الفهرس 
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Abstract
In this research work, four nano-sized catalysts were prepared using the electroless deposition method and via using two different reducing agents. Two of these catalysts are based on cobalt while the other two are nickel based catalysts. The current study reveals new technique of preparation by the electroless deposition of which catalysts with mixed structures; namely zero-valente and hydroxide forms of the metals, were obtained. The structure and texture properties of the prepared catalysts were firmly confirmed and identified throughout different tools of analysis. The XRD patterns of the prepared catalysts had verified the simultaneous existence of the metallic cobalt or nickel as well as their hydroxides in the corresponding catalysts. The TEM micrographs of the cobalt catalysts showed domination of HCP and FCC phases within their structures. On the other hand, the nickel catalysts had revealed the presence of two phases, particularly FCC and nano-tubes of nickel. The elemental analysis and surface characteristics of all catalysts have been also detected by both EDX and SBET analysis. The four catalysts had shown different surface properties; specifically total pores volume and average pores radius. This in turn had led to different values of surface areas for each of the four catalysts. The nickel catalysts had shown bigger pores volume and smaller pores radius than the cobalt catalysts. The four catalysts, after they were fully characterized, they were transferred to the stage of catalytically removing the sulphur compounds from a gas oil fraction (contains 10,000 ppm). The catalytic process was investigated at different operating variables. Particularly, the effect of different temperatures, LHSV and hydrogen to feed ratio on the desulphurization process was studied. The four catalysts displayed significant catalytic activity towards the desulphurization of the gas oil fraction feedstock to produce low sulfur diesel fuels, at the end. New advances in the diesel fuel industry could be provided during this research work based on carrying out the production process at non-severe conditions. Specifically, no pressure was applied; an operational temperature of 100 °C and a low rate of hydrogen stream were used. The utilization of a nano-structured metallic/hydroxide (as mixed structures) cobalt based catalysts for the catalytic production of low sulphur diesel fuel can also be counted as a novelty point of the presented work. These advances can obviously initiate a new platform of the catalytic desulphurization routes throughout the production of diesel fuels. from the economic perspective, the stated route through this work can be of a high interest on the industrial scale owing to the capability of producing marketable low sulphur diesel at considerable operational costs. The desulphurization rates which were obtained at the end of this investigation have been extremely high taking into account the non-severe operational conditions. In practical, a diesel fuel with a sulphur content of 1000 ppm was obtained by the cobalt catalysts while it was 220 ppm in the case of nickel catalysts. In reference to the content of sulphur compounds in the original feedstock, the cobalt and nickel catalysts have attained desulphurization of 90 and 97.8 wt. % respectively.