II. Electrical Properties of Ni/Silica Gel and Pt/γ-Alumina Catalysts in Relation to Catalytic Activity

Gobara, Heba M.; Gomaa, Mohamed M.

doi:10.1080/10916460802608669

Cited by 15 publications

(7 citation statements)

References 35 publications

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“…Thereby electrical property of CaO-M and CaO-F are the function of frequency of the applied field. The boost in conductivity is well thought-out as a fine gauge of a decline in activation energy (activation energy is always related to its catalytic activity) [14]. The observed increase in conductivity is in accordance with the increase of catalytic activity and mobility of charge carriers [15].…”

Section: Ac Conductivity and Dielectric Studiesmentioning

confidence: 63%

Structural, AC conductivity, dielectric and catalytic behavior of calcium oxide nanoparticles derived from waste eggshells

Madhu¹,

Bhagyalakshmi²,

Shruthi³

et al. 2021

SN Appl. Sci.

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Calcium Oxide (CaO) nanoparticles have been synthesized from waste eggshells (ES) as a source of calcium by solution combustion technique using muffle furnace and microwave oven. CaO nanoparticles obtained using muffle furnace (CaO-F) and via microwave oven (CaO-M) were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, AC conductivity and dielectric studies to correlate the physico-chemical behavior. The frequency dependence of AC conductivity, the permittivity (ε′) and dielectric loss tangent (D) studies have been undertaken in the frequency range 50 Hz–5 MHz at room temperature. AC conductivity was found to enhance with an increase in the frequency. The ε′ was found to decrease initially with the frequency and finally reaching a constant value at higher frequencies. The frequency dependence of D was found to exhibit a resonance peak in the studied frequency region. Catalytic activity of CaO-M was correlated with its dielectric behavior.

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Section: Ac Conductivity and Dielectric Studiesmentioning

confidence: 63%

Structural, AC conductivity, dielectric and catalytic behavior of calcium oxide nanoparticles derived from waste eggshells

Madhu¹,

Bhagyalakshmi²,

Shruthi³

et al. 2021

SN Appl. Sci.

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“…For the supported materials, CPE3–R3 was added to the circuit model in order to adjust the experimental data considering the transport of charge at the grain boundary. As shown in Figure 5, the proposed circuits adjust the experimental data and differ from that reported by [17] due to differences in experimental conditions such as the type of electrode used and the type of contact between the sample and the electrode. Table 3 presents a summary of the adjusted circuit parameters and shows the changes in the CPE values in each of the charge transport mechanisms.…”

Section: Resultsmentioning

confidence: 90%

“…The literature results for DC conductivity in alumina pellets at room temperature are of the magnitude 10 −10 [27], while for AC conductivity at 0.1 Hz under a stimulus of 1 V [17], they are 5 × 10 −8 Ω −1 ·cm −1 . As such, the alumina values reported in this work are in the range reported in the literature.…”

Section: Resultsmentioning

confidence: 99%

“…The mechanism of charge transport in supported catalysts is a little-explored aspect of this process. Some studies have reported on the electrical properties of metals, such as Pt and Ni supported in γ-alumina and silica gel, and their relationship with catalytic activity [16,17], as well as charge transport mechanisms in chromium oxide supported in alumina [18]. To the best of our knowledge, there are no studies in which the processes and mechanisms of electrical transport in catalysts formed by supported metal transition oxides are systematically identified.…”

Section: Introductionmentioning

confidence: 99%

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Electrical Behavior of a Catalyst Composed of Laminar Manganese Oxide Supported on γ-Al2O3

2019

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The electrical characterization of catalysts composed of layered manganese oxide in the form of birnessite supported on γ-Al2O3, which have been successfully used in the combustion of soot, is presented. The results indicate that the electrical conduction and ion conduction processes are influenced by the amount of the active phase. There was also evidence of Grotthuss-type proton conductivity favored by the presence of surface water on the exposed alumina surface. The above is supported by the porous nature of the catalyst in which the surface area varied between 125.2 ± 1.2 and 159.0 ± 1.1 m2/g, evidencing changes in the alumina surface. The conductivity, determined from measurements of impedance spectroscopy, at low frequency showed changes associated with the amount of the active phase. The values ranged from 2.61 × 10−8 ± 2.1 × 10−9 Ω−1·cm−1 (pure alumina) to 7.33 × 10−8 ± 5.9 × 10−9 Ω−1·cm−1, 7.21 × 10−8 ± 5.8 × 10−9 Ω−1·cm−1 and 4.51 × 10−7 ± 3.6 × 10−8 Ω−1·cm−1 at room temperature for catalysts with nominal active phase contents of 5.0, 10.0 and 20.0%, respectively. Such results indicate that it is possible to modulate the electrical properties with variations in the synthesis parameters.

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“…13,37,38 Moreover, the metal sites and electrical conductivity of the catalyst also promoted the formation of carbenium ion to enhance the cracking activity. 47,48 The electrical conductivity of the CNT was stronger than that of Al 2 O 3 and HA, which was another reason why the CNT catalyst maintained a higher cracking activity.…”

Section: Catalytic Activitymentioning

confidence: 99%

A Clean Hydroprocessing of Jatropha Oil into Biofuels over a High Performance Ni-HPW/CNT Catalyst

Yang

Liu

et al. 2017

NANO

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The nickel (Ni) and phosphotungstic acid (HPW) supported on carbon nanotubes (CNT) were prepared by impregnation method for hydroprocessing of Jatropha oil. The Ni-HPW/CNT catalyst was characterized by XRD, XPS, FT-IR, N2 adsorption-desorption, SEM, NH3-TPD, and TGA. The effects of reaction parameters, such as reaction temperature (280–400[Formula: see text]C), time-on-stream (0–100[Formula: see text]h), types of support, the amount of added HPW, and coking deposition were investigated. The cracking performance was evaluated by gas chromatography (GC). The yield of C15–C18 alkanes was 88.5[Formula: see text]wt.%, Iso/n ratio was 0.8 and conversion was 97.7% at 320[Formula: see text]C, 3.0[Formula: see text]MPa and 1.0/h over the Ni-HPW/CNT catalyst, while the yield of [Formula: see text] alkanes reached 51.9[Formula: see text]wt.% at 400[Formula: see text]C. The distribution of products could be adjusted by reaction temperature. The cracking performance was elevated by the addition of HPW and the electrical conductivity. The C15–C18 alkanes were further cracked through two cracking circulations. Meanwhile, the catalyst was used without sulfurization and the cracking process was green.

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II. Electrical Properties of Ni/Silica Gel and Pt/γ-Alumina Catalysts in Relation to Catalytic Activity

Cited by 15 publications

References 35 publications

Structural, AC conductivity, dielectric and catalytic behavior of calcium oxide nanoparticles derived from waste eggshells

Structural, AC conductivity, dielectric and catalytic behavior of calcium oxide nanoparticles derived from waste eggshells

Electrical Behavior of a Catalyst Composed of Laminar Manganese Oxide Supported on γ-Al2O3

A Clean Hydroprocessing of Jatropha Oil into Biofuels over a High Performance Ni-HPW/CNT Catalyst

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