How to increase the cetane number of diesel?

by Alex

Expert answer:

Quick Answer

The cetane number of diesel can be increased by adding cetane improver additives like 2-ethylhexyl nitrate (2-EHN), ditertiary butyl peroxide, or commercial cetane boosters. Typical dosage rates range from 0.1% to 0.5% by volume. Blending with higher cetane base fuels or biodiesel also increases overall cetane rating.

Expanded Answer (Simplified)

There are several practical ways to increase the cetane number of diesel fuel, with the most common being the use of commercial cetane booster additives. These products are readily available and designed for easy use – you simply add the recommended amount to your fuel tank before filling up.

The most effective method is using proven chemical additives like 2-EHN (2-ethylhexyl nitrate), which is the industry standard for cetane improvement. Commercial cetane boosters containing this compound can increase cetane numbers by 2-8 points, depending on the base fuel quality and dosage used.

Another approach is blending diesel with higher-cetane fuels. Biodiesel, for example, typically has cetane numbers of 50-65, so adding even small amounts can boost the overall cetane rating. Some fuel suppliers also offer premium diesel grades with naturally higher cetane numbers, though these cost more than standard diesel.

Expanded Answer (Technical)

Cetane number enhancement can be achieved through multiple methodologies including chemical additive treatment, fuel blending strategies, and base fuel optimization, each offering specific advantages and limitations for different applications and operational requirements.

Chemical Additive Methods

Chemical cetane improvers represent the most practical and widely used approach for cetane enhancement, offering precise control over cetane number increases and compatibility with existing fuel infrastructure.

2-EHN (2-ethylhexyl nitrate): Industry standard providing 2-8 cetane point increase
Ditertiary butyl peroxide (DTBP): Alternative improver with different performance characteristics
Alkyl nitrates: Various organic nitrate compounds for cetane enhancement
Treat rates: Typically 0.1-0.5% by volume for optimal effectiveness

Fuel Blending Strategies

Blending approaches involve combining diesel with higher-cetane components to achieve desired cetane numbers while maintaining fuel specification compliance and performance characteristics.

Biodiesel blending: B5-B20 blends increasing cetane by 1-5 points
High-cetane base stocks: Blending with premium diesel components
Synthetic fuel components: Fischer-Tropsch diesel with cetane numbers 70+
Hydroprocessed fuels: Refined products with enhanced cetane characteristics

Refinery Process Optimization

Upstream approaches involve modifying refinery processes and feedstock selection to produce diesel with inherently higher cetane numbers, though these require significant infrastructure investment.

Hydrocracking optimization: Process conditions favoring high-cetane components
Feedstock selection: Crude oils producing naturally high-cetane diesel fractions
Catalytic processes: Advanced catalysts promoting cetane-enhancing reactions
Distillation optimization: Fractionation strategies for cetane improvement

Quality Control and Verification

Effective cetane enhancement requires systematic quality control including testing, verification, and compliance with fuel specifications to ensure consistent performance and regulatory compliance.

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