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48 results on '"Perez-Maqueda, L.A."'

37. Combined kinetic analysis of solid-state reactions: A powerful tool for the simultaneous determination of kinetic parameters and the kinetic model without previous assumptions on the reaction mechanism

Author

Perez-Maqueda, L.A., Criado, J.M., and Sanchez-Jimenez, P.E.

Subjects
Dynamics -- Analysis, Solid state chemistry -- Research, Chemicals, plastics and rubber industries
Abstract

The combined kinetic analysis is modified by using an empirical equation that fits every f[alpha] of the ideal kinetic models and their deviations produced by particle size distributions or heterogeneities in particle morphologies. The proposed procedure has allowed the combined kinetic analysis of data obtained under any experimental conditions without any previous assumptions about the kinetic model followed by the reaction.

Published
2006

41. Nanosilica supported CaO: A regenerable and mechanically hard CO2 sorbent at Ca-looping conditions.

Author

Sanchez-Jimenez, P.E., Perez-Maqueda, L.A., and Valverde, J.M.

Subjects
*SINTERING, *CALCINATION (Heat treatment), *LIME (Minerals), *CALCIUM nitrate, *ULTRASONIC imaging, *IRRADIATION
Abstract

Highlights: [•] A synthetic CO2 sorbent is prepared by impregnation of calcium nitrate on a nanosilica matrix. [•] Sintering of the nascent CaO in the calcination stage of carbonation/calcination cycles is hindered. [•] CaO conversion reaches a stable value well above the residual conversion of natural limestone. [•] Particle fragmentation as caused by ultrasonic irradiation in a liquid dispersion is hindered. [ABSTRACT FROM AUTHOR]

Published
2014
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42. Effect of sonication on the thermal decomposition of ammonium vermiculite as studied by TG-MS hyphenated technique.

Author

Perez-Maqueda, L.A., Poyato, J., and Pérez-Rodríguez, J.L.

Subjects
*VERMICULITE, *AMMONIUM compounds, *PYROLYSIS, *CHEMICAL decomposition, *THERMOGRAVIMETRY, *MASS spectrometry
Abstract

The thermal decomposition of the ammonium exchanged vermiculite takes place in three steps. A strong correlation exists between the mass loss of ammonia and water suggesting a simultaneous release. It is proposed that proton transfer from the ammonium ion to the hydroxyl units results in this simultaneous release. This behaviour could be explained by a mechanism where a resulting proton, produced by the release of ammonia out of ammonium cation, combines with a structural hydroxyl to form water. Sonication produces a substantial reduction in the particle size of the vermiculite sample. Thus, the macroscopic particle size of the untreated material is drastically reduced to the micrometers range while the structure as assayed by XRD remains unchanged. The particle size reduction produced by the sonication treatment modifies the thermal decomposition profile, mainly the mass percentages of the different steps. [ABSTRACT FROM AUTHOR]

Published
2004
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48. Calcium-looping for post-combustion CO2 capture. On the adverse effect of sorbent regeneration under CO2.

Author

Valverde, J.M., Sanchez-Jimenez, P.E., and Perez-Maqueda, L.A.

Subjects
*CALCIUM, *COMBUSTION, *CARBON dioxide, *SORBENTS, *CARBONATION (Chemistry), *CALCINATION (Heat treatment)
Abstract

Highlights: [•] Carbonation/calcination tests are reported in which the sorbent is regenerated under high CO2 partial pressure. [•] A drastic drop of CaO conversion occurs in just a few carbonation/calcination cycles. [•] Recarbonation has an adverse effect. [•] The growth of the CaO crystal structure along reactive oriented surfaces is precluded. [•] The presence of H2O would counteract the adverse effect of regeneration under CO2. [ABSTRACT FROM AUTHOR]

Published
2014
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