Application of modulation excitation-phase sensitive detection-DRIFTS for in situ/operando characterization of heterogeneous catalysts

2019 ◽  
Vol 4 (5) ◽  
pp. 862-883 ◽  
Author(s):  
Priya D. Srinivasan ◽  
Bhagyesha S. Patil ◽  
Hongda Zhu ◽  
Juan J. Bravo-Suárez
Keyword(s):  
Fourier Transform ◽  
Heterogeneous Catalysts ◽  
Diffuse Reflectance ◽  
Sensitive Detection ◽  
Phase Sensitive ◽  
Phase Sensitive Detection ◽  
Modulation Excitation ◽  
General Method

A new more general method and guidelines for the implementation of modulation excitation-phase sensitive detection-diffuse reflectance Fourier transform spectroscopy (ME-PSD-DRIFTS).

Design, modelling, and application of a low void-volume in situ diffuse reflectance spectroscopic reaction cell for transient catalytic studies

2019 ◽  
Vol 4 (4) ◽  
pp. 667-678 ◽  
Author(s):  
Bhagyesha S. Patil ◽  
Priya D. Srinivasan ◽  
Ed Atchison ◽  
Hongda Zhu ◽  
Juan J. Bravo-Suárez
Keyword(s):  
Fourier Transform ◽  
Diffuse Reflectance ◽  
Fourier Transform Spectroscopy ◽  
Void Volume ◽  
Sensitive Detection ◽  
Reaction Cell ◽  
Phase Sensitive ◽  
Phase Sensitive Detection ◽  
Modulation Excitation

A new low void-volume in situ reaction cell enables application of modulation excitation-phase sensitive detection-diffuse reflectance Fourier transform spectroscopy (ME-PSD-DRIFTS).

scholarly journals CO2 Methanation over Rh/CeO2 Studied with Infrared Modulation Excitation Spectroscopy and Phase Sensitive Detection

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 601
Author(s):  
Felix Hemmingsson ◽  
Andreas Schaefer ◽  
Magnus Skoglundh ◽  
Per-Anders Carlsson
Keyword(s):  
Reaction Pathway ◽  
Sensitive Detection ◽  
Side Reactions ◽  
Co2 Methanation ◽  
Individual Contributions ◽  
Phase Sensitive ◽  
Phase Sensitive Detection ◽  
Modulation Excitation Spectroscopy ◽  
Modulation Excitation

Methane is a well-established fuel molecule whose production from CO 2 through methanation garners increasing interest as an energy storage solution. While often produced with Ni based catalysts, other metals are of interest thanks to higher robustness and activity-selectivity numbers. The Rh/CeO 2 catalyst has shown appreciable properties for CO 2 methanation and its structural dynamics has been studied in situ. However, the reaction pathway is unknown. Here, we present infrared modulation excitation spectroscopy measurements with phase sensitive detection of a Rh/CeO 2 catalyst adsorbate composition during H 2 pulsing (0–2 vol.%) to a constant CO 2 (0.5 vol.%) feed. Various carbonyl (CO) and carbonate (b-CO 3 /p-CO 3 ) ad-species clearly respond to the hydrogen stimulus, making them potential reaction intermediates. The different CO ad-species are likely intermediates for product CO and CH 4 but their individual contributions to the respective formations are not unambiguously ascertained. As for the carbonate dynamics, it might be linked to the reduction/oxidation of the CeO 2 surface upon H 2 pulsing. Formate (HCOO) ad-species are clearly visible but appear to be, if not spectators, linked to slow side reactions possibly also affected by CeO 2 redox processes.

In Situ Fourier Transform Infrared Diffuse Reflectance and Photoacoustic Spectroscopy Characterization of Sulfur-Oxygen Species Resulting from the Reaction of SO2 with CaCO3

1988 ◽  
Vol 42 (6) ◽  
pp. 945-951 ◽  
Author(s):  
Meg Martin Thompson ◽  
Richard Alan Palmer
Keyword(s):  
Fourier Transform ◽  
Photoacoustic Spectroscopy ◽  
Diffuse Reflectance ◽  
Fourier Transform Infrared ◽  
Oxygen Species ◽  
Ft Ir

Fourier transform photoacoustic and diffuse reflectance spectroscopies (FT-IR-PAS and -DRS) have been used in situ to monitor the reaction of SO2 (1.5% in N2) with particulate CaCO3 at temperatures up to 400°C (PAS) and 690°C (DRS). The PA spectra indicate that at 360°C SO2 is physisorbed on the CaCO3 surface. This species is readily desorbed by N2 purging. Under continuous SO2/N2 exposure at 400°C and above, the physisorbed species is shown by the DR data to be converted first to oxygen-bound and then to nonspecifically bound pyramidal SO3−. Reaction of the SO3= with SO2 to form SO4− begins at 400°C and is essentially complete at 690°C. The DR data further indicate that for the SO4−: (1) at temperatures between 400 and 640°C a monodentate C3 v species forms; (2) above 640°C the SO4− ion has nearly Td symmetry; and (3) upon subsequent cooling, the SO4− exhibits the characteristics of a chelating C2 v species.

Diffuse Reflectance FT-IR Characterization of Active Sites under Reaction Conditions: The Production of Oxygenates in the CO/H2 Reaction

1994 ◽  
Vol 48 (10) ◽  
pp. 1208-1212 ◽  
Author(s):  
J. J. Benítez ◽  
I. Carrizosa ◽  
J. A. Odriozola
Keyword(s):  
Infrared Spectra ◽  
Active Sites ◽  
Diffuse Reflectance ◽  
Reaction Conditions ◽  
In Situ Drifts ◽  
Ft Ir

The reactivity of a Lu2O3-promoted Rh/Al2O3 catalyst in the CO/H2 reaction is reported. Methane, heavier hydrocarbons, methanol, and ethanol are obtained. In situ DRIFTS has been employed to record the infrared spectra under the actual reaction conditions. The structure of the observed COads DRIFTS bands has been resolved into its components. The production of oxygenates (methanol and ethanol) has been correlated with the results of the deconvolution calculation. Specific sites for the production of methanol and ethanol in the CO/H2 reaction over a Rh,Lu2O3/Al2O3 catalyst are proposed.

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