Determination of Carbon, Hydrogen and Nitrogen in Coke (CHN828)

Significance of the Topic

Coke serves as a vital fuel in metallurgical and industrial operations. Accurate quantification of its carbon, hydrogen, and nitrogen content enables optimization of combustion efficiency, energy balances, and emissions assessment, supporting both regulatory compliance and process improvement.

Objectives and Study Overview

This application note details the protocol for determining C, H, and N in coke using the LECO CHN828 analyzer under ASTM D5373. The aim is to present sample preparation, calibration, drift correction, and performance validation with common coke reference materials.

Methodology and Instrumentation

The LECO CHN828 employs vertical quartz-furnace combustion in pure oxygen, followed by gas scrubbing and separation. CO2 and N2 are measured via infrared and thermal conductivity detectors, while H2O is quantified by a separate IR cell.

• Sample preparation: ASTM D346/D346M for homogenization; analysis as received with moisture correction per ASTM D5373.
• Reference materials: LECO LCRM®, LRM® and NIST SRM for calibration spanning 0.05–0.14 g.
• Carrier gas: Helium for highest sensitivity, or Argon as an alternative.
• Operating conditions: Furnace at 950 °C; afterburner at 850 °C; ballast equilibration 10 s; aliquot loop 10 cm3; interleaved analysis enabled.

Key Results and Discussion

Analysis of three types of coke yielded:

• Metallurgical coke: ~88.0 % C, 0.09 % H, 0.97 % N; Helium carrier precision: 0.1 % C, 0.01 % H, <0.01 % N (s).
• Petroleum coke: ~88.3 % C, 3.89 % H, 1.44 % N; precision within 0.2 % C, 0.05 % H, <0.01 % N.
• Furnace coke (NIST SRM 2776): ~89.0 % C, 0.27 % H, 1.21 % N; reproducibility within 0.3 % C, 0.02 % H, 0.03 % N.

Helium and Argon carriers delivered comparable accuracy, with Helium offering improved nitrogen sensitivity at trace levels.

Benefits and Practical Applications

• Rapid, high-precision elemental analysis for process control and QA/QC.
• Compliance with established ASTM methodologies.
• Automated sample handling reduces labor and enhances throughput.
• Versatility across diverse coke matrices with minimal prep.

Future Trends and Potential Applications

Advancements may include enhanced data algorithms for lower detection limits, integration into continuous online monitoring for real-time fuel characterization, and coupling with techniques such as GC–MS or XPS for comprehensive material profiling.

Conclusion

The LECO CHN828 achieves reliable, reproducible determination of carbon, hydrogen, and nitrogen in coke according to ASTM D5373. Its robust design, dual carrier gas flexibility, and automated workflows meet the demands of industrial and research laboratories.

References

• ASTM D5373 Standard Test Methods for Determination of Carbon, Hydrogen, and Nitrogen in Analysis Samples of Coal and Coke.