Investigation into multifunctional catalysis for organic synthesis

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Preparation, Characterization and Catalytic Activity of Nickel Molybdate (NiMoO4) Nanoparticles

Nickel molybdate (NiMoO4) nanoparticles were synthesized via calcination of an oxalate complex in static air at 500 °C. The oxalate complex was analyzed by thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The as-synthesized nickel molybdate was characterized by Brunauer–Emmett–Teller technique (BET), X-ray diffraction (XRD), and transmission electron microscopy (TEM) and its catalytic efficiency was tested in the reduction reaction of the three-nitrophenol isomers. The nickel molybdate displays a very high activity in the catalytic reduction of the nitro functional group to an amino. The reduction progress was controlled using Ultraviolet-Visible (UV-Vis) absorption

Controlling textural, surface and adsorption characteristics of MCM-48 via hydrothermal treatment

Excluding the autoclaving step in the synthesis recipe of MCM-48 resulted in the formation of silica lacking the three-dimensional channel system, the cubic microstructure and the surface silanol groups. This sample has poor wettability that limits the diffusion rate in aqueous media. Adsorption of methylene blue, MB, on such solid is pH-independent, dispersion forces-controlled, practically reversible, endothermic, non-spontaneous, and follows the pseudo-first-order kinetics and Freundlich mode of adsorption. The adsorbed molecules, 15 mg/g, lay flat on the surface with the formation of a double layer. The usual MCM-48 formed after autoclaving possessed a high adsorption capacity of 480 mg/g obtained through the specific mode of adsorption that increased with pH and proceeded practically irreversibly, exothermically, spontaneously, following the pseudo-second-order kinetics and favorable according to Langmuir model. In case of both types of obtained silica the adsorption of MB resulted in a general decrease in the entropy function

Enhanced catalytic reduction of para-nitrophenol using α-MoO3 molybdenum oxide nanorods and stacked nanoplates as catalysts prepared from different precursors

Molybdenum oxide, α-MoO3, nanorods and stacked nanoplates were prepared from oxalate, citrate and tartrate precursors. These molybdenum oxides showed high efficiencies in the reduction of para-nitrophenol to para-aminophenol in the presence of NaBH4. The prepared precursors were first characterized by thermal gravimetric analysis (TGA) and then thermally decomposed at 350°C (oxalate precursor) and 550°C (citrate and tartrate precursors). The final oxides were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and the Braunauer–Emmet–Teller (BET) technique. The oxalate precursor is the most efficient catalyst for the reduction reaction

Preparation and Characterization of α-Zinc Molybdate Catalyst: Efficient Sorbent for Methylene Blue and Reduction of 3-Nitrophenol

Zinc molybdate (ZnMoO4) was prepared by thermal decomposition of an oxalate complex under a controlled temperature of 500 °C. Analyses of the oxalate complex were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). On the other hand, analyses of the synthesized zinc molybdate were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller technique (BET). The efficiency of the synthesized catalyst was tested with the reduction reaction of 3-nitrophenol (3-NP), and was also applied as a sorbent for methylene blue dye (MB) in aqueous solutions. The catalytic test of zinc molybdate shows a very high activity. The concentration reduction progress and adsorption of the dye were followed by an ultraviolet-visible (UV-vis) spectrophotometer

Modified Nigella Sativa Seeds as a Novel Efficient Natural Adsorbent for Removal of Methylene Blue Dye

The aim of this work was to investigate the use of modified nigella sativa seeds (MNS) for removing of methylene blue (MB) dye from aqueous solution. The nigella sativa (NS) seeds have been pre-treated at different temperatures and periods of time. The maximum adsorption of MB was achieved using NS sample washed with distilled water pre-heated at 65 °C for one hour, then ground to 250 µm particle size (MNS-4). Different parameters were modified to optimize the removal process of MB using MNS-4, such as contact times, temperatures, initial dye concentrations, adsorbent doses, and pH of the solution. MNS-4 exhibited a removal efficiency of 99% for initial dye concentrations greater than 800 ppm at pH value of 11. The kinetic study indicated that the removal process follows the pseudo second order model. The removal was spontaneous, endothermic and favorable, and this was indicated by the thermodynamic study. Maximum removal capacity was 194 mg/g as deduced from Langmuir model. The removal efficiency was maintained after four recycle uses. The modified nigella sativa seeds were characterized before, and after adsorption and regeneration by Fourier Transform infrared (FTIR) and scanning electron microscopy (SEM). The data suggested that nigella sativa seeds could be a prospective agent for removing MB from wastewater

High Catalytic Efficiency of Nanostructured β-CoMoO4 in the Reduction of the Ortho-, Meta- and Para-Nitrophenol Isomers

Nanostructured β-CoMoO4 catalysts have been prepared via the thermal decomposition of an oxalate precursor. The catalyst was characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The efficiency of these nanoparticles in the reduction of ortho- and meta-nitrophenol isomers (2-NP, 3-NP, and 4-NP) to their corresponding aminophenols was tested using UV-visible spectroscopy measurements. It was found that, with a β-CoMoO4 catalyst, NaBH4 reduces 3-NP instantaneously, whilst the reduction of 2-NP and 4-NP is slower at 8 min. This difference is thought to arise from the lower acidity of 3-NP, where the negative charge of the phenolate could not be delocalized onto the oxygen atoms of the meta-nitro group

Catalytic Activity of Sulfated and Phosphated Catalysts towards the Synthesis of Substituted Coumarin

New modified acidic catalysts were prepared from the treatment of silica, titania and silica prepared from hydrolyzed tetraethyl orthosilicate (TEOS) with sulfuric and phosphoric acid. The sulfated and phosphated silica synthesized from TEOS were calcined at 450 and 650 °C. These catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and scanning electron microscope (SEM). The surface areas, total pore volume, and mean pore radius of the acidic catalysts were investigated, while the pore size distribution was determined by the Barrett, Joyner and Halenda (BJH) method. The catalytic activity of the sulfated and phosphated silica and/or titania were examined with the Pechmann condensation reaction, in which different phenols reacted with ethyl acetoacetate as a neat reaction to obtain the corresponding coumarin derivatives. The results indicated that the treatment of the catalysts with sulfuric or phosphoric acid led to a decrease in the phases’ crystallinity to a certain degree. The morphology and the structure of the acidified catalysts were examined and their particle size was calculated. Furthermore, the amount of the used catalysts played a vital role in controlling the formation of the products as well as their performance was manipulated by the number and nature of the active acidic sites on their surfaces. The obtained results suggested that the highest catalytic conversion of the reaction was attained at 20 wt % of the catalyst and no further increase in the product yield was detected when the amount of catalyst exceeded this value. Meanwhile the phenol molecules were a key feature in obtaining the final product