Operando time-gated Raman spectroscopy of solid catalysts

Area of Science:

• Analytical Chemistry
• Materials Science
• Catalysis

Background:

• Operando Raman spectroscopy provides insights into catalyst function and deactivation.
• Background fluorescence often hinders spectral interpretation in Raman spectroscopy.
• Time-gated Raman spectroscopy utilizes pulsed excitation and detection to suppress fluorescence.

Purpose of the Study:

• To demonstrate and quantify the advantages of time gating for operando Raman spectroscopy.
• To optimize time gating parameters for maximum signal-to-background-noise ratio.
• To investigate propane dehydrogenation over Pt-Sn catalysts as a case study.

Main Methods:

• Application of time-gated Raman spectroscopy during the propane dehydrogenation reaction.
• Fitting experimental data to a time-trace model for parameter optimization.
• Comparison of time-gated and time-integrated Raman spectra of catalysts.

Main Results:

• Time-gated Raman spectra of spent catalysts exhibited significantly lower background fluorescence.
• Optimized time gating improved the signal-to-background-noise ratio.
• Distinct Raman features were obtained using time gating, particularly in early coking stages.

Conclusions:

• Time-gated Raman spectroscopy is a valuable technique for overcoming fluorescence in operando catalyst studies.
• The method enhances spectral quality, enabling better understanding of catalyst deactivation.
• This approach is particularly beneficial for analyzing complex catalytic systems like Pt-Sn during propane dehydrogenation.