Separation of Heat Stable Amine Salts in Methyldiethanolamine (MDEA) Solutions Using High-Pressure IC

Significance of the topic

Removal of acid gases from natural gas streams is essential to prevent corrosion and meet product specifications Monitoring heat stable amine salts formed during solvent regeneration ensures optimal absorber performance and reduces operational costs

Study objectives and overview

This work evaluates the separation of common inorganic anions and heat stable amine salts in methyldiethanolamine solutions using a highpressure ion chromatography system equipped with a 4 micrometer anionexchange column

Methodology and instrumentation

Samples of 10 to 50 weight percent MDEA spiked with fluoride chloride nitrate nitrite bromide sulfate phosphate acetate formate propionate sulfite thiosulfate and thiocyanate were prepared in deionized water Standards were generated by mixing individual stock solutions and diluting to the target concentrations An HPIC gradient using potassium hydroxide was applied with a flow rate of 0.38 mLmin injection volume of 25 µL and column temperature of 30 °C

Instrumentation

• Dionex ICS5000+ HPIC system with SPDP pump module
• EGC 500 KOH eluent generator with highpressure degas module
• CRATC 500 cation trap column
• Dionex IonPac AG11HC4µm guard and AS11HC4µm separation columns
• ASRS 300 selfregenerating suppressor in recycle mode
• Thermo Scientific Chromeleon CDS ver 6.8 or 7.1

Main results and discussion

The method achieved baseline resolution of 14 anions in water and MDEA up to 30 weight percent with recoveries of 95 to 100 percent and run times under 35 minutes System pressure around 3620 psi demonstrated continuous highpressure operation Elution of thiocyanate in 30 weight percent MDEA was completed within 50 minutes with excellent peak efficiency

Benefits and practical applications

The highpressure RFIC approach delivers enhanced resolution rapid analysis and reproducible quantification for quality control of amine treating processes The ability to operate at 5000 psi with small particle columns improves sensitivity and reduces analysis time

Future trends and applications

Continued developments may include faster gradients microbore and capillary formats coupling to mass spectrometry and advanced data analytics for real time process monitoring and compliance

Conclusion

The combination of a 4 micrometer Dionex IonPac AS11HC column with the ICS5000+ HPIC system enables efficient separation and reliable quantification of heat stable amine salts in MDEA solutions offering a robust tool for industrial amine management

References

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