Effect of Pt nanoparticle size on the specific catalytic activity of Pt/SiO2 and Pt/TiO2 in the total oxidation of methane and n-butane

2010 ◽  
Vol 59 (9) ◽  
pp. 1713-1719 ◽  
Author(s):  
A. Yu. Stakheev ◽  
A. M. Gololobov ◽  
I. E. Beck ◽  
G. O. Bragina ◽  
V. I. Zaikovsky ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Nanoparticle Size ◽  
Pt Nanoparticle ◽  
Total Oxidation ◽  
Oxidation Of Methane ◽  
Specific Catalytic Activity

scholarly journals Influence of the support on rhodium speciation and catalytic activity of rhodium-based catalysts for total oxidation of methane

2020 ◽  
Vol 10 (17) ◽  
pp. 6035-6044
Author(s):  
Yu Zhang ◽  
Peter Glarborg ◽  
Martin Peter Andersson ◽  
Keld Johansen ◽  
Thomas Klint Torp ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Total Oxidation ◽  
Oxidation Of Methane ◽  
Zeolite Supports

In Rh-catalysts for CH4-oxidation, Si-rich zeolite supports yield the more active Rh2O3 nanoparticle form and the highest SO2 and H2O tolerance.

Pt nanocluster size effects in the hydrogen evolution reaction: approaching the theoretical maximum activity

2020 ◽  
Vol 22 (34) ◽  
pp. 19059-19068
Author(s):  
Jens Klein ◽  
Albert K. Engstfeld ◽  
Sylvain Brimaud ◽  
R. Jürgen Behm
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Size Effects ◽  
State Of The Art ◽  
Maximum Activity ◽  
Nanoparticle Size ◽  
Pt Nanoparticle ◽  
Theoretical Maximum

Reducing the Pt nanoparticle size into the nanocluster range dramatically increases the catalytic activity for the HER compared to state-of-the-art Pt/C catalysts.

Platinum nanoparticle size effect on specific catalytic activity in n-alkane deep oxidation: Dependence on the chain length of the paraffin

2009 ◽  
Vol 50 (6) ◽  
pp. 830-836 ◽  
Author(s):  
A. M. Gololobov ◽  
I. E. Bekk ◽  
G. O. Bragina ◽  
V. I. Zaikovskii ◽  
A. B. Ayupov ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Size Effect ◽  
Chain Length ◽  
Deep Oxidation ◽  
Nanoparticle Size ◽  
Platinum Nanoparticle ◽  
Specific Catalytic Activity

scholarly journals Total Oxidation of Methane on Oxide and Mixed Oxide Ceria-Containing Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 427
Author(s):  
Marius Stoian ◽  
Vincent Rogé ◽  
Liliana Lazar ◽  
Thomas Maurer ◽  
Jacques C. Védrine ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Methane Oxidation ◽  
Catalytic Combustion ◽  
Oxygen Vacancies ◽  
High Heat ◽  
Atmospheric Environment ◽  
Total Oxidation ◽  
Oxidation Of Methane ◽  
Ceo2 Sample ◽  
Crystallographic Facets

Methane, discovered in 1766 by Alessandro Volta, is an attractive energy source because of its high heat of combustion per mole of carbon dioxide. However, methane is the most abundant hydrocarbon in the atmosphere and is an important greenhouse gas, with a 21-fold greater relative radiative effectiveness than CO2 on a per-molecule basis. To avoid or limit the formation of pollutants that are dangerous for both human health and the atmospheric environment, the catalytic combustion of methane appears to be one of the most promising alternatives to thermal combustion. Total oxidation of methane, which is environmentally friendly at much lower temperatures, is believed to be an efficient and economically feasible way to eliminate pollutants. This work presents a literature review, a statu quo, on catalytic methane oxidation on transition metal oxide-modified ceria catalysts (MOx/CeO2). Methane was used for this study since it is of great interest as a model compound for understanding the mechanisms of oxidation and catalytic combustion on metal oxides. The objective was to evaluate the conceptual ideas of oxygen vacancy formation through doping to increase the catalytic activity for methane oxidation over CeO2. Oxygen vacancies were created through the formation of solid solutions, and their catalytic activities were compared to the catalytic activity of an undoped CeO2 sample. The reaction conditions, the type of catalysts, the morphology and crystallographic facets exposing the role of oxygen vacancies, the deactivation mechanism, the stability of the catalysts, the reaction mechanism and kinetic characteristics are summarized.

scholarly journals Oscillatory Behaviour of Ni Supported on ZrO2 in the Catalytic Partial Oxidation of Methane as Determined by Activation Procedure

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2495
Author(s):  
Daniela Pietrogiacomi ◽  
Maria Cristina Campa ◽  
Ida Pettiti ◽  
Simonetta Tuti ◽  
Giulia Luccisano ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Partial Oxidation ◽  
Active Sites ◽  
Direct Reduction ◽  
Partial Oxidation Of Methane ◽  
Catalytic Partial Oxidation ◽  
Oxidation Of Methane ◽  
Short Contact Time ◽  
Oxidation Reduction ◽  
Ni Species

Ni/ZrO2 catalysts, active and selective for the catalytic partial oxidation of methane to syngas (CH4-CPO), were prepared by the dry impregnation of zirconium oxyhydroxide (Zhy) or monoclinic ZrO2 (Zm), calcination at 1173 K and activation by different procedures: oxidation-reduction (ox-red) or direct reduction (red). The characterization included XRD, FESEM, in situ FTIR and Raman spectroscopies, TPR, and specific surface area measurements. Catalytic activity experiments were carried out in a flow apparatus with a mixture of CH4:O2 = 2:1 in a short contact time. Compared to Zm, Zhy favoured the formation of smaller NiO particles, implying a higher number of Ni sites strongly interacting with the support. In all the activated Ni/ZrO2 catalysts, the Ni–ZrO2 interaction was strong enough to limit Ni aggregation during the catalytic runs. The catalytic activity depended on the activation procedures; the ox-red treatment yielded very active and stable catalysts, whereas the red treatment yielded catalysts with oscillating activity, ascribed to the formation of Niδ+ carbide-like species. The results suggested that Ni dispersion was not the main factor affecting the activity, and that active sites for CH4-CPO could be Ni species at the boundary of the metal particles in a specific configuration and nuclearity.

scholarly journals The Study on the Reaction Order and Kinetics of Total Oxidation Reaction of m-xylene over LaMnO3 Perovskite Catalyst

2018 ◽  
Vol 34 (3) ◽  
Author(s):  
Tran Thi Thu Huyen ◽  
Dang Thi Minh Hue ◽  
Nguyen Thi Tuyet Mai ◽  
Tran Thi Luyen ◽  
Nguyen Thi Lan
Keyword(s):  
Catalytic Activity ◽  
Reaction Order ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Deep Oxidation ◽  
Perovskite Oxide ◽  
Mixed Metal Oxide ◽  
Total Oxidation ◽  
Kinetics Of ◽  
Perovskite Type

Gases of m-xylene is one of the popurlar toxic pollutants in the exhaust gases, it is emitted into the environment from factories and engines because the fuel in the engine does not burn completely. The best solution in order to remove this toxic gases of m-xylene to protect the environment is transforming them completely into CO2 and H2O by catalysts. Perovskite of LaMnO3 is one of the catalysts that was synthesized and studied the catalytic properties in total oxidation of m-xylene in our previous report. Obtained results showed that the LaMnO3 perovskite has good catalytic characterizations such as large surface area and the amount of α-oxygen adsorbed on the catalyst is large too. So, it exhibits a good catalytic activity in total oxidation of m-xylene at relatively low reaction temperature. In present work, the reaction order  and kinetics of this reaction are determined. The obtained results demonstrated that the reaction order value with respect to m-xylene is equal to about 1, to oxygene is proximately equal to 0 and the order of reaction is equal to about 1. Based on reaction order data, it was thought that the pathway of m-xylene oxidation by air oxygen  over LaMnO3 may be followed through which the Langmuir - Hinshelwood mechanism. Keywords Catalyst, perovskite, oxidation, m-xylene, kinetics References [1] Penã M.A and Fierro J.L.G (2001), << Chemical Stuctures and Performance of Perovskite Oxide>>, Chem. Rev, 101, pp 1981-2018. [2] Seiyama T., Yamazoe N. and Eguchi K. (1985), <<Characterization and Activity of some Mixed Metal Oxide Catalysts>>, Ind. Eng. Chem. Prod. Res. Dev., 24, pp. 19-27.[3] [3] Van Santen R. A., Neurock M. (2006), Molecular Heterogeneous catalysis, Wiley – VCH, pp.62-244. [4] Petrovics, Terlecki - Baricevic A., Karanovic Lj., Kirilov - Stefanov P. , Zdujic M., Dondur V., Paneva D., Mitov I., Rakic V. (2008), <<LaMO3 (M = Mg, Ti, Fe) perovskite type oxides : Preparation, Characterization and Catalytic Properties in Methane deep Oxidation>>, Appl. Catal. B, Env., 79, pp. 186-198. [5] Spinicci R., Tofanari A., Faticanti M., Pettiti I. and Porta P. (2001), <<Hexane Total Oxidation on LaMO3 (M = Mn, Co, Fe) perovskite-type oxides>>, J. Mole. Catal., 176, pp. 247-252. [6] Trần Thị Thu Huyền, Nguyễn Thị Minh Hiền, Nguyễn Hữu Phú (2006), <<Study on the preparation of perovskite oxides La1-xSrxMnO3 (x = 0; 0,3; 0,5) by sol - gel citrate method and their catalytic activity for m-xylene toltal oxidation>>, Hội nghị xúc tác và hấp phụ toàn quốc lần thứ IV, Tp. Hồ Chí Minh, Tr. 477-482.[7] Trần Thị Thu Huyền, Nguyễn Thị Minh Hiền, Nguyễn Hữu Phú (2009), <<Nghiên cứu động học của phản ứng oxi hóa hoàn toàn m-xylen trên các xúc tác perovskit LaMnO3 và La0,7A0,3MnO3 (A = Sr, Ca, Mg)>>, Tạp chí Hóa học, T.47 (6A), Tr 132-136.[8] Geoffrey C. Bond, Catherine Louis, David T. Thompson (2006), <<Catalysis by Gold>>, Catalytic Science Series-Vol.6.

scholarly journals Microkinetic Modeling of the Oxidation of Methane Over PdO Catalysts—Towards a Better Understanding of the Water Inhibition Effect

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 922
Author(s):  
Kevin Keller ◽  
Patrick Lott ◽  
Henning Stotz ◽  
Lubow Maier ◽  
Olaf Deutschmann
Keyword(s):  
Active Sites ◽  
Catalyst Deactivation ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Excess Oxygen ◽  
Total Oxidation ◽  
Kinetic Measurements ◽  
Microkinetic Model ◽  
Oxidation Of Methane ◽  
Catalytically Active

Water, which is an intrinsic part of the exhaust gas of combustion engines, strongly inhibits the methane oxidation reaction over palladium oxide-based catalysts under lean conditions and leads to severe catalyst deactivation. In this combined experimental and modeling work, we approach this challenge with kinetic measurements in flow reactors and a microkinetic model, respectively. We propose a mechanism that takes the instantaneous impact of water on the noble metal particles into account. The dual site microkinetic model is based on the mean-field approximation and consists of 39 reversible surface reactions among 23 surface species, 15 related to Pd-sites, and eight associated with the oxide. A variable number of available catalytically active sites is used to describe light-off activity tests as well as spatially resolved concentration profiles. The total oxidation of methane is studied at atmospheric pressure, with space velocities of 160,000 h−1 in the temperature range of 500–800 K for mixtures of methane in the presence of excess oxygen and up to 15% water, which are typical conditions occurring in the exhaust of lean-operated natural gas engines. The new approach presented is also of interest for modeling catalytic reactors showing a dynamic behavior of the catalytically active particles in general.

scholarly journals SECRETION OF PLASMINOGEN ACTIVATOR BY STIMULATED MACROPHAGES

1974 ◽  
Vol 139 (4) ◽  
pp. 834-850 ◽  
Author(s):  
Jay C. Unkeless ◽  
Saimon Gordon ◽  
E. Reich
Keyword(s):  
Amino Acids ◽  
Catalytic Activity ◽  
Plasminogen Activator ◽  
Electrophoretic Mobility ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Plasminogen Activators ◽  
Peritoneal Macrophages ◽  
Chemical Labeling ◽  
Specific Catalytic Activity

Cultured thioglycollate-stimulated peritoneal macrophages synthesize, accumulate, and continuously release high levels of plasminogen activators for at least 4 days whereas cultures of unstimulated macrophages do not; the higher specific catalytic activity of released vs. cell-associated enzyme suggests that the plasminogen activators are actively secreted. The major macrophage plasminogen activator is a serine protease of mol wt 48,000, and thus resembles the comparable enzyme released by virally transformed fibroblasts. Macrophages release a second plasminogen activator of mol wt 28,000 that is also a serine enzyme. The secretion products released by stimulated and unstimulated macrophages have been compared by SDS-polyacrylamide gel electrophoresis after chemical labeling with 3H-DFP or biosynthetic labeling with 14C-amino acids. These procedures show that some proteins are formed in both cultures, whereas others are uniquely secreted by each type of macrophage. The serine enzymes released by the two kinds of macrophages differ in specificity and electrophoretic mobility.

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