Hydrocarbons, C2 – C4 - Analysis of C1 + C2 impurities in ethylene

Importance of the Topic

Trace-level C1–C2 impurities in ethylene impact polymerization catalysts, product quality and process safety. Fast, reliable analysis is essential for industrial quality control and regulatory compliance.

Objectives and Study Overview

This study presents a gas chromatography method for separating methane, ethane and acetylene from an ethylene matrix in under eight minutes, demonstrating high resolution at elevated column temperatures.

Methodology

An Agilent CP-Al2O3/Na2SO4 PLOT UltiMetal column (0.53 mm×50 m, 10 μm) was employed.
Temperature program: hold 70 °C for 5 min, ramp to 170 °C at 10 °C/min.
Carrier gas: N2 at 5 mL/min, 10 kPa.
Injector: split mode at 150 °C; detector: FID at 250 °C.
Sample volume: 2000 μL; analyte concentrations ranged from 10 ppm to balance.

Instrumentation

• GC system: wide-bore configuration
• Column: Agilent CP-Al2O3/Na2SO4 PLOT UltiMetal
• Detector: Flame ionization (FID)

Main Results and Discussion

• Complete baseline separation of methane, ethane, ethylene and acetylene achieved in eight minutes.
• Detection limits down to 10 ppm for acetylene and 20 ppm for methane.
• Elevated column temperatures improved cycle time without sacrificing resolution.

Benefits and Practical Applications

The method delivers rapid, robust quantitation of light hydrocarbons in ethylene feedstreams, supporting catalyst protection and product purity monitoring in petrochemical operations.

Future Trends and Opportunities

Developments in faster PLOT columns, coupling with mass spectrometry for enhanced specificity and integration into process analytical technology (PAT) platforms will further optimize real-time monitoring.

Conclusion

An optimized GC-FID method using a CP-Al2O3/Na2SO4 column provides efficient, high-throughput analysis of C1–C2 impurities in ethylene, meeting industrial QC demands.

References

Application Note A01514, Agilent Technologies, October 2011.