Dissertation for receiving the master's degree "M.Sc. "
Treatment: "Biochemical Engineering
Abstract:
The presence of sulfur compounds in gasoline creates a serious problem in air pollution, environment, corrosion of equipment and destruction of human health. The new environmental standards also impose strict limits on the amount of sulfur and aromatic compounds in gasoline. Desulfurization using a catalyst is one of the most important methods to remove such compounds in gasoline. In this regard, the catalyst was first synthesized by the impregnation method. The structural variables, including the percentage of cobalt, molybdenum, titania, and alumina, were optimized by the Taguchi design method. The variables of pressure, temperature, and space velocity were optimized within the range 230-250?, 15-21 bar, and 11-5 h were investigated. The optimal operational conditions resulting from the statistical design results were obtained as follows: temperature 300 ?, pressure 21 bar, and space velocity 17 h. Kinetic studies of this process were carried out in the presence of CoMo/Al2O3-TiO2 catalyst in the Ingrali fixed bed reactor, and finally a model was obtained with the help of solver software and Newtonian optimization method.
Key words: desulfurization, thiophene, catalyst, cobalt, molybdenum, titania, alumina, kinetic model, experiment design, optimization
Introduction
The main goal of a refinery is to produce valuable products from oil feed using physical and chemical processes of Distillation, extraction, reforming, hydrogenation, cracking, and mixing of the main products include liquid gas, gasoline, jet and diesel fuels, waxes, lubricants, bitumen, and petrochemical products. Also, hydrogen and energy for internal and external use are produced in refineries.
Recently, there have been changes in refining processes in refineries to produce quality products. These changes are due to some external factors. Among environmental laws, economic factors, changes in crude oil, new materials, reactor and process design, the demand for high-value and cheap products have been applied.
The restrictions imposed through environmental laws on the quality of fuels produced for transportation purposes are the most important factor in the changes made in refineries, and for this reason, they have caused an increase in costs. The primary goals of these laws are to reduce the percentage of sulfur in gasoline.
Gasoline, diesel and other fuels are about 75 to 80 percent of the products of refineries and the most desulfurization belongs to them. The presence of sulfur in fuels leads to air pollution with SOX produced by vehicles. In order to reduce the negative effects of exhaust gases and prevent environmental pollution, the percentage of sulfur in motor fuels should be reduced.
Currently, the main goal for desulfurization is to choose a material that does not require high capital, does not consume much energy and hydrogen, and also increases the octane number.
Now these questions are raised: What type of catalyst is suitable for separating sulfur compounds? to all the above questions, the goal is to use a suitable catalyst and examine it in different operational conditions in terms of temperature, pressure, and space velocity.
The best research method to answer the questions and achieve the stated goals is to conduct experiments and statistically analyze the results.In the end, according to the analysis of the effective parameters in the process with the help of Solver software and the Newtonian optimization method, the steps of research in this field are: style="direction: rtl;">Performing experiments
Analyzing the results
Performing supplementary experiments
Writing the final report
The chapters presented in this The research includes:
Chapter One: Generalities
Chapter Two: Catalyst
Chapter Three: Experiments
Chapter Four: Optimization
Chapter Five Conclusions and suggestions
Chapter One
Generalities
1 Air pollution caused by petroleum products:
Although more than two thirds of air pollution is caused by combustion It is fossil fuels, but the majority of air pollution is caused by the evaporation of volatile organic compounds known as VOC 1. These compounds include a wide range of hydrocarbons that are emitted from different sources. In general, VOC refers to carbonaceous compounds except CO, CO2, CH4, and CFCs, including hydrocarbons with low vapor pressure (<0.1 mmHg). In addition to pollution and creating environmental problems, the loss of these materials costs a lot of money every year from an economic point of view.
Gasoline, as one of the most important petroleum fractions for vehicle fuel, is one of the sources of VOC production, which contains hydrocarbons from C4 to about C10. Gasoline with an initial boiling point of about 20-30? and a final boiling point of more than 170-200? can cause many of volatile organic compounds. Although the relative amount of VOC caused by gasoline (less than 10% compared to other sources) is not very high, but its absolute amount is significant, as it reaches one million tons per year in the European Union countries alone. The estimate made for the evaporative losses of gasoline in Iran is about 223,000 tons per year. It is worth noting that other sources of VOC production include:
Transportation system and transportation (about 30 to 45 percent), fuel combustion (about 10 percent), petrochemical industries (about 6 to 10 percent), solvents (about 18 percent), and other sources about 20 percent. The idea of ??saving energy in today's world
is extremely important, it is necessary to evaluate the quality of liquid and vapor gasoline in terms of compounds
1: Volative Organic Compounds
Although common standard tests determine the general properties of gasoline, they do not provide accurate information regarding the specific chemical composition of sulfur.
Gasoline is used as one of the most important petroleum fractions for vehicle fuel. Currently, three types of gasoline with the initial names of regular gasoline, super gasoline, and Euro 4 gasoline are on the market. The difference is in their octane number.]1]
1-2-1 The importance of car gasoline characteristics:
The amount of anti-knock and volatility express the general characteristics of gasoline. Other characteristics depend on the concentration limits of undesirable compounds so that these compounds do not have an adverse effect on the performance of the engine and ensure the stability of the gasoline as well as its compatibility with the materials used in engines and systems used in engines and fuel systems. [2]
1-2-1-1 Degree of anti-knock:
The degree of anti-knock of gasoline is the measure of its resistance to impact and depends on the design of the engine and its operation and atmospheric conditions. Using gasoline with a degree of knocking higher than necessary to prevent impact does not improve the performance of the engine. But cars that are equipped with impact limiters.