First steps in combining modulation excitation spectroscopy with synchronous dispersive EXAFS/DRIFTS/mass spectrometry for in situ time resolved study of heterogeneous catalysts

2010 ◽  
Vol 12 (21) ◽  
pp. 5634 ◽  
Author(s):  
Davide Ferri ◽  
M. Santosh Kumar ◽  
Ronny Wirz ◽  
Arnim Eyssler ◽  
Oxana Korsak ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Heterogeneous Catalysts ◽  
Time Resolved ◽  
Modulation Excitation Spectroscopy ◽  
Modulation Excitation

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.

Time-resolved in situ monitoring of photocatalytic reactions by probe electrospray ionization mass spectrometry

The Analyst ◽  
2020 ◽  
Vol 145 (9) ◽  
pp. 3313-3319
Author(s):  
Zhongbao Han ◽  
Xiaoyu Gu ◽  
Shirong Wang ◽  
Liyan Liu ◽  
Ying Wang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Real Time ◽  
Electrospray Ionization Mass Spectrometry ◽  
In Situ Monitoring ◽  
Ionization Mass ◽  
Time Resolved ◽  
Photocatalytic Reactions ◽  
Probe Electrospray Ionization

We report the application of PESI-MS to in situ monitoring of photocatalytic reactions of cationic dyes in suspensions in real-time.

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).

The WF6-Si reaction studied in situ by time-resolved mass spectrometry

1991 ◽  
Vol 53 ◽  
pp. 30-34 ◽  
Author(s):  
P.A.C. Groenen ◽  
J.G.A. Hölscher ◽  
H.H. Brongersma
Keyword(s):  
Mass Spectrometry ◽  
Time Resolved

In-situ X-ray Studies of Clean Catalytic Technologies

2011 ◽  
Vol 1351 ◽  
Author(s):  
Adam F. Lee ◽  
Christine V. Ellis ◽  
Mark A. Newton ◽  
Christopher M. Parlett ◽  
Karen Wilson
Keyword(s):  
Rational Design ◽  
Heterogeneous Catalysts ◽  
Molecular Level ◽  
Aerobic Oxidation ◽  
Allylic Alcohols ◽  
Time Resolved ◽  
X Ray ◽  
Adsorbed Layers ◽  
Insight Into

ABSTRACTThe rational design of new heterogeneous catalysts for clean chemical technologies can be accelerated by molecular level insight into surface chemical processes. In-situ methodologies, able to provide time-resolved and/or pressure dependent information on the evolution of reacting adsorbed layers over catalytically relevant surfaces, are therefore of especial interest. Here we discuss the application of in-situ XPS and in-situ, synchronous DRIFTS/MS/XAS methodologies to elucidate the active site in Pd-catalyzed, selective aerobic oxidation of allylic alcohols.

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

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