About Premium Unleaded Fuel

What is premium-unleaded petrol?

Premium unleaded petrol refers to premium motor spirit that has been refined without the use of lead.

What is the rationale of introducing unleaded petrol in the market?

There are a number of pollutants that are emitted as a result of fossil fuel usage. Although lead is among these pollutants, when it is used to enhance the octane rating of petrol (there are other chemicals that can serve the same purpose), it is not the only harmful emission. The real problem is that lead damages the catalytic converter, which is the gadget fitted in vehicles to reduce the toxicity of many of the pollutants in exhaust emissions.

The idea of introducing unleaded petrol in Africa was mooted in June 2001 at a meeting in Dakar, Senegal, where a Declaration was adopted on the phase-out of leaded petrol in the continent.

What is a catalytic converter and how does it work?

A catalytic converter is simply a mesh of platinum through which exhaust fumes are passed before release through the exhaust pipe into the atmosphere. The toxic level of the various chemical components in the fumes are reduced. The key issue is that lead reacts with platinum, and destroys its ability to break down the harmful chemicals in emission material.

If lead is harmful, why add it to petrol?

Traditionally, lead was the only material available to increase the octane rating of crude oil in the refining process, to enable it to burn as required in the engine. Lead has also been used to assist in the lubrication of the engine valves and valve seats.

Unleaded petrol has undergone alternative processes to enhance its octane rating, but it lacks lubrication properties.

Exhaust catalysts have a limited operational life, and will be immediately poisoned if misfuelled with leaded fuel. Catalyst failure can result in higher levels of toxic emissions if catalysts or engine management systems are not replaced or repaired when defective. Maximum benefits of the switch to unleaded are obtained when the introduction of unleaded is accompanied by the introduction of exhaust catalysts. In other words, in the case of Kenya, even if your car is a new model (manufactured after 1980) and is possibly fitted with a catalytic converter, the converter is most likely already worn out from use of leaded petrol, and is therefore largely useless. Therefore all motorists who have been using leaded petrol will have to install a catalytic converter in order to derive any benefit from using unleaded fuel. If you are buying a new car today, confirm from the manufacturer that it is fitted with a catalytic converter, and immediately start using unleaded petrol.

Most vehicles manufactured after 1980 have specially hardened valves to withstand the lack of lubrication in unleaded fuel. Older engines will be damaged due to lack of lubrication.

Consult with your vehicle manufacturer before you make this decision.

Yes, Kenol/Kobil shall continue to provide leaded petrol in all service stations, at separate pumps, until the phase out period is complete. Full phase out will probably take several years.

What is my guarantee that what I will find at the service station is not contaminated with lead in the transportation process?

At Kenol/Kobil, we put quality first. We have an efficient quality system that quarantines unleaded products from leaded products and guarantees the customer delivery at required specifications.

Unleaded premium is available in most Kenol and Kobil service stations in the country.

About Low Sulphur Diesel

What is Low Sulphur Diesel?

Low Sulphur Diesel is Automotive Diesel Fuel with a sulphur content restricted to 500ppm maximum (or 0.05% by mass).

How is Low Sulphur Diesel different from regular diesel?

What are the benefits of Low Sulphur Diesel?

Health benefits:

• reduced odours
• improved local air quality.

Performance benefits:

• decreased corrosion in pistons and/or cylinder liner wear
• reduced maintenance costs
• potentially extended lubricant life and increased oil drain
• improved long-term storage life of diesel fuel.

Environmental benefits:

• Particulate Emissions 10%-30 % lower
• Extremely low Sulphur Dioxide Emissions
• Nitrogen Oxide Emissions 2%-10% lower
• Less unpleasant odours from exhaust gases and fuel itself
• less smoke after cold start

Why is sulphur being removed from diesel?

Diesel engines are very efficient with low levels of hydrocarbon and carbon monoxide exhaust emissions. The main concern with diesel engine emissions has always been smoke because it is clearly visible, particularly at high engine loads. In the past, this smoke was considered to be undesirable because of aesthetics and odour, but now there is growing concern about the health effects of this particulate matter when it is breathed into the lungs. Reducing the sulphur content of diesel fuel reduces the smoke levels.

Basics About Oil

Where does crude oil come from?

The generally accepted origin of crude oil is from plant life up to 3 billion years ago, but predominantly from 100 to 600 million years ago.

The molecular structure of the hydrocarbons and other compounds present in fossil fuels can be linked to the leaf waxes and other plant molecules of marine and terrestrial plants believed to exist during that era. There are various biogenic marker chemicals (such as isoprenoids from terpenes, porphyrins and aromatics from natural pigments, pristane and phytane from the hydrolysis of chlorophyll, and normal alkanes from waxes), whose size and shape cannot be explained by known geological processes. The presence of optical activity and the carbon isotopic ratios also indicate a biological origin.

There is another hypothesis that suggests crude oil is derived from methane from the earth's interior. The current main proponent of this abiotic theory is Thomas Gol. However, abiotic and extraterrestrial origins for fossil fuels were also considered at the turn of the 20th Century, and were discarded then. A large amount of additional evidence for the biological origin of crude oil has accumulated since then.

What is the history of gasoline?

In the late 19th Century, the most suitable fuels for the automobile 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, but the automotive engines were rapidly being improved and required a more suitable fuel. During the 1910s, laws prohibited the storage of gasolines on residential properties, so Charles F. Kettering (yes - he of ignition system fame) modified an IC engine to run on kerosene. However, the kerosene-fuelled engine would "knock" and crack the cylinder head and pistons. He assigned Thomas Midgley Jr. to confirm that the cause was from the kerosine droplets vaporising on combustion as they presumed.

Midgley demonstrated that the knock was caused by a rapid rise in pressure after ignition, not during pre-ignition as believed. This then led to the long search for antiknock agents, culminating in tetra ethyl lead. Typical mid-1920s gasolines were 40 - 60 Octane.

Because sulphur in gasoline inhibited the octane-enhancing effect of the alkyl lead, the sulphur content of the thermally cracked refinery streams for gasolines was restricted. By the 1930s, the petroleum industry had determined that the larger hydrocarbon molecules (kerosene) had major adverse effects on the octane of gasoline, and were developing consistent specifications for desired properties. By the 1940s, catalytic cracking was introduced, and gasoline compositions became fairly consistent between brands during the various seasons.

The 1950s saw the start of the increase of the compression ratio, requiring higher octane fuels. Octane ratings, lead levels, and vapour pressure increased, whereas sulphur content and olefins decreased. Some new refining processes (such as hydrocracking), specifically designed to provide hydrocarbons components with good lead response and octane, were introduced.

Minor improvements were made to gasoline formulations to improve yields and octane until the 1970s - when unleaded fuels were introduced to protect the exhaust catalysts that were also being introduced for environmental reasons. From 1970 until 1990, gasolines were slowly changed as lead was being phased out, lead levels plummetted, octanes initially decreased, and then remained 2-5 numbers lower, vapour pressures continued to increase, and sulphur and olefins remained constant, while aromatics increased. In 1990, the US Clean Air Act started forcing major compositional changes on gasoline, resulting in plummeting vapour pressure and increaing oxygenate levels.

These changes will continue into the 21st Century, because gasoline use in SI engines is a major pollution source.

The move to unleaded fuels continues worldwide, however several countries have increased the aromatics content ( up to 50% ) to replace the alkyl lead octane enhancers. These highly aromatic gasolines can result in damage to elastomers and increased levels of toxic aromatic emissions if used without exhaust catalysts.

What are the hydrocarbons in gasoline?

Hydrocarbons (HCs) are any molecules that contain hydrogen and carbon, both of which are fuel molecules that can be burnt (oxidised) to form water (H2O) or carbon dioxide (CO2). If the combustion is not complete, carbon monoxide (CO) may be formed. As CO can be burnt to produce CO2, it is also a fuel.

Gasoline contains over 500 hydrocarbons that may have between 3 to 12 carbons, and gasoline used to have a boiling range from 30C to 220C at atmospheric pressure. The boiling range is narrowing as the initial boiling point is increasing, and the final boiling point is decreasing, both changes are for environmental reasons.

What do the refining processes do?

Crude oil contains a wide range of hydrocarbons, organometallics and other compounds containing sulfur, nitrogen etc.

A refinery will distill crude oil into various fractions and, depending on the desired final products, will further process and blend those fractions.

Typical final products could be: gases for chemical synthesis and fuel, liquefied gases (LPG), butane, aviation and automotive gasolines, aviation and lighting kerosenes, diesels, distillate and residual fuel oils, lubricating oil base grades, paraffin oils and waxes. Many of the common processes are intended to increase the yield of blending feedstocks for gasolines.