New DRIFTS Cell Design for the Simultaneous Acquisition of IR Spectra and Kinetic Data Using On-Line Product Analysis

2001 ◽  
Vol 55 (11) ◽  
pp. 1537-1543 ◽  
Author(s):  
M. M. Schubert ◽  
T. P. Häring ◽  
G. Bräth ◽  
H. A. Gasteiger ◽  
R. J. Behm
Keyword(s):  
Co Oxidation ◽  
Gas Flow ◽  
Reaction Rates ◽  
Gas Analysis ◽  
Cell Design ◽  
Product Analysis ◽  
Kinetic Measurements ◽  
On Line ◽  
Improved Performance ◽  
Diffuse Reflectance Infrared

A new design for a DRIFTS (diffuse reflectance infrared Fourier transform spectrometry) cell for in situ studies in heterogeneous catalysis is presented, which allows for improved reaction control (i.e., gas flow, temperature, minimized background conversion) and for precise kinetic measurements via on-line gas analysis by a tandem-arranged gas chromatograph. Specifically, the very low background activity of the cell itself for CO and H2 oxidation makes it possible to study the preferential CO oxidation in H2-rich gases (PROX) at relevant reaction temperatures (150–350 °C) and reactant concentrations (≤1 kPa CO and O2). Comparison with results obtained in a quartz tube reactor shows excellent agreement with the reaction rates obtained in the DRIFTS cell. The improved performance of the new DRIFTS cell design is demonstrated by examining the influence of CO2 on the PROX reaction over a Au/Fe2O3 catalyst. The addition of CO2 to idealized reformate (varying CO and O2 partial pressures, 75 kPa H2, balance N2) significantly reduces both the CO oxidation rate and the selectivity of the PROX reaction on Au/α-Fe2O3 and strongly affects the frequency of the C–O stretch vibration of adsorbed CO due to CO2 coadsorption.

scholarly journals Thermal decomposition of tris(O-ethyldithiocarbonato)-antimony(III)—a single-source precursor for antimony sulfide thin films

2021 ◽  
Author(s):  
Jako S. Eensalu ◽  
Kaia Tõnsuaadu ◽  
Jasper Adamson ◽  
Ilona Oja Acik ◽  
Malle Krunks
Keyword(s):  
Thin Films ◽  
Thermal Decomposition ◽  
Mass Loss ◽  
Solid Phase ◽  
Evolved Gas Analysis ◽  
Gas Analysis ◽  
Thermal Decomposition Mechanism ◽  
Product Analysis ◽  
Gaseous Species ◽  
Single Source Precursor

AbstractThermal decomposition of tris(O-ethyldithiocarbonato)-antimony(III) (1), a precursor for Sb2S3 thin films synthesized from an acidified aqueous solution of SbCl3 and KS2COCH2CH3, was monitored by simultaneous thermogravimetry, differential thermal analysis and evolved gas analysis via mass spectroscopy (TG/DTA-EGA-MS) measurements in dynamic Ar, and synthetic air atmospheres. 1 was identified by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) measurements, and quantified by NMR and elemental analysis. Solid intermediates and final decomposition products of 1 prepared in both atmospheres were determined by X-ray diffraction (XRD), Raman spectroscopy, and FTIR. 1 is a complex compound, where Sb is coordinated by three ethyldithiocarbonate ligands via the S atoms. The thermal degradation of 1 in Ar consists of three mass loss steps, and four mass loss steps in synthetic air. The total mass losses are 100% at 800 °C in Ar, and 66.8% at 600 °C in synthetic air, where the final product is Sb2O4. 1 melts at 85 °C, and decomposes at 90–170 °C into mainly Sb2S3, as confirmed by Raman, and an impurity phase consisting mostly of CSO 2 2− ligands. The solid-phase mineralizes fully at ≈240 °C, which permits Sb2S3 to crystallize at around 250 °C in both atmospheres. The gaseous species evolved include CS2, C2H5OH, CO, CO2, COS, H2O, SO2, and minor quantities of C2H5SH, (C2H5)2S, (C2H5)2O, and (S2COCH2CH3)2. The thermal decomposition mechanism of 1 is described with chemical reactions based on EGA-MS and solid intermediate decomposition product analysis.

Monitoring and modelling an industrial trickling filter using on-line off-gas analysis and respirometry

2000 ◽  
Vol 41 (12) ◽  
pp. 139-148 ◽  
Author(s):  
H. Vanhooren ◽  
D. Demey ◽  
I. Vannijvel ◽  
P. A. Vanrolleghem
Keyword(s):  
Phase Equilibrium ◽  
Model Calibration ◽  
Inorganic Carbon ◽  
Diffusion Constant ◽  
Gas Analysis ◽  
Trickling Filter ◽  
Process Characteristics ◽  
Substrate Diffusion ◽  
On Line ◽  
Ph Dependent

The process characteristics of an industrial scale trickling filter plant were quantified by means of a five day intensive measurement campaign with the use of on-line respirometry and on-line off-gas analysis. Respirometry was used to measure the readily biodegradable CODst and the off-gas sensor was used to monitor the O2 and CO2 content of the off-gases. To model the biodegradation in the filters, the model developed by Rauch et al. (1999) was used. It is based on the decoupling of two basic processes in biofilm systems, substrate diffusion and biodegradation. This model was extended with equations for the production and the pH-dependent liquid-phase equilibrium for inorganic carbon (IC). The measured effluent and off-gas concentrations could be followed very closely by the calibrated model. O2 and CO2 measurements revealed that the system was not always oxygen limited. The model calibration thus required the use of a very low value of the diffusion constant for readily biodegradable substrate.

Empirical Model to Estimate Mn2+ Precipitation Rate from a Leaching Solution Using SO2/O2 as Oxidizing Agent

2012 ◽  
Vol 1380 ◽  
Author(s):  
S. Bello-Teodoro ◽  
R. Pérez-Garibay
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Reaction Rates ◽  
Precipitation Process ◽  
Low Grade ◽  
Gas Flow Rate ◽  
Oxidative Precipitation ◽  
Leaching Solution ◽  
Good Concordance ◽  
Main Influence

ABSTRACTA method, based in leaching with SO2, to process low grade pyrolusite minerals has shown good results at laboratory scale. After the separation of the solid impurities, the dissolved manganese is subsequently precipitated using the SO2/O2 gas mixture as oxidising agent. In this research it was obtained a mathematical model to estimate the oxidative precipitation process, as a function of temperature, pH and SO2 gas flow rate. It was found that pH and temperature have the main influence in the reaction rate. An optimal SO2 concentration in the mixture must be used to avoid generation of reductive conditions. It was observed a most efficient reaction with a low gas flow rate injection. The predicted reaction rates presents a good concordance with the experimental results (R2=0.97), showing a worthy potential for practical uses.

scholarly journals The influence of physical parameters on the in-situ metal carbonyl complex formation studied with the Fast On-line Reaction Apparatus (FORA)

2021 ◽  
Vol 109 (4) ◽  
pp. 261-281
Author(s):  
Yves Wittwer ◽  
Robert Eichler ◽  
Dominik Herrmann ◽  
Andreas Türler
Keyword(s):  
Gas Flow ◽  
Metal Carbonyl ◽  
Fission Products ◽  
Reaction Chamber ◽  
Single Atom ◽  
Physical Parameters ◽  
Carbonyl Complex ◽  
Reaction Conditions ◽  
On Line ◽  
The Impact

Abstract The Fast On-line Reaction Apparatus (FORA) was used to investigate the influence of various reaction parameters onto the formation and transport of metal carbonyl complexes (MCCs) under single-atom chemistry conditions. FORA is based on a 252Cf-source producing short-lived Mo, Tc, Ru and Rh isotopes. Those are recoiling from the spontaneous fission source into a reaction chamber flushed with a gas-mixture containing CO. Upon contact with CO, fission products form volatile MCCs which are further transported by the gas stream to the detection setup, consisting of a charcoal trap mounted in front of a HPGe γ-detector. Depending on the reaction conditions, MCCs are formed and transported with different efficiencies. Using this setup, the impact of varying physical parameters like gas flow, gas pressure, kinetic energy of fission products upon entering the reaction chamber and temperature of the reaction chamber on the formation and transport yields of MCCs was investigated. Using a setup similar to FORA called Miss Piggy, various gas mixtures of CO with a selection of noble gases, as well as N2 and H2, were investigated with respect to their effect onto MCC formation and transport. Based on this measurements, optimized reaction conditions to maximize the synthesis and transport of MCCs are suggested. Explanations for the observed results supported by simulations are suggested as well.

Electrochemistry of La0.3Sr0.7Fe0.7Cr0.3O3−δ as an oxygen and fuel electrode for RSOFCs

2015 ◽  
Vol 182 ◽  
pp. 159-175 ◽  
Author(s):  
Beatriz Molero-Sánchez ◽  
Paul Addo ◽  
Aligul Buyukaksoy ◽  
Scott Paulson ◽  
Viola Birss
Keyword(s):  
Cyclic Voltammetry ◽  
Co Oxidation ◽  
Detailed Analysis ◽  
Oxygen Reduction ◽  
Oxygen Evolution ◽  
Open Circuit ◽  
Solid Oxide ◽  
Cell Design ◽  
Half Cell ◽  
Manufacturing Costs

The use of a single porous mixed ion-electron conducting (MIEC) material as both the oxygen and fuel electrodes in reversible solid oxide cells is of increasing interest, primarily due to the resulting simplified cell design and lower manufacturing costs. In this work, La0.3Sr0.7Fe0.7Cr0.3O3−δ (LSFCr-3) was studied in a 3-electrode half-cell configuration in air, pure CO2 and in a 1 : 1 CO2 : CO mixture, over a temperature range of 650–800 °C. A detailed analysis of the impedance (EIS) data, under both open circuit and polarized conditions, as well as the cyclic voltammetry response of LSFCr-3 has shown that it is very active in all of these environments, but with oxygen evolution being somewhat more facile that oxygen reduction, and CO2 reduction more active than CO oxidation. Evidence for a chemical capacitance, associated with the Fe3+/4+ redox process in LSFCr-3, was also obtained from the EIS and CV data in all gas environments.

scholarly journals Reaction-Induced Cluster Ripening and Initial Size-Dependent Reaction Rates for CO Oxidation on Ptn/TiO2(110)-(1×1)

2014 ◽  
Vol 136 (24) ◽  
pp. 8702-8707 ◽  
Author(s):  
Simon Bonanni ◽  
Kamel Aït-Mansour ◽  
Wolfgang Harbich ◽  
Harald Brune
Keyword(s):  
Co Oxidation ◽  
Reaction Rates ◽  
Initial Size ◽  
Size Dependent

A Supported Ultrathin Window for Improved Performance in Gas Flow Proportional Counters

1997 ◽  
pp. 881-884
Author(s):  
Andrew J. Nelson ◽  
David Tingey ◽  
Takashi Shoji ◽  
Kazuaki Shimizu
Keyword(s):  
Gas Flow ◽  
Proportional Counters ◽  
Improved Performance

An Evaluation of the Kenz Calorie Counter during Progressive Treadmill Exercise in Adults and Children

1996 ◽  
Vol 8 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Nicholas J. Walters ◽  
David A. Brodie
Keyword(s):  
Linear Regression ◽  
Energy Expenditure ◽  
Body Mass ◽  
Correction Factor ◽  
Treadmill Exercise ◽  
Gas Analysis ◽  
Age Group ◽  
Measured Energy ◽  
Adults And Children ◽  
On Line

The purpose of this study was to assess the validity of data derived from the Kenz calorie counter during progressive, incremental treadmill exercise. Direct comparisons were made with calories calculated from on-line gas analysis. The subjects were 18 adults, 18 postadolescent children, and 24 preadolescent children. Linear regression (r2 > .95) showed a progressive deviation away from a 1:1 relationship between Kenz data and V̇O2 data with increasing age of subject which remained when standardized to kcal · kg−1 body mass or kcal · m−2 · hour−1. The Kenz calorie counter, after applying an age group correction factor, can thus be used as a suitable analog for measured energy expenditure.

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