Effect of drying rate on the performance of Pt-Sn-K/γ-Al2O3 catalyst for propane dehydrogenation

The dehydrogenation of propane to propylene over Pt-Sn-K/γ-Al2O3 catalysts prepared by sequential impregnation was studied. Three drying rates of 5, 10 and 15 °C/min were applied after the incipient wetness impregnation of the support (1.6-1.8 mm in diameter) with KNO3. The obtained catalysts were characterized by N2 physisorption, SEM-EDAX analysis and XRF for textural and chemical properties. Catalytic performance tests were performed in a fixed-bed quartz reactor under kinetically controlled conditions for the proper catalyst screening. The EDAX measurement results illustrated that the potassium concentration profile changed with the drying rate and the catalyst prepared by the lower drying rate exhibited the highest K concentration at the center and the highest propylene yield. These were attributed to the retraction of the impregnation solution during drying at slow rates which results in a lower concentration of acidic sites in the catalyst center, thereby reducing the contact time of the propylene product with strong acid sites during the reaction.