Petroleum

1. History of petroleum

2. Origins of petroleum

3. Composition of petroleum

4. Petroleum products

5. Atomic Emission

6. Inductive coupled plasma ICP

7. Trace element in Petroleum and Petroleum products

8. Application.

1. History of petroleum

Petroleum or crude oil has been known for a long time. Archeologists have shown

that it had already been extracted and used for about 5-6 thousand years before

Christ. The most ancient known oil wells are those at Ephrata and the Kerch coast

in the Chinese province of Sychuan. The mention of petroleum has been found in

many ancient manuscripts and books. For example, the Bible writes about "pitch

wells in the vicinities of the Dead Sea"(1).

The use of petroleum and its derivatives was practiced in pre-common era times

and is known largely through historical use in many of the older civilizations.

Early references to petroleum and its derivatives occur in the Bible, although by

the time the various books of the Bible were written, the use of petroleum and

bitumen was established (2).

In ancient times, petroleum had some applications in medicine as well as civil

works. For example, the ancient Greek scientist Hippocrates (IV-V century B.C.)

has described many recipes of medicines which included petroleum.

Even though the history of crude oil could be traced back by more than two

thousand years, real production of crude oil perhaps began in August 27, 1859,

when the first industrial-scale crude oil well with a depth of 22 meters was

opened in Oil Creek, Pennsylvania. After this first industrial crude oil well was

opened, there was the commencement of a rapid development of crude oil

production and treatment. Probably, this day could be said to mark the birth of

modern crude oil chemistry. In 1878, the Swedish businessman Alfred B. Nobel

together with his brothers formed the Naphtha Company Brothers Nobel. The

company extracted the crude oil in Baku, Russia and transported it to the first

crude oil refineries via the pipelines built by Naphtha Co., which still exists now

(1).

The modern petroleum industry began in 1859 with the discovery and

subsequent commercialization of petroleum in Pennsylvania (Bell, 1945). During

the 6,000 years of its use, the importance of petroleum has progressed from the

relatively simple use of asphalt from Mesopotamian seepage sites to the present-

day refining operations that yield a wide variety of products and petrochemicals

(2).

1.2 Definition of petroleum

Petroleum naturally occurring oil that consists chiefly of hydrocarbons with

some other elements, such as sulphur, oxygen, and nitrogen. In its unrefined form

petroleum is known as crude oil (sometimes rock oil). Petroleum is believed to

have been formed from the remains of living organisms that were deposited,

together with rock particles and biochemical and chemical precipitates, in shallow

depressions, chiefly in marine conditions. Under burial and compaction the

organic matter went through a series of processes before being transformed into

petroleum, which migrated from the source rock to become trapped in large

underground reservoirs beneath a layer of impermeable rock. The petroleum

often floats above a layer of water and is held under pressure beneath a layer of

natural gas. (3)

2. The Origins of petroleum

There are two theories on the origin of carbon fuels: the abiogenic theory and the

biogenic theory.

2.1 ABIOGENIC ORIGIN

This theory described by some chemists

A- Marcellin Berthelot:

In 1866, Berthelot considered acetylene the basic material and crude oil

constituents were produced from the acetylene. Initially, inorganic carbides

were formed by the action of alkali metals on carbonates after which

acetylene was produced by the reaction of the carbides with water.

B- Dmitri Mendelejeff

Mendelejeff, who proposed that the action of dilute acids or hot water on

mixed iron and manganese carbides produces a mixture of hydrocarbons from

which petroleum evolved, described another theory in which acetylene is

considered to be the basic material:

2.2 BIOGENIC ORIGIN

In 1911 Engler was the first author to postulate that an organic substance other

than coal was the source material of petroleum. He invoked the concept of three

separate development stages.

A- In the first stage, animal and vegetable deposits accumulate at the bottom

of inland seas (lagoon conditions) and are then decomposed by bacteria;

the carbohydrates and the bulk of the protein are converted into water-

soluble material or gases and thus removed from the site. The fats, waxes,

and other fat-soluble and stable materials (rosins, cholesterol, and others)

remain.

B- The second stage, high temperatures and pressures cause carbon dioxide to

evolve from compounds containing a carboxyl group, and water is

produced from the hydroxyl acids and alcohols to leave a bituminous

residue. Continued application of the heat and pressure causes light

cracking, producing a liquid product with high olefin content

(protopetroleum). Engler also produced experimental evidence which

showed that distillation of fats under pressure brought about the formation

of a petroleum type of material, and he assumed that time and high

pressure offset the fact that the temperature in oil source rocks is lower

than that used experimentally.

C- In the third stage, the unsaturated components of the protopetroleumare

polymerized under the influence of contact catalysts and thus the

polyolefins are converted into paraffins and=or cycloparaffins naphthenes).

Aromatics were presumed to be formed either directly during cracking, by

cyclization through condensation reactions, or even during the

decomposition of protein (4).

3. Compositions of Crude oil

Petroleum is a complex mixture of various organic compounds. It consists of

different hydrocarbons and heteroatomic compounds.

Table 3.1 the percent range of element in the crude oil

Also these ranges are change with geological area

Table 3.2 Amount of element in crude oil in difference area

3.1 HYDROCARBON CONSTITUENTS

The isolation of pure compounds from petroleum is an exceedingly difficult task,

and the overwhelming complexity of the hydrocarbon constituents of the higher

molecular weight fractions as well as the presence of compounds of sulfur,

oxygen, and nitrogen, are the main causes for the difficulties encountered. It is

difficult on the basis of the data obtained from synthesized hydrocarbons to

determine the identity or even the similarity of the synthetic hydrocarbons to

those that constitute many of the higher boiling fractions of petroleum.

Nevertheless, it has been well established that the hydrocarbon components of

petroleum are composed of paraffinic, naphthenic, and aromatic groups (Table

3.3). Olefin groups are not (4).

Table 3.3 Hydrocarbon and Heteroatom Types in Petroleum

Usually found in crude oils, and acetylenic hydrocarbons are very rare indeed. It

is therefore convenient to divide the hydrocarbon components of petroleum into

the following three classes:

1. Paraffins, which are saturated hydrocarbons with straight or branched chains,

but without any ring structure

2. Naphthenes, which are saturated hydrocarbons containing one or more rings,

each of which may have one or more paraffinic side chains (more correctly known

as alicyclic hydrocarbons)

3. Aromatics, which are hydrocarbons containing one or more aromatic nuclei,

such as benzene, naphthalene, and phenanthrene ring systems, which may be

linked up with (substituted) naphthene rings or paraffinic side chains (2)

3.2 NONHYDROCARBON CONSTITUENTS

Crude oils contain appreciable amounts of organic non hydrocarbon

constituents, mainly sulfur, nitrogen, and oxygen containing compounds and, in

smaller amounts, organometallic compounds in solution and inorganic salts in

colloidal suspension. These constituents appear throughout the entire boiling

range of the crude oil, but tend to concentrate mainly in the heavier fractions and

in the nonvolatile residues.

The presence of traces of nonhydrocarbons may impart objectionable

characteristics in finished products, such as discoloration, lack of stability on

storage, or a reduction in the effectiveness of organic lead antiknock additives. It

is thus obvious that a more extensive knowledge of these compounds and of their

characteristics could result in improved refining methods and even in finished

products of better quality.

Also Metallic constituents are found in every crude oil and the concentrations

have to be reduced to convert the oil to transportation fuel. Metals affect many

upgrading processes and cause particular problems because they poison catalysts

used for sulfur and nitrogen removal as well as other processes such as catalytic

cracking. The trace metals Ni and V are generally orders of magnitude higher than

other metals in petroleum, except when contaminated with coproduced brine

salts (Na, Mg, Ca, and Cl) or corrosion products gathered in transportation (Fe)

(4).

4. PRODUCTS FROM CRUDE OIL

The list of products from petroleum is endless. Oil products fuel planes, trains,

cars, trucks, buses, and so on. Oil is also used to heat homes. Chemicals made

from oil are used to make products that range from makeup, toys, fabrics,

sneakers and football helmets to aspirin, toothpaste, deodorant, clothes, hair

dryers and lipstick to name just a few. Plastics made from oil are widely used in

everything from compact discs and video cassette recorders, to computers,

television sets, and telephones (1).

Typical final products are:

1. Gases for chemical synthesis and fuel, liquefied gases

2. Aviation and automotive gasoline

3. Aviation (jet) and lighting kerosene

4. Diesel fuel

5. Distillate and residual fuel oils

6. lubricating oil base grades

7. Paraffin oils and waxes

Table 4.1 Product of petroleum with boiling point range

4.1 Liquefied petroleum gas LPG

It is a mixture of Gaseous hydrocarbons propane (C3H8) and butane (C4H10) that

producing during natural gas refining.

Properties of LPG

1- Free from ethane.

2- Free from pentane.

3- Free from unsaturated hydrocarbon.

4- Free from H2S (5).

Figure 4.1 Separation of LPG from petroleum product

4.2 NAPHTHA

The more common method of naphtha preparation is distillation. Depending on

the design of the distillation unit, either one or two naphtha steams may be

produced: (1) a single naphtha with an end point of about 205∞C (400∞F) and

similar to straight-run gasoline or (2) this same fraction divided into a light naphtha

and heavy naphtha. The end point of the light naphtha is varied to suit the

subsequent subdivision of the naphtha into narrower boiling fractions and may be

of the order of 120∞C (250∞F).

The variety of applications emphasizes the versatility of naphtha. For example,

naphtha is used by paint, printing ink and polish manufacturers and in the rubber

and adhesive industries as well as in the preparation of edible oils, perfumes, glues,

and fats. Further uses are found in the drycleaning, leather, and fur industries and

also in the pesticide field (2).

4.3 GASOLINE OR PETROLE

Gasoline (also referred to as motor gasoline, petrol in Britain, benzine in

Europe) is a mixture of volatile, flammable liquid hydrocarbons derived from

petroleum that is used as fuel for internal combustion engines such as occurs in

motor vehicles (2).

In the late 19th century, the most suitable fuels for automobile use were coal tar

distillates and the lighter fractions from the distillation of crude oil. During the

early 20th Century, the oil companies were producing gasoline as a simple

distillate from petroleum.

Gasoline as a fuel is composed of a mixture of various hydrocarbons, which can

be burnt to form water (H2O) and CO2. If combustion is not complete, carbon

monoxide (CO) is also formed. The following main groups of hydrocarbons are

contained in gasoline:

• saturated hydrocarbons or alkanes

• Unsaturated hydrocarbons or olefins

• Naphthenic or cyclic hydrocarbons

• Aromatics

• oxygenates

• Other hetero-atom compounds (1).

The boiling range of motor gasoline falls between –1°C (30°F) and 216°C (421°F)

and has the potential to contain several hundred isomers of the various

hydrocarbons (Tables 4.1 and 4.2) (2).

Table 4.1 General Summary of Product Types and Distillation Range

Table 4.2 Increase in the number of Isomers with Carbon Number

4.4 KEROSINE

Kerosene (kerosine), also called paraffin or paraffin oil, is a flammable pale

yellow or colorless oily liquid with a characteristic odor intermediate in volatility

between gasoline and gas/diesel oil that distills between 125°C (257°F) and 260°C

(500°F).

In the early years of the petroleum industry kerosene was its largest selling and

most important product. The demand was such that many refiners, using a variety

of crude oils, made as wide a distillation cut as possible to increase its availability,

thereby causing the product to have a dangerously low flash point and to include

undesirable higher-boiling fractions. Kerosene is less volatile than gasoline

(boiling range approximately 140°C/285°F to 320°C/610°F) and is obtained by

fractional distillation of Petroleum. Kerosene is a very stable product, and additives

are not required to improve the quality.

Kerosene, because of its use as burning oil, must be free of aromatic and

unsaturated hydrocarbons as well as free of the more obnoxious sulfur compounds

(2).

4.5 Diesel fuel

Diesel fuel is derived from petroleum. Diesel, gasoline and jet fuel are different

cuts from the refining of petroleum. The difference is that diesel contains heavier

hydrocarbons with a higher boiling point than gasoline and jet fuel. The term diesel

fuel is therefore generic; it refers to any fuel mixture developed to run a diesel-

powered vehicle, i.e. engines with compression ignition engines.

Diesel is a hydrocarbon fraction that typically boils between 250-380°C. Diesel

engines use the cetane (n-hexadecane) rating to assess ignition delay.

In most diesel engines, the ignition delay is shorter than the duration of

injection. Under these circumstances, the total combustion period can be divided

into the following four stages:

• Ignition delay

• Rapid pressure rise

• Constant pressure or controlled pressure rise

• Burning on the expansion stroke

The next important parameter of diesel fuel is stability or storage stability (1).

4.6 DISTILLATE FUEL OIL

Fraction Boiling

Range / °C

No. of Carbon

atoms per

molecule

Uses

DISTILLATE

FUEL OIL

216 - 421 C12 – C20

Most petroleum products can be used as fuels, but the term fuel oil, if used

without qualification, may be interpreted differently depending on the context.

However, because fuel oils are complex mixtures of hydrocarbons, they cannot be

rigidly classified or defined precisely by chemical formulae or definite physical

properties.

The arbitrary division or classification of fuel oils is based more on their

application than on their chemical or physical properties. However, two broad

classifications are generally recognized:

(1) Distillate fuel oil and

(2) Residual fuel oil

Distillate fuel oils are vaporized and condensed during a distillation process and

thus have a definite boiling range and do not contain high boiling oils or asphaltic

components (2).

4.7 LUBRICATING OILS AND LUBRICANTS

4.7.1 MINERAL OIL (WHITE OIL)

In the present context, the term mineral oil or white oil refers to colorless or

very pale oils within the lubricating oil Minerals (mineral) oils belong to two main

groups, medicinal (pharmaceutical) oils and technical oils.

Medicinal oils represent the most refined of the bulk petroleum products,

especially when the principal use is for the pharmaceutical industry. Thus mineral

oil destined for pharmaceutical purposes must meet stringent specifications to

ensure that the oil is inert and that it does not contain any materials that are

suspected to be toxic.

Technical mineral oil (as opposed to pharmaceutical mineral oil) must meet

much less stringent specifications requirements because the use is generally for

transformer oil, cosmetic preparations (such as hair cream), in the plastics industry,

and in textiles processing. Many of the same test methods are applied to all mineral

oils (2).

4.7.2 LUBRICATING OIL

Lubricating oil is used to reduce friction and wear between bearing metallic

surfaces that are moving with respect to each other by separating the metallic

surfaces with a film of the oil. Lubricating oil is distinguished from other fractions

of crude oil by a high (>400°C/>750°F) boiling point.

In the early days of petroleum refining, kerosene was the major product,

followed by paraffin wax wanted for the manufacture of candles. Lubricating oils

were at first by-products of paraffin wax manufacture. The preferred lubricants in

the 1860s were lard oil, sperm oil, and tallow, but as the trend to heavier industry

increased, the demand for mineral lubricating oils increased, and after the 1890s

petroleum displaced animal and vegetable oils as the source of lubricants for most

purposes (2).

5. Atomic Emission Theory

Atomic emission spectroscopy uses quantitative measurement of the optical

emission from excited atoms to determine analyte concentration

Analyte atoms in solution are aspirated into the excitation region where they are

desolvated, vaporized, and atomized by plasma.

Figure 5.1 Excitation diagram.

`Excited StateGround State

E

Relaxation

Excitation

Excitation Electrons can be in their ground state (unexcited) or enter one of the

upper level orbitals when energy is applied to them. This is the excited state.

Atomic Emission A photon of light is emitted when an electron falls from its

excited state to its ground state

Figure 5.2 Emission diagram.

Each element has a unique set of wavelengths that it can emit.

Lower wavelengths are shorter and have more energy, higher wavelengths e.g. in

the Visible region, are longer and have less energy.

Today have different Emission sources like

• Flames

• Arcs / Sparks

• Direct Current Plasmas (DCP)

• Inductively Coupled Plasmas (ICP)

Inductively Coupled Plasma (ICP) :

source, plasma formation, plasma zones

• Quartz torch surrounded by induction coil

• Magnetic coupling to ionized gas

• High temperature – equivalent to 10,000k

Plasma Advantages

• High Temperature – allows for full dissociation of sample components

• Argon is Inert – non reactive with sample

• Linearity – analysis of samples from ppb to ppm range in the same method

• Matrix tolerance – robust and flexible design with Duo and Radial options

(6).

6. INDUCTIVE COUPLED PLASMA

Different procedures are found in the literature for the determination of metals in

petroleum derivatives. More recently, a rapid, sensitive, and multi-elemental

method is then required to analysis trace elements occurring in crude oil or other

petroleum products.

Inductively coupled plasma mass spectrometry (ICP-MS) has been applied for

trace element determination in oil and derivatives due to the known advantages of

this technique, such as lower limits of detection (LOD), multi-element and

isotopic-ratio measurement capability, and steadily decreasing investment costs.

Nevertheless, ICP-OES has been applied not only for the inorganic

characterization of crude oil and derivatives, but also as a valuable tool for

studying the physicochemical fundamentals of plasma–solvent interactions.

Sample throughput and multi-elemental capabilities are some common benefits

of ICP-OES and ICP-MS compared to classical atomic absorption spectrometry or

WDXRF. The combination of these two techniques thus provides a very wide

concentration range of metal compounds to be determined on a routine basis, ICP-

OES being preferred for major element analysis (Fe, Ni and V) whereas ICP-MS is

particularly convenient for ultra-trace metals analysis. However, these two

techniques were not initially designed for organic samples analysis and specific

configuration of sample introduction systems are required in order to minimize

organic solvent load into the ICP plasma. The presence of organic vapors in the

plasma generates plasma instability and high reflected power that could lead to

plasma extinction (7, 8).

6.1 Instrument Components of an ICP

There are five basic components to an ICP

1. Sample Introduction. 2- Energy Source. 3- Spectrometer.

4- Detector. 5- Computer and Software

Figure 6.1 Instrumentation component of an ICP

Now define each part in briefly.

6.1.1. Sample Introduction

The sample solution cannot be put into the energy source directly. The solution

must first be converted to an aerosol. The function of the sample introduction

system is to produce a steady aerosol of very fine droplets.

There are three basic parts to the sample introduction system.

1. the Peristaltic pump draws up sample solution and delivers it to

2. the Nebulizer which converts the solution to an aerosol that is sent to

3. The Spray chamber which filters out the large, uneven droplets from the

aerosol.

Figure 6.4 Sample Introduction the A. Peristaltic pump, B. The Nebulizer and C.

The Spray chamber

6.1.2 Energy Source

The sample aerosol is directed into the center of the plasma. The energy of the

plasma is transferred to the aerosol. The main function of the energy source is to

get atoms sufficiently energized such that they emit light.

There are three basic parts to the energy source.

1- The Radio frequency generator which generates an oscillating electromagnetic

field at a frequency of 27.12 million cycles per second. This radiation is directed

to.

2- The Load coil which delivers the radiation to.

3- The Torch which has argon flowing through it which will form plasma in the RF

field. Figure 6.6 Energy source parts A. Radio

Frequency generator, B. Load coil and C. Torch

Plasma Configuration

1- Axial design: best sensitivity, lowest detection limits.

• Environmental

• Chemical

2- Radial design: Robust, fewer interferences

• Petrochemical

• Metallurgy

3- Axial and Radial

6.1.3 Spectrometer

Once the atoms in a sample have been energized by the plasma, they will emit

light at specific wavelengths. No two elements will emit light at the same

wavelengths.

The function of the spectrometer is to diffract the white light from the plasma

into wavelengths through polychromatic.

6.1.4 Detector

Now that there are individual wavelengths, their intensities can be measured

using a detector. The intensity of a given wavelength is proportional to the

concentration of the element.

The function of the detector is to measure the intensity of the wavelengths. The

output from the detector is processed by a set of electronics. The electronics

control the detector as well as collect the readings from the pixels.

The function of the electronics is to measure and process the output of the

detector.

6.1.5 Computer and Software

The software, via a computer, controls and runs the instrument. Not only are

measurements made but the other five components of the instrument are controlled

and monitored by the computer and software.

The function of the computer and software is to operate, monitor, and collect

data from the instrument.

6.2 ICP Performance

• Typical analysis time for ICP is ~2-3 minutes. This includes flush time,

multiple repeats, printing, etc. (Analysis time is independent of the number

of elements being determined)

• Typical precision, amongst repeats within an analysis, is ~ 0.5%

• Typical drift is ≤ 2% per hour

Typical detection limits are ~ 1-10 parts per billion (6)

7. TRACE ELEMENT

7.1 TRACE ELEMENT IN CRUDE OIL

Crude oils’ primary constituents are organic but also contain trace concentrations

of inorganics or metals in the range of subparts per billion (ppb) to tens and

occasionally hundreds of parts per million (ppm). The trace content of metals in

crude oil is of interest for the potential contamination of the environment.

Environmental risks depend on the toxicity and concentration of each metal in the

crude oil.

Trace metals have been found in different proportions in different crudes and

consequently in their derivatives, Frequently Ni and V are found in largest

concentrations contributing to environmental pollution. Because of their mutagenic

and carcinogenic potential Ni and V emissions have been strictly con- trolled in

several countries.

The other metal ions reported form crude oils; include copper, lead, iron,

magnesium, sodium, molybdenum, zinc, cadmium, titanium, manganese,

chromium, cobalt, antimony, uranium, aluminum, tin, barium, gallium, silver and

arsenic.

But the concentrations of these elements are changing according to location and

geological are of crude oil.

Table 7.1 Concentration of trace elements in petroleum, in ppm. In Tamsagbulag

basin and Tsagaan Els basin

Element Tamsagbulag basin Tsagaan Els basin

Alkali metals Na 20.98 35.6

Li <0.01 <0.01

Total 20.98 35.6

Alkaline earth metals

Be 0.05 <0.01

Mg 0.19 1.11

Ca 1.78 2.63

Ba <0.05 0.19

Sr 0.46 2.43

Total 2.48 6.36

Sub-Group Ib Cu 0.51 0.37

Ag 0.03 0.04

Total 0.54 0.41

Sub-Group IIb Zn 3.01 0.62

Cd 1.65 0.26

Total 4.66 0.88

Sub-Group IIIa

Sc <0.01 0.04

Y 0.01 0.07

La 0.01 <0.01

Total 0.02 0.11

Sub-Group IIIb B 2.88 3.18

Al 0.36 2.11

Total 3.24 5.29

Sub-Group IVb

Si 1.35 5.76

Sn 0.23 0.71

Pb 0.18 1.16

Total 1.77 7.63

Sub-Group Vb

P 0.22 0.06

Sb 0.14 0.15

Bi 0.20 0.01

Total 0.56 0.22

Sub-Group Via

Cr 1.15 1.03

Mo 0.39 0.29

W 2.79 <0.01

Total 4.18 1.32

Group VIII

Fe 2.91 4.5

Co 0.07 0.59

Ni 3.68 2.82

Total 6.66 7.91

Other group elements

Ti 0.18 0.29

V 0.56 0.97

Mn 0.06 0.17

Sum 46.12 67.43

Trace metals have been used as a tool to understand the depositional environments

and source rock. The metal ions and their ratios have been observed as a valuable

tool in oil-oil correction and oil-source rock correlation studies.

The determination of metal ions in crude oils has environmental and industrial

importance. The metal ions like vanadium, nickel, copper and iron, behave as

catalyst poisons during catalytic cracking process in refining of crude oil. The

metal ions are released in the environment during exploration, production and

refining of crude oil. The determination of mercury content in crude oil is also

important for petroleum industry, because the metal can deposit in the equipment,

which could affect the maintenance and operation.

In general these elements are present in the crude oils as inorganic salts (mainly

as chloride and sulphate of K, Mg, Na and Ca), associated with water phase of

crude oil emulsions, or as organometallic compounds of Ca, Cu, Cr, Mg, Fe, Ni,

Ti, V and Zn adsorbed in water-soil interface acting as emulsion stabilizers (9- 12).

Even minute amounts of iron, copper, and particularly nickel and vanadium in

the charging stocks for catalytic cracking affect the activity of the catalyst and

result in increased gas and coke formation and reduced yields of gasoline. In high

temperature power generators, such as oil fired gas turbines, the presence of

metallic constituents, particularly vanadium in the fuel, may lead to ash deposits on

the turbine rotors, thus reducing clearances and disturbing their balance. More

particularly, damage by corrosion may be very severe.

The majority of the vanadium, nickel, iron, and d copper in residual stocks may

be precipitated along with the asphaltenes by hydro carbon solvent s. Thus,

removal of the asphaltenes with n-pentane reduces the vanadium content of the oil

by up to 95% with substantial reductions in the amounts of iron and nickel (4).

7.2 TRACE ELEMENT IN PETROLEUM PRODUCTs

Products of petroleum contain various elements and controlling the range of

these elements is need. In this section describe element in kerosene, gasoline and

lubricating oil.

7.2.1 Kerosene

The presence of trace metals in fuels, unless they are added purposely, is usually

undesirable, as they may be responsible for the decomposition and poor

performance of the fuel, leading to corrosion of the motor and formation of

precipitates. Some metals are natural constituents of the crude oil, others can be

introduced into the kerosene as contaminants, e.g. through contact with refining

and distilling equipment, or during storage and transport.

Many methods of preconcentration of metal ions from solutions have been

described. Of particular interest are those which involve inorganic solid surfaces

modified with chelating groups and so have advantage of selectivity.

Preconcentration methods can removal of some interferes which may be present in

the sample solution, can considerably improve the obtained results extending the

limit of detection to lower concentration levels.

The present paper describes the preparation of silica gel chemically modified

with 2-aminothiazole (SiAT) to produce an efficient collector for separation and

determination of metal ions dispersed into the kerosene fuel by FAAS.in the table

7.2 show that concentration of (Zn, Cu, Fe and Ni) in different kerosene (13).

Table7.2 Determination of copper, iron, nickel and zinc in different kerosene fuel

samples by FAAS with preconcentration on a column packed with SiAT.

Sample Concentration of metal ion in (µg/L)

Copper Iron Nickel Zinc

Petrobras 8.0 11. 3.0 8.0

Neiva 6.0 9.0 4.0 6.0

Texaco 7,4 9.2 5.3 7.2

5.2.2 Gasoline

Gasoline was at first produced by distillation, simply separating the volatile,

more valuable fractions of crude petroleum, and was composed of the naturally

occurring constituents of petroleum. Later processes, designed to raise the yield of

gasoline from crude oil, split higher-molecular-weight constituents into lower-

molecular-weight products by processes known as cracking.

The needs of the petroleum industry in studies dedicated to trace metals

determination are highly related to exploration, but also to exploitation activities

for corrective actions during oil production and refining.

A classical pneumatic nebulizer was used with ICP-OES in order to analyze

various elements in different matrices such as asphaltenes fraction, residue, crude

oil or diesel and gasoline. Depending on the type and volatility of the matrix, the

sample must be diluted by a factor ranging from 10 to 50 in xylene. The highest

dilutions were typically performed when gasoline samples were analyzed in order

to minimize the organic vapor load. However, this in turn degrades significantly

the quantification limit of the elements in the gasoline. In order to reduce this

effect, nebulization with an ultrasonic nebulizer (USN) with a cooled condenser

was tested for gasoline, where lower dilution factor (typically 5) was found

acceptable for the plasma due to lower solvent load. Finally, a microflow

pneumatic concentric nebulizer associated with a chilled spray chamber was used

for an optimal analysis of petroleum products by ICP-MS (14).

Table 7.3 determination of Ni (µg/L) and Pb (mg/L) in commercial gasoline

samples

5.2.3 LUBRICATIOG OIL

Lubricating oils from petroleum are mainly composed of paraffinic, naphthenic

and, to a lesser extent, aromatic hydrocarbons. Several additives, including

metalloid organic ones, are also part of the final composition of commercial

lubricating oil. Wear has both physical (friction between metallic parts, high

temperature and pressure) and chemical (corrosion) sources.

Increasing amounts of some key elements in the lubricating oil may indicate the

extent of the wear of wetted components. For instance, an abrupt increase of Ni, Sn

or Cr indicates corrosion in bearings, valves and pistons, Fe indicates corrosion in

various parts, and Na indicates oil contamination with anti-freeze fluids and so on

Elements such as Ag, B, Ba, Bi, Ca, Cd, Co, Cr, Fe, Hg, Mg, Mo, Ni, P, Sb, Se,

Sn, Ti and Zn, are also deliberately introduced in small portions to lubricating oils

to address requisites for special applications.

Samples Ni in (µg/L) Pb (mg/L)

Gasolin1 114 ±4 0.6 ± 0.02

Gasolin2 105±1 0.02± 0.003

Gasolin6 158±2 0.44 ± 0.02

Apart from the existence of a few electro analytical and XRF, methods for the

determination of Zn, Cu, Pb, Fe, Cr, Ni, As and Cd in lubricating oils, the majority

of analytical methods reported in the literature are based on atomic spectrometric

techniques such as FAAS, ET AAS, DC or ICP OES, ICP MS and AFS (15).

Table 7.3 Spectroanalytical methods for determination of trace elements in

lubricating oil

Element technique LOD

Pb ICP MS 0.2 μg/L

Sb ETAAS 0.2 μg/g

V ICP-OES 0.01 μg/g

Zn ICP-OES 0.015 μg/g

Ni FAAS 10 μg/L

Fe ICP-OES 0.015 μg/g

Na LA-ICP-TOFMS 4 ng/g

8. Application of ICP in determination of element of petroleum and

petroleum product

8.1 Determination of Mo, Zn, Cd, Ti, Ni, V, Fe, Mn, Cr and Co in crude oil

using inductively coupled plasma optical emission spectrometry and sample

introduction as detergentless microemulsions

A procedure to prepare crude oil samples as detergentless microemulsions was

optimized and applied for the determination of Mo, Zn, Cd, Si, Ti, Ni, V, Fe, Mn,

Cr and Co by ICP OES. Propan-1-ol was used as a co-solvent allowing the

formation of a homogeneous and stable system containing crude oil and water. The

optimum composition of the microemulsion was crude oil /propan-1-ol /water /

concentrated nitric acid, 6/70/ 20/4 w/w/w/w. This simple sample preparation

procedure together with an efficient sample introduction (using a Meinhard K3

nebulizer and a twister cyclonic spray chamber) allowed a fast quantification of the

analytes using calibration curves prepared with analyte inorganic standards. In this

case, Sc was used as internal standard for correction of signal fluctuations and

matrix effects. Oxygen was used in the nebulizer gas flow in order to minimize

carbon building up and background. Limits of detection in the ng /g−1

range were

achieved for all elements. The methodology was tested through the analysis of one

standard reference material (SRM NIST 1634c, Residual Fuel Oil) with recoveries

between 97.9% and 103.8%. The method was also applied to two crude oil samples

and the results were in good agreement with those obtained using the acid

decomposition procedure. The precision (n=3) obtained was below 5% and the

results indicated that the method is well suited for oil samples containing low

concentrations of trace elements (11).

8.2 Trace Metal Analysis in Petroleum Products Sample Introduction

Evaluation in ICP-OES and Comparison with an ICP-MS Approach

The needs of the petroleum industry in studies dedicated to trace metals

determination are highly related to exploration, but also to exploitation activities

for corrective actions during oil production and refining. Two techniques provide

a very large concentration range of metal compounds to be determined on a routine

basis, ICP-OES being preferred for major element analysis whereas ICP-MS is

particularly convenient for ultra-trace metals analysis.

Direct introduction of petroleum product in the plasma require a methodical

approach in order to minimize matrix effect. Here, three different sample

introduction modes have been investigated depending on the elements of interest

and the matrix analyzed. A classical pneumatic nebulizer and an ultra-sonic

nebulizer (USN) were compared for ICP-OES. These introduction modes were

compared with a microflow pneumatic concentric nebulizer associated with a

chilled spray chamber used with ICP-MS.

Classical pneumatic nebulisation with ICP-OES leads to ppm range limit of

quantification in the petroleum product and five times higher with gasoline due to

important dilution factor. The use of an USN coupled with ICP-OES reduce limit

of quantification in gasoline to the 50 ppb range, but further study of matrix effects

with such an introduction must be done. The PFA-100 associated with a cooled

Scott chamber used with ICP-MS reduce also limit of quantification in the

petroleum product to the 10 ppb range for most elements. The initial important

dilution factor allows the introduction of light matrices without further dilution, but

requires anyhow the use of a standard addition method, which is time-consuming.

Then, the choice of a technique is definitively dependents on the needs required by

the laboratory between high throughput analyses and very low limit of

quantification (16-18).

8.3 Preconcentration of molybdenum, antimony and vanadium in gasoline

samples using Dowex 1-x8 resin and their determination with inductively

coupled plasma–optical emission spectrometry.

Strong ion exchangers (Dowex 50W-x8 and Dowex 1-x8) were used for the

separation and preconcentration of trace amounts of Mo, Sb and V in gasoline

samples. Dowex 1-x8 resin was found to be suitable for the quantitative retention

of these metal ions from organic matrices. The elution of the metal ions from

Dowex 1-x8 resins was achieved by using 2.0 mol L-1

HNO3 solution. The Dowex

1-x8 preconcentration and separation method gave an enrichment factor of 120

with limits of detection equal to 0.14, 0.05 and 0.03 mgL-1

for Mo, Sb and V,

respectively. The limits of quantification were found to be 0.48, 0.18 and 0.10

mgL-1

for Mo, Sb and V, respectively. Under optimized conditions, the relative

standard deviations of the proposed method (n¼20) were o4%. The accuracy of

Dowex 1-x8 preconcentration procedure was verified by the recovery test in the

spiked samples of gasoline sample. The Dowex 1-x8 preconcentration method was

applied to Conostan custom made oil based certified reference material for the

determination of Mo, Sb and V. The results of the paired t-test at a 95% confidence

level showed no significant difference. The separation and preconcentration

procedure was also applied to the gasoline samples collected from different filling

stations (19).

References

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57-63,

2- J. G. Speight, Handbook of Petroleum Product Analysis, 1st, John Wiley & Sons, Inc., Hoboken, New Jersey,

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