Barthe, Laurie and Desportes, Serge
and Steinmetz, Daniel
and Hemati, Mehrdji
Metallic salt deposition on porous particles by dry
impregnation in fluidized bed: Effect of drying conditions
on metallic nanoparticles distribution.
(2009)
Chemical Engineering Research and Design, 87 (7). 915-922. ISSN 0263-8762
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(Document in English)
PDF (Author's version) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader 693kB |
Official URL: http://dx.doi.org/10.1016/J.CHERD.2008.07.002
Abstract
In this paper, the fluidized bed dry impregnation of coarse alumina porous particles by a metallic salt, manganese nitrate, is investigated. In this technique the penetration of each drop of metallic solution in the porous solid particle and solvent evaporation takes place at the same time, then liquid diffusion phenomenon is negligible. So, the metal loading is directly related to the operating time and liquid flow rate and concentration. It is found that the competition between two phenomena, drying and capillary flow, controls the deposit location. In order to determine the importance of the solvent evaporation process compared to the solution penetration by capillarity, an impregnation module, IM, was defined as the ratio between the drying characteristic time and a capillary penetration time. The adequate choice of the operating conditions (bed temperature, liquid and fluidization gas flow rate) allows a uniform deposition of the metallic precursor inside the porous matrix or on the support surface. The impregnation under slow drying conditions (IM ≥ 10 and solvent content in the bed atmosphere τs ≥ 0.2) leads to a homogeneous deposition inside the pores. Under fast drying conditions (IM < 5 and τs < 0.2), the deposit is located at the particle external surface.In the case of slow drying, the impregnation kinetics can be represented by a “shrinking core” model. The critical impregnation rate is controlled by the competition between dissolution and recrystallization at the elementary grain scale. The size of the metal crystallites depends on the pore mean size and size distribution and on the drying rate.
Item Type: | Article |
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Additional Information: | Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at : http://www.sciencedirect.com/science/article/pii/S0263876208002062 |
HAL Id: | hal-03562727 |
Audience (journal): | International peer-reviewed journal |
Uncontrolled Keywords: | |
Institution: | French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE) Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE) Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE) |
Laboratory name: | Laboratoire de Génie Chimique - LGC (Toulouse, France) - Réaction, mélange & séparation (RMS) |
Statistics: | download |
Deposited On: | 15 Jun 2012 10:15 |
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