Insight into the structure of supported palladium catalysts during the total oxidation of methane

Grunwaldt, Jan‐Dierk; Vegten, Niels van; Baiker, Alfons

doi:10.1039/b710222d

Cited by 116 publications

(109 citation statements)

References 34 publications

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“…The microreactor was heated with a gas blower (FMB Oxford) from room temperature up to 500°C using a heating rate of 5°C min −1 similar to the setup in ref. 40.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Stability and resistance of nickel catalysts for hydrodeoxygenation: carbon deposition and effects of sulfur, potassium, and chlorine in the feed

Mortensen

Gardini

Carvalho

et al. 2014

Catal. Sci. Technol.

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aThe long term stability and resistance toward carbon deposition, sulfur, chlorine, and potassium of Ni/ZrO 2 as a catalyst for the hydrodeoxygenation (HDO) of guaiacol in 1-octanol (as a model compound system for bio-oil) has been investigated at 250°C and 100 bar in a trickle bed reactor setup. Without impurities in the feed good stability of the Ni/ZrO 2 catalyst could be achieved over more than 100 h of operation, particularly for a sample prepared with small Ni particles, which minimized carbon deposition.Exposing the catalyst to 0.05 wt% sulfur in the feed resulted in rapid deactivation with complete loss of activity due to the formation of nickel sulfide. Exposing Ni/ZrO 2 to chlorine-containing compounds (at a concentration of 0.05 wt% Cl) on-stream led to a steady decrease in activity over 40 h of exposure.Removal of the chlorine species from the feed led to the regaining of activity. Analysis of the spent catalyst revealed that the adsorption of chlorine on the catalyst was completely reversible, but chlorine had caused sintering of nickel particles. In two experiments, potassium, as either KCl or KNO 3 , was impregnated on the catalyst prior to testing. In both cases deactivation was persistent over more than 20 h of testing and severely decreased the deoxygenation activity while the hydrogenation of guaiacol was unaffected. Overall, sulfur was found to be the worst poison, followed by potassium and then chlorine. Thus, removal/limitation of these species from bio-oil is a requirement before long term operation can be achieved with this catalyst.

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“…The microreactor was heated with a gas blower (FMB Oxford) from room temperature up to 500°C using a heating rate of 5°C min −1 similar to the setup in ref. 40.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

Stability and resistance of nickel catalysts for hydrodeoxygenation: carbon deposition and effects of sulfur, potassium, and chlorine in the feed

Mortensen

Gardini

Carvalho

et al. 2014

Catal. Sci. Technol.

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“…For the operando XAS experiments the catalyst sample was diluted with Al 2 O 3 (1:1) and placed into a 1.5-mm quartz glass capillary (100-200 µm sieved fraction, 10 mg, 10 mm catalyst bed) and fixed with quartz wool plugs [72]. Spectra were acquired at the middle of the catalyst bed.…”

Section: Operando Xas Experimentsmentioning

confidence: 99%

Surface Oxidation of Supported Ni Particles and Its Impact on the Catalytic Performance during Dynamically Operated Methanation of CO2

et al. 2017

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Abstract:The methanation of CO 2 within the power-to-gas concept was investigated under fluctuating reaction conditions to gather detailed insight into the structural dynamics of the catalyst. A 10 wt % Ni/Al 2 O 3 catalyst with uniform 3.7 nm metal particles and a dispersion of 21% suitable to investigate structural changes also in a surface-sensitive way was prepared and characterized in detail. Operando quick-scanning X-ray absorption spectroscopy (XAS/QEXAFS) studies were performed to analyze the influence of 30 s and 300 s H 2 interruptions during the methanation of CO 2 in the presence of O 2 impurities (technical CO 2 ). These conditions represent the fluctuating supply of H 2 from renewable energies for the decentralized methanation. Short-term H 2 interruptions led to oxidation of the most reactive low-coordinated metallic Ni sites, which could not be re-reduced fully during the subsequent methanation cycle and accordingly caused deactivation. Detailed evaluation of the extended X-ray absorption fine structure (EXAFS) spectra showed surface oxidation/reduction processes, whereas the core of the Ni particles remained reduced. The 300-s H 2 interruptions resulted in bulk oxidation already after the first cycle and a more pronounced deactivation. These results clearly show the importance and opportunities of investigating the structural dynamics of catalysts to identify their mechanism, especially in power-to-chemicals processes using renewable H 2 .

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“…In all cases, PdO x species appear stable up to 570-580 °C, and fully decomposed above 900-950 °C, values in strong agreement with literature data. 31,32 The maximum decomposition temperature was 791, 733, 847 and 722 °C, for AP6, AP10, ZP6 and ZP10 respectively. Two main points warrant closer analysis.…”

Section: Resultsmentioning

confidence: 99%

“…31,32 However, these techniques are unable to detect traces of either chemical states of palladium. Due to the fact that PdO x is necessary for good catalytic activity, various studies have examined the possibility of controlling and changing PdO x stability, firstly by altering the support material and mean particle diameter of the palladium species, secondly by introducing promoters either on the metal or in the support, and lastly by using a large number of preparation techniques.…”

Section: Introductionmentioning

confidence: 99%

Palladium-supported catalysts in methane combustion: comparison of alumina and zirconia supports

Domingos¹,

Rodrigues²,

Brandão³

et al. 2012

Quím. Nova

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Recebido em 4/8/11; aceito em 6/2/12; publicado na web em 15/5/12Palladium catalysts supported on alumina and zirconia were prepared by the impregnation method and calcined at 600 and 1000 °C. Catalysts were characterized by BET measurements, XRD, XPS, O 2 -TPD and tested in methane combustion through temperature programmed surface reaction. Alumina supported catalysts were slightly more active than zirconia supported catalysts, but after initial heat treatment at 1000 °C, zirconia supported palladium catalyst showed better performance above 500 °C A pattern between temperature interval stability of PdOx species and activity was observed, where better PdOx stability was associated with more active catalysts.

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Insight into the structure of supported palladium catalysts during the total oxidation of methane

Cited by 116 publications

References 34 publications

Stability and resistance of nickel catalysts for hydrodeoxygenation: carbon deposition and effects of sulfur, potassium, and chlorine in the feed

Stability and resistance of nickel catalysts for hydrodeoxygenation: carbon deposition and effects of sulfur, potassium, and chlorine in the feed

Surface Oxidation of Supported Ni Particles and Its Impact on the Catalytic Performance during Dynamically Operated Methanation of CO2

Palladium-supported catalysts in methane combustion: comparison of alumina and zirconia supports

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