Partial oxidation of methane over potassium cerium molten carbonates
This presentation is the property of its rightful owner.
Sponsored Links
1 / 1

PARTIAL OXIDATION OF METHANE OVER POTASSIUM-CERIUM MOLTEN CARBONATES PowerPoint PPT Presentation


  • 76 Views
  • Uploaded on
  • Presentation posted in: General

G. Lopes , A. Ferreira, A. P. Gonçalves and J. B. Branco Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2686-953 Sacavém, Portugal Unidade de Ciências Químicas e Radiofarmacêuticas. Introduction and Objective.

Download Presentation

PARTIAL OXIDATION OF METHANE OVER POTASSIUM-CERIUM MOLTEN CARBONATES

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Partial oxidation of methane over potassium cerium molten carbonates

G. Lopes, A. Ferreira, A. P. Gonçalves and J. B. Branco

Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2686-953 Sacavém, Portugal

Unidade de Ciências Químicas e Radiofarmacêuticas

Introduction and Objective

The applications of molten salts have been well recognized for more than a century. In spite of the use of high temperature corrosive liquids, molten salts offer unique opportunities. Low temperature multi component molten salts, as well as room temperature ionic liquids have been developed for materials processing. Currently, molten salts are finding applications in fuel cell technology, in the field of separation processes of minor actinides from the rest of the fission products that are contained in the irradiated nuclear fuel, for the direct catalytic conversion of methane under mild conditions and the partial oxidation of methane to synthesis gas [1]. Here, we report the synthesis, characterization and behaviour for the partial oxidation of methane of potassium-cerium (K-Ce) molten carbonates.

Experimental

All experiments were carried out using an K2CO3-Li2CO3 (50:50 wt.%) eutectic mixture (T=600 ºC) as solvent and the cerium molten carbonates prepared by the addition to this mixture of an appropriate amounts of Ce2(CO3)3 (5 and 15 wt.%). The molten salts were characterized by Differential Scanning Calorimetry (PAC-ATD ADI prototype, DSC recorded under argon-50 mL/min, 20 oC (hold 15 min) until 1000 oC at a 10 oC/ min heating rate), X-Ray Powder Diffraction (XRD, reflection geometry with a PANalitycalX’Pert Pro diffractometer using Cu, ka monochromatic radiation l=1.5406 Å), Infrared Spectroscopy (IR, recorded on a Bruker spectrometer with samples mounted as Nujol mulls) as well as Elemental Analysis (C,H,N, S and O, performed on a CE instrument EA1110 automatic analyzer).

PARTIAL OXIDATION OF METHANE OVER POTASSIUM-CERIUM MOLTEN CARBONATES

Catalysts Characterization

DSC tests before catalytic test

XRD patterns for the molten salts

  • XRD tests were performed before and after the catalytic tests.

  • The melting of the salts leads to the CeO2formation.

Phase diagram for the eutectic mixture

  • Melting temperatures between 484 ºC and 506 ºC;

  • The addition and increase of cerium % decreases the transition temperature

IR results for the molten salts

DSC tests after catalytic test

  • New features are not seen before and after the catalytic reaction.

  • Slight contraction of the CeO2 lattice is observed.

  • Characteristic bands of CO3.

Catalytic Results

The study of the Gas Hourly Space Velocity (GHSV, mL of CH4 / g of catalyst. h) and CH4 / O2 molar ratio was undertaken. The outlet gas composition was analyzed on-line by gas chromatography (GC) with a thermal conductivity detector (TCD). Catalyst activity was defined as the number of mL of methane converted per g of catalyst and per hour (mLCH4/g.h), m≈25 g.

  • New features are not seen before and after the catalytic reaction.

  • Slight contraction of the CeO2 lattice is observed.

Effect of GHSV at CH4/O2 molar ratio = 2

Effect of CH4/O2 molar ratio at GHSV= 8520

Selectivity results for GHSV = 2863 and CH4/O2 molar ratio = 2

  • Lower GHSV and CH4/O2 molar ratio influences the catalyst

  • activity. CO2 is the only product of the reaction.

  • Conversion of methane increases with the increase

  • of the cerium amount.

  • Molten carbonate with 15% Ce is the only that

  • shows selectivities to hydrocarbons

References

Acknowledgements

[1] a) B. Mishraet al., Journal of Physics and Chemistry of Solids, 2005, 66, 396; b) T.R. Griffiths et al., Journal of Alloys and Compounds, 2006, 418, 116; c) J.J.Peng, et al., Applied Catalysis A: General, 2000, 201, L55; d) Y.G. Wei, et al., Journal of Natural Gas Chemistry, 2007, 16, 6.

This work was supported by FCT, under contract number PTDC/QUI/72290/2006


  • Login