Sulfur and Carbon in Hydrocarbons1

Importance of the topic

Accurate determination of sulfur and carbon content in hydrocarbons is essential for fuel quality control, regulatory compliance and environmental monitoring. These measurements support process optimization in petrochemical industries and help minimize pollutant emissions.

Objectives and Study Overview

This application note presents a validated analytical method for simultaneous measurement of sulfur and carbon in hydrocarbon samples using the LECO SC632 instrument. It outlines sample preparation, calibration strategy, operational parameters and performance with reference materials.

Methodology and Instrumentation

The method employs high-temperature combustion at 1350 °C followed by infrared detection. Key elements include:

• Instrument: LECO SC632 sulfur and carbon analyzer
• Combustion support: 528-203 ceramic boat and 502-321 Com-Cat™ catalyst
• Calibration standards: NIST or LECO hydrocarbon reference materials
• Method parameters: nominal sample mass 1.0000 g, lance delay 20 s, automatic range selection with switch levels for S (3500/3000 ppm) and C (4000/3500 ppm)
• Gas conservation timeout: 5 min; furnace standby at 1050 °C

Main Results and Discussion

Typical performance was evaluated on residual oil, paraffin oil, diesel and light hydrocarbons using single-standard calibration:

• Sulfur ranged from 0.097 % to 4.52 % with repeatability (s) of 0.01–0.03 %
• Carbon ranged from 82.21 % to 86.37 % with repeatability (s) of 0.06–0.22 %

These results demonstrate strong agreement with certified values and low relative standard deviations, confirming method precision and accuracy across boiling ranges above 177 °C.

Benefits and Practical Applications

The described protocol offers:

• Rapid, automated analysis with minimal sample handling
• High sensitivity for low-level sulfur detection and wide dynamic range for carbon
• Reproducible results suitable for QA/QC laboratories in petrochemical and environmental settings

Future Trends and Potential Uses

Advancements may include integration with autosamplers for higher throughput, coupling with advanced detectors for other heteroatoms (e.g., nitrogen, chlorine), and application to emerging bio-derived hydrocarbons. Data analytics and real-time monitoring could further enhance process control.

Conclusion

The LECO SC632 method provides a robust, accurate approach for simultaneous determination of sulfur and carbon in hydrocarbon matrices. Its proven performance with standard reference materials makes it a reliable choice for routine quality and compliance analyses.

References

• LECO SC632 Operator’s Manual, Form No. 203-821-312
• NIST SRMs and LECO Hydrocarbon Reference Materials
• LECO Corporation, ISO-9001:2000 Certification