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Papers by Fakhreia Al-sagheer

Research paper thumbnail of Study of the polymerization of solid vinyl monomers using differential scanning calorimetry

Two vinyl monomers with a heterocyclic group have been prepared. The solid state polymerization o... more Two vinyl monomers with a heterocyclic group have been prepared. The solid state polymerization of the two monomers was investigated by DSC. The activation energy as well as the order of reaction were calculated using different free radical initiators. It has been shown that the nature of the monomer and the initiator affect the behavior of polymerization. 1 H NMR spectroscopy was used to confirm the polymerization.

Research paper thumbnail of Surface and related bulk properties of titania nanoparticles recovered from aramid–titania hybrid films: A novel attempt

Materials Research Bulletin, 2012

For several application-worthy surface and bulk properties, titania (TiO 2 ) is widely used in di... more For several application-worthy surface and bulk properties, titania (TiO 2 ) is widely used in diverse applications . It is employed as an important ingredient in the manufacturing of pigments, paints, cosmetics, UV blockers, photovoltaics, oxide electronics and advanced sensors . It is, also, used not only as a potential catalyst for a number of technologically and industrially important reactions, but also as an interactive support for a variety of applied metal and metal oxide catalysts .

Research paper thumbnail of Surface Chemistry of Acetone on Metal Oxides:  IR Observation of Acetone Adsorption and Consequent Surface Reactions on Silica−Alumina versus Silica and Alumina

Langmuir, 2000

Pathways and generated surface species of adsorption and consequent surface reactions of acetone ... more Pathways and generated surface species of adsorption and consequent surface reactions of acetone vapor on characterized silica, alumina, and ∼5 wt % silica-alumina were examined by in-situ infrared (IR) spectroscopy, following degassing at room (RT) and higher temperatures (100-400°C). For reference and confirmatory purposes, adsorptives of mesityl oxide and acetic acid, and adsorbents of K-modified and pyridine-covered silica-alumina, were employed. In the absence of Lewis and Bronsted acid sites, as well as of basic sites (i.e., on silica), acetone molecules are weakly hydrogen-bonded to surface OH δ+ groups to desorb completely at 100°C, without involvement in any further surface reactions. The availability of such acid-base sites on alumina and silica-alumina facilitates acetone chemisorption and activation for aldol condensation type surface reactions, leading to formation of surface species of mesityl oxide at RT to 200°C and their oxidative conversion into acetate species at 300-400°C. A more obvious availability of Bronsted acid sites on silica-alumina enhances progression of the surface reactions involved.

Research paper thumbnail of Monopropellant decomposition catalysts

Applied Catalysis A: General, 2002

The need for highly concentrated hydrogen peroxide solutions to fuel spacecraft propulsion system... more The need for highly concentrated hydrogen peroxide solutions to fuel spacecraft propulsion systems necessitates the development of new catalytic formulations mainly based on supported manganese oxides. In order to improve the preparation of such catalysts, the thermal decomposition and the hydrothermal reduction of different permanganate precursors were studied, as well as the effect of washing on the products. The test samples were characterized by X-ray power diffraction (XRD) and surface area determination, and compared for their catalytic activity towards H 2 O 2 decomposition using a constant pressure reactor (for 1.71% H 2 O 2 ) and a constant volume reactor (for 50% H 2 O 2 ). The catalysts prepared by thermal decomposition of KMnO 4 or NaMnO 4 ·H 2 O have shown the intermediate formation of potassium (or sodium) manganate, and its partial dissolution during washing with water; higher catalytic activity and larger surface area were observed for the decomposition products of KMnO 4 . The hydrothermal reduction yielded products exhibiting larger surface area and higher specific catalytic activity when carried out under stoichiometric conditions. Comparable kinetic parameters were determined using both catalytic reactors. Unsupported and alumina supported catalysts displayed comparable activity per gram of manganese.

Research paper thumbnail of Surface Texture of Microcrystalline Tunnel-structured Manganese(IV) Oxides: Nitrogen Sorptiometry and Electron Microscopy Studies

Adsorption Science & Technology, 2002

Research paper thumbnail of Synthesis and surface characterization of todorokite-type microporous manganese oxides: implications for shape-selective oxidation catalysts

Various todorokite-type Mn(IV)-oxides, namely, Mg-, Ni-and Cu-todorokite, were synthesized via hy... more Various todorokite-type Mn(IV)-oxides, namely, Mg-, Ni-and Cu-todorokite, were synthesized via hydrothermal treatment of corresponding buserites. The bulk chemical and phase compositions, crystalline structure, particle morphology and thermal stability, were determined by means of atomic absorption spectroscopy, X-ray powder diffractometry, infrared spectroscopy, and thermogravimetry. The surface chemical composition, texture and structure were assessed using X-ray photoelectron spectroscopy, nitrogen sorptiometry, and scanning and high-resolution transmission electron microscopy. The results revealed that (i) the bulk is crystalline and thermally stable up to 200°C, (ii) nature of the decomposition residues is dependent on type of the divalent metal ion contained, (iii) the crystallites are nano-sized fibrils and expose low-index (0 0 2) crystal facet, (iv) the surface chemical composition reflects that of the bulk, and (v) the surface texture constitutes moderate specific areas, slit-shaped mesopores associated with particle interstices, and micropores assuming surface accessibility for the bulk structural tunnels of the test todorokites. Thus, application of such test oxides as shape-selective oxidation catalysts has been rendered worth attempting.

Research paper thumbnail of Study of the polymerization of solid vinyl monomers using differential scanning calorimetry

Two vinyl monomers with a heterocyclic group have been prepared. The solid state polymerization o... more Two vinyl monomers with a heterocyclic group have been prepared. The solid state polymerization of the two monomers was investigated by DSC. The activation energy as well as the order of reaction were calculated using different free radical initiators. It has been shown that the nature of the monomer and the initiator affect the behavior of polymerization. 1 H NMR spectroscopy was used to confirm the polymerization.

Research paper thumbnail of Surface and related bulk properties of titania nanoparticles recovered from aramid–titania hybrid films: A novel attempt

Materials Research Bulletin, 2012

For several application-worthy surface and bulk properties, titania (TiO 2 ) is widely used in di... more For several application-worthy surface and bulk properties, titania (TiO 2 ) is widely used in diverse applications . It is employed as an important ingredient in the manufacturing of pigments, paints, cosmetics, UV blockers, photovoltaics, oxide electronics and advanced sensors . It is, also, used not only as a potential catalyst for a number of technologically and industrially important reactions, but also as an interactive support for a variety of applied metal and metal oxide catalysts .

Research paper thumbnail of Surface Chemistry of Acetone on Metal Oxides:  IR Observation of Acetone Adsorption and Consequent Surface Reactions on Silica−Alumina versus Silica and Alumina

Langmuir, 2000

Pathways and generated surface species of adsorption and consequent surface reactions of acetone ... more Pathways and generated surface species of adsorption and consequent surface reactions of acetone vapor on characterized silica, alumina, and ∼5 wt % silica-alumina were examined by in-situ infrared (IR) spectroscopy, following degassing at room (RT) and higher temperatures (100-400°C). For reference and confirmatory purposes, adsorptives of mesityl oxide and acetic acid, and adsorbents of K-modified and pyridine-covered silica-alumina, were employed. In the absence of Lewis and Bronsted acid sites, as well as of basic sites (i.e., on silica), acetone molecules are weakly hydrogen-bonded to surface OH δ+ groups to desorb completely at 100°C, without involvement in any further surface reactions. The availability of such acid-base sites on alumina and silica-alumina facilitates acetone chemisorption and activation for aldol condensation type surface reactions, leading to formation of surface species of mesityl oxide at RT to 200°C and their oxidative conversion into acetate species at 300-400°C. A more obvious availability of Bronsted acid sites on silica-alumina enhances progression of the surface reactions involved.

Research paper thumbnail of Monopropellant decomposition catalysts

Applied Catalysis A: General, 2002

The need for highly concentrated hydrogen peroxide solutions to fuel spacecraft propulsion system... more The need for highly concentrated hydrogen peroxide solutions to fuel spacecraft propulsion systems necessitates the development of new catalytic formulations mainly based on supported manganese oxides. In order to improve the preparation of such catalysts, the thermal decomposition and the hydrothermal reduction of different permanganate precursors were studied, as well as the effect of washing on the products. The test samples were characterized by X-ray power diffraction (XRD) and surface area determination, and compared for their catalytic activity towards H 2 O 2 decomposition using a constant pressure reactor (for 1.71% H 2 O 2 ) and a constant volume reactor (for 50% H 2 O 2 ). The catalysts prepared by thermal decomposition of KMnO 4 or NaMnO 4 ·H 2 O have shown the intermediate formation of potassium (or sodium) manganate, and its partial dissolution during washing with water; higher catalytic activity and larger surface area were observed for the decomposition products of KMnO 4 . The hydrothermal reduction yielded products exhibiting larger surface area and higher specific catalytic activity when carried out under stoichiometric conditions. Comparable kinetic parameters were determined using both catalytic reactors. Unsupported and alumina supported catalysts displayed comparable activity per gram of manganese.

Research paper thumbnail of Surface Texture of Microcrystalline Tunnel-structured Manganese(IV) Oxides: Nitrogen Sorptiometry and Electron Microscopy Studies

Adsorption Science & Technology, 2002

Research paper thumbnail of Synthesis and surface characterization of todorokite-type microporous manganese oxides: implications for shape-selective oxidation catalysts

Various todorokite-type Mn(IV)-oxides, namely, Mg-, Ni-and Cu-todorokite, were synthesized via hy... more Various todorokite-type Mn(IV)-oxides, namely, Mg-, Ni-and Cu-todorokite, were synthesized via hydrothermal treatment of corresponding buserites. The bulk chemical and phase compositions, crystalline structure, particle morphology and thermal stability, were determined by means of atomic absorption spectroscopy, X-ray powder diffractometry, infrared spectroscopy, and thermogravimetry. The surface chemical composition, texture and structure were assessed using X-ray photoelectron spectroscopy, nitrogen sorptiometry, and scanning and high-resolution transmission electron microscopy. The results revealed that (i) the bulk is crystalline and thermally stable up to 200°C, (ii) nature of the decomposition residues is dependent on type of the divalent metal ion contained, (iii) the crystallites are nano-sized fibrils and expose low-index (0 0 2) crystal facet, (iv) the surface chemical composition reflects that of the bulk, and (v) the surface texture constitutes moderate specific areas, slit-shaped mesopores associated with particle interstices, and micropores assuming surface accessibility for the bulk structural tunnels of the test todorokites. Thus, application of such test oxides as shape-selective oxidation catalysts has been rendered worth attempting.