Quality Control of Petroleum products using FT-NIR Spectroscopy

Significance of the Topic

Continuous monitoring of petroleum product quality is crucial due to volatile feedstock costs, stringent environmental regulations and evolving engine requirements. Rapid and reliable analytics support efficient process control and help refineries maintain product specifications in closed-loop systems.

Study Objectives and Overview

This application note outlines the use of Fourier transform near-infrared (FT-NIR) spectroscopy for comprehensive quality control of crude oil and derived fuels. It aims to demonstrate how a single FT-NIR spectrum, combined with multivariate analysis, can quantify chemical and physical parameters such as PIONA composition, octane and cetane ratings, density and vapor pressure across refinery streams.

Methodology and Instrumentation

FT-NIR measurements capture overtone and combination bands of functional groups including C–H, C=O, O–H, N–H and S–H across the near-infrared region. Multivariate calibration models relate spectral features to reference data from standard methods (e.g. GC PIONA analysis, ASTM octane testing, distillation). Data acquisition requires minimal to no sample preparation, enabling analysis within seconds.

Used Instrumentation

Analysis can be performed in the laboratory, at-line or on-line using FT-NIR spectrometers and fiber-optic or flow-through probes. Common configurations include:

• TANGO: Routine lab analyzer for fast, unattended operation.
• MPA II: Flexible multi-purpose analyzer accommodating diverse sample presentations.
• MATRIX-F: Robust system for process monitoring, supporting multiplexing of multiple probes over long distances.
• Accessory probes and flow cells: Available in variants for hazardous areas and varied process conditions.

Main Results and Discussion

Calibration models provided accurate predictions for key quality parameters in gasoline and diesel streams. Validation results include:

• Diesel distillation midpoint (T50) over 244°C–326°C with tight correlation to reference distillation curves.
• Gasoline research octane number (RON) across 87–101 with high predictive precision.

Simultaneous determination of density, Reid vapor pressure, octane numbers (RON, MON), cetane number and index, cloud point, pour point, PIONA fractions, and oxygenate content was achieved in under one minute per sample. Real-time spectral acquisition and chemometric evaluation support closed-loop adjustment of process parameters.

Benefits and Practical Applications

FT-NIR spectroscopy offers several advantages for petroleum quality control:

• Speed: Multi-parameter results in less than 60 seconds without sample preparation.
• Non-destructive and reagent-free analysis reducing hazardous waste.
• Cost efficiency from lower operational costs and improved process throughput.
• Flexibility: Deployment in lab, at-line or on-line environments with real-time data for process optimization.

Future Trends and Opportunities

Emerging developments are extending FT-NIR capabilities through enhanced chemometric algorithms, integration with machine learning for predictive maintenance, and miniaturized spectrometer designs for portable or field-deployable applications. The trend toward fully automated, digitalized refinery operations will further drive adoption of on-line FT-NIR to enable smart, energy-efficient hydrocarbon processing.

Conclusion

FT-NIR spectroscopy provides a rapid, reliable and environmentally friendly approach for comprehensive quality control of petroleum products. Its ability to deliver multi-parameter analysis in real time supports efficient production, regulatory compliance and product consistency across refinery operations.