Emissions Characterization of Diesel and Biodiesel Fuels

The combustion of conventional diesel and biodiesel blends gives rise to a complex mixture of regulated and unregulated pollutants whose formation depends on fuel composition, engine operating conditions and after-treatment systems. Regulated emissions such as carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter have long been used to assess compliance with air-quality standards, while unregulated species—including volatile organic compounds, carbonyl compounds and polycyclic aromatic hydrocarbons—are increasingly scrutinised for their health and climate impacts. Biodiesel, derived from vegetable oils or waste lipids via transesterification, differs chemically from petroleum diesel in oxygen content, cetane number and volatility; these distinctions alter flame temperature, soot formation pathways and the speciation of gaseous by-products. Modern analytical techniques—including Fourier-transform infrared spectroscopy, gas chromatography–mass spectrometry and electron microscopy—permit detailed quantification of both gaseous and particulate fractions, while advances in sampling design and statistical optimisation refine the accuracy of emission profiles. Understanding the interplay between fuel chemistry, combustion dynamics and emission control technologies is essential to inform fuel formulation, engine calibration and public-health risk assessment on a global scale.

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Emissions Characterization of Diesel and Biodiesel Fuels publication trend

The graph below shows the total number of articles in emissions characterization of diesel and biodiesel fuels across all publications each year (not limited to Nature Index journals).

Technical terms

NOx: Oxides of nitrogen, primarily nitric oxide and nitrogen dioxide, formed at high combustion temperatures and linked to ozone formation.

Particulate matter (PM): Suspended solid or liquid particles in exhaust, including soot aggregates and metallic or carbonaceous residues.

Polycyclic aromatic hydrocarbons (PAHs): Unregulated organic compounds comprising fused aromatic rings, generated during incomplete combustion and known for carcinogenicity.

Volatile organic compounds (VOCs): Organic chemicals that readily vapourise at ambient temperature, contributing to secondary pollutant formation and health risks.

Carbonyl compounds: Oxygenated organic pollutants such as formaldehyde and acetaldehyde, formed by partial oxidation of hydrocarbons in the combustion process.

References

1. Zero-Carbon and Carbon-Neutral Fuels: A Review of Combustion Products and Cytotoxicity. Energies (2023).
2. Soot Particle Size Distribution, Regulated and Unregulated Emissions of a Diesel Engine Fueled with Palm Oil Biodiesel Blends. Energies (2020).
3. Carbonyl compounds emitted by a diesel engine fuelled with diesel and biodiesel–diesel blends: Sampling optimization and emissions profile. Atmospheric Environment (2008).