Effects of γ-Irradiation and Ageing on Surface and Catalytic Properties of nano-sized CuO/MgO System towards dehydrogenation and condensation reactions

2009 ◽  
Author(s):  
Sahar A. El-Molla ◽  
Marwa M. Ibrahim ◽  
Sahar A. Ismail
Keyword(s):  
Catalytic Properties ◽  
Γ Irradiation ◽  
Condensation Reactions

Influence of γ-irradiation on the catalytic properties of zinc oxide

1982 ◽  
Vol 19 (2) ◽  
pp. 101-105 ◽  
Author(s):  
Ch Sudhakar ◽  
V.R.S Rao ◽  
J.C Kuriacose
Keyword(s):  
Zinc Oxide ◽  
Catalytic Properties ◽  
Γ Irradiation

scholarly journals Effects of γ-Irradiation on the Surface and Catalytic Properties of Co3O4/MgO Systems Aged for One Year

2002 ◽  
Vol 20 (10) ◽  
pp. 1037-1049 ◽  
Author(s):  
G.A. El-Shobaky ◽  
S.A. El-Molla ◽  
S.A. Ismail
Keyword(s):  
Catalytic Activity ◽  
Surface Area ◽  
Rate Constant ◽  
Reaction Rate ◽  
Catalytic Properties ◽  
Reaction Rate Constant ◽  
Unit Surface Area ◽  
Γ Irradiation ◽  
Γ Rays ◽  
One Year

The effects of γ-rays (20–160 Mrad) on the surface and catalytic properties of two Co3O4/MgO systems were investigated. The formulae of the investigated solids were 0.05Co3O4/MgO and 0.2Co3O4/MgO, respectively, both prepared by the impregnation method and calcined at 500°C. The irradiated samples were left for one year in sealed tubes before any measurements were undertaken. γ-Irradiation of the investigated solids resulted in a progressive decrease in the particle size of the Co3O4 and MgO phases. This treatment also led to a measurable increase in the specific surface area of the treated solids to an extent proportional to the γ-ray dosage. Treatment of the Co3O4/MgO system with different doses of γ-rays brought about a significant increase in the catalytic activity expressed both as the reaction rate constant and as the reaction rate constant per unit surface area. However, the curve relating to the catalytic activity and dosage of γ-rays showed maxima located at 40 and 80 Mrad for samples having the formula 0.05Co3O4/MgO and 0.2Co3O4/MgO, respectively. Furthermore, samples exposed to 160 Mrad showed a larger catalytic activity than the unirradiated samples. The results demonstrate the role of γ-rays in inhibiting the deterioration of the catalytic activity of the investigated systems as a function of aging time. The irradiation process did not modify the activation energy of the catalyzed reaction but altered the concentration of active centres on the surfaces of the solids without changing their energetic nature.

A bifunctional covalent organic framework as an efficient platform for cascade catalysis

2017 ◽  
Vol 1 (7) ◽  
pp. 1310-1316 ◽  
Author(s):  
Qi Sun ◽  
Briana Aguila ◽  
Shengqian Ma
Keyword(s):  
Catalytic Properties ◽  
Knoevenagel Condensation ◽  
Aerobic Oxidation ◽  
Covalent Organic Framework ◽  
Condensation Reactions ◽  
Organic Framework ◽  
Cascade Catalysis

A covalent organic framework bearing pyridine moieties, which serves as a promising platform for cascade catalysis, exhibits extraordinary catalytic properties as exemplified by aerobic oxidation–Knoevenagel condensation reactions.

scholarly journals Surface and Catalytic Properties of the CuO/Al2O3 System as Influenced by Doping with CeO2 or ZrO2 and by γ-Irradiation

2001 ◽  
Vol 19 (10) ◽  
pp. 779-793 ◽  
Author(s):  
Gamil A. El-Shobaky ◽  
Farouk M. Radwan ◽  
Abd. El-Mohsen M. Turky ◽  
Ayman Abd. El-Moemen
Keyword(s):  
Catalytic Properties ◽  
Γ Irradiation

scholarly journals Effect of γ-Irradiation on Some Surface and Catalytic Properties of Cr2O3/Al2O3 Solids Precalcined at 700°C

1998 ◽  
Vol 16 (3) ◽  
pp. 163-174 ◽  
Author(s):  
G.A. El-Shobaky ◽  
A.M. Ghozza ◽  
G.M. Mohamed
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Opposite Effect ◽  
Catalytic Properties ◽  
Surface Characteristics ◽  
Mechanical Mixing ◽  
Γ Irradiation ◽  
Untreated Sample ◽  
Surface Parameters ◽  
Catalytically Active

The effects of γ-irradiation (20–160 Mrad) on the surface characteristics (SBET, VP and r) and catalytic properties (in CO oxidation by O2) of chromia/ alumina solids have been investigated. The solids were prepared by mechanical mixing of CrO3 with finely powdered Al(OH)3, followed by drying at 120°C and calcination in air at 700°C. The amounts of chromia in the samples were 8.2 wt% and 27.1 wt%, respectively. The results obtained show that doses of 20–40 Mrad brought about a measurable increase in the surface characteristics (SBET, 46%; VP, 93%; r, 31%) of the sample containing 27.1 wt% Cr2O3 but doses above this limit had the opposite effect. However, the various surface parameters of the sample treated with 160 Mrad were still higher than those of the untreated sample. With the sample containing 8.2 wt% Cr2O3, varying the dosage of γ-irradiation in the range 20–160 Mrad led to smaller variations in the surface parameters. The catalytic activities of both types of sample were decreased by γ-irradiation, with the decrease being more pronounced for samples rich in chromia. Curves relating catalytic activity to dosage exhibited minima at 40 Mrad. The observed decrease in catalytic activity with γ-irradiation was attributed to a decrease in the concentration of catalytically active sites taking part in chemisorption and catalysis of the oxidation of CO by O2 without any change in their energetic nature.

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