Observing Chemical Reactions by Time-Resolved High-Resolution Neutron Imaging
(2018) The Journal of Physical Chemistry C — Vol. 122, n° 41, p. 23574-23581 (2018)
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- Authors
Borgschulte, Andreas 
- Abstract
- We developed an operando technique based on time-resolved high-resolution neutron imaging to map the water concentration distribution inside millimeter-sized catalyst beads catalyzing the sorption-enhanced CO2 methanation reaction. By combining the spatially resolved results from neutron microscopy with the space-integrated reaction kinetics by gas analysis, we are able to study the reaction kinetics including production rates of molecules and mass transport on the mesoscale. We find that the diffusion of water through catalysts is a critical reaction constraint for the sorption-enhanced methanation reaction. We derive the Thiele parameter of a technical catalyst as a quantitative measure, supporting the materials and reactor design of sorption-enhanced methanation. From this, we conclude that nanostructuring sorption catalysts to shorten the diffusion pathway is advantageous over physical mixtures of macroscopic sorbents and catalysts, resulting in long diffusion path lengths. Water accumulation inducing a neutron contrast is specific to a few sorption-enhanced reactions. To extend the applicability of the method to other catalytic systems without sorption enhancement, we introduce a combination of neutron microscopy with steady-state isotopic transient kinetic analysis: hydrogen–deuterium exchange as a measure of the catalytic activity can be followed by neutron imaging.
- Affiliations
Swiss Federal Laboratories for Materials Science and Technology Laboratory for Advanced Analytical Technologies University of Zürich Department of Chemistry Zürcher Hochschule für Angewandte Wissenschaften Institute of Materials and Process Engineering Paul Scherrer Institut Laboratory for Neutron Scattering and Imaging
Citations
Terreni, J., Trottmann, M., Delmelle, R., Heel, A., Trtik, P., Lehmann, E. H., & Borgschulte, A. (2018). Observing Chemical Reactions by Time-Resolved High-Resolution Neutron Imaging. The Journal of Physical Chemistry C, 122(41), 23574-23581. https://doi.org/10.1021/acs.jpcc.8b07321 (Original work published 2018)