Low temperature catalytic activity of cobalt oxide and ceria promoted Pt and Pd: -influence of pretreatment and gas composition

Metal nickel and copper grids are shown to be suitable supports for structured combustion catalysts. The increase of specific surface area (SSA) of metal grids was achieved due to the porous outer layer with the structure of Raney metal developed on the wire surface. Transition metals (Co, Cu, Mn, Cr) oxides were deposited as active components on the pre-oxidized support and tested in total propane oxidation. Cobalt oxide demonstrated the highest activity. Reductive pre-treatment in the flow of hydrogen resulted in a more active catalyst than the activation in oxygen atmosphere. This effect was assigned to the partial reduction of Co 3 O 4 until metallic Co, which was detected by XPS on the catalyst surface. Deactivation of the pre-reduced Co-oxide catalyst was observed during propane combustion in excess of oxygen and was ascribed to the oxidation of partially reduced active phase. After 4 h on stream, the catalyst reached his steady-state and showed stable activity without further deactivation. The catalytic activity expressed in the terms of propane conversion was observed to depend on the propane/oxygen ratio.

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“…This agrees with the results reported by different authors [1,2,[9][10][11][12][13][14][15] for total oxidation of hydrocarbons:…”

Section: Catalyst Screeningsupporting

confidence: 93%

Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

Yuranov

Dunand

Kiwi‐Minsker

et al. 2002

Applied Catalysis B: Environmental

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“…As reported by different authors [6,[22][23][24], cobalt oxide based catalysts generally are very active in total hydrocarbon oxidation. However, their activity depends on the cobalt oxidation state under the reaction conditions.…”

Section: Propane Combustionmentioning

confidence: 70%

“…However, their activity depends on the cobalt oxidation state under the reaction conditions. In particular, catalytic performance of cobalt oxide is dependent on the propane/oxygen ratio [6,22]. The pre-reduced catalyst demonstrates higher activity and stability in a sto- ichiometric reactant mixture.…”

Section: Propane Combustionmentioning

confidence: 99%

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Structured combustion catalysts based on sintered metal fibre filters

Yuranov

Kiwi‐Minsker

Renken

2003

Applied Catalysis B: Environmental

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Novel efficient structured combustion catalysts based on sintered metal fibre filters (MFF) were developed. To increase specific surface area (SSA), metal fibres were coated by crack-free porous oxide films of SiO 2 , Al 2 O 3 , porous glass, and mesoporous SBA-15 silica. The composite materials presented uniform open macrostructure of the non-treated MFF filters and were suitable supports for deposition of catalytically active phases (Pd, Pt, and Co 3 O 4 ). These catalysts were tested in hydrocarbon (CH 4 , C 3 H 8 ) combustion. Co 3 O 4 supported on MFF without any coating (6.8% Co 3 O 4 /MFF) was the most active for propane total oxidation. At the same time in methane combustion the activity of this catalyst was relatively low. Pd supported on the MFF coated by mesoporous SBA-15 film (0.5% Pd/SBA-15/MFF) demonstrated the highest activity in methane total oxidation due to the high palladium dispersion.The SBA-15 film supported on MFF provided the highest dispersion of the deposited noble metals (Pd, Pt) with an average particle size ∼2.0 nm. The metal nanoparticles formed within the mesopore channels were stable against sintering during calcination and the particle diameter was observed not to exceed the diameter of the silica pores. These catalysts did not undergo deactivation under reaction conditions at temperatures up to 500 • C. On the contrary, the Pd supported on MFF coated by the microporous SiO 2 and Al 2 O 3 films, prepared by sol-gel technique, suffered from metal sintering during the calcination step and also during reaction, demonstrating strong catalyst deactivation.The catalytic filters are suitable materials for assembling different multiple layers to obtain structured catalytic beds with the composition/concentration gradients of active component in the axial direction. The enhanced overall catalytic performance was observed in adiabatic catalytic reactor during propane combustion due to a synergy of the 0.5% Pd/SBA-15/MFF and the 0.5% Pt/SBA-15/MFF catalytic layers assembled in the appropriate order forming gradient catalytic bed.

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“…The particle size of the prepared [12]. The data showed that the apparent area under peaks for Pt/TiO 2 is larger than that for PtCe 0.1 /TiO 2 indicating that the dispersion of Pt in the former is higher than that in the later [11].…”

Section: Resultsmentioning

confidence: 96%

Adsorption of CO and NO on Ceria- and Pt-Supported TiO<sub>2</sub>: <i>In Situ</i> FTIR Study

El‐Bahy¹

2013

MRC

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Pt/TiO 2 , Ce/TiO 2 and binary system PtCe/TiO 2 catalysts were prepared by impregnation method and the structural properties of these catalysts were investigated by means of XRD, CO-TPD and UV-vis diffuse reflectance spectroscopy. As investigated by XRD, the composition of the prepared samples anatase and rutile phases with higher amount of anatase phase and its particle size was in the range of 19 -22 nm. The band gap also decreased from 3.1 to 2.85 after addition of metal to TiO 2 . The adsorption and interaction properties of NO and/or CO gases were monitored using an in situ FTIR technique. The intensity and position of the infrared peaks were strongly dependent on the composition of the catalyst. In presence of Pt, the main oxidative reductive products of (NO + CO) are CO 2 and NCO complex. The formation of NCO depends on not only the presence of platinum in the catalyst but also the presence of Lewis acid sites which is Ti 4+ in this study. However, the interaction between NO and CO gases increased in presence of CeO 2 . The optimum Ce content in PtCe/TiO 2 was 0.1% (Ce/TiO 2 ) at which the maximum peak intensity was observed for NCO and CO 2 .

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Low temperature catalytic activity of cobalt oxide and ceria promoted Pt and Pd: -influence of pretreatment and gas composition

Cited by 120 publications

References 12 publications

Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

Structured combustion catalysts based on sintered metal fibre filters

Adsorption of CO and NO on Ceria- and Pt-Supported TiO<sub>2</sub>: <i>In Situ</i> FTIR Study

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Low temperature catalytic activity of cobalt oxide and ceria promoted Pt and Pd: -influence of pretreatment and gas composition

Cited by 120 publications

References 12 publications

Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

Metal grids with high-porous surface as structured catalysts: preparation, characterization and activity in propane total oxidation

Structured combustion catalysts based on sintered metal fibre filters

Adsorption of CO and NO on Ceria- and Pt-Supported TiO&lt;sub&gt;2&lt;/sub&gt;: &lt;i&gt;In Situ&lt;/i&gt; FTIR Study

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Adsorption of CO and NO on Ceria- and Pt-Supported TiO<sub>2</sub>: <i>In Situ</i> FTIR Study