khaled.mohammed

Khaled M. H. Mohammed

Lecturer - Lecturer in Physical Chemistry

Faculty of science

Address: Chemistry Department, Faculty of Science, Sohag University, Sohag, 82524, Egypt

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Elucidating the role of CO2 in the soft oxidative dehydrogenation of propane over ceria-based catalysts

2018 | Keywords Reverse water gas shift, Propene, Propane, Oxidative dehydrogenation, CO2, CeO2,
Elucidating the role of CO2 in the soft oxidative dehydrogenation of propane over ceria-based catalysts
A mixed oxide support containing Ce, Zr, and Al was synthesized using a physical grinding method and applied in the oxidative dehydrogenation of propane using CO2 as the oxidant. The activity of the support was compared with that of fully formulated catalysts containing palladium. The Pd/CeZrAlO_x_ material exhibited long-term stability and selectivity to propene (during continuous operation for 140 h), ... Read more

High surface area nanostructured activated carbons derived from sustainable sorghum stalk

2017 | Keywords Purification, Environmental, Adsorption, Nanoporous, Biomass, Activated carbon,
High surface area nanostructured activated carbons derived from sustainable sorghum stalk
The Durra (Sorghum) stalk was employed as a novel precursor for the formation of high surface area activated carbons (ACs) by utilizing ZnCl2 as activating agent followed by pyrolysis in a flow ofN2 gas. The formation of ACs has been investigated at different pyrolysis temperatures (400, 500 and 600 °C) and different ZnCl2 impreg- nation concentrations. The results indicated that, ... Read more

A flexible gas flow reaction cell for in situ x-ray absorption spectroscopy studies

2016 | Keywords Micro-reactor, Operating conditions, Time resolved, In situ, Operando, Combined XAFS-XRD, Combined XAFS-MS, EXAFS, XANNES, X-ray absorption spectroscopy,
A flexible gas flow reaction cell for in situ x-ray absorption spectroscopy studies
A capillary-based sample environment with hot air blower and integrated gas system was developed at Diamond to conduct X-ray absorption spectroscopy (XAS) studies of materials under time-resolved, _in situ_ conditions. The use of a hot air blower, operating in the temperature range of 298-1173 K, allows introduction of other techniques e.g. X-ray diffraction (XRD), Raman spectroscopy for combined techniques studies. ... Read more

Design and control of Lewis acid sites in Sn-substituted microporous architectures

2016 | Keywords XRD, DRIFTS, Solid state DR UV/Vis, Solid state NMR, DFT Calculations, EXAFS, Lewis active sites, Designing active sites,
Design and control of Lewis acid sites in Sn-substituted microporous architectures
Monometallic and bimetallic tin-containing framework architectures have been prepared by hydrothermal methods. Structural and spectroscopic techniques were used to probe the nature of the solid-acid sites, at the molecular level, using a combination of XRD, DR UV-Vis, solid state MAS NMR (119Sn, 27Al and 31P) and XAFS. The nature and strength of the solid-acid sites were experimentally probed by FT-IR ... Read more

In situ spectroscopic investigations of MoOx/Fe2O3 catalysts for the selective oxidation of methanol

2015 | Keywords In situ, Advanced spectroscopy, EXAFS, MoOx/Fe2O3, DRIFTS, Methanol oxidation,
In situ spectroscopic investigations of MoOx/Fe2O3 catalysts for the selective oxidation of methanol
Multicomponent oxide shell@core catalysts have been prepared, affording overlayers of MoO_x_ on Fe2O3. This design approach allows bulk characterization techniques, such as X-ray Absorption Fine Structure (XAFS), to provide surface sensitive information. Coupling this approach with _in situ_ methodologies provides insights during crucial catalytic processes. Calcination studies were followed by a combination of XAFS and Raman, and demonstrate that amorphous ... Read more

Restructuring of AuPd Nanoparticles Studied by a Combined XAFS/DRIFTS Approach

2015 | Keywords Au-Pd supported catalysts, XAFS/DRIFTS, EXAFS, TEM,
Restructuring of AuPd Nanoparticles Studied by a Combined XAFS/DRIFTS Approach
The use of AuPd nanoparticles in catalysis is widespread, with the activity being attributed to their precise structural properties. We demonstrate the restructuring of AuPd nanoparticles under CO oxidation conditions using a combined XAFS/DRIFTS approach. The fresh catalyst exhibits PdO islands at the surface of the nanoparticles, which are reduced under reaction conditions, a process observed via both DRIFTS and ... Read more

Tailoring the selectivity of glycerol oxidation by tuning the acid–base properties of Au catalysts

2014 | Keywords Au catalysts, MCM-41, Sulfated zirconia, XPS, Glycerol, Oxidation, Acid-base properties,
Tailoring the selectivity of glycerol oxidation by tuning the acid–base properties of Au catalysts
Supported gold nanoparticles are very effective catalysts for the selective oxidation of glycerol which represents an important bio-derived feedstock. In this paper we report that the acid/base properties, especially the acid site density, of these catalysts are the key factor in tuning the selectivity. A range of supported AuPt catalysts have been prepared by sol immobilization using acidic (H-mordenite, SiO2, ... Read more

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