Bringing attention to metal (un)availability in encapsulated catalysts

2018 ◽  
Vol 8 (3) ◽  
pp. 798-805 ◽  
Author(s):  
A. H. Habibi ◽  
R. E. Hayes ◽  
N. Semagina
Keyword(s):  
Active Sites ◽  
Methane Combustion ◽  
Catalytic Behavior ◽  
Encapsulation Method ◽  
Encapsulated Catalysts

The encapsulation method significantly affects the shell porosity, the availability of active sites and the catalytic behavior of Pd@SiO2 materials in methane combustion.

Flame-made MgAl2−xMxO4 (M=Mn, Fe, Co) mixed oxides: Structural properties and catalytic behavior in methane combustion

2010 ◽  
Vol 97 (3-4) ◽  
pp. 398-406 ◽  
Author(s):  
Niels van Vegten ◽  
Tinku Baidya ◽  
Frank Krumeich ◽  
Wolfgang Kleist ◽  
Alfons Baiker
Keyword(s):  
Structural Properties ◽  
Mixed Oxides ◽  
Methane Combustion ◽  
Catalytic Behavior

Performance of Transition Metal Ions Exchanged Zeolite 13X in Greenhouse Gas Reduction

2007 ◽  
Author(s):  
K. S. Hui ◽  
Christopher Y. H. Chao ◽  
C. W. Kwong ◽  
M. P. Wan
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Transition Metal ◽  
Apparent Activation Energy ◽  
Surface Area ◽  
Active Sites ◽  
Methane Combustion ◽  
Bet Surface Area ◽  
Metal Loading ◽  
Zeolite 13X

This study investigated the performance of multi-transition metal (Cu, Cr, Ni and Co) ions exchanged zeolite 13X catalysts on methane emission abatement, especially at methane level of the exhaust from natural gas fueled vehicles. Catalytic activity of methane combustion using multi-ions exchanged catalyst was studied under different parameters: mole % of metal loading, inlet velocity and inlet methane concentration at atmospheric pressure and 500 °C. Performance of the catalysts was investigated and explained in terms of the apparent activation energy, number of active sites and BET surface area of the catalyst. This study showed that the multi-ions exchanged catalyst outperformed the single-ions exchanged and the acidified 13X catalysts. Lengthening the residence time could also lead to higher methane conversion %. Catalytic activity of the catalysts was influenced by the mole % of metal loading which played important roles in affecting the apparent activation energy of methane combustion, active sites and also the BET surface area of the catalyst. Increasing mole % of metal loading in the catalyst decreased the apparent activation energy for methane combustion and also the BET surface area of the catalyst. In view of these, there existed an optimized mole % of metal loading where the highest catalytic activity was observed.

The Influence Of The Support On The Deactivation Behaviour of Pt-Sn Reforming Catalysts

2005 ◽  
Vol 3 (1) ◽  
Author(s):  
Ignacio Contreras ◽  
Gustavo Pérez ◽  
Tomás Viveros
Keyword(s):  
Active Sites ◽  
Catalyst Deactivation ◽  
Mixed Oxides ◽  
Kinetic Constant ◽  
Coke Formation ◽  
Formation Kinetic ◽  
Catalytic Behavior ◽  
Reforming Catalysts ◽  
Metal Support Interaction ◽  
S Model

The effect of Al2O3-ZrO2, Al2O3-TiO2 and Al2O3-La2O3 mixed oxides on the deactivation of bifunctional Pt-Sn/ Al2O3 reforming catalysts has been investigated. The n-heptane reforming at 500°C was used as a test reaction. Changes in the catalytic behavior due to differences of the acidity and the support-metal interaction were observed. Levenspiel´s and Beltramini´s deactivation models were developed assuming a series fouling for the carbonaceous deposits. Through the Beltramini’s model it was possible to distinguish the amount of acidity that participates in the deactivation processes. Both models successfully correlated with the experimental profiles of n-heptane activity decay. The following deactivation decreasing order, Al2O3-TiO2-1>Al2O3-ZrO2-25>Al2O3-TiO2-2> Al2O3>Al2O3-La2O3-10 was found with both deactivation models. A quasi-linear correlation between the deactivation order and the coke formation kinetic constant (Levenspiel’s parameters) was observed. The catalyst acidity and the n-heptane conversion were correlated with Beltramini’s model. It was found that a high acidity (12 X 10-17 acid sites/g cat.) or metal dispersion (83%) increases the catalyst deactivation and it is necessary to have a balance of active sites in order to have a catalyst working as a bifunctional catalyst. On the other hand, the auto-regeneration Beltramini’s parameter suggests that the lowest deactivation of the Pt-Sn/ Al2O3-La2O3-10 catalyst is attributed to the cleaning capacity of the active sites. It was observed that the highest deactivation (80-92%) of the platinum-tin catalysts supported in alumina-titania mixed oxides were a result of the strong metal-support interaction (SMSI) effect. The Pt-Sn/Al2O3-La2O3-10 showed the best catalytic behavior with high initial and residual conversions (70 and 48%, respectively) and low deactivation (17 %) at a 50-minute reaction time. Furthermore, in the Pt-Sn/Al2O3 catalyst, the benzene yield was 1%, while the Pt-Sn/Al2O3-La2O3-10 showed a total inhibition of benzene production yield at residual conversions.

Preparation, characterization and catalytic behavior of Pt-Cu nanoparticles in methane combustion

2011 ◽  
Vol 20 (5) ◽  
pp. 537-542 ◽  
Author(s):  
Florica Papa ◽  
Catalin Negrila ◽  
Gianina Dobrescu ◽  
Akane Miyazaki ◽  
Ioan Balint
Keyword(s):  
Methane Combustion ◽  
Cu Nanoparticles ◽  
Catalytic Behavior

Procedure to tailor activity of methane combustion catalyst: Relation between Pd/PdOx active sites and methane oxidation activity

2011 ◽  
Vol 397 (1-2) ◽  
pp. 54-61 ◽  
Author(s):  
Niko M. Kinnunen ◽  
Janne T. Hirvi ◽  
Tapani Venäläinen ◽  
Mika Suvanto ◽  
Tapani A. Pakkanen
Keyword(s):  
Methane Oxidation ◽  
Active Sites ◽  
Methane Combustion ◽  
Oxidation Activity ◽  
Combustion Catalyst

scholarly journals Catalytic Behavior of Alkali Treated H-MOR in Selective Synthesis of Ethylenediamine via Condensation Amination of Monoethanolamine

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 386
Author(s):  
Feng-Wei Zhao ◽  
Qian Zhang ◽  
Feng Hui ◽  
Jun Yuan ◽  
Su-Ning Mei ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Active Sites ◽  
Alkali Treatment ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Selective Synthesis ◽  
Catalytic Behavior ◽  
X Ray ◽  
Bulk Catalyst ◽  
Temperature Programmed

Catalytic behavior of alkali treated mordenite (H-MOR) in selective synthesis of ethylenediamine (EDA) via condensation amination of monoethanolamine (MEA) was investigated. Changes in the structural and acidic properties of alkali treated H-MOR were systematically investigated by N2 adsorption/desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), temperature programmed ammonia desorption (NH3-TPD), pyridine adsorption was followed by infrared spectroscopy (Py-IR), and X-ray fluorescence (XRF) analyses. The results show that alkali treatment produces more opening mesopores on the H-MOR crystal surfaces and leads to an increase in the number of B acid sites and the strength of the acid sites. The mesopores effectively enhance the rate of diffusion in the bulk catalyst. Moreover, the B acid sites are active sites in selective synthesis of EDA. Due to improvements in the diffusion conditions and reactivities, alkali treated H-MOR shows an excellent catalytic performance under mild reaction conditions. The conversion of MEA was 52.8% and selectivity to EDA increased to 93.6%, which is the highest selectivity achieved so far. Furthermore, possible mechanism for the formation of EDA is discussed.

Catalytic behavior and active sites structure of PtAu/Al2O3 bimetallic catalysts prepared by surface redox reactions

2000 ◽  
Vol 164 (1-2) ◽  
pp. 253-262 ◽  
Author(s):  
G Espinosa ◽  
G Del Angel ◽  
J Barbier ◽  
P Bosch ◽  
V Lara ◽  
...  
Keyword(s):  
Bimetallic Catalysts ◽  
Redox Reactions ◽  
Active Sites ◽  
Catalytic Behavior ◽  
Surface Redox
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