Sharif Digital Repository

Nickel hydroxide modified nickel electrodes prepared by cycling the potential of a nickel electrode in alkaline solution exhibited electrocatalytic activity for the oxidation of methane in alkaline media. In the presence of methane the oxidation peak current of nickel hydroxide increases while that of the reverse process decreases. This is attributed to the mediation of nickel species, probably β-NiOOH phase, in the process of electrocatalysis. The mechanism of methane oxidation has also been discussed in terms of the formations of intermediates normally encountered in small organics electro-oxidation. It has also been suggested that in the further oxidation of the intermediates, ions in the... 

A dense membrane of La0.6Sr0.4Co0.8Fe0.2O3- δ (LSCF) perovskite was prepared by a new chelating agent, ethylene diamine N,N,N′,N′-tetra N-acetyl diamine (EDTNAD). As a potent ligand, EDTNAD provided a facile one-step method to form complexes of the four metal ions, simultaneously. The oxygen permeation flux through the pure perovskite LSCF dense membrane was measured over temperature range of 1073-1223 K, thickness of 0.7-1.0 mm and oxygen partial pressure of 0.1-1.0 bar. Oxidative coupling of methane (OCM) reaction using LSCF disk in the atmospheric membrane reactor and over the temperature range of 1073-1173 K showed a C2 selectivity of 100% and C2 yield of 5.01% at 1153 K. Furthermore,... 

Oxidative coupling of methane in a bench scale fixed bed tubular reactor over Mn-Na2WO4/SiO2 catalyst has been studied. Four kinetic models have been considered for oxidative coupling of methane reactions and compared through experimental data, and the best kinetic model has been selected. For removing the heat of reaction, a molten salt bath system surrounding the reactor tube has been proposed. Effects of different factors, such as CH4/O2 ratio, are investigated through experimental and simulation studies. A good agreement has been observed between simulation and experimental data. The reactor behaviors under isothermal and adiabatic conditions have also been simulated  

The perovskite oxide BaTiO3, doped with Ge oxides oxidized methane to C2 coupled hydrocarbons. The ultraviolet-visible spectra of pure barium titanate and Ge doped BaTi(1-x)GexO3(x=0.05,0.1) were compared. The pure barium titanate exhibited an ultraviolet absorption effect. The addition of GeO2 resulted in an increase in absorption of wavelength. Therefore, small amount of Ge decreased band gap energy. Oxygen is inserted by nucleophilic attack which may be considered as an acid-base process. For promoted BaTiO3catalysts with stable cation valance, electron donation ability of lattice oxygen is parallels to its ability of adsorb and active oxygen, and decrease the chance of deep oxidation of... 

Pt@Bi-TiO2 photocatalysts with different Bi (0–5 wt%) and Pt (0–2 wt%) contents were prepared by a two-step sol-gel and photo-deposition technique and were used in photo-reduction of CO2. The synthesized catalysts were characterized by X-ray powder diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), scanning and transmission electron microscopy (SEM and TEM), nitrogen sorption measurement (BET), Raman spectroscopy, Electron paramagnetic resonance (EPR) spectroscopy and photoluminescence spectroscopy (PL). CO2 photo-reduction results revealed that the introduction of Bi into TiO2 structure and subsequent loading of Pt on its surface significantly increased the methane yield....