Catalytic combustion of methane over mesoporous silica supported palladium

Bassil, Joëlle; Albarazi, Abdulkader; Costa, Patrick Da; Boutros, Maya

doi:10.1016/j.cattod.2011.05.026

Cited by 48 publications

(28 citation statements)

References 39 publications

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“…The models were built using structures of silsesquioxane type that simulate the 6 (H 14 Figure S1). The termination of these clusters was achieved by H-Si≡ groups instead of H-O-Si≡ groups, to avoid additional intramolecular hydrogen bonds and unrealistic physico-chemical properties.…”

Section: Theoretical Modelsmentioning

confidence: 99%

“…13 Furthermore palladium supported on acid silica-alumina amorphous mesoporous supports, such as Al-MCM-41 or SBA-15, is an excellent heterogeneous catalyst for the direct oxidation of methane. 7,14 Because of this, supported palladium oxides have been widely studied. [3][4][5][6][7][8][9][10][11][12][13] The oxidation state, dispersion, oxide nature and the morphology of the particles are dependent on the preparation method and on the nature of the support, which complicates the characterization efforts to elucidate the nature of the active site for methane oxidation.…”

Section: Introductionmentioning

confidence: 99%

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Oxidation of Methane to Methanol over Single Site Palladium Oxide Species on Silica: A Mechanistic view from DFT

et al. 2017

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Abstract:A theoretical analysis was carried out on the mechanism of methane oxidation to methanol occurring on single site palladium oxide species [PdO] 2+ supported on a model of Al-MCM-41 silica. Both 6 and 8-membered ring structures were considered to represent the support.The energy profile for each elementary reaction was determined from density functional theory calculations with the OPBE functional. The calculated overall activation energies are close to the experimental values. Our calculations confirm that spin inversion can play a significant role in decreasing the barrier heights for the pathways. Indeed, in this type of reactions we could show a crossing between singlet and triplet reaction paths. We showed that the mechanism for the C-H bond cleavage and for the formation of methanol has a radical nature. According to our results, the [PdO] 2+ species located on a 8-membered ring of silica is more active than that deposited on a 6-membered ring. The calculated activation energies to cleave the methane C-H bond are 35 and 84 kJ/mol for the radical and ionic pathways, respectively. The activation barrier and the transition state geometry of this H-abstraction step are directly correlated with the optimal angle at which the substrate should approach the [Pd=O] 2+ moiety, with the elongation of the Pd-O oxo bond and finally with the energy of the π* acceptor orbital.2

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Section: Theoretical Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oxidation of Methane to Methanol over Single Site Palladium Oxide Species on Silica: A Mechanistic view from DFT

et al. 2017

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“…More recently, templated mesoporous silicas of MCM-41 and SBA-15 types with pore varying from 2 to 120 nm were also investigated to support palladium for methane combustion [4,[12][13][14]. Their attractiveness lies in their high surface area and relatively large mesopores that favor diffusion of molecules in comparison to microporous zeolites and their micropores smaller than 1.5 nm [15].…”

mentioning

confidence: 98%

“…This difficulty is overcome using a catalytic route where palladium oxide was shown to be the most efficient among other metals and phases [2,3]. Various Pd-supported catalysts were studied using conventional supports such as silica and alumina [4,5]. Zeolites were found good supports and the presence of Al 3+ was shown beneficial to the catalytic process [6,7].…”

mentioning

confidence: 98%

Surface engineering and palladium dispersion in MCM-41 for methane oxidation

Zribi

Albela

Bonneviot

et al. 2015

Applied Catalysis A: General

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“…For the catalytic combustion of CH 4 in lean conditions many different catalysts have been studied so far, ranging from noble metals, mainly Pd and/or Pt supported on oxides or mixed oxides [12][13][14][15], to perovskites [16][17][18], and non-noble oxides [19,20]. In particular, among non-noble oxides in recent years cobalt oxides attracted great attention thanks to their catalytic properties, useful in many different applications, for example as magnetic materials [21,22], electrochemical devices [23,24], and various catalytic systems [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

et al. 2016

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In this work a series of cobalt spinel catalysts was synthesized by different methods and doped with 1 wt% of palladium via incipient wetness impregnation or solution combustion synthesis (SCS). Both undoped and Pd-doped spinels were characterized from the structural and surface point of view (XRD, XRF, lRS, BET, FESEM) and tested toward the oxidation of methane in lean conditions, in gas mixtures containing from 0.5 to 2 vol% of CH 4 . These methane concentrations are typical of processes involving combustion of CH 4 in lean conditions as the after-treatment of unconverted CH 4 in compressed natural gas-fed vehicle exhausts, or the treatment of fugitive CH 4 from leaks in coal mines. The temperature window for the catalytic activity of the undoped Co 3 O 4 materials spread from 350 to 600°C. The preparation method affected the catalytic activity of undoped Co 3 O 4 , with the best catalytic activity related to the spinel prepared by SCS employing urea. The addition of 1 wt% of Pd lowered the temperature window for the catalytic activity to the range of 250-500°C, with insignificant differences for the various preparation methods. The beneficial effect of Pd-doping was assigned to the enhancement of the reduction of cobalt in the oxide structure.

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Catalytic combustion of methane over mesoporous silica supported palladium

Cited by 48 publications

References 39 publications

Oxidation of Methane to Methanol over Single Site Palladium Oxide Species on Silica: A Mechanistic view from DFT

Oxidation of Methane to Methanol over Single Site Palladium Oxide Species on Silica: A Mechanistic view from DFT

Surface engineering and palladium dispersion in MCM-41 for methane oxidation

The Effect of the Preparation Method of Pd-Doped Cobalt Spinel on the Catalytic Activity in Methane Oxidation Under Lean Fuel Conditions

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