Organic chloride in naphtha fraction of crude oil distillation according to ASTM D8150

Significance of the Topic

Organic chloride content in naphtha fractions influences corrosion and environmental compliance in downstream processes. Accurate quantification is vital for quality control and regulatory adherence.

Study Objectives and Overview

This application note presents a protocol based on ASTM D8150 to determine organic chloride in naphtha from crude oil distillation. The method also enables optional sulfur quantification using the same setup.

Methodology and Instrumentation

• Sample Preparation: Distillation of crude oil to isolate the naphtha fraction, followed by washing with caustic solution and water to remove hydrogen sulfide and inorganic halides.
• Combustion IC Setup: Utilizes Combustion Ion Chromatography with flame sensor technology and intelligent Partial Loop Injection Technique featuring inline matrix elimination.
• Chromatographic Separation: Metrosep A Supp 5 and A PCC 2 HC columns with conductivity detection after sequential suppression.
• Reagents and Solutions: 3.2 mmol/L sodium carbonate / 1.0 mmol/L sodium bicarbonate eluent, 100 mmol/L sulfuric acid suppressor regenerant, STREAM rinse, and 100 mg/L hydrogen peroxide absorber solution.
• Operational Parameters: Flow 0.7 mL/min, 50 µL injection, 30 °C column temperature, 20 min runtime; Combustion under Ar/O₂ at 1050 °C with post-combustion absorption.

Main Results and Discussion

Organic chlorine was quantified at 0.4 mg/kg with an RSD of 0.7 %, while sulfur measured 146.3 mg/kg with an RSD of 0.5 %. The method demonstrates high precision, sensitivity, and robustness for routine analysis.

Practical Benefits and Applications

• Low detection limits and excellent reproducibility for quality control in petrochemical and refining industries.
• Minimal sample preparation and inline matrix elimination reduce manual handling and contamination risk.
• Simultaneous sulfur analysis adds value for comprehensive quality assessment.

Future Trends and Potential Applications

Advances may include full automation, miniaturized combustion IC systems, broader hydrocarbon matrix compatibility, and real-time process monitoring. Emerging regulatory requirements for trace halogen analysis drive method refinement and integration into process analytical technology.

Conclusion

The ASTM D8150-based combustion IC method provides a reliable, sensitive, and efficient approach for determining organic chloride in naphtha fractions, with the added capability of sulfur quantification. This protocol supports rigorous quality control in modern petrochemical operations.

Reference

• Metrohm. Application Note CIC–024: Organic Chloride in Naphtha Fraction of Crude Oil Distillation According to ASTM D8150; Version 1, February 2018.
• ASTM International. ASTM D8150-16: Standard Test Method for Combustion Ion Chromatographic Determination of Organic Chlorine in Petroleum Products.