Iranian Journal of Chemical Engineering (IJChE)

Abstract The dehydrogenation of propane to propylene over Pt-Sn-K/γ-Al2O3 catalysts prepared by sequential impregnation was studied. Three drying rates, that is, 5, 10 and 15 °C/min were applied after 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 proper catalyst screening. The EDAX measurement results illustrated that the potassium concentration profile changed with drying rate with the catalyst prepared by lower drying rate exhibited highest K concentration at the center as well as highest propylene yield. These were attributed to the retraction of impregnation solution during drying at slow rates which results in lower concentration of acidic sites in catalyst center, thereby reducing the contact time of the propylene product with strong acid sites during reaction.

Abstract In this paper, the experimental data of the onion drying process by a batch cabinet dryer is investigated. Obtained experimental data including moisture content, shrinkage, and rehydration via random factorial scheme are analyzed. Comparison of data average is carried out with the help of the multi amplitude test of Duncan. Statistical analysis of experimental data shows that time, temperature, and their combined effect have a reasonable impact on the moisture content and rehydration value of dried samples. However, a combined effect of time and temperature on the shrinkage value is not meaningful (P>0.05). The results also show that increasing time and temperature leads to a decrease in the moisture content of the samples, but it increases the value of rehydration and the shrinkage of samples.