Operando Time-Gated Raman Spectroscopy of Solid Catalysts

An article titled Operando Time-Gated Raman Spectroscopy of Solid Catalysts has been published in the Royal Society of Chemistry.

This research studies the use of operando Raman spectroscopy, an advanced analytical method aimed at gaining insights into how solid catalysts function and deactivate. Specifically, the study explores the application of time-gated Raman spectroscopy (TG-Raman) to overcome the challenges caused by intense fluorescence interference during operando Raman analysis of solid catalysts. The research showcases the effectiveness of time gating by employing Pt–Sn-based catalysts used in propane dehydrogenation as a case study. Time-gated Raman spectroscopy is introduced as a technique to enhance the quality of spectra by suppressing background fluorescence, which has slower temporal dynamics compared to Raman scattering.

Moreover, the study discusses the wide-ranging benefits of time-gating in various scientific fields and provides quantitative evidence of its advantages in operando catalyst analysis, demonstrating improvements in signal quality. The findings highlight the importance of accounting for sample heterogeneity and emphasize that time-gating effectively reduces background fluorescence, enhancing the distinction of Raman features.

Abstract

Operando Raman spectroscopy is a powerful analytical tool to provide new insights in the working and deactivation principles of solid catalysts. Intense fluorescence can obscure Raman spectra to the extent that they become uninterpretable. Time-gated Raman spectroscopy, based on pulsed excitation and time-gated detection, suppresses background fluorescence based on its slower time dynamics compared to Raman scattering. In this work, we demonstrate and quantify the benefit of time gating for operando Raman spectroscopy, using the propane dehydrogenation reaction over Pt–Sn-based catalyst materials as a case study. Experimental time-gated Raman spectroscopy data are fitted to a time-trace model that is used to optimize time gating for the maximum signal-to-background-noise ratio. Time-gated Raman spectra of a spent propane dehydrogenation catalyst material show lower background fluorescence compared to the time-integrated Raman spectra counterparts. Simultaneous operando time-gated and time-integrated Raman spectroscopy experiments demonstrate the benefit of time gating to obtain more distinct Raman features, especially in the early coking stages where spectra are dominated by background fluorescence. 

The open-access article can be found here.