Physicochemical and catalytic properties of the system chromium oxides-oxygen-water

Dere, J

doi:10.1016/0021-9517(63)90040-x

Cited by 116 publications

(4 citation statements)

References 5 publications

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“…The surface excess oxygen was measured by the method described in reference [46]. This method consists in reducing the surface excess oxygen on the oxide catalyst surface with hydrazine and measuring the amount of nitrogen gas evolved with the aid of gasometric technique which early described by Deren et al [47].…”

Section: Surface Excess Oxygen Measurementmentioning

confidence: 99%

Synthesis and Characterization of Nano CuO-NiO Mixed Oxides

Said¹,

El-Wahab²,

Soliman³

et al. 2014

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A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the NiC 2 O 4 .2H 2 O and/or CuC 2 O 4 precursors which obtained via the reaction between alcoholic metal nitrates and oxalic acid solutions. Thermal behavior of the single and mixed salts has been studied using thermal analysis (TG and DTA). Thermal products were characterized using Fouier transform infrared (FTIR), X-ray diffraction (XRD), Electron microscopy (SEM&TEM), Nitrogen adsorption at -196 o C and surface excess oxygen measurements. The results revealed that, pure NiC 2 O 4 .2H 2 O and CuC 2 O 4 decomposed at 355 and 325 o C, respectively. Also, it was found that the addition of NiO to CuO brought a significant increase in the degree of crystallinity of the mixed oxides which is accompanying with an increase in their particle size and a decrease in the surface area. Moreover, addition of NiO to CuO, also reduces the amount of surface excess oxygen of CuO due to a synergistic effect.

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Section: Surface Excess Oxygen Measurementmentioning

confidence: 99%

Synthesis and Characterization of Nano CuO-NiO Mixed Oxides

Said¹,

El-Wahab²,

Soliman³

et al. 2014

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“…Additionally, milling without catalyst under standard milling reaction conditions showed no oscillations in CO and CO 2 until there was enough material abraded from the steel milling vessel to induce these. Furthermore, reactions at a propene-to-oxygen ratio outside of the explosion limit also showed oscillatory behavior for both CeO 2 the surface with the uptake of oxygen has been reported in several studies [26][27][28]. In the case of CeO 2 , its redox properties and high lability of lattice oxygen are also known to contribute to its catalytic activity in oxidation reactions [29].…”

Section: Radical Versus Catalytic Combustionmentioning

confidence: 99%

Oscillatory combustion of propene during in situ mechanical activation of solid catalysts

2017

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Mechanochemical activation of solids can lead to a strong increase in their activity as catalysts in heterogeneously catalyzed reactions. In the following, we report on the effects of solid catalyst activation during ball milling that lead to oscillatory behavior in CO and CO 2 formation during propene oxidation. The oscillations arise under in situ ball milling conditions over chromium(III) oxide (Cr 2 O 3 ) and cerium(IV) oxide (CeO 2 ), respectively. The experiments were conducted under continuous gas flow at ambient pressure and temperature, using both a modified steel and a tungsten carbide milling vessel. Abrasion of particles from the steel milling vessel could be eliminated as the sole cause for the oscillations through substitution by a tungsten carbide milling vessel. The intensity and frequency of oscillations are shown to be dependent on the propene-to-oxygen ratio, the milling frequency, milling ball size and metal oxide used. Overall, Cr 2 O 3 shows higher activity for oscillatory propene combustion under in situ mechanical activation than CeO 2 .

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“…The effect was first observed by Meyer-Neldel [18] in electronic conductivity of oxide semiconductors (WO 3 , Al 2 O 3 , Ta 2 O 5 and Fe 2 O 3 ). Though it is observed in two main fields that are diffusion processes and semiconductor conduction, MN rule has wide range of applicability in various phenomena of physics, chemistry, biology and electronics [17,[19][20][21][22][23][24][25][26]. Though, universally single MN rule explanation for different system is found to be controversial [27,28].…”

Section: Introductionmentioning

confidence: 99%

“…is successful. The latest study includes number of activated phenomenon such as solid-state diffusion in crystals and polymers, dielectric relaxation and conduction in polymers, thermally stimulated processes in polymers and electronic conduction in amorphous semiconductors [19][20][21][22][23][24][25][29][30][31][32][33][34]. There are also reports of MN rule in kinetic processes, such as amorphous to crystal transition [26,35,36].…”

Section: Introductionmentioning

confidence: 99%

Crystallization kinetics of glassy Se90In10-xAgx alloys: Observation of Mayer-Neldel rule

Singh

Mehta

Sharma

et al. 2016

PAC

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Glassy alloys of Se 90 In 10-x Ag x were prepared using melt quenching technique. Non-isothermal differential scanning calorimetric (DSC) studies were done on Se 90 In 10-x Ag x (x = 0, 2, 4, 6, 8 at.%) glassy alloys at four different heating rates (β = 5, 10, 15, 20°C/min). Well defined endothermic and exothermic peaks were obtained at glass transition (T g) and crystallization temperature (T c), respectively. Augis and Bennett's method was used to obtain the composition dependent crystallization activation energy (E c) and the pre-exponential factor (η 0) of the Arrhenius expression. A linear dependence between ln η 0 and E c was observed showing the existence of compensation effects of the Meyer-Neldel type. These compensation effects confirm the applicability of Meyer-Neldel (MN) rule for the non-isothermal crystallization in the present case.

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Physicochemical and catalytic properties of the system chromium oxides-oxygen-water

Cited by 116 publications

References 5 publications

Synthesis and Characterization of Nano CuO-NiO Mixed Oxides

Synthesis and Characterization of Nano CuO-NiO Mixed Oxides

Oscillatory combustion of propene during in situ mechanical activation of solid catalysts

Crystallization kinetics of glassy Se90In10-xAgx alloys: Observation of Mayer-Neldel rule

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