scholarly journals Promoting Effect of Palladium on ZnAl2O4-Supported Catalysts Based on Cobalt or Copper Oxide on the Activity for the Total Propene Oxidation

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4814
Author(s):  
Marco Antonio Ocsachoque ◽  
María Silvia Leguizamón-Aparicio ◽  
Mónica Laura Casella ◽  
Ileana Daniela Lick
Keyword(s):  
Catalytic Activity ◽  
Supported Catalysts ◽  
Structural Defects ◽  
Synergic Effect ◽  
Oxidation Reactions ◽  
Promoting Effect ◽  
Propene Oxidation ◽  
Oxide Phases ◽  
Catalytic Stability ◽  
Good Catalytic Activity

Palladium-modified Co-ZnAland Cu-ZnAl materials were used and found active for the catalytic oxidation of propene and propane. According to the results obtained by XRD, TPR and XPS, the zinc aluminate-supported phases are oxide phases, Co3O4, CuO and PdOx for Co-ZnAl, Cu-ZnAl and Pd-ZnAl catalysts, respectively. These reducible oxide species present good catalytic activity for the oxidation reactions. The addition of palladium to Co-ZnAl or Cu-ZnAl samples promoted the reducibility of the system and, consequently, produced a synergic effect which enhanced the activity for the propene oxidation. The PdCo-ZnAl sample was the most active and exhibited highly dispersed PdOx particles and surface structural defects. In addition, it exhibited good catalytic stability. The H2 pre-treated PdCu-ZnAl, PdCo-ZnAl and Pd-ZnAl samples showed higher activity than the original oxide catalysts, evidencing the important role of the oxidation state of the species, mainly of the palladium species, on the catalytic activity for the propene combustion. The synergic effect between metal transition oxides and PdOx could not be observed for the propane oxidation.

scholarly journals Comparative Study of Strategies for Enhancing the Performance of Co3O4/Al2O3 Catalysts for Lean Methane Combustion

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 757
Author(s):  
Andoni Choya ◽  
Beatriz de Rivas ◽  
Jose Ignacio Gutiérrez-Ortiz ◽  
Rubén López-Fonseca
Keyword(s):  
Supported Catalysts ◽  
Porous Alumina ◽  
Methane Combustion ◽  
Redox Properties ◽  
Oxidation Reactions ◽  
Promoting Effect ◽  
Spinel Type ◽  
Surface Protection ◽  
Cobalt Aluminate ◽  
Highly Active

Spinel-type cobalt oxide is a highly active catalyst for oxidation reactions owing to its remarkable redox properties, although it generally exhibits poor mechanical, textural and structural properties. Supporting this material on a porous alumina can significantly improve these characteristics. However, the strong cobalt–alumina interaction leads to the formation of inactive cobalt aluminate, which limits the activity of the resulting catalysts. In this work, three different strategies for enhancing the performance of alumina-supported catalysts are examined: (i) surface protection of the alumina with magnesia prior to the deposition of the cobalt precursor, with the objective of minimizing the cobalt–alumina interaction; (ii) coprecipitation of cobalt along with nickel, with the aim of improving the redox properties of the deposited cobalt and (iii) surface protection of alumina with ceria, to provide both a barrier effect, minimizing the cobalt–alumina interaction, and a redox promoting effect on the deposited cobalt. Among the examined strategies, the addition of ceria (20 wt % Ce) prior to the deposition of cobalt resulted in being highly efficient. This sample was characterized by a notable abundance of both Co3+ and oxygen lattice species, derived from the partial inhibition of cobalt aluminate formation and the insertion of Ce4+ cations into the spinel lattice.

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

Deactivation of arenetitanium(II) bromoalane complexes in the cyclotrimerization of butadiene

1986 ◽  
Vol 51 (12) ◽  
pp. 2751-2759 ◽  
Author(s):  
Jindřich Poláček ◽  
Helena Antropiusová ◽  
Lidmila Petrusová ◽  
Karel Mach
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Model System ◽  
Highly Active ◽  
Catalytic Stability

The C6H6.Ti(II)(AlBr4)2 (Ib) catalyst deactivates during the butadiene cyclotrimerization to give a solid containing all titanium (mostly as TiBr3) and a mixture of AlBr3 and RAlBr2 compounds dissolved in benzene. The residual cationic catalytic activity of the deactivated Ib system is due to presence of AlBr3. In contrast to TiCl3, the deactivated Ib system and the model system TiBr3 + AlBr3 are not activated by the addition of EtAlCl2 in the presence of butadiene: the highly active benzenetitanium(II) system is re-constituted only after reduction of TiBr3 with Et3Al followed by the addition of EtAlCl2. The addition of Et2AlBr to Ib accelerates the deactivation of the system. Deactivation products of this system contain mainly Ti(II) species which forms benzenetitanium(II) catalytic system after addition of EtAlCl2. All the EtAlCl2 reactivated systems produce (Z, E, E)-1,5,9-cyclododecatriene with high catalytic stability and considerable selectivity (>90%). This behaviour points to the catalysis by benzenetitanium(II) chloroalane complexes containing only low amount of bromine atoms and ethyl groups.

Strong Promoting Effect of Gold Nanoparticles on the CO Abatement Catalytic Activity of CoO x /Clay‐Bonded SiC Catalysts Produced by AA‐MOCVD Method Using Co(acac) 2 as Precursor

2020 ◽  
Vol 5 (44) ◽  
pp. 13878-13887
Author(s):  
Golnoosh MirMoghtadaei ◽  
Manoj K. Ghosalya ◽  
Luca Artiglia ◽  
Jeroen A. Bokhoven ◽  
Cavus Falamaki
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Promoting Effect

scholarly journals CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131 ◽  
Author(s):  
Rola Mohammad Al Soubaihi ◽  
Khaled Mohammad Saoud ◽  
Myo Tay Zar Myint ◽  
Mats A. Göthelid ◽  
Joydeep Dutta
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Active Sites ◽  
Bond Activation ◽  
Dissociative Adsorption ◽  
High Catalytic Activity ◽  
Good Catalytic Activity ◽  
Pretreatment Conditions ◽  
Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

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.

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.

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