This study focuses on the removal of sulfur compounds from liquid fuels specifically gasoline and diesel fuels. The paper centers on the urgency and effect of environmental regulations due to health and global warming concerns on the emerging methods of achieving ultralow sulfur fuels (ULSF).
The traditional hydrodesulphurization process is reviewed and its limitations to achieving ULSF is highlighted. The effect and challenge in achieving ULSF such as change in octane and cetane numbers and the reduced quality of the fuels were also foregrounded. Alternative methods for improved desulfurization process including Biodesulfurization and adsorption desulfurization were examined. Current works by researchers on the methods and processes of achieving ULSF were also investigated.
Desulfurization is the process or processes used to remove or reduce the sulfur content of natural gas and other refined petroleum products such as diesel and gasoline. Sulfur is a non-metallic chemical element which is yellow in color and solid at room temperature. It is abundant in nature and is usually found in elemental form and also occurs as a sulfide or sulfate mineral. Sulfur can be used for many productive processes such in the manufacture of fertilizers and insecticides and it is an essential element for all living organism.
Despite its usefulness, sulfur when exposed in a certain form to the environment can lead to environmental, material and health damage. One of the major sources of sulfur today is the petroleum industry where sulfur occurs as thiols, thiophenes, organic sulfides and disulfides. They occur in several refined petroleum products such as gasoline, diesel, kerosene, jet fuel, coal, and fuel oils. They constitute as contaminants and therefore are undesirable constituents in the oil and gas industry.
In the petroleum industry sulfur is a process contaminant as it deactivates some catalyst during the refining process and causes the corrosion of pumping, pipeline, and refining equipment. Sulfur compounds left in fuels also lead to massive emissions of sulfur gases which not only have environmental impacts but health and material effects as well.
When sulfur gases are emitted, they react with water in the atmosphere to form sulfuric acid and sulfates which turns to acid rain. Acid rain and sulfates cause damage to buildings, automotive painting, they acidify the soil which leads to deforestation and eventually damage to some ecosystem.
Table of Contents
4. Introduction
5. Sulfur in Fuels
6. Thiols
7. Sulfide
8. Thiophenes
9. Impact and Legislature
10. Effect of Desulfurization on Octane and Cetane number
11. Desulfurization Techniques
12. Hydrodesulphurization
13. Oxidative Desulfurization
14. Biodesulfurization
16. Adsorptive Desulfurization
17. Conclusion
Research Objectives and Topics
This study aims to evaluate the necessity and efficacy of various desulfurization processes required to meet stringent global environmental regulations for ultra-low sulfur fuels (ULSF), while addressing the technical challenges inherent in these methods.
- Environmental impact and legislative drivers for sulfur reduction in fuels.
- Limitations of traditional hydrodesulfurization (HDS) processes in achieving ULSF.
- Impact of deep desulfurization on fuel quality parameters like octane and cetane numbers.
- Emerging alternative technologies including oxidative, biodesulfurization, and adsorption methods.
- Optimization and technical hurdles in scaling new desulfurization processes for commercial use.
Excerpt from the Book
1.4 Thiophenes
Thiophene is the simplest sulfur containing aromatic compound in the thiophene family. It has a molecular formula C4H4S and is like benzene in physical and chemical properties. Thiophenes have high reactivity towards sulfonation, and it forms azeotrope with water. Unlike thiols and sulfides, thiophenes are not effectively removed from liquid fuels by HDS process (Achmann et al, 2010). Benzothiophene is another sulfur organic compound, it has a molecular formula C8H6S. It occurs naturally in petroleum related products such as lignite tar. They are mostly found in diesel and gasoline. Their steric structure poses a hindrance which causes HDS to be difficult to achieve. When combusted, they produce sulfur dioxide, a major source of acid rain, equipment corrosion and catalyst poisoning (Liu et al, 2014). Dibenzothiophene is another organosulfur compound with two benzene rings fused to a central thiophenes ring. It has the molecular formula C12H8S. It is found in diesel and gasoline and difficult to remove using HDS process.
Summary of Chapters
Introduction: Outlines the definition of desulfurization, its necessity in the petroleum industry, and the severe environmental and health consequences caused by sulfur emissions.
Sulfur in Fuels: Discusses the chemical forms of sulfur present in crude oil and the analytical methods used for their detection.
Thiols: Details the characteristics of thiol functional groups and their impact on refining catalysts and combustion quality.
Sulfide: Explores organic and inorganic sulfide compounds and their efficient removal from fuel.
Thiophenes: Examines complex aromatic thiophenic compounds that present significant removal challenges for standard refinery processes.
Impact and Legislature: Reviews regulatory frameworks like the Clean Air Act and the resulting mandate for low-sulfur fuels.
Effect of Desulfurization on Octane and Cetane number: Analyzes how deep desulfurization can negatively affect engine performance metrics.
Desulfurization Techniques: Provides an overview of various technological approaches to sulfur removal.
Hydrodesulphurization: Explains the mechanism of conventional catalytic HDS and its operational limitations.
Oxidative Desulfurization (ODS): Describes ODS as a cost-effective, complementary approach to HDS for refractory compounds.
Biodesulfurization: Investigates the use of microbial biocatalysts as a non-invasive, mild-condition alternative for desulfurization.
Absorptive Desulfurization: Focuses on physical adsorption methods using solid matrices for sulfur removal at ambient conditions.
Conclusion: Synthesizes the findings, noting that while ULSF is critical, commercial implementation of newer technologies still faces scalability and efficiency challenges.
Keywords
Desulfurization, Hydrodesulphurization, ULSF, Sulfur, Petroleum, Gasoline, Diesel, Environmental Regulations, Biodesulfurization, Oxidative Desulfurization, Adsorption, Thiophenes, Catalysis, Emission Standards, Fuel Quality.
Frequently Asked Questions
What is the primary focus of this research?
The work focuses on the necessity and technical challenges of removing sulfur compounds from liquid fuels, specifically gasoline and diesel, to meet current environmental standards.
Which fuels are the subject of this study?
The research primarily centers on gasoline and diesel fuels within the petroleum industry.
What is the main goal regarding fuel sulfur levels?
The primary goal is the achievement of Ultra-Low Sulfur Fuels (ULSF) to mitigate environmental and health damage caused by sulfur emissions.
What is the standard industrial method used for desulfurization?
The standard industrial method is Hydrodesulphurization (HDS), which utilizes catalytic treatment with hydrogen at elevated temperatures and pressures.
What are the major disadvantages of the HDS process?
HDS has difficulties with refractory sulfur compounds like thiophenes and can negatively impact fuel quality by reducing octane and cetane numbers.
What alternative methods are discussed in the paper?
The paper examines Oxidative Desulfurization (ODS), Biodesulfurization (BDS), and Adsorption Desulfurization (ADS).
How is Biodesulfurization different from traditional methods?
Biodesulfurization uses microorganisms as biocatalysts to remove organosulfur compounds under mild, room temperature conditions, which is more sustainable than HDS.
Why is sulfur a specific problem for fuel cells?
Fuel cells have very low tolerance for sulfur because it causes cumulative and irreversible poisoning of the anode catalyst, rendering the system inefficient.
- Quote paper
- Ogheneruemu Osirim (Author), 2017, Desulfurization of Liquid Fuels. Industrial Productivity and Environmental Health in Petroleum Refining, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/1419185
