Adsorption for Carbon Dioxide Purification for Flue Gas Applications

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Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion

Bowtie‐Shaped NiCo₂O₄ Catalysts for Low‐Temperature Methane Combustion