Simulated Distillation of a Heavy Gasoil and FCC Feed according to IP 480

Significance of the Topic

Simulated distillation by capillary gas chromatography is a cornerstone technique for determining the boiling range distribution of petroleum fractions. It offers a rapid, automated alternative to classical distillation, enabling detailed profiling of complex mixtures such as heavy gasoil and FCC feed. Accurate boiling point distributions are essential for product quality control, feedstock evaluation and process optimization in petroleum refining.

Objectives and Study Overview

This study evaluates the performance of a simulated distillation system following the IP 480 method. Two sample types—heavy gasoil and fluid catalytic cracker (FCC) feed—were analyzed to assess method reproducibility, accuracy in initial and final boiling point determinations, and compliance with the IP 480 reproducibility requirements.

Methodology

Samples were prepared as 2–3% (m/v) solutions in carbon disulfide. Calibration involved spiking Polywax 1000 with a homologous series of n-alkanes to establish a retention time–boiling point correlation. A CS2 blank run was used for baseline subtraction. Key GC parameters:

• Injection volume: 1 μL
• Carrier gas: Helium at 19 mL/min
• Oven program: 35 °C initial, ramp at 10 °C/min to 430 °C
• Injector temperature program: 100 °C initial, ramp at 15 °C/min to 430 °C
• Detector: High-temperature flame ionization detector at 450 °C

Instrumentation

The analysis was performed on a Varian 450-GC Simulated Distillation Analyzer equipped with:

• On-column temperature-controlled injector (Model 1093) with electronic flow control
• High-temperature FID with full electronic flow control
• Varian CP-SimDist UltiMetal™ capillary column (5 m × 0.53 mm × 0.09 μm)
• Varian CP-8410 AutoSampler or CP-8400 AutoInjector
• Galaxie™ software with SimDist plug-in for control, data handling and boiling point calculations

Results and Discussion

Retention times of calibration n-alkanes enabled precise calculation of initial boiling point (IBP) and final boiling point (FBP) for both sample types. Reproducibility over five replicate runs showed standard deviations below 0.35 °C for IBP and below 0.64 °C for FBP in heavy gasoil, and below 0.40 °C for IBP and 0.47 °C for FBP in FCC feed. These values meet or exceed IP 480 criteria. Baseline subtraction using a CS2 blank effectively compensated for column bleed at high temperatures.

Benefits and Practical Applications

• High reproducibility and compliance with established industry standards
• Reduced analysis time compared to classical distillation
• Small sample volume reduces solvent use and waste
• Automated data processing and integration with laboratory information management systems
• Applicability to a wide range of petroleum fractions, including middle distillates and heavy feedstocks

Future Trends and Opportunities

Advances in column materials and stationary phases will further minimize bleed and extend upper temperature limits. Integration with machine learning algorithms may improve prediction of complex mixture behaviors. Development of portable GC platforms could enable field-based boiling range analysis. Enhanced software features may streamline method validation and regulatory compliance.

Conclusion

The Varian (now Agilent) simulated distillation system provides robust, reproducible boiling range distributions for heavy gasoil and FCC feed, fully compliant with IP 480 requirements. Its speed, accuracy and automation make it an invaluable tool for refining process control and quality assurance.

Reference

IP 480, 2007 “Determination of boiling range distribution by gas chromatography method - Part 1: Middle distillates and lubricating base oils,” Energy Institute, London, UK.