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In situ analysis of gas phase reaction processes within monolithic catalyst supports by applying NMR imaging methods

Paper ID Volume ID Publish Year Pages File Format Full-Text
53226 46955 2016 8 PDF Available
Title
In situ analysis of gas phase reaction processes within monolithic catalyst supports by applying NMR imaging methods
Abstract

•3D MRSI is employed to study gas phase reactions.•In situ spatial mapping of chemical composition is shown inside catalytic monoliths.•Dependencies between concentration profiles and catalytic monoliths are shown.•The measured concentration profiles are compared to a model of the reactor.

Measuring spatially resolved concentration distributions in gas phase reaction systems is an important tool to validate simulation calculations, improve the understanding of transport processes within the catalyst, and identify potentials for improvements of monolithic catalyst supports. The commonly used measurement methods for such opaque systems are invasive and, thus, might be misleading due to alteration of the system.To overcome this issue, a 3D magnetic resonance spectroscopic imaging (MRSI) method was developed and implemented on a 7-Tesla NMR imaging system to map the concentration distributions within opaque monolithic catalysts using the ethylene hydrogenation process as case study. The reaction was catalyzed by a coated sponge packing or a honeycomb monolith within an NMR compatible packed bed reactor. Temperatures at the inlet and the outlet of the catalyst beds were simultaneously determined by analyzing the spectra of inserted ethylene glycol filled glass capsules. Steady state concentration profiles and temperature levels were measured at different reaction conditions. In order to prove the plausibility of the measured spatial distributions of compound concentrations, the experimental results were compared to a 1D model of the reactor based on kinetic data from literature. Furthermore, a comparison with integral concentration measurements using a mass spectrometer demonstrated deviations below 5%. The results show that 3D MRSI is a valuable and reliable tool to non-invasively measure spatially resolved process parameters within optically and/or mechanically inaccessible structured monolithic catalyst supports, even if only standard thermal polarization is exploited and the use of expensive and technically challenging signal enhancement techniques (hyperpolarization) is avoided. We expect that 3D MRSI can pave the way toward deeper insight into the interactions between catalyst, catalyst support, and gas phase.

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Keywords
3D magnetic resonance spectroscopic imaging; Catalytic monolith; Gas phase reaction; Non-invasive concentration measurement
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In situ analysis of gas phase reaction processes within monolithic catalyst supports by applying NMR imaging methods
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 273, 15 September 2016, Pages 91–98
Authors
, , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us