Structural and catalytic properties of MoO3-NiO mixed oxides system

1989 ◽  
Vol 54 (6) ◽  
pp. 1508-1513 ◽  
Author(s):  
Abd El Aziz A. Said ◽  
Ehsan A. Hassan ◽  
Ahmed M. El-Awad ◽  
Khalf-Alla M. Abd El-Salaam
Keyword(s):  
Electrical Conductivity ◽  
Catalytic Activity ◽  
Solid State ◽  
Surface Area ◽  
Solid State Reaction ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Xrd Analysis ◽  
Conductivity Measurements ◽  
Activity Measurements

The unsupported MoO3-NiO catalysts were investigated. The addition process of NiO was followed by electrical conductivity measurements, IR, XRD, surface area and finally catalytic activity measurements. The conductivity measurements revealed an increase in σ values when 2-propanol vapour was admitted in the gas feed. IR and XRD analysis detected a solid state reaction at about 500 °C and its maximum was shown around 70 mole % Ni2+ where NiMoO4 lattice diffraction type was detected. Parallel with these measurements, the catalytic activity was determined for the catalysts calcined at 500 °C using the decomposition of 2-propanol. The conversion and the selectivity increased as Ni2+ was added to a concentration of 70 mole % Ni2+ ions. The results were discussed in respect to the creation of holes associated to Ni2+ addition.

scholarly journals Influence of the Reduction Temperature and the Nature of the Support on the Performance of Zirconia and Alumina-Supported Pt Catalysts for n-Dodecane Hydroisomerization

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 88
Author(s):  
Diana García-Pérez ◽  
Maria Consuelo Alvarez-Galvan ◽  
Jose M. Campos-Martin ◽  
Jose L. G. Fierro
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Catalytic Properties ◽  
Catalytic Performance ◽  
Major Influence ◽  
Pt Catalysts ◽  
Reduction Temperature ◽  
Metal Dispersion ◽  
Tungsten Oxides ◽  
Supported Pt Catalysts

Catalysts based on zirconia- and alumina-supported tungsten oxides (15 wt % W) with a small loading of platinum (0.3 wt % Pt) were selected to study the influence of the reduction temperature and the nature of the support on the hydroisomerization of n-dodecane. The reduction temperature has a major influence on metal dispersion, which impacts the catalytic activity. In addition, alumina and zirconia supports show different catalytic properties (mainly acid site strength and surface area), which play an important role in the conversion. The NH3-TPD profiles indicate that the acidity in alumina-based catalysts is clearly higher than that in their zirconia counterparts; this acidity can be attributed to a stronger interaction of the WOx species with alumina. The PtW/Al catalyst was found to exhibit the best catalytic performance for the hydroisomerization of n-dodecane based on its higher acidity, which was ascribed to its larger surface area relative to that of its zirconia counterparts. The selectivity for different hydrocarbons (C7–10, C11 and i-C12) was very similar for all the catalysts studied, with branched C12 hydrocarbons being the main products obtained (~80%). The temperature of 350 °C was clearly the best reduction temperature for all the catalysts studied in a trickled-bed-mode reactor.

Synthesis of New Chalcogenide Materials. The Novel One-Dimensional Semiconductor K4 Ti3 S14

1987 ◽  
Vol 97 ◽  
Author(s):  
Steven A. Sunshine ◽  
Doris Kang ◽  
James A. Ibers
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Alkali Metal ◽  
The Novel ◽  
Conductivity Measurements ◽  
One Dimensional ◽  
General Utility ◽  
Solid State Materials ◽  
Chalcogenide Materials

ABSTRACTThe use of A2 Q/Q melts (A - alkali metal, Q - S or Se) for the synthesis of new one-dimensional solid-state materials is found to be of general utility and is illustrated here for the synthesis of K4 Ti3 SI4. Reaction of Ti metal with a K2 S/S melt at 375°C for 50 h affords K4 Ti3 SI4. The structure possesses one-dimensional chains of seven and eightcoordinate Ti atoms with each chain isolated from all others by surrounding K atoms. There are six S-S pairs (dave - 2.069(3) Å) so that the compound is one of TiIV and may be described as K4 [Ti3 (S)2 (S2)6]. Electrical conductivity measurements indicate that this material is a semiconductor.

Electron Donating, Acid-Base and Catalytic Properties of Perovskite-Type Mixed Oxides of Rare Earths

1995 ◽  
Vol 60 (6) ◽  
pp. 977-982
Author(s):  
S. Sugunan ◽  
V. Meera
Keyword(s):  
Catalytic Activity ◽  
Electron Donor ◽  
Rare Earths ◽  
Electron Affinity ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Surface Acidity ◽  
Electron Acceptors ◽  
Acid Base ◽  
Perovskite Type

The electron donor properties of perovskite-type mixed oxides (LaFeO3, PrFeO3, SmFeO3, LaCoO3, PrCoO3, SmCoO3, LaNiO3, PrNiO3 and SmNiO3) were studied based on the adsorption of electron acceptors exhibiting different electron affinity viz. 7,7,8,8-tetracyanoquinodimethane, 2,3,5,6-tetrachloro-1,4-benzoquinone, p-dinitrobenzene, and m-dinitrobenzene. The surface acidity/basicity of the oxides was determined using a set of Hammett indicators. The data were correlated with the catalytic activity of the oxides for the reduction of cyclohexanone with 2-propanol.

scholarly journals Surface and Catalytic Properties of γ-Irradiated Cr2O3/Al2O3 Solids

1997 ◽  
Vol 15 (6) ◽  
pp. 465-476 ◽  
Author(s):  
G.A. El-Shobaky ◽  
A.M. Ghozza ◽  
G.M. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Surface Area ◽  
Pore Volume ◽  
Active Sites ◽  
Catalytic Properties ◽  
Total Pore Volume ◽  
Bet Surface Area ◽  
Two Samples ◽  
Γ Rays

Two samples of Cr2O3/Al2O3 were prepared by mixing a known mass of finely powdered Al(OH)3 with a calculated amount of CrO3 solid followed by drying at 120°C and calcination at 400°C. The amounts of chromium oxide employed were 5.66 and 20 mol% Cr2O3, respectively. The calcined solid specimens were then treated with different doses of γ-rays (20–160 Mrad). The surface and catalytic properties of the different irradiated solids were investigated using nitrogen adsorption at −196°C and the catalysis of CO oxidation by O2 at 300–400°C. The results revealed that γ-rays brought about a slight decrease in the BET surface area, SBET (15%), and in the total pore volume, Vp (20%), of the adsorbent containing 5.66 mol% Cr2O3. The same treatment increased the total pore volume, Vp (36%), and the mean pore radius, r̄ (43%), of the other adsorbent sample without changing its BET surface area. The catalytic activities of both catalyst samples were found to increase as a function of dose, reaching a maximum value at 80–160 Mrad and 40 Mrad for the solids containing 5.66 and 20 mol% Cr2O3, respectively. The maximum increase in the catalytic activity measured at 300°C was 59% and 100% for the first and second catalyst samples, respectively. The induced effect of γ-irradiation on the catalytic activity was an increase in the concentration of catalytically active sites taking part in chemisorption and in the catalysis of CO oxidation by O2 without changing their energetic nature. This was achieved by a progressive removal of surface hydroxy groups during the irradiation process.

Method of High Active Preparation and Electrical Properties of CuFeO2 Delafossite-Type

2014 ◽  
Vol 979 ◽  
pp. 302-306 ◽  
Author(s):  
Chalermpol Rudradawong ◽  
Aree Wichainchai ◽  
Aparporn Sakulkalavek ◽  
Yuttana Hongaromkid ◽  
Chesta Ruttanapun
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Solid State ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Metal Powders ◽  
High Power Factor

In this paper, the CuFeO2compound were prepared by classical solid state reaction (CSSR) and direct powder dissolved solution (DPDS) method from starting material metal oxides and metal powders. Preparation of two methods shows that, direct powder dissolved solution faster recover phases than classical solid state reaction method. The fastest method gets from starting materials Cu and Fe metal powders, the electrical conductivity, Seebeck coefficient, carrier concentration and mobility are 10.68 S/cm, 244.59 μV/K, 12.86×1016cm-3and 494.96 cm2/V.s, respectively. In addition, each CuFeO2compounds were investigated on crystal structure and electrical properties. From XRD and SEM results, all samples have a crystal structure delafossite-typeand a large grain boundary more than 15 μm by electrical conductivity corresponds to grain boundary and lattice parameter: a increases. Within this paper, from above results exhibit that preparation CuFeO2from Cu and Fe by direct powder dissolved solution method most appropriate for thermoelectric oxide materials due to high active for preparation else high lattice strain and high power factor are 0.00052 and 0.64×10-4W/mK2, respectively.

Studies on metal hydroxy compounds. XV. Electrical conductivity measurements on Cd(OH)Cl, Cu(OH)Cl, and PbOHCl

1977 ◽  
Vol 55 (19) ◽  
pp. 3377-3379
Author(s):  
Mahadeva Natarajan ◽  
Etalo A. Secco
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Temperature Measurements ◽  
Conductivity Measurements ◽  
Decomposition Step ◽  
Hydroxy Compounds

The electrical conductivity dependence on temperature measurements for three metal basic chlorides are reported. The conductivity results yield energy values which are interpreted in terms of active solid state processes leading up to, and including, the decomposition step.

W6+ & Br− codoped Li4Ti5O12 anode with super rate performance for Li-ion batteries

2015 ◽  
Vol 3 (26) ◽  
pp. 13706-13716 ◽  
Author(s):  
Qianyu Zhang ◽  
Huansheng Lu ◽  
Haoxiang Zhong ◽  
Xiaodan Yan ◽  
Chuying Ouyang ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Anode Material ◽  
Solid State Reaction ◽  
Rate Performance ◽  
Li Ion Batteries ◽  
Li Ion ◽  
Li4ti5o12 Anode ◽  
Simple Solid State Reaction

We report a novel Li4Ti5−xWxO12−xBrx (x = 0.025, 0.050 and 0.100) anode material simultaneously doped with W6+ and Br− ions prepared by a simple solid-state reaction in air, aiming to significantly improve electrical conductivity of Li4Ti5O12.

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