Cetane Improver, usually translated into Chinese as cetane number improver or diesel anti-knock agent, is a fuel additive added to diesel to increase the cetane number of diesel.

1. Core Concept: What is cetane number?
Cetane number is a key indicator for measuring the ignition performance of diesel in diesel engines.

It indicates the delay time from when diesel is injected into the high-temperature and high-pressure cylinder to when it ignites and burns by itself (i.e., the "lag period").

The higher the cetane number, the shorter the ignition delay period of the fuel, and it can burn faster and more smoothly.

A low cetane number can lead to an excessively long combustion delay, causing the accumulated fuel to suddenly burn fiercely, resulting in a sharp increase in pressure. This is known as knocking (commonly called "knocking"), which can cause a decrease in engine power, increased wear, and a rise in noise and black smoke emissions.

A simple analogy: cetane number is as important to diesel engines as octane number is to gasoline engines. However, the opposite effect occurs - high-octane gasoline resists knocking, while high-cetane diesel promotes smooth ignition.

2. The Functions and benefits of cetane number improvers
By increasing the cetane number of diesel, the modifier can bring the following main benefits:

Improve cold start performance: In low-temperature environments, the engine starts more easily.

Achieve smoother combustion: Shorten the ignition delay period, make the combustion more gentle, and reduce knocking.

Reduce engine noise and vibration: Smooth combustion directly translates into quieter and more stable operation.

Reduce harmful emissions

Reduce particulate matter and black smoke: More complete combustion reduces the generation of soot.

Reduce carbon monoxide and hydrocarbon emissions: Higher combustion efficiency.

Improving fuel economy: More complete combustion means more efficient energy utilization, which may lead to a slight improvement in fuel consumption.

Protecting the engine: Reducing knocking and rough combustion can lower the mechanical stress of the engine and extend its service life.

3. Main chemical components
The most common commercial cetane number improvers are:

Alkyl nitrate esters, among which the most representative one is 2-ethylhexyl nitrate.

After being heated and decomposed, it generates free radicals, which can significantly promote the oxidation reaction of diesel fuel, thereby greatly shortening the ignition delay period.

This compound is highly efficient. Usually, only a very small amount (several hundred to several thousand ppm, that is, a few ten-thousandths to a few thousandths) needs to be added to significantly increase the cetane number.

4. Application scenarios
Refinery: Add to diesel before it leaves the factory to ensure that its cetane number meets the national or regional fuel standards (for example, the Chinese National VI standard requires that the cetane number of vehicle diesel be no less than 51).

Blending agent: It is used to blend low-quality diesel components into high-quality diesel that meets standards.

End users: As an after-sales additive, car owners or fleet operators can purchase it themselves and add it to the fuel tank to improve engine performance, especially when using diesel of uncertain quality.

5. Differences from gasoline additives
Please note that Cetane Improver is used for diesel and it is essentially different from Octane Booster used for gasoline. The two have opposite effects and completely different chemical compositions. They must never be used interchangeably.