The evolution in the oxidation state of Cu and Ce in a benchmark catalyst is studied
under different conditions: temperature programmed reduction with propane and hydrogen,
and isothermal reduction with propane and hydrogen.
Analytical methods used involve operando X-ray absorption spectroscopy (XAS) in
transmission mode at the Cu K edge and Ce LIII edge, as well as online mass spectrometry
(MS) at the outlet of the reactor.
In situ XAFS studies of carbon supported Pt and PtNi(1:1) catalysts for the o...qjia
it\'s a presentation for APS Meeting In Iowa. It mainly introduces our work of rationalizing the superior reactivity of certain commercial alloy nanocatalysts by probing their physical and chemical properties through x-ray experiments and theoretical model simulation.
Effect of ordering of PtCu3 electrocatalyst structure on the stability for ox...Nejc Hodnik
Presentation at the 10th European Symposium on Electrochemical Engineering, Sardinia, Italy
September 28, 2014 to October 02, 2014
Authors:
Nejc Hodnik1,2, C. Jeyabharathi1,3, K. Phani3, A. Rečnik4, M. Bele2, S. Hočevar2, M. Gaberšček2 and K. Mayrhofer1
1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
Department of Interface Chemistry and Surface Engineering
Electrocatalysis Group
2National Institute of Chemistry, Ljubljana, Slovenia
3CSIR-Central Electrochemical Research Institute, Tamil Nadu, India
4Jožef Stefan Institute, Ljubljana, Slovenia
In situ XAFS studies of carbon supported Pt and PtNi(1:1) catalysts for the o...qjia
it\'s a presentation for APS Meeting In Iowa. It mainly introduces our work of rationalizing the superior reactivity of certain commercial alloy nanocatalysts by probing their physical and chemical properties through x-ray experiments and theoretical model simulation.
Effect of ordering of PtCu3 electrocatalyst structure on the stability for ox...Nejc Hodnik
Presentation at the 10th European Symposium on Electrochemical Engineering, Sardinia, Italy
September 28, 2014 to October 02, 2014
Authors:
Nejc Hodnik1,2, C. Jeyabharathi1,3, K. Phani3, A. Rečnik4, M. Bele2, S. Hočevar2, M. Gaberšček2 and K. Mayrhofer1
1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
Department of Interface Chemistry and Surface Engineering
Electrocatalysis Group
2National Institute of Chemistry, Ljubljana, Slovenia
3CSIR-Central Electrochemical Research Institute, Tamil Nadu, India
4Jožef Stefan Institute, Ljubljana, Slovenia
Enzo palmieri experimental results on thermal boundary resistance for niobi...thinfilmsworkshop
Unless of a few eclectic scientists that have studied the problem of Kapitza resistance, a superconducting cavity is almost always seen as an adiabatic system of the electromagnetic fields interacting with a Niobium sheet cooled at 4,2K or at temperatures between 1,8K and 2 K. In this talk it will be shown that the real system to consider is that of Electromagnetic fields, Niobium and liquid Helium.
And liquid Helium is a component much more complex than an infinite heat exchanger at fixed temperature. Even at superfluid temperatures indeed, at the interface between Helium and the superfluid, it will be always a nanometric thick layer of normal helium and the thickness of this layer depends on the RF power.
Niobium sputtered cavities will be also examined under the point of view of thermal boundary Resistance, arriving to the conclusion that more advanced comprehension of SRF cannot prescind from a deep understanding of Cryogenics
The industry of ultrafine and nanopowder materials requires new methods for their production and hardware equipment for engineering processes. Among them there is plasmachemical synthesis of powder materials with the use of electric arc generators of low-temperature plasma. Plasma heating of initial inputs allows evaporation of almost any material and performance of the required chemical reactions in the gas phase with following vapor condensation to the nanodisperse solid phase. Considering the capacities of plasma generators and plasmachemical reactors achieved for today (many hundreds of kilowatts), we can expect that productivity by the desired product can be hundreds of kilograms per hour. Moreover, the plasma equipment demonstrates high universality relative to the initial materials, possible synthesis of complex powders and continuous conditions of operatingprocedure. The developed electric-arc plasmatrons and reactors allow different high-temperature processes, including powder processing in plasma flows . Now the most common constructions ofplasma reactors are the direct-flow ones with co-axial plasmatron and the three-jet ones with three plasmatrons tilted at 30–45° relative to the reactor axis and located in 120° intervals on the water-cooled upper lid. The plasmatron with sectioned inter-electrode insertion and shaped outlet nozzle-electrode ensure diffuse glow of the anode region of the arc discharge, what leads to the uniform temperature field and flow velocity at the nozzle edge. These parameters of the plasma jet have a good impact on reproducibility of powder processing, high coefficient of initial material use and production of powder with the given physical-chemical properties. Application of the three-jet plasmachemical reactor ensures the uniform temperature field along the reaction zone, allows easy control of productivity due
Practical issues in UV, HPLC analysis and Formulation developmentVijay Kumar Ekambaram
This presentation discuses variation in UV spectrum drawn on different days for same solution, peak splitting in reversed phase HPLC, and lack of repeatability due to nuisance factors
On the Energy resolution optimization of CsI(Tl) crystals for the R3B Calorim...Martin Gascon
On the Energy resolution optimization of CsI(Tl) crystals for
the R3B Calorimeter. Talk given on a group meeting at the Particle Physics Department, Universidad de Santiago de Compostela, June 1, 2007
Determination of Oxygen in Anhydrous Ammonia
SCOPE AND FIELD OF APPLICATION
This method is suitable for the determination of trace amounts of oxygen in Liquefied anhydrous ammonia.
The trace oxygen analyzer provides for trace oxygen analysis in decade steps ranging from 0 - 10 to 0 - 10,000 ppm v/v (full scale).
Enzo palmieri experimental results on thermal boundary resistance for niobi...thinfilmsworkshop
Unless of a few eclectic scientists that have studied the problem of Kapitza resistance, a superconducting cavity is almost always seen as an adiabatic system of the electromagnetic fields interacting with a Niobium sheet cooled at 4,2K or at temperatures between 1,8K and 2 K. In this talk it will be shown that the real system to consider is that of Electromagnetic fields, Niobium and liquid Helium.
And liquid Helium is a component much more complex than an infinite heat exchanger at fixed temperature. Even at superfluid temperatures indeed, at the interface between Helium and the superfluid, it will be always a nanometric thick layer of normal helium and the thickness of this layer depends on the RF power.
Niobium sputtered cavities will be also examined under the point of view of thermal boundary Resistance, arriving to the conclusion that more advanced comprehension of SRF cannot prescind from a deep understanding of Cryogenics
The industry of ultrafine and nanopowder materials requires new methods for their production and hardware equipment for engineering processes. Among them there is plasmachemical synthesis of powder materials with the use of electric arc generators of low-temperature plasma. Plasma heating of initial inputs allows evaporation of almost any material and performance of the required chemical reactions in the gas phase with following vapor condensation to the nanodisperse solid phase. Considering the capacities of plasma generators and plasmachemical reactors achieved for today (many hundreds of kilowatts), we can expect that productivity by the desired product can be hundreds of kilograms per hour. Moreover, the plasma equipment demonstrates high universality relative to the initial materials, possible synthesis of complex powders and continuous conditions of operatingprocedure. The developed electric-arc plasmatrons and reactors allow different high-temperature processes, including powder processing in plasma flows . Now the most common constructions ofplasma reactors are the direct-flow ones with co-axial plasmatron and the three-jet ones with three plasmatrons tilted at 30–45° relative to the reactor axis and located in 120° intervals on the water-cooled upper lid. The plasmatron with sectioned inter-electrode insertion and shaped outlet nozzle-electrode ensure diffuse glow of the anode region of the arc discharge, what leads to the uniform temperature field and flow velocity at the nozzle edge. These parameters of the plasma jet have a good impact on reproducibility of powder processing, high coefficient of initial material use and production of powder with the given physical-chemical properties. Application of the three-jet plasmachemical reactor ensures the uniform temperature field along the reaction zone, allows easy control of productivity due
Practical issues in UV, HPLC analysis and Formulation developmentVijay Kumar Ekambaram
This presentation discuses variation in UV spectrum drawn on different days for same solution, peak splitting in reversed phase HPLC, and lack of repeatability due to nuisance factors
On the Energy resolution optimization of CsI(Tl) crystals for the R3B Calorim...Martin Gascon
On the Energy resolution optimization of CsI(Tl) crystals for
the R3B Calorimeter. Talk given on a group meeting at the Particle Physics Department, Universidad de Santiago de Compostela, June 1, 2007
Determination of Oxygen in Anhydrous Ammonia
SCOPE AND FIELD OF APPLICATION
This method is suitable for the determination of trace amounts of oxygen in Liquefied anhydrous ammonia.
The trace oxygen analyzer provides for trace oxygen analysis in decade steps ranging from 0 - 10 to 0 - 10,000 ppm v/v (full scale).
More about the X-ray Photoelectron Spectrometer (XPS) K-Alpha (Thermo Scientific), that was acquired by LNNano in January, 2014. The equipment is a fully integrated, monochromated small-spot XPS system with depth profiling capabilities and ideal for a multi-user environment.
Note: presentation updated on April 2016
Breve descrição sobre a técnica de microtomografia de raios X e o modelo de microtomógrafo adquirido pelo Laboratório Nacional de Nanotecnologia (LNNano)
Phase Behaviour and EoS Modelling of the Carbon Dioxide-Hydrogen System, Martin Trusler, Imperial College London. Presented at CO2 Properties and EoS for Pipeline Engineering, 11th November 2014
Asymmetric Multipole Plasmon-Mediated Catalysis Shifts the Product Selectivit...Pawan Kumar
Cu/TiO2 is a well-known photocatalyst for the photocatalytic transformation of CO2 into methane. The formation of C2+ products such as ethane and ethanol rather than methane is more interesting due to their higher energy density and economic value, but the formation of C–C bonds is currently a major challenge in CO2 photoreduction. In this context, we report the dominant formation of a C2 product, namely, ethane, from the gas-phase photoreduction of CO2 using TiO2 nanotube arrays (TNTAs) decorated with large-sized (80–200 nm) Ag and Cu nanoparticles without the use of a sacrificial agent or hole scavenger. Isotope-labeled mass spectrometry was used to verify the origin and identity of the reaction products. Under 2 h AM1.5G 1-sun illumination, the total rate of hydrocarbon production (methane + ethane) was highest for AgCu-TNTA with a total CxH2x+2 rate of 23.88 μmol g–1 h–1. Under identical conditions, the CxH2x+2 production rates for Ag-TNTA and Cu-TNTA were 6.54 and 1.39 μmol g–1 h–1, respectively. The ethane selectivity was the highest for AgCu-TNTA with 60.7%, while the ethane selectivity was found to be 15.9 and 10% for the Ag-TNTA and Cu-TNTA, respectively. Adjacent adsorption sites in our photocatalyst develop an asymmetric charge distribution due to quadrupole resonances in large metal nanoparticles and multipole resonances in Ag–Cu heterodimers. Such an asymmetric charge distribution decreases adsorbate–adsorbate repulsion and facilitates C–C coupling of reaction intermediates, which otherwise occurs poorly in TNTAs decorated with small metal nanoparticles.
Palestra plenária do XII Encontro da SBPMat (Campos do Jordão, setembro/outubro de 2013). Palestrante: Mercouri G Kanatzidis - Northwestern University e Argonne National Laboratory (EUA).
Master Thesis Total Oxidation Over Cu Based Catalysts
1. Student : Alba Calvo García Promotor: Prof. Dr. M. F. Reyniers Coach(es): Dr. Anilkumar Mettu, Dr. Hilde Poelman Academic year: 2009-2010 Laboratory for Chemical Technology, Ghent University Total oxidation over Cu based catalysts: Structure-activity relationship of metal oxides
2. 1. Introduction: Justification, Objective, Analytical methods 2. Methodology 2.1 Description of the process 2.2 Experimental setup 3. Campaign November 2009 in Grenoble 3.1 Synchrotron: source of X-rays 3.2 Experiments 4. XANES analysis 4.1 Processing of data: importing raw data, normalization 4.2 Analysis of data : PCA, LCF, WL analysis 5. Results and discussion 5.1 Structure of the catalyst at ambient and pretreatment conditions 5.2 Temperature programmed reductions 5.3 Isothermal reductions 6. Conclusions 7. Future work Overview
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6. e Methodology: experimental setup E xperimental setup in the beamline 26 (ESRF Grenoble, France) Normal sequence of operation : Purging the setup in He, as it is an inert gas Calibrating the mass spectrometer with different gases Pre-treating the catalyst with oxygen 423K, 1h Purging the reactor with He Feeding the mixture and performing the experiment
7. Campaign November 2009, Grenoble: Experiments Experiments performed at the beam line 26: Time resolution: fast scans -> 1min/spectra; slow scans -> 6, 15 or 20 min/spectra Experiment Quick C 3 H 8 -TPR Quick H 2 -TPR Isothermal C 3 H 8 -reduction Isothermal H 2 -reduction Total oxidation Gas inlet (%) 5%C 3 H 8 /He 5%H 2 /He 5%C 3 H 8 /He 5%H 2 /He 1%C 3 H 8 -10%O 2 /He T Cu K edge ( ºC) 200 to 450ºC 200 to 450ºC 300 to 450ºC per 50ºC 200 to 450ºC per 50ºC 300 to 400ºC per 50ºC T Ce L3 edge ( ºC) 100 to 400ºC - 300 to 400ºC per 50ºC 200 to 400ºC per 50ºC 300 to 400ºC per 50ºC Pressure (atm) 1 1 1 1 1 Total flow (mol/s) 1.5 10 -5 mol/s 1.5 10 -5 mol/s 1.5 10 -5 mol/s 1.5 10 -5 mol/s 0.5 - 1.5 10 -5 mol/s
8. 2. Normalization -> µ(E) = (µ (E) - µ 0 (E))/ µ 0 (E 0 ) 2.1. Value of E 0 2.2. Pre-edge and post-edge 2.3. Normalized μ (E) XANES analysis: processing of data Athena: interactive graphical utility for processing EXAFS data 1. Import raw data 3. Data analysis
9. XANES analysis: processing of data Data analysis PCA (Sixpack) : number of principal components to describe the evolution in a given set of spectra. IND function number of components Target transormation Good selection of principal components Acceptable SPOIL number (<6) Good fitting of reference spectra LCF analysis
10. XANES analysis: processing of data Data analysis LCF (Athena) : fits a linear combination of standard spectra to an unknown spectrum. Different libraries of references: pellets Cu 2+ , Cu 1+ , Cu 0 CuO, Cu 2 O, Cu capillaries merged files first spectrum, Cu 2 O reference, last spectrum pellets Ce 4+ , Ce 3+ CeO 2 , CeF 3 capillaries merged files Molar fractions of Cu 2+ , Cu 1+ , Cu 0 or Ce 4+ , Ce 3+ vs T
11. XANES analysis: processing of data Data analysis WL analysis : estimating the average oxidation state of Cu/Ce in each spectrum Cu 2+ , Cu 1+ , Cu 0 / Ce 4+ , Ce 3+ references E WL oxidation state linear relationship : Ox. State = f(E WL ) E WL unknown spectra T unknown spectra Oxidation state vs T Reduction of the active phase causes a shift in the WL
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13. Results and discussion: Temperature programmed reductions C 3 H 8 TPR Cu K XANES Ce L3 XANES WL ↓ and shifts to ↓ energies Shoulder feature -> Pre-edge peak ↓ 2 trends: Cu 1+ and Cu 0 Changes less appreciable in Ce L3 WL ↑ and shifts slightly to ↓ energies Pronounced shoulder on the low energy side of the WL References + catalyst after reduction
14. Results and discussion: Temperature programmed reductions C 3 H 8 TPR Cu K XANES Ce L3 XANES Final ox. state (400⁰C)= 3,8 Reduction 280-300 ⁰C 100% Cu 0 obtained Cu 2 O (300-450⁰C) ↓ max 380 ⁰C Final ox. state (446⁰C) ≈ 0 ↑ T ↑ reduction Only 20,9% Ce 3+ obtained
15. Results and discussion: Temperature programmed reductions H 2 TPR Cu K XANES Reduction with H 2 -> faster WL ↓ and shifts rapidly to ↓ energies Shoulder feature -> Pre-edge peak (Cu 0 ) CuO reference + catalyst at 226 ºC All spectra resemble Cu 0 except for the first (226⁰) 226⁰ -> Catalyst is not totally oxidized Cu K XANES
16. Results and discussion: Temperature programmed reductions H 2 TPR Cu K XANES 3 principal components -> first one much more weight E WL values are close to Cu 0 except for the first one Initial ox. state (226⁰C)= 1,2 T ≥ 250 ⁰C -> Ox. State ≈ 0
17. Results and discussion: Isothermal reductions Cu K XANES T ≥ 250 ⁰C -> Ox. State ≈ 0 T = 300 ⁰C -> hardly reduced T > 350 ⁰C -> Cu 0 T = 350 ⁰C -> features Cu 2 O T ≥ 250 ⁰C -> Spectra resemble the one of Cu 0 Reduction with H 2 starts at lower temperatures and occurs faster Isothermal reduction with C 3 H 8 Isothermal reduction with H 2
18. Results and discussion: Isothermal reductions Ce L3 XANES Isothermal reduction with C 3 H 8 Isothermal reduction with H 2 CeO 2 is hardly reduced by C 3 H 8 , even at high T Reduction ↑ by using H 2 Bigger changes in the spectra CeO 2 and CeF 3 references + catalyst at 400 ºC Pronounced shoulder on the low energy side of the WL
19. Results and discussion: Isothermal reductions Isothermal reduction with C 3 H 8 Isothermal reduction with H 2 Ce L3 XANES 200 ºC -> Reduction starts (2 scans) ↑ T isothermal r eduction -> ↑ final %CeF 3 CeO 2 is hardly reduced by C 3 H 8 Final Ox. state (400⁰C)= 3,73 Reduction ↑ by using H 2 -> 60,9% CeF 3 Final Ox. state (400⁰C)= 3,04 (WL&LCF)
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21. Future work - Synchronize temperature in XAS and MS measurements - MS measurements should be performed on other gases apart from the compounds involved in the reaction -> detect leaks or capillary breakage - Experiments could be done in a Cu based catalyst and a Ce based catalyst separately -> how each element in the catalyst works - XANES analysis in the Ce K edge could be performed -> Better resolution with the contribution of different coordination cells. - XAS data could be examined in the EXAFS region as well -> structural information (distances between atoms, coordination number..)
