Simulated Distillation of Petroleum Products by Packed Column and Capillary Column GC

Significance of the Topic

The boiling range distribution of petroleum streams underpins product quality, regulatory compliance, and process optimization in refining and petrochemical operations. Simulated distillation (SIMDIS) via gas chromatography provides a fast, high-resolution proxy for classical distillation, delivering critical data on fuel volatility profiles for gasoline, kerosene, diesel, and lubricant fractions.

Study Objectives and Overview

This bulletin evaluates chromatographic media designed for ASTM Methods D3710 (gasoline range to 260 °C) and D2887 (higher-boiling fractions to 538 °C). It compares traditional packed supports against advanced polymer-coated packed columns (Petrocol A and B) and introduces wide-bore capillary columns (Petrocol 3710 and 2887) engineered to minimize bleed, control resolution, and maintain linear boiling point/retention relationships.

Methodology and Instrumentation

• Analytical Platforms: GC systems adaptable for packed or capillary flow with flame ionization detectors.
• Carrier Gases: Helium (25–30 mL/min) for packed columns; nitrogen (6–30 mL/min) for capillaries to achieve target efficiency.
• Columns: 20 ft×1/8″ stainless steel packed columns with 10 % phase loading; 5–10 m×0.53–0.75 mm ID capillaries with 0.5–5.0 µm bonded stationary phases.
• Temperature Programming: Subambient starts (–25 °C to 30 °C) up to 200–350 °C at 15–20 °C/min, with hold times for high-boiling fractions.

Main Results and Discussion

• Petrocol A/B packed columns exhibit up to 66 % lower bleed, symmetric peak shapes, and lot-to-lot reproducibility, meeting resolution specifications (nC12/nC13 R=2–4 for D3710; nC16/nC18 R=3–8 for D2887).
• Wide-bore capillary columns deliver near-linear boiling point vs retention time curves, especially with ambient initial temperatures, and maintain excellent baseline return even at 320 °C.
• Nitrogen carrier gas allows column efficiencies to fall within ASTM targets at lower flows, conserving gas and simplifying setup.
• Capillary analyses shift paraffin elution temperatures ~20 °C lower than packed columns, enabling extension of measurable boiling ranges with improved accuracy.
• Comparative SIMDIS profiles for standard gasoline and gas oil blends show less than 5 % relative difference between packed and capillary methods, confirming capillary performance enhancements.

Benefits and Practical Applications

• Rapid column conditioning (15 min–1 h vs ≥16 h) and extended lifetime due to bonded phases.
• Enhanced accuracy in boiling point distributions for quality control in refineries and laboratories.
• Shorter run times and reduced baseline drift improve throughput and simplify final boiling point determination.
• Compatibility with existing packed-column GC instruments via simple conversion kits.

Future Trends and Potential Applications

• Adoption of wide-bore capillaries for SIMDIS of emerging biofuels, heavy oils, and complex petrochemical blends.
• Coupling SIMDIS columns with mass spectrometry for comprehensive compositional and volatility analysis.
• Automated calibration and data processing workflows for enhanced inter-laboratory reproducibility and LIMS integration.
• Miniaturized and high-throughput GC formats for near-real-time process monitoring.

Conclusion

Petrocol packed and capillary columns satisfy and surpass ASTM SIMDIS requirements, providing superior chromatographic performance, data reliability, and operational efficiency. Transitioning to capillary formats delivers extended boiling range coverage, faster analyses, and reduced maintenance, optimizing simulated distillation workflows across petrochemical applications.

Used Instrumentation

• Gas chromatographs equipped for packed and capillary column temperature programming (–25 °C to 350 °C).
• Flame ionization detectors with sensitivities of 32–256×10⁻¹⁰ A full scale.
• Carrier gases: helium (25–30 mL/min) and nitrogen (6–30 mL/min).

References

• ASTM D3710: Test Method for Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography; ASTM International Annual Book of Standards, Vol. 5.03, 1988.
• ASTM D2887: Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography; ASTM International Annual Book of Standards, Vol. 5.02, 1988.