High Temperature GC Analysis of Fischer-Tropsch Reaction Products using the Agilent J&W FactorFour VF-5ht Ultimetal Column

Significance of the Topic

The production of alternative diesel fuels such as gas to liquid and coal to liquid via the Fischer-Tropsch process offers a pathway to synthetic hydrocarbons independent of crude oil. Effective analysis of the resulting long-chain alkanes, which can extend up to C100, requires gas chromatography at oven temperatures reaching 440 °C. High temperature stability and column durability are therefore critical for reliable quantification and quality control of Fischer-Tropsch products.

Aims and Overview of the Study

This application note evaluates the performance of the Agilent J&W FactorFour VF-5ht Ultimetal column for the high temperature GC analysis of Fischer-Tropsch synthetic paraffins. Key objectives include demonstrating the column capability to elute heavy hydrocarbons, assessing thermal stability over extended use, and verifying chromatographic resolution under rigorous conditions.

Methodology

High temperature GC methods were implemented with oven temperature programs rising from 90 °C to 440 °C to elute C90–C100 fractions. Analyses included initial and repeated runs to track retention stability and peak shapes over multiple high temperature cycles.

Instrumentation Used

• GC Column VF-5ht Ultimetal, 30 m × 0.32 mm × 0.10 μm
• Sample volume 1 μl
• Carrier gas hydrogen at 2.5 ml per minute constant flow
• Cool on-column injection
• Oven program ramp from 90 °C at 25 °C per minute to 150 °C, then 8 °C per minute to 440 °C with 15 minute hold
• Flame ionization detector at 440 °C

Main Results and Discussion

Initial chromatograms demonstrated full elution of paraffin chains including fractions above C90 with sharp, well resolved peaks. After 500 analysis cycles, equivalent to 125 hours at 440 °C, only minor retention time shifts were observed for mid-range fractions (C35–C55), indicating slight stationary phase loss. Peak resolution remained excellent, underlining the thermal robustness of the VF-5ms arylene stabilized phase coated on metal tubing. The UltiMetal treated stainless steel tubing provided exceptional mechanical strength and inertness compared to conventional fused silica.

Benefits and Practical Applications of the Method

• Reliable separation of heavy Fischer-Tropsch hydrocarbons up to C100
• High thermal stability enabling repeated high temperature runs without performance loss
• Enhanced column durability through metal tubing resistant to breakage and coating degradation
• Consistent chromatographic resolution for quality control in alternative fuel production

Future Trends and Potential Applications

As alternative fuel production scales, high temperature GC columns will play an increasing role in process optimization and quality assurance. Future developments may include novel stationary phases with even higher temperature limits and inertness enhancements. Integration with advanced detectors and automated sampling will further streamline synthetic fuel analysis workflows.

Conclusion

The Agilent J&W FactorFour VF-5ht Ultimetal column delivers robust, high resolution analysis of Fischer-Tropsch reaction products under extreme temperature conditions. Its proven thermal stability and mechanical durability make it a valuable tool for detailed hydrocarbon profiling in alternative fuel research and industrial quality control.

References

• Kuipers J and Buchwaldt S High Temperature GC Analysis of Fischer-Tropsch Reaction Products using the Agilent J&W FactorFour VF-5ht Ultimetal Column Agilent Technologies Application Note SI-2105 2010
• Buchwaldt S Data contributions courtesy of Sasol Wax GmbH