Laser induced temperature-jump time resolved IR spectroscopy of zeolites

Hawkins, Alexander P., Edmeades, Amy E. ORCID: https://orcid.org/0000-0001-7495-3355, Hutchison, Christopher D. M., Towrie, Michael, Howe, Russell F., Greetham, Gregory M. and Donaldson, Paul M. 2024. Laser induced temperature-jump time resolved IR spectroscopy of zeolites. Chemical Science 15 (10) , pp. 3453-3465. 10.1039/D3SC06128K

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Abstract

Combining pulsed laser heating and time-resolved infrared (TR-IR) absorption spectroscopy provides a means of initiating and studying thermally activated chemical reactions and diffusion processes in heterogeneous catalysts on timescales from nanoseconds to seconds. To this end, we investigated single pulse and burst laser heating in zeolite catalysts under realistic conditions using TR-IR spectroscopy. 1 ns, 70 μJ, 2.8 μm laser pulses from a Nd:YAG-pumped optical parametric oscillator were observed to induce temperature-jumps (T-jumps) in zeolite pellets in nanoseconds, with the sample cooling over 1–3 ms. By adopting a tightly focused beam geometry, T-jumps as large as 145 °C from the starting temperature were achieved, demonstrated through comparison of the TR-IR spectra with temperature dependent IR absorption spectra and three dimensional heat transfer modelling using realistic experimental parameters. The simulations provide a detailed understanding of the temperature distribution within the sample and its evolution over the cooling period, which we observe to be bi-exponential. These results provide foundations for determining the magnitude of a T-jump in a catalyst/adsorbate system from its absorption spectrum and physical properties, and for applying T-jump TR-IR spectroscopy to the study of reactive chemistry in heterogeneous catalysts.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	Royal Society of Chemistry
ISSN:	2041-6520
Date of First Compliant Deposit:	25 March 2024
Date of Acceptance:	29 January 2024
Last Modified:	25 Mar 2024 10:34
URI:	https://orca.cardiff.ac.uk/id/eprint/166180

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