Cyclic Process for Propylene Production via Oxidative Dehydrogenation of Propane with N2O over FeZSM-5

Abstract

Steam-activated FeZSM-5 (Si/Al = 31.3 and 0.67 wt % Fe) is a highly efficient catalyst for the N2O-mediated oxidative dehydrogenation of propane (ODHP), with propene yields up to 25% at 723 K, but strongly deactivates due to coke formation. Because the initial ODHP performance was recovered upon air-regeneration of the spent catalyst, a process for continuous propylene production via alternation of reaction and regeneration cycles has been evaluated. A tapered element oscillating microbalance (TEOM) coupled to on-line analysis of products has been applied to correlate activity, deactivation, and regeneration of FeZSM-5 by simultaneous measurement of reaction and mass changes. This information was used to optimally design the cyclic process. In a system with five fixed-bed reactors in parallel, stable propene yields >20% were demonstrated during continuous operation for 1500 min (12 cycles), using reaction and regeneration periods of 25 and 90 min, respectively, at the same temperature (723 K). This novel ...