Effect of the crystal plane figure on the catalytic performance of MnO2for the total oxidation of propane

CrystEngComm ◽  
2015 ◽  
Vol 17 (15) ◽  
pp. 3005-3014 ◽  
Author(s):  
Yujie Xie ◽  
Yanyan Yu ◽  
Xueqing Gong ◽  
Yun Guo ◽  
Yanglong Guo ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Crystal Plane ◽  
Plane Figure ◽  
Total Oxidation

scholarly journals Influence of Alumina Precursor Properties on Cu-Fe Alumina Supported Catalysts for Total Toluene Oxidation as a Model Volatile Organic Air Pollutant

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 252
Author(s):  
Tadej Žumbar ◽  
Alenka Ristić ◽  
Goran Dražić ◽  
Hristina Lazarova ◽  
Janez Volavšek ◽  
...  
Keyword(s):  
Surface Characterization ◽  
Iron Concentration ◽  
Catalytic Performance ◽  
Air Pollutant ◽  
Molar Ratio ◽  
Homogeneous Distribution ◽  
Total Oxidation ◽  
Alumina Support ◽  
Determining Factors ◽  
Volatile Organic

The structure–property relationship of catalytic supports for the deposition of redox-active transition metals is of great importance for improving the catalytic efficiency and reusability of the catalysts. In this work, the role of alumina support precursors of Cu-Fe/Al2O3 catalysts used for the total oxidation of toluene as a model volatile organic air pollutant is elucidated. Surface characterization of the catalysts revealed that the surface area, pore volume and acid site concentration of the alumina supports are important but not the determining factors for the catalytic activity of the studied catalysts for this type of reaction. The determining factors are the structural order of the support precursor, the homogeneous distribution of the catalytic sites and reducibility, which were elucidated by XRD, NMR, TEM and temperature programed reduction (TPR). Cu–Fe/Al2O3 prepared from bayerite and pseudoboehmite as highly ordered precursors showed better catalytic performance compared to Cu-Fe/Al2O3 derived from the amorphous alumina precursor and dawsonite. Homogeneous distribution of FexOy and CuOx with defined Cu/Fe molar ratio on the Al2O3 support is required for the efficient catalytic performance of the material. The study showed a beneficial effect of low iron concentration introduced into the alumina precursor during the alumina support synthesis procedure, which resulted in a homogeneous metal oxide distribution on the support.

The Synthesis of Iron Oxides with Different Phases or Exposure Crystal Planes and their Catalytic Property for Propene Oxidation

2012 ◽  
Vol 463-464 ◽  
pp. 189-193
Author(s):  
Kong Zhai Li ◽  
Masaaki Haneda ◽  
Masakuni Ozawa
Keyword(s):  
Catalytic Activity ◽  
Iron Oxides ◽  
Catalytic Property ◽  
Significant Influence ◽  
Catalytic Performance ◽  
Selective Growth ◽  
Crystal Plane ◽  
Low Density ◽  
Fe2o3 Nanoparticles ◽  
Propene Oxidation

Maghemite (γ-FeSubscript text2OSubscript text3) and hematite (α-Fe2O3) nanoparticles with various dominant exposure crystal planes were prepared by several different methods. The structure and the reducibility of these materials were investigated by XRD, Raman and H2-TPR technologies, and their catalytic performance for propene oxidation was also discussed. The maghemite (γ-FeSubscript text2OSubscript text3) showed a better reducibility than hematite (α-FeSubscript text2OSubscript text3), but its activity for propene oxidation is relatively lower. The exposure crystal plane of hematite has a significant influence on its catalytic activity for propene oxidation. Among the prepared four samples, the hematite-1 sample showed the best activity. The selective growth of any planes with a relative low density of Fe atoms for the α-FeSubscript text2OSubscript text3 catalyst would lead to an obvious decrease in the catalytic activity.

scholarly journals Simultaneous Catalytic Oxidation of a Lean Mixture of CO-CH4 over Spinel Type Cobalt Based Oxides

2020 ◽  
Vol 15 (2) ◽  
pp. 490-500
Author(s):  
Neha Neha ◽  
Ram Prasad ◽  
Satya Vir Singh
Keyword(s):  
Mixed Oxides ◽  
Structural Disorder ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Total Oxidation ◽  
Spinel Type ◽  
Molar Ratios ◽  
Long Term Stability ◽  
Nickel Cobalt ◽  
Temperature Programmed

A series of nickel-cobalt bimetal oxides in varying molar ratios and its single metal oxides were synthesized by reactive calcination of coprecipitated basic-carbonates. Several characterization techniques, such as: Bruneuer Emmett Teller (BET), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR), and Hydrogen Temperature Programmed Reduction (H2-TPR), were performed over the oxides. Activities of oxides were evaluated in methane total oxidation in the presence or the absence of CO. The best catalytic performance was observed over NiCo catalyst with a Ni/Co molar ratio of 1:1, and the complete conversion of CO-CH4 mixture was achieved at 390 °C. Moreover, the presence of carbon monoxide improves CH4 total oxidation over nickel-cobalt mixed oxides. Structural analysis reveals that the insertion of nickel into the spinel lattice of cobalt oxide causes the structural disorder, which probably caused the increase of the amount of octahedrally coordinated divalent nickel cations that are responsible for catalytic activity. Stability of the best-performed catalyst has been tested in the two conditions, showing remarkable long-term stability and thermal stability, however, showed deactivation after thermally ageing at 700 °C. Copyright © 2020 BCREC Group. All rights reserved 

scholarly journals Highly Active Transition Metal-Promoted CuCeMgAlO Mixed Oxide Catalysts Obtained from Multicationic LDH Precursors for the Total Oxidation of Methane

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 613
Author(s):  
Hussein Mahdi S. Al-Aani ◽  
Mihaela M. Trandafir ◽  
Ioana Fechete ◽  
Lucia N. Leonat ◽  
Mihaela Badea ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transition Metal ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Catalytic Performance ◽  
Atomic Ratio ◽  
Total Oxidation ◽  
X Ray ◽  
Oxidation Of Methane ◽  
Al2o3 Catalyst

To improve the catalytic performance of an active layered double hydroxide (LDH)-derived CuCeMgAlO mixed oxide catalyst in the total oxidation of methane, it was promoted with different transition-metal cations. Thus, two series of multicationic mixed oxides were prepared by the thermal decomposition at 750 °C of their corresponding LDH precursors synthesized by coprecipitation at constant pH of 10 under ambient atmosphere. The first series of catalysts consisted of four M(3)CuCeMgAlO mixed oxides containing 3 at.% M (M = Mn, Fe, Co, Ni), 15 at.% Cu, 10 at.% Ce (at.% with respect to cations), and with Mg/Al atomic ratio fixed to 3. The second series consisted of four Co(x)CuCeMgAlO mixed oxides with x = 1, 3, 6, and 9 at.% Co, while keeping constant the Cu and Ce contents and the Mg/Al atomic ratio. All the mixed oxides were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with X-ray energy dispersion analysis (EDX), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption at −196 °C, temperature-programmed reduction under hydrogen (H2-TPR), and diffuse reflectance UV-VIS spectroscopy (DR UV-VIS), while thermogravimetric and differential thermal analyses (TG-DTG-DTA) together with XRD were used for the LDH precursors. The catalysts were evaluated in the total oxidation of methane, a test reaction for volatile organic compounds (VOC) abatement. Their catalytic performance was explained in correlation with their physicochemical properties and was compared with that of a reference Pd/Al2O3 catalyst. Among the mixed oxides studied, Co(3)CuCeMgAlO was found to be the most active catalyst, with a temperature corresponding to 50% methane conversion (T50) of 438 °C, which was only 19 °C higher than that of a reference Pd/Al2O3 catalyst. On the other hand, this T50 value was ca. 25 °C lower than that observed for the unpromoted CuCeMgAlO system, accounting for the improved performance of the Co-promoted catalyst, which also showed a good stability on stream.

scholarly journals Effect of Y Modified Ceria Support in Mono and Bimetallic Pd–Au Catalysts for Complete Benzene Oxidation

Catalysts ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 283 ◽  
Author(s):  
Lyuba Ilieva ◽  
Anna Venezia ◽  
Petya Petrova ◽  
Giuseppe Pantaleo ◽  
Leonarda Liotta ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Benzene Oxidation ◽  
Total Oxidation ◽  
Pd Catalysts ◽  
X Ray ◽  
Close Relationship ◽  
Ceria Support ◽  
Co Precipitation

Mono metallic and bimetallic Pd (1 wt. %)–Au (3 wt. %) catalysts were prepared using two ceria supports doped with 1 wt. % Y2O3. Yttrium was added by impregnation or co-precipitation. The catalyst synthesis was carried out by deposition–precipitation method, with sequential deposition–precipitation of palladium over previously loaded gold in the case of the bimetallic samples. The obtained materials, characterized by X-ray powder diffraction (XRD), High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and temperature programmed reduction (TPR) techniques, were tested in the complete benzene oxidation (CBO). The results of the characterization analyses and the catalytic performance pointed to a close relationship between structural, redox, and catalytic properties of mono and bimetallic catalysts. Among the monometallic systems, Pd catalysts were more active as compared to the corresponding Au catalysts. The bimetallic systems exhibited the best combustion activity. In particular, over Pd–Au supported on Y-impregnated ceria, 100% of benzene conversion towards total oxidation at the temperature of 150 °C was obtained. Comparison of surface sensitive XPS results of fresh and spent catalysts ascertained the redox character of the reaction.

Crystal-Plane-Controlled Surface Restructuring and Catalytic Performance of Oxide Nanocrystals

2011 ◽  
Vol 123 (51) ◽  
pp. 12502-12506 ◽  
Author(s):  
Huizhi Bao ◽  
Wenhua Zhang ◽  
Qing Hua ◽  
Zhiquan Jiang ◽  
Jinlong Yang ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Crystal Plane ◽  
Surface Restructuring

scholarly journals Catalytic performance of gold catalysts in the total oxidation of VOCs

Gold Bulletin ◽  
2007 ◽  
Vol 40 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Cristina Della Pina ◽  
Nikolaos Dimitratos ◽  
Ermelinda Falletta ◽  
Michele Rossi ◽  
Attilio Siani
Keyword(s):  
Gold Catalysts ◽  
Catalytic Performance ◽  
Total Oxidation

scholarly journals CuAlCe Oxides Issued from Layered Double Hydroxide Precursors for Ethanol and Toluene Total Oxidation

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 870
Author(s):  
Hadi Dib ◽  
Rebecca El Khawaja ◽  
Guillaume Rochard ◽  
Christophe Poupin ◽  
Stéphane Siffert ◽  
...  
Keyword(s):  
Layered Double Hydroxide ◽  
Mixed Oxides ◽  
Synergetic Effect ◽  
Catalytic Performance ◽  
Total Oxidation ◽  
X Ray ◽  
Volatile Organic ◽  
Temperature Programmed ◽  
Toluene Total Oxidation ◽  
Double Hydroxide

CuAlCe oxides were obtained from hydrotalcite-type precursors by coprecipitation using a M2+/M3+ ratio of 3. The collapse of the layered double hydroxide structure following the thermal treatment leads to the formation of mixed oxides (CuO and CeO2). The catalytic performance of the copper-based catalysts was evaluated in the total oxidation of two Volatile Organic Compounds (VOCs): ethanol and toluene. XRD, SEM Energy-Dispersive X-ray Spectrometry (EDX), H2-temperature programmed reduction (TPR) and XPS were used to characterize the physicochemical properties of the catalysts. A beneficial effect of combining cerium with CuAl-O oxides in terms of redox properties and the abatement of the mentioned VOCs was demonstrated. The sample with the highest content of Ce showed the best catalytic properties, which were mainly related to the improvement of the reducibility of the copper species and their good dispersion on the surface. The presence of a synergetic effect between the copper and cerium elements was also highlighted.

scholarly journals The Effect of Citric Acid Concentration on the Properties of LaMnO3 as a Catalyst for Hydrocarbon Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 226 ◽  
Author(s):  
Zakaria Sihaib ◽  
Fabrizio Puleo ◽  
Giuseppe Pantaleo ◽  
Valeria La Parola ◽  
José Luis Valverde ◽  
...  
Keyword(s):  
Citric Acid ◽  
Physicochemical Properties ◽  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Morphological Properties ◽  
Molar Ratio ◽  
Hydrocarbon Oxidation ◽  
Total Oxidation ◽  
Propene Oxidation ◽  
X Ray

LaMnO3 (LM) catalysts with a molar ratio of citric acid (CA) to metal (La3+ + Mn2+) nitrates ranging from 0.5 to 2 (LM0.5 to LM2) were synthesized by the citrate sol–gel method with the aim of studying the effect of the citric acid ratio on the physicochemical properties and the catalytic performance in hydrocarbon oxidation. Structural and morphological properties of these catalysts were characterized by X-ray diffraction (XRD) and specific surface area (N2 adsorption) measurements, while the chemical composition was determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES). In the selected samples, additional characterizations were carried out by thermogravimetric and differential thermal analysis (TGA/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), temperature-programmed reduction by hydrogen (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The results showed that the amount of citric acid used significantly influenced the TGA/DTA profile of gels along with the physicochemical properties of the catalysts. The XRD patterns are consistent with the perovskite formation as the main phase. The segregation of a small amount of Mn3O4, detected for molar ratios ranging between 0.5 and 1.5, suggested the formation of a slightly nonstoichiometric LaMn1−xO3 phase with a relatively high content of Mn4+. The catalytic performance was evaluated in the total oxidation of two selected hydrocarbons, toluene and propene, which represent typical volatile organic compounds (VOCs). Typically, three consecutive catalytic cycles were performed in order to reach steady-state performance in toluene and propene oxidation. Moreover, the stability of the catalysts under reaction conditions was investigated through 24-h experiments at 17% of toluene conversion. The catalysts LM1.2, LM1.3, and LM1.5 showed the best catalytic performance in both hydrocarbon oxidations, well comparing with the Pd/Al2O3 used as a reference.

The catalytic performance of mesoporous cerium oxides prepared through a nanocasting route for the total oxidation of naphthalene

2010 ◽  
Vol 93 (3-4) ◽  
pp. 395-405 ◽  
Author(s):  
Begoña Puertolas ◽  
Benjamín Solsona ◽  
Said Agouram ◽  
Ramón Murillo ◽  
Ana María Mastral ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Total Oxidation ◽  
Cerium Oxides ◽  
Nanocasting Route
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