Dual Channel Simulated Distillation of Carbon and Sulfur with the Agilent 7890A GC and 355 Sulfur Chemiluminescence Detector

Significance of the Topic

Simultaneous simulated distillation of hydrocarbon and sulfur fractions is critical for refining process optimization, quality control and compliance with product specifications. By generating boiling point distributions for both carbon and sulfur components in a single run, operators can better understand feedstock behavior, monitor sulfur removal efficiency and ensure that fuels meet regulatory requirements.

Objectives and Study Overview

This application note describes a dual-channel gas chromatographic simulated distillation (SimDis) method for simultaneous analysis of hydrocarbon and sulfur fractions. The study aims to demonstrate the use of an Agilent 7890A GC equipped with a high-temperature programmable vaporizer inlet and combined sulfur chemiluminescence (SCD) and flame ionization (FID) detection. Calibration, repeatability, and compliance with ASTM D2887 (hydrocarbons) and ASTM D7213 (sulfur) are evaluated using calibration mixtures, a reference gas oil sample, and a light cycle oil (LCO).

Methodology and Instrumentation

• Gas chromatograph: Agilent 7890A with high-temperature programmable temperature vaporizer (HT-PTV) inlet
• Detectors: Agilent 355 sulfur chemiluminescence detector (SCD) in series with flame ionization detector (FID)
• Columns: HP-1 (10 m × 0.53 mm i.d., 0.88 μm film) for hydrocarbon SimDis; DB-HT-SimDis (5 m × 0.53 mm i.d., 0.15 μm film) for sulfur SimDis
• SimDis Software: Agilent SimDis for baseline subtraction, boiling point calibration, validation, and report generation; supports dual-channel processing
• Calibration mixtures: n-alkanes C5–C40 (ASTM D2887) and Polywax 500 plus C5–C18 in toluene (ASTM D7213)
• QC reference: Diesel sample with known sulfur content used for response factor determination

Main Results and Discussion

A series of calibration runs demonstrated excellent retention time repeatability (RSD < 0.2% for hydrocarbons and < 0.1% for sulfur) and linear boiling point correlations consistent with ASTM tolerances. Reference gas oil analysis yielded boiling point percentiles within allowable differences for both carbon and sulfur channels, with RSD values below 0.6%. Light cycle oil measurements showed consistent boiling point distributions and a measured sulfur content of 248 ppm (3.5% RSD) across five replicates. Chromatographic overlays confirmed stable performance over multiple injections.

Practical Applications and Benefits

• Streamlined analysis: Simultaneous hydrocarbon and sulfur SimDis saves time and sample material by combining two workflows
• Enhanced process control: Boiling point distributions support catalyst selection, feed blending and process optimization
• Regulatory compliance: Precise sulfur profiling aids in meeting fuel sulfur standards and environmental regulations
• Quality assurance: Integrated QC reference ensures reliable, repeatable results for routine laboratory operations

Future Trends and Potential Applications

Advancements may include expanded heteroatom SimDis (e.g., nitrogen or oxygen), higher throughput columns for faster separations, tighter software integration with laboratory information management systems, and the application of artificial intelligence for automated anomaly detection. The approach can also be adapted for renewable feedstocks, heavy crudes, and biofuels to support evolving energy sector demands.

Conclusion

The dual-channel SimDis method using an Agilent 7890A GC with HT-PTV inlet and SCD/FID detection delivers reliable, repeatable boiling point distributions for both hydrocarbons and sulfur. Compliance with ASTM D2887 and D7213 was demonstrated, highlighting the method’s suitability for refining process optimization, quality control, and regulatory compliance.

Reference

• C. Wang and R. Firor, Simulated Distillation System for ASTM D2887, Agilent Technologies Publication 5989-2726EN
• ASTM D2887-06 Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography, ASTM International
• ASTM D7213-05 Standard Test Method for Boiling Point Distribution of Petroleum Distillates from 100 °C to 615 °C by Gas Chromatography, ASTM International