Extraction, Chromatograhic Separation and Characterization of Polar Acidic Species in Crude Oils and Naphthenate Deposits by Ultrahigh Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
Mapolelo, Mmilili Myles (author)
Marshall, Alan G. (professor directing dissertation)
Froelich, Philip N. (university representative)
Stiegman, Albert E. (committee member)
Cooper, William T. (committee member)
Rodgers, Ryan P. (committee member)
Department of Chemistry and Biochemistry (degree granting department)
Florida State University (degree granting institution)
Throughout human history, societies have always had the quest to harness the energy sources nature has provided. The discovery of fire, by humans was the most significant step into human civilization. Fire provided light and heat, to heat dwellings and cook food. Thus, the burning of wood provided energy. As human civilization advanced the drive to explore other sources of energy became a necessity which eventually led to the discovery of fossil fuels such as petroleum by the end of the 19th century. Petroleum is the cradle of our civilization and it is one of the primary energy sources for modern societies. Today, many industrialized and developing nations obtain their energy from the world's petroleum reserves. This demand has led to depletion of some of the reserves such as those that contain "light" sweet crude oil. To meet this never ending demand, petroleum reserves that contain "heavy" conventional and unconventional crudes are being harnessed at present. Crude oil is arguably one of the most complex mixtures in the world, and its composition varies widely, depending upon origin and age. Comprehensive compositional knowledge of crude oils from different origin is a necessity as it improves their production and processing, and ultimately determines their market value. Detailed characterization of the elemental composition of "heavy" conventional and unconventional crudes is imperative as these crudes are rich in polar heteroatoms (nitrogen, sulfur and oxygen containing compounds). The polar heteroatomic species in crude oils have some detrimental effects that can result in economic loss during production and processing (e.g., catalyst deactivation, corrosion and storage instabilliy). In addition, combustion of such crude oils results in harmful environmental implications such as atmospheric pollution from nitrogen oxides (NxOy) and sulfur oxides (OySz). A better tool to facilitate detailed characterization of crude oils is mass spectrometry. Mass spectrometry has surpassed many analytical tools in crude oil characterization. The advent of ultrahigh resolution FT-ICR mass spectrometry revolutionized crude oil characterization by its abililty to afford high mass resolving power and mass accuracy, crucial parameters necessary for detailed elemental composition of a complex mixture such as crude oil. Chapter 1 provides a brief introduction to FT-ICR principles, instrumentation and data analysis. Figures of merit (e.g., high mass resolution and mass accuracy) that make FT-ICR MS an outstanding tool for complex mixture analysis are also discussed. I also highlight the breakthrough and significance of electrospray ionization (ESI) in characterization of polar molecules in fossil fuels such as petroleum and petroleum derived materials. In Chapter 2, a detailed description of naphthenic acids and naphthenate deposits is presented. The challenges of naphthenic acids characterization, their role in naphthenate deposition and economic significance are discussed. Chapter 3 highlights naphthenic acids that form calcium and sodium naphthenate deposits. The solid deposits and emulsions are formed by the interaction of naphthenic acids with divalent (Ca2+, Mg2+) or monovalent (Na+, K+) ions in produced waters. Calcium naphthenate formation, an interfacial phenomenon, is thought to depend largely on tetraprotic naphthenic acids known as "ARN" acids with C80 hydrocarbon skeleton whereas sodium naphthenates originate from lower molecular weight (C15 to C35) monoprotic saturated naphthenic acids. In Chapter 4, the characterization of naphthenic acids isolated from calcium and sodium naphthenates by collision activated dissociation (CAD) and infrared multiphoton dissociation (IRMPD) is discussed. IRMPD and CAD experiments reveal structural differences of the naphthenic acids found in calcium and sodium naphthenate deposits. IRMPD fragmentation of ARN acids results in dehydration and decarboxylation of the carboxylic acid groups without dealkylation whereas CAD fragmentation gives similar results to IRMPD with extensive fragmentation that leads to dealkylation of the hydrocarbon skeleton. In Chapter 5, we present our first attempts to preconcentrate and determine the broadband limit of detection (LOD), and consequently quantify ARN acids in whole crude oils. We highlight the significance of the preconcentration step as a method to enhance the detection of ARN acids and consequently yield good quantitation. Chapter 6 highlights the extraction and isolation of naphthenic acids from calcium naphthenate deposits of different geographical origin, by use of ammonia in a custom built deposition reaction cell. The acid extracts were characterized by negative-ion ESI FT-ICR MS. The ammonia extraction method effectively extracts and isolates tetraprotic naphthenic acids known as ARN acids, with a C80 hydrocarbon skeleton from all the calcium naphthenate deposits. Low molecular weight ARN acids with C53-59 and C60-79 hydrocarbon skeletons were also identified in some of the calcium naphthenate deposits. The ammonia extraction method further confirms that ARN acids are the main constituent of and a prerequisite for calcium naphthenate deposition. In Chapter 7, we discuss and compare naphthenic acid extraction in crude oils by two different extraction methods. The efficiency of three basic alcoholic solutions of increasing base strength in the extraction of naphthenic acids in crude oils by a liquid-liquid extraction method is evaluated. The three different basic alcoholic solutions of increasing basic strength were; ammonium hydroxide (NH4OH)
Ion Cyclotron Resonance, Petroleum, FT-ICR, Naphthenic Acids, Naphthenates, Electrospray
April 30, 2010.
A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Includes bibliographical references.
Alan G. Marshall, Professor Directing Dissertation; Philip N. Froelich, University Representative; Albert E. Stiegman, Committee Member; William T. Cooper, Committee Member; Ryan P. Rodgers, Committee Member.
Florida State University
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