Synthesis and catalytic performance of Ti-MCM-68 for effective oxidation reactions

2008 ◽  
pp. 6224 ◽  
Author(s):  
Yoshihiro Kubota ◽  
Yoshihito Koyama ◽  
Taku Yamada ◽  
Satoshi Inagaki ◽  
Takashi Tatsumi
Keyword(s):  
Catalytic Performance ◽  
Oxidation Reactions

scholarly journals Nickel Phosphide Catalysts as Efficient Systems for CO2 Upgrading via Dry Reforming of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 446
Author(s):  
Miriam González-Castaño ◽  
Estelle le Saché ◽  
Cameron Berry ◽  
Laura Pastor-Pérez ◽  
Harvey Arellano-García ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Lower Surface ◽  
Catalytic Performance ◽  
Dry Reforming Of Methane ◽  
Oxidation Reactions ◽  
Surface Areas ◽  
Ceo2 Sample ◽  
Conversion Rates ◽  
Ni Oxidation ◽  
Catalytic Behaviour

This work establishes the primordial role played by the support’s nature when aimed at the constitution of Ni2P active phases for supported catalysts. Thus, carbon dioxide reforming of methane was studied over three novel Ni2P catalysts supported on Al2O3, CeO2 and SiO2-Al2O3 oxides. The catalytic performance, shown by the catalysts’ series, decreased according to the sequence: Ni2P/Al2O3 > Ni2P/CeO2 > Ni2P/SiO2-Al2O3. The depleted CO2 conversion rates discerned for the Ni2P/SiO2-Al2O3 sample were associated to the high sintering rates, large amounts of coke deposits and lower fractions of Ni2P constituted in the catalyst surface. The strong deactivation issues found for the Ni2P/CeO2 catalyst, which also exhibited small amounts of Ni2P species, were majorly associated to Ni oxidation issues. Along with lower surface areas, oxidation reactions might also affect the catalytic behaviour exhibited by the Ni2P/CeO2 sample. With the highest conversion rate and optimal stabilities, the excellent performance depicted by the Ni2P/Al2O3 catalyst was mostly related to the noticeable larger fractions of Ni2P species established.

scholarly journals First of Its Kind Automotive Catalyst Prepared by Recycled PGMs-Catalytic Performance

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 942
Author(s):  
Anastasia Maria Moschovi ◽  
Mattia Giuliano ◽  
Marios Kourtelesis ◽  
Giovanna Nicol ◽  
Ekaterini Polyzou ◽  
...  
Keyword(s):  
Oxygen Storage Capacity ◽  
Catalytic Performance ◽  
Platinum Group Metals ◽  
Oxygen Storage ◽  
Small Scale ◽  
Gas Mixture ◽  
Oxidation Reactions ◽  
Fresh Catalyst ◽  
Metal Precursors ◽  
Automotive Catalytic Converters

The production of new automotive catalytic converters requires the increase of the quantity of Platinum Group Metals in order to deal with the strict emission standards that are imposed for vehicles. The use of PGMs coming from the recycling of spent autocatalysts could greatly reduce the cost of catalyst production for the automotive industry. This paper presents the synthesis of novel automotive Three-Way Catalysts (PLTWC, Pd/Rh = 55/5, 60 gPGMs/ft3) and diesel oxidation catalysts (PLDOC, Pt/Pd = 3/1, 110 gPGMs/ft3) from recovered PGMs, without further refinement steps. The catalysts were characterized and evaluated in terms of activity in comparison with benchmark catalysts produced using commercial metal precursors. The small-scale catalytic monoliths were successfully synthesized as evidenced by the characterization of the samples with XRF analysis, optical microscopy, and N2 physisorption. Hydrothermal ageing of the catalysts was performed and led to a significant decrease of the specific surface area of all catalysts (recycled and benchmarks) due to sintering of the support material and metal particles. The TWCs were studied for their activity in CO and unburned hydrocarbon oxidation reactions under a slightly lean environment of the gas mixture (λ > 1) as well as for their ability to reduce NOx under a slightly rich gas mixture (λ < 1). Recycled TWC fresh catalyst presented the best performance amongst the catalysts studied for the abatement of all pollutant gases, and they also showed the highest Oxygen Storage Capacity value. Moreover, comparing the aged samples, the catalyst produced from recycled PGMs presented higher activity than the one synthesized with the use of commercial PGM metal precursors. The results obtained for the DOC catalysts showed that the aged PLDOC catalyst outperformed both the fresh catalyst and the aged DOC catalyst prepared with the use of commercial metal precursors for the oxidation of CO, hydrocarbons, and NO. The latter reveals the effect of the presence of several impurities in the recovered PGMs solutions.

MICROWAVE IRRADIATION ASSISTED GROWTH OF Cu, Ni, Co METALS AND/OR OXIDES NANOCLUSTERS AND THEIR CATALYTIC PERFORMANCE

NANO ◽  
2012 ◽  
Vol 07 (05) ◽  
pp. 1250034 ◽  
Author(s):  
O. A. FOUAD ◽  
M. S. EL-SHALL
Keyword(s):  
Microwave Irradiation ◽  
Chemical Reduction ◽  
Catalytic Performance ◽  
The Other ◽  
High Catalytic Activity ◽  
Basic Solution ◽  
Short Time Period ◽  
Oxidation Reactions ◽  
Time Period ◽  
Short Time

Copper, nickel and cobalt metals and oxides needle-like shape nanoclusters have been synthesized successfully by chemical reduction in solution without using a surfactant. XRD analyses showed that copper and nickel metals could be synthesized in a short time period by a microwave irradiation (MWI) — assisted step wise reduction of metal ions in basic solution using hydrazine as a reducing agent whereas cobalt was mainly precipitated in the form of either hydroxide or oxide. TEM images showed that the size of needle-like shape nanoclusters varying from about 5 nm to few hundred nanometers length. On the other hand, copper and cobalt showed high catalytic activity toward CO oxidation than that of nickel. The mechanism of catalytic oxidation reactions over unsupported metals and oxides are also discussed.

scholarly journals Crystalline-phase-dependent catalytic performance of MnO2 for aerobic oxidation reactions

2017 ◽  
Vol 60 (12) ◽  
pp. 1196-1204 ◽  
Author(s):  
Yangzheng Xu ◽  
Jiannan Huang ◽  
Shengshuang Yang ◽  
Jianfeng Wang ◽  
Wei Chen ◽  
...  
Keyword(s):  
Crystalline Phase ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Oxidation Reactions

scholarly journals Enhanced Adhesion Strength of Pt/γ-Al2O3 Catalysts on STS-444 Substrate via γ-Al2O3 Intermediate Layer Formation: Application for CO and C3H6 Oxidation

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 38
Author(s):  
Seung-Hee Ryu ◽  
Cheol Hong Hwang ◽  
Hojin Jeong ◽  
Giyeong Kim ◽  
Sung Il Ahn ◽  
...  
Keyword(s):  
Adhesion Strength ◽  
Intermediate Layer ◽  
Substrate Surface ◽  
Surface Oxidation ◽  
Catalytic Performance ◽  
Pack Cementation ◽  
Oxidation Reactions ◽  
Monolithic Catalysts ◽  
Simultaneous Oxidation ◽  
Potential Applications

Pt/γ-Al2O3 catalysts coated on honeycomb-shaped stainless STS-444 steel substrates with a γ-Al2O3 intermediate layer were prepared using a conventional washcoating method. The intermediate layer was formed on the substrate surface through oxidation using pack cementation. The monolithic catalysts with the intermediate layer were fabricated for potential applications to pre-turbocharger catalysts, which suffer from severe conditions such as vibrations of the engine and high flow rates of exhaust gas. Adhesive strength tests and simultaneous oxidation reactions of CO and C3H6 were carried out for the Pt/γ-Al2O3 monolithic catalysts with and without the intermediate layer. The catalysts with an intermediate layer showed much stronger adhesion than the catalysts without an intermediate layer. Thus, the formation of a γ-Al2O3 intermediate layer by surface oxidation through pack cementation facilitated a significant enhancement of the catalyst adhesion strength without catalytic performance degradation.

scholarly journals Selective Catalytic Oxidation of Lean-H2S Gas Stream to Elemental Sulfur at Lower Temperature

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 746
Author(s):  
Daniela Barba ◽  
Vincenzo Vaiano ◽  
Vincenzo Palma
Keyword(s):  
Fluorescence Analysis ◽  
Catalytic Performance ◽  
Oxidation Reactions ◽  
Inlet Concentration ◽  
X Ray Diffraction ◽  
Fixed Temperature ◽  
Raman Analysis ◽  
X Ray ◽  
Selective Catalytic Oxidation ◽  
Lower Temperature

Ceria-supported vanadium catalysts were studied for H2S removal via partial and selective oxidation reactions at low temperature. The catalysts were characterized by N2 adsorption at 77 K, Raman spectroscopy, X-ray diffraction techniques, and X-ray fluorescence analysis. X-ray diffraction and Raman analysis showed a good dispersion of the V-species on the support. A preliminary screening of these samples was performed at fixed temperature (T = 327 °C) and H2S inlet concentration (10 vol%) in order to study the catalytic performance in terms of H2S conversion and SO2 selectivity. For the catalyst that exhibited the higher removal efficiency of H2S (92%) together with a lower SO2 selectivity (4%), the influence of temperature (307–370 °C), contact time (0.6–1 s), and H2S inlet concentration (6–15 vol%) was investigated.

Functionalized Carbon Nanotube Matrix for Inducing Noncovalent Interactions Toward Enhanced Catalytic Performance of Metallic Electrode

2013 ◽  
Vol 1549 ◽  
pp. 135-140
Author(s):  
Le Q. Hoa ◽  
Hiroyuki Yoshikawa ◽  
Masato Saito ◽  
Eiichi Tamiya
Keyword(s):  
Carbon Nanotube ◽  
Noncovalent Interactions ◽  
Electrochemical Characterizations ◽  
Alcohol Oxidation ◽  
Catalytic Performance ◽  
Oxidation Reactions ◽  
Metallic Electrode ◽  
Environmental Friendliness ◽  
Direct Alcohol Fuel Cells ◽  
Functionalized Carbon Nanotube

ABSTRACTHerein, we investigated the noncovalent interactions derived from functionalized carbon nanotube matrices grafting metallic alloy PtRu nanoparticle-decorated Vulcan carbon (fMWCNTs-g-PtRu/C) toward the enhancement of alcohol oxidation reactions. The fMWCNTs noncovalently grafted PtRu/C was successfully synthesized and demonstrated significant enhancement of the electro-catalytic activity and stability toward alcohol oxidation reactions as revealed by electrochemical characterizations. The presented results indicate that the grafting matrix specifically enhances ethanol oxidation reaction kinetics much more than methanol and propanol oxidation reactions. Since the same loading of PtRu/C was used for all tests, the differentiation between these reactants revealed the different strength of noncovalent interactions between the functional matrix and corresponding reactants. This result reveals a new strategy for using fMWCNTs matrix as potential catalyst supports due to its facile fabrication and functionalization, cost effectiveness and environmental friendliness, factors in which all of them are necessary for the practical application of direct alcohol fuel cells in near future.

scholarly journals Oscillatory Behavior of Pd-Au Catalysts in Toluene Total Oxidation

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 574 ◽  
Author(s):  
Tarek Barakat ◽  
Joanna Rooke ◽  
Dayan Chlala ◽  
Renaud Cousin ◽  
Jean-François Lamonier ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Active Phase ◽  
Catalytic Performance ◽  
Reaction Scheme ◽  
Oscillatory Behavior ◽  
Oh Radicals ◽  
Oxidation Reactions ◽  
Total Oxidation ◽  
Diffuse Reflectance Infrared

In this work, the activity of bimetallic Pd-Au doped hierarchically structured titania catalysts has been investigated in the total oxidation of toluene. In earlier works, doping titania with group Vb metal oxides ensured an increased catalytic performance in the elimination of VOC molecules. A synergy between gold and palladium loaded at the surface of titania supports provided better performances in VOC oxidation reactions. Therefore, the main focus in this work was to investigate the durability of the prepared catalysts under long time-on-stream periods. Vanadium-doped catalysts showed a stable activity throughout the whole 110 h test, whereas, surprisingly, niobium-doped catalysts presented a cycle-like activity while nevertheless maintaining a high performance in toluene elimination. Operando Diffuse Reflectance Infrared Fourrier Transform spectroscopy (DRIFT) experiments revealed that variations in the presence of OH radicals and the presence of carbonaceous compounds adsorbed at the surface of spent catalysts varies with the occurrence of oscillations. X-ray Photoelectron Spectroscopy (XPS) results show that interactions between the material and the active phase provided extra amounts of mobile oxygen species and participated in easing the reduction of palladium. An enhanced redox reaction scheme is thus obtained and allows the occurrence of the cyclic-like performance of the catalyst.

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