Al2O3 and TiO2 supports modified by impregnation with PO4-ions and SAPO-11 and SAPO-34 samples were synthesized and characterized by physico-chemical methods. The acidic properties of these catalysts were determined by ammonia TPD. The gas-phase dehydration of glycerol in presence of water was investigated at 280 degrees C. Glycerol conversion and acrolein selectivity depended on the total acidity and on the textural properties. Additionally, the formation of by-products during the dehydration of glycerol and the conversion of 1-hydroxyacetone and 3-hydroxypropionaldehyde catalysts was studied. The SAPO samples showed high selectivity at low reaction times. Rapid deactivation and formation of carbonaceous deposits was observed for all tested catalysts. The properties of the deactivated catalysts were studied by TPD-NH3 and TPO analysis. (C) 2009 Elsevier B.V. All rights reserved.