EXTRACTION AND CHARACTERISATION OF MALTENE AND ASPHALTENE FROM AGBABU BITUMEN

ABSTRACT

Extraction  is  an  important  separation  process   for  separating  high  value-added  light  oils  from unconventional oils matrix such as bitumen and extra heavy oil.  Thus it is important to understand the extraction process and the characterization of its products. Extraction of Agbabu bitumen yield 54.3 % maltene, 23.7% asphaltene and 21% impurities. The yield of maltene is almost twice (2 times) the yield of asphaltene. Agbabu bitumen, maltene and asphaltene fractions were analyzed using a thermogravimetric analyzer, XRD, FTIR and GC MS. From TGA It is observed that the pyrolysis behavior of maltene was similar to that of bitumen with one wide shoulder and one narrow peak, while that of asphaltene shows only one peak. The FTIR analysis of the bitumen and it compound shows the presence of aromatic, phenolic and aliphatic compounds. Scanning electron microscopy images showed that the structure of the bitumen is composed of quartz particles surrounded by a mixture of organic matter and clay minerals.

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background to the Study

The high energy consumption in the world is predominantly caused by increase in human population, urbanization and industrialization and their associated need such as electricity and transport fuel. The global increase in oil demand was seen in 2004 with world consumption   of about 600,000 barrels per day oil in third quarter (BP, 2014). This energy demand has become a major challenge of our time since it has outpaced the discovery of conventional fossil fuel sources. There are two major source of energy, these include renewable and non-renewable. Renewable energy are from solar radiation, wind energy, hydropower,    biomass, geothermal energy. While non-renewable are from fossil fuels and nuclear fuels (Sangcheol et al., 2017).

Non-renewable is also called conventional energy which include nuclear fuels, hydropower and fossil fuels. Fossil fuels further divided into natural gas, coal, petroleum, oil, and liquefied petroleum gas. However, Tar sand and oil shale belong to unconventional source of petroleum.

Between 1980 and 2007, the During last a few decades (1980–2007), the average annual growth rate of Gross Domestic Product (GDP) was more than 9% and the primary energy consumption increased more than  three  times.  Recently,  Chinese  rapid  economic  growth  entails  explosive  growth  in  energy consumption (Zhang et al., 2009; Zhang et al., 2013). Although USA is still the largest oil consumer, China and India became world’s second and third largest oil consumer, respectively, with the development of economy and industry (BP, 2016). In the last decade, the consumption of light transportation fuels, such as aviation and motor gasolines, jet and heating kerosene, and gas and diesel oils, has increased as energy demand  increased.  On  the  other  hand,  fuel  oil  consumption  has  decreased  because  of  increasingly stringent environmental regulation and the opposite effect of growing demand for light products. The world has heavily leaned on conventional crude oil as a major source of energy, however, crude oil is a finite resource and its production would be lacked to meet growing demand (Na et al., 2012; Owen et al., 2010; Shin et al., 2016).

Therefore, the development of alternative energy sources for conventional oil is required to fill the gap between energy supply and demand. The demand for energy is expected to be met by unconventional oil resources such as oil sand bitumen and extra heavy oil because unconventional oils are abundant in deposits compared to conventional oils and can be used to produce light transportation fuel and petrochemicals (Gai et al., 2016; Liu et al., 2016;).

Crude oil is an important feedstock for the petrochemical industry and the dominant energy source driving the world economy, but known oil reserves will cover demand for no more than 50 years at the current rate of consumption. In the quest for alternate energy sources, oil sand appears particularly attractive because of the large deposits. Oil sand (tar sand or bitumen sand), a kind of fossil fuels, consists of organic matter, water and mineral matter. The bitumen is a black syrupy material with a viscosity of several thousand centipoise at formation temperature of 5 °C with a specific gravity of about 1.03 g/cm3. The oil sand resources in the world are abundant (Shin et al., 2016).

There is no thorough exploration and well-founded estimation of tar sand. The biggest oil sand reserve is located in Canada. Russia, Venezuela, America and China also have many oil sand resources (Shin et al., 2016). Bitumen is one of the richly deposited mineral resources in Nigeria and in some countries in the world, just like crude oil, it is found in Ondo, Lagos, Ogun, and Edo State. The bitumen deposit in Nigeria is in huge quantity and recorded as the largest deposit in Africa and second largest deposit in the world.

Oil sand bitumen is a mixture of high molecular weight hydrocarbons contained in oil sand and itis highly viscous. Bitumen can be recovered by solvent extraction processes like hot water extraction widely used in Canadian oil sand industry. Bitumen is known as a more environment-friendly and less toxic hydrocarbon  resource  than  coal  (Zhao  et  al.,  2012).To  utilize unconventional  heavy oils,  upgrading processes are indispensable and they are largely categorized into carbon rejection and hydrogen addition (Ahn et al., 2016; Li et al 2008). Hydrogen addition processes are often desirable to obtain high liquid yield, however, these are expensive processes because of the necessity of equipment withstanding harsh conditions and large amounts of hydrogen supply. Carbon rejection processes, such as thermal cracking, catalytic cracking, and solvent extraction, typically produce rejected high carbon materials besides gas and oil products. Tar san, also known as oil sands or bituminous sands consist of a highly viscous petroleum- like material called bitumen, mixed together in an intimate matrix with sands (khot, 1995). The bitumen is a black syrupy material with a viscosity of several thousand centipoises  at formation temperature of  5 degree Celsius with a specific gravity of about 1.03g/cm3 (Ma Y, 2012). The oil sands resources in the world are abundant. Proven worldwide resources of tar sands have been estimated to be approximately 2.5 trillion barrels of petroleum equivalent (Meyer and Dufford, 1998).  Most refined bitumen are used in the construction industry. Mainly, it is use in paving and roofing application. 85% of all bitumen is used as a binder in asphalt for roads, runways, parking lots and foot paths. Gravel and crushed rocks are mixed with tick bitumen, holding it together and it is then applied to roadways. 10% of bitumen used worldwide is used in the roofing industry as its waterproofing qualities help make roof function well while 5% of bitumen is used for sealing and insulating purposes in various building materials such as carpet tile backing and paint ( Donev et  al., 2018).

1.2 Statement of the Research Problem

Fluctuating oil prices have led to an uncertain future for an oil-dependent industrial world. Different countries are investing in other sources for oil other than conventional oil wells and these include oil shale, biomass, and tar sand (also named oil sand). Despite the fact that Nigeria is an oil producing country, the high price of oil makes industrial development a considerable challenge. In addition to the enormous unutilized oil shale reserves in Nigeria, there is a significant amount of tar sand which is principally located in Ondo, Lagos, Ogun, and Edo State. The high percentage of inorganic materials present in these tar sands would make the future use of this bitumen material uncertain without further beneficiation to remove such materials.

1.3 Aim and Objectives of the Research

The aim of this research is to study the extraction of bitumen crude and it derived products. This can be achieved through the following objectives

i.      To carryout Proximate and Ultimate analysis of the sample

ii.       Separation of maltene and asphaltene fraction from bitumen via solvent extraction process.

iii.     Characterization of bitumen and the extracted components via TGA, FTIR, SEM and GC MS.

1.4 Justification of the Study

Bitumen is a precursor to crude oil. However, its viscous nature relegates its use as a source of fuel. Consequently, the need for a viable energy sources have become imperative. Bitumen can be processed for oil recovery using solvent extraction, pyrolysed or the hot-water oil extraction. Due to inherent large throughput and fast rate of processing, the cost of the pyrolysis process is relatively low.

1.5 Scope of the Work

The scope of this study is limited to the collection and extraction of Agbabu as a means of determining its suitability as a fuel.

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