Spatial activity profiling along a fixed bed of powder catalyst during selective oxidation of propylene to acrolein. Issue 17 (21st June 2021)

• Record Type: Journal Article
• Authors: Stehle, Matthias; Sheppard, Thomas L.; Thomann, Michael; Fischer, Achim; Besser, Heino; Pfleging, Wilhelm; Grunwaldt, Jan-Dierk
• Is Part Of: Catalysis science & technology. Volume 11:Issue 17(2021)
• Page Start: 5781
• Page End: 5790
• Publication Date: 2021-06-21
• Subjects: Catalysis -- Periodicals; 541.395
• DOI: 10.1039/d1cy00553g
• Languages: English
• ISSNs: 2044-4753

Abstract

Abstract : Spatially resolved activity profiling along a fixed bed of powder catalyst during selective oxidation of propylene to acrolein revealed gradients in the gas phase composition and temperature, and thus the reaction network. Abstract : Spatial profiling of the reactant and product concentration including the gas phase temperature during the selective oxidation of propylene to acrolein along a catalyst bed allowed locating and distinguishing between specific processes occurring in each individual point of a chemical reactor. For this purpose, a lab-scale testing setup capable of resolving concentration and temperature gradients in a fixed-bed reactor was developed. The local gas phase composition and temperature were determined using a sampling capillary and mass spectrometry along a multicomponent Bi–Mo–Co–Fe oxide catalyst bed during selective oxidation of propylene to acrolein under high conversion conditions. In this way, the reaction progress in terms of conversion, selectivities and yields along the reactor was revealed. While ca. 66% of the integral propylene conversion occurred in the first third of the catalyst bed with high selectivity towards acrolein, the latter third of the bed was dominated by the formation of acrylic acid and CO2 as further and total oxidation products, respectively. Acrylic acid, which originates from the sequential oxidation of propylene to acrolein, was the by-product with the highest yield and especially formed above 440 °C. CO and CO2 were observed directly from propylene, along with consecutive pathways of propylene oxidation, which favor CO2 formation. The numerous insights obtained by even a single profile highlight the strong capabilities of spatially resolved activity and temperature measurements for diagnostics of packed-bed reactors and identifying the reaction pathways occurring within.