Oxidative desulfurization of diesel fuels

• Main Author: Alshahrani, Farhan M.
• Published: University of Oxford 2008
• Subjects: 622
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491293

This thesis describes the development of a simplified catalytic system for the deep removal of sulfur from hydrocarbon-based transportation fuel. The work is divided into four main parts, a literature review of different desulfurization technologies, oxidative desulfurization, the newly developed ODS process and its results, a quantitative and kinetic study of the ODS process. The principal aims of this research were to (i) explore and develop a new oxidative desulfurization process, (ii) measure the efficiency of the process on desulfurization of model solution representing hydrocarbon-based fuels, (iii) explore further the feasibility of applying the ODS process on a commercial diesel samples (iv) make comparison of the effect of the ODS process on different sulfur containing compounds (v) quantitative analysis of the biphasic system ~s a result of the oxidative desulfurization reaction and (vi) kinetic study of the ODS process to determine the reaction constants and activation energy at different reaction temperatures. This thesis is composed of six chapters as the following: CHAPTER l: The thesis commences with comprehensive introduction divided into two parts: Part I discusses the origin of petroleum and its hydrocarbon derivatives and describes the major components of crude oil and their refining processes. In addition, the hydrotreating process was given more attention since it has been for long the conventional hydrodesulfurizaion (HDS) unit in most refineries. Moreover, .the sulfur recovery after refining is also included. Part II describes the major oil contaminates with emphasis on the nature of sulfur compounds present and their removal. It also includes the different hydrotreating, e.g HDS, and non-hydrotreating routes for sulfur removal such as adsorption, photocatalysis, ultrasonic technique, ~ j1IIIIIII extraction, ionic liquids, biodesulfurization and oxidation. CHAPTER 2: With showing the pros and cons of using HDS for deep removal of sulfur compounds, this chapter covers a general overview of the catalytic oxidation desulfurization of transportation fuel. This chapter sheds some light on the history and development of the oxidative processes over the last sixty years or so. The main components of oxidative catalytic processes such as oxidizing agent, catalyst, phase transfer agent and solvents were also explained with mentioning previous publications in this regard. CHAPTER 3: This chapter is focusing comprehensively on the chemical materials and feedstock like diesel that was used in this research. This chapter describes step supervision of Prof. Malcolm L. H. Green, FRS. The experimental procedures covers the Inorganic Chemistry Laboratory of the University of Oxford under the by step the overall experimental procedures carried out over the last three years in· I I ___J III about pervious very relevant oxidative catalytic processes and the rational behind all the lab work carried out to develop a simplified ODS process for diesel. A section selecting the sodium tungstate system is also included. CHAPTER 4: As a result, this chapter explains the results of discovered ODS process compose of 30% hydrogen peroxide, sodium tungstate and acetic acid. The effects of the ODS catalytic system .on model solutions of selected sulfur compounds is also included in this chapter. The result of applying the ODS catalytic system on a commercial hydrotreated diesel obtained from Saudi Aramco is thoroughly explained .with supportive' analytical results from the ICL and the Royal Institute of Great Britain, RIGB. Comments on the mechanism of the ODS reaction is also included in this chapter. CHAPTER 5: After establishing the ODS catalytic system, an in depth study of the optimum material quantities and reaction conditions is included in this chapter. In fact, it starts with quantitative calculations of the two layers as a result of having a biphasic solution. A comprehensive kinetic study of the effect of ODS catalytic system on nine different sulfur containing compounds is also included in this chapter. The reaction rate constants and activation energy at different reaction temperature of the said sulfur compounds have also been explored. Based on their reaction rate, this concludes by shown the trend of desulfurization of the selected different sulfur compounds. CHAPTER 6: The aim of this chapter is to give a final comprehensive conclusion of tllis thesis, Based on the ODS bench scale discovery, this chapter proposed as well the necessity of taking this research further for scale up if possible.