Theoretical and experimental evaluation of mass transfer limitation in gas phase dehydration of glycerol to acrolein over supported HSiW catalyst

Abstract

Experimental and theoretical studies were performed to evaluate the existence of internal and external mass transfer limitations in the gas phase glycerol dehydration to acrolein over supported HSiW catalyst. In the experimental method, the internal and external diffusions were determined by varying the gas mass flow-rate (mg), catalyst pellet size (dp), and catalytic bed volume (Vcat). In the theoretical approach the dimensionless parameters such as effectiveness factor (η), Thiele modules (φ1), and overall effectiveness factor (Ω) were calculated. The experimental results indicated no external mass transfer limitation due to constant glycerol conversion (94-97%) at various conditions. In addition, both the theoretical and experimental approaches confirmed no internal mass transfer limitation in glycerol dehydration reaction with catalyst pellet sizes of dp = 2-and 5-μm due to effectiveness factor equal to 1 (η = 1). Calculation of the overall effectiveness factor (Ω) also confirmed the absence of external and internal diffusion in presence of catalysts with pellet size of dp < 13-17 μm.