الفهرس 
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Abstract
The current research work deals with the preparation of organic based composite structures as novel catalysts for the photocatalytic desulfurization of a petroleum diesel fuel. Several desulfurization techniques can be employed; however, photocatalytic desulfurization can be considered as the safest and cost-effective route to achieve such goal.
The removal or extreme reduction of sulfur compounds in diesel fuels is a crucial stage, during their production, in terms of protecting the environment from harmful emissions. Additionally, the use of a cost-effective process, for such a purpose, is strongly favorable from economic prospectives. Thus, this research work aims to produce low-sulfur diesel fuel through a photocatalytic route under the effect of visible light. Hybrid structures made by combining organic and inorganic compounds are presented as novel photocatalysts during this study. Such combination was meant to enhance the overall photocatalytic performances of these structures, as well as, to increase their capability toward the adsorption of sulfur compounds. It had been noticed that the usage of aliphatic chains, bearing functional groups, and increment of electron donor atoms, in the organic part of photocatalyst, could increase the desulfurization percentage. Moreover, the introduction of this structure in its polymerized state had significantly enhanced the desulfurization process.
As soon as the proposed structures both organic (acrylate-based compounds) and metal oxide (MO) were prepared, they were sent to the process of photocatalytic desulfurization of a diesel fuel feedstock (collected from Cairo Oil Refinery Co. having a sulfur content of 12,500 ppm). The designated application had started by investigating the efficiency of MO nanoparticles, as a photocatalyst, toward disposal of sulfur compounds. This stage was carried out under visible light irradiation and at fixed operating conditions (90 min and catalysts dose of 10 g/L). Subsequently, hybrid photocatalysts made by a combination of MO nanoparticles with each of the three prepared acrylamide derivatives were tested against the sulfur removal from diesel fuel at the same operational conditions, as previously stated. The preparation of these three photocatalysts was performed by mechanical mixing of MO and organic compounds (1:1 by weight). After exploring the photocatalyst which could achieve the highest desulfurization percentage, studying the effect of turning its acrylamide derivative into its corresponding polymer, on the process of sulfur removal, had taken place. The effect of metal oxide/polymer ratio, the concentration of photocatalyst, and time of exposure to visible light radiation on the desulfurization process had been studied.
In this research study, three acrylamide derivatives (1 aliphatic and 2 aromatics) N-(2-aminoethyl) acrylamide, N-(2-aminophenyl) acrylamide and N-(2-hydroxyphenyl) acrylamide were firstly prepared and their structural characteristics had been proved through both proton and 13C NMR. Simultaneously, MO (copper oxide and nickel oxide) nanoparticles, as proved by XRD and FTIR analyses, were synthesized via chemical precipitation technique. The MO nanoparticles had shown a high level of purity and thermal stability through detection of ultra-low weight loss (less than 1 Wt %) via the TGA analysis. They had also presented mixed porous nature (micro-/ mesopores) and reasonable specific surface area. Then, MO nanoparticles and their sub-driven composites with the three acrylamide derivatives had shown reasonable photocatalytic desulfurization activity. However, the aliphatic derivative of acrylamide coupled with MO could displayed the highest desulfurization level among the four samples. The three acrylamide derivatives were then transformed to polymers and were subsequently used to produce three hybrid Photocatalysts. The photocatalyst composed of polymer of acrylamide aliphatic derivative had massively improved the photocatalytic desulfurization percentage (78 %), compared to the two aromatic derivatives of acrylamide. The optical properties of the photocatalyst, which showed the maximum removal of sulfur compounds, could verify its enhanced performance in comparison to blank CuO. Particularly, the presence of two amino groups, in each molecule of the polymer, could reduce the bandgap of CuO. This reduction could in turn increase the number of photocatalytic cycles of attacks during the desulfurization process. Additionally, the provided intense electron clouds, by nitrogen atoms lone pairs, along the hybrid photocatalyst could significantly improve its PL property. Therefore, an elevated photocatalytic desulfurization level could be attained by this composite structure. Moreover, this composite could exhibit high reliability through a stable desulfurization level over 5 cycles of reusability. Also, the use of this composite through a consecutive multi-stage process could achieve 97 % removal of the sulfur content in the utilized diesel fuel sample during this study.
On the other hand, the composite of NiO and polymer of aliphatic acrylamide derivatives could attain a sulfur removal percentage of 60 Wt % using the feedstock contain 12500 ppm, as a sulfur content. This percentage of desulfurization could be obtained at operating conditions of: 90 min, 20 g/L and photocatalyst composition of 1:1, by weight, polymer to NiO. The observed sulfur removal % by the presented composite during this study is counted as extremely high in terms of pure photocatalytic route with no further assistance. The corresponding photocatalysts, as reported in literature, in similar application (desulfurization of real diesel fuel sample) could achieve maximum desulfurization percentages ranged between 25-30 %.