Quantitative Analysis of FAME (Fatty Acid Methyl Ester) in Diesel Fuel by FTIR

Importance of the Topic

Diesel engines are a major source of transportation energy and require reliable fuel quality control. Bio derived fatty acid methyl esters FAME serve as renewable biodiesel blends reducing sulfur oxide emissions and improving lubricity. Accurate monitoring of FAME content is essential for regulatory compliance safety and engine performance.

Objectives and Study Overview

This study presents a quantitative method using Fourier transform infrared FTIR spectroscopy in transmission mode to measure FAME concentration in diesel fuel. The approach is developed in line with EN14078 and evaluates calibration linearity precision and accuracy across the range of 0.1 to 1.0 vol percent FAME.

Methodology and Instrumentation

A Shimadzu IRSpirit-T FTIR equipped with a KBr window and a Pearl horizontal type liquid transmission accessory was used for sample analysis. Samples were prepared by diluting 90 percent FAME in diesel fuel with cyclohexane. Spectra were acquired at 4 cm-1 resolution over 20 scans using Sqr-Triangle apodization and a DLATGS detector. Calibration was based on peak height at 1747.82 cm-1 with baselines at 1670 and 1820 cm-1.

• Instrument: IRSpirit-T FTIR with KBr window plate
• Accessory: Pearl horizontal type liquid FTIR transmission accessory 25 µm path length
• Measurement settings: 4 cm-1 resolution 20 scans Sqr-Triangle apodization DLATGS detector

Main Results and Discussion

The calibration curve exhibited excellent linearity with a correlation coefficient of 0.999 over the studied concentration range. Characteristic carbonyl absorption near 1750 cm-1 enabled reliable quantitation. Duplicate measurements at 0.6 vol percent FAME yielded a maximum error of 0.003 vol percent which is well below the EN14078 allowable error of 0.029 vol percent.

Benefits and Practical Applications

• Rapid and non destructive quantitation of FAME in diesel blends
• Simple sample handling and cleaning compared to conventional liquid cells
• Compliance with EN and regional standards for fuel quality control
• Potential for routine QA QC in biodiesel production and distribution

Future Trends and Opportunities

Advancements may include integration of FTIR systems with automated sampling and chemometric analysis for complex mixtures. Real time inline monitoring portable field deployable accessories and extension to other biofuel blends are promising development paths.

Conclusion

FTIR transmission measurement with the Pearl accessory provides an efficient accurate and precise method for determining FAME in diesel fuel. The robust calibration and low measurement error confirm suitability for regulatory compliance and routine quality monitoring.

Reference

1. EN14214 Liquid petroleum products Fatty acid methyl esters for use in diesel engines and heating applications Requirements and test methods
2. EN590 Automotive fuels Diesel Requirements and test methods
3. METI Agency for Natural Resources and Energy website Securing the Quality of Petroleum Products as of July 16 2019
4. EN14078 Liquid petroleum products Determination of fatty acid methyl ester content in middle distillates Infrared spectrometry method