Marien, José[Université de Liège - ULg > > Chimie générale et chimie physique >]
Crine, Michel[Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires >]
Pirard, Jean-Paul[Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Génie catalytique >]
Léonard, Angélique[Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Opérations physiques unitaires - Département de chimie appliquée >]
[en] Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied in order to optimize the synthesis conditions. The convective air-drying process was used, and the drying duration was studied with regard to the synthesis conditions. The aging time has no effect on the pore texture after 24 h at 90 degrees C or 48 h at 70 C, whatever the R/C value. The synthesis-aging step can be shortened by increasing the temperature. Nevertheless, the pore size tends then to decrease, especially when R/C is high, but this can be counterbalanced by increasing R/C. Moreover, bubbles often appear in the gel at high synthesis temperature, which limits the temperature to about 70 degrees C in the case of monolithic parts. At 70 degrees C and with an air velocity of 2 m/s, the elimination of 90% of the solvent requires 1 h drying when the pore size reaches 400-600 nm, 2.5 h for 50 nm wide pores and 3 h when the pore size decreases to 15-20 nm. The drying duration does not exceed 8 h in all cases and could be shortened by increasing the temperature at the end of the process. (c) 2005 Elsevier B.V. All rights reserved.
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS
[Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Génie catalytique >]
