Online process monitoring of octane number during catalytic reforming

Importance of Octane Number Monitoring in Catalytic Reforming

In modern refineries, maintaining high octane numbers is critical for producing premium gasoline and jet fuels. Real-time monitoring of Research Octane Number (RON) and Motor Octane Number (MON) ensures process safety, optimizes catalyst performance in reformers, and maximizes profitability while reducing operational costs.

Objectives and Study Overview

This application note demonstrates an inline near-infrared spectroscopy (NIRS) approach compliant with ASTM D2699 and D2700 to measure octane numbers directly in the catalytic reforming stream. The goal is to provide continuous, accurate RON and MON data to support rapid process adjustments and maintain product quality.

Methodology and Used Instrumentation

The workflow integrates sample conditioning and NIRS analysis:

• Sample Preconditioning:
  A filtration panel removes suspended solids and a temperature control unit stabilizes sample temperature to prevent spectral drift. A take-off port allows validation samples for calibration checks.
• NIRS Measurement:
  A Metrohm NIRS XDS Process Analyzer – MicroBundle 9-channel system acquires spectra every 30 seconds via flow-through cells. Probes and flow cells are installed at various points in ATEX-certified zones or pressurized shelters, with fiber-optic bundles reaching up to 35 meters from the analyzer.
• Data Processing and Validation:
  Spectral data are compared against Cooperative Fuel Research (CFR) engine test results to build a quantitative calibration model. Predicted RON and MON values are transmitted to the distributed control system (DCS) or programmable logic controller (PLC).

Main Results and Discussion

The inline NIRS method achieved:

• Accuracy (SEC V): 0.27 RON units, 0.15 MON units
• Precision: 0.01 RON and MON units
• Measurement Ranges: RON 90–107, MON 80–100
• ASTM Conformance: D2699 for RON, D2700 for MON with ±0.9 and ±1.2 units respectively at typical reformate levels

These performance metrics match laboratory engine tests while providing immediate feedback for process control. Inline monitoring identified process upsets and feedstock fluctuations in real time, enabling swift corrective actions.

Benefits and Practical Applications

The NIRS-based inline octane monitoring delivers:

• Faster return on investment through reduced sampling time and labor
• Enhanced product consistency by continuous quality assurance
• Improved safety by minimizing manual sample handling in hazardous areas
• Greater process transparency and immediate detection of feed or catalyst anomalies

Future Trends and Applications

Potential developments include:

• Expansion of multivariate models to predict additional fuel properties (e.g., density, aromatic content)
• Integration with advanced process analytics platforms and machine learning to optimize reformer conditions
• Adoption of fiberoptic miniaturized sensors for remote and mobile refinery units

Conclusion

Online NIRS analysis of octane numbers in catalytic reforming offers a robust, ASTM-compliant solution for real-time process control. By delivering accurate RON and MON values every 30 seconds, refiners can enhance product quality, operational efficiency, and profitability while maintaining stringent safety standards.

References

• ASTM International. ASTM D2699-18: Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel.
• ASTM International. ASTM D2700-18b: Standard Test Method for Motor Octane Number of Spark-Ignition Engine Fuel.
• Metrohm AG. Application Note AN-PAN-1052: Online Process Monitoring of Octane Number during Catalytic Reforming.
• Real-time inline predictions of jet fuel properties by NIRS. Metrohm Process Analytics.
• Inline monitoring of water content in naphtha fractions by NIRS. Metrohm Process Analytics.