Applications of Ion Chromatography in the Petrochemical Industry
Ion chromatography (IC) is certainly not the most important separation method for the analysis of petrochemical samples, but the exploration and production of petroleum products involve numerous applications of IC in which inorganic and low-molecular weight organic ions are determined in fuels, lubrication oils, gas washing solutions, and the so-called formation water that is a by-product of crude oil drilling.
Gas washing to remove sour gases such as H2S and CO2 is usually performed with amine-containing solutions. In most refineries, alkanolamines are used for absorbing sour gases. Because alkanolamines are expensive chemicals, losses due to leakages or degradation reactions increase operating costs. Common alkanolamines can be separated in refinery wastewaters by cation-exchange chromatography utilizing suppressed conductivity detection. Due to alkanolamine degradation, various anions are permanently enriched in those solutions, thereby forming heat-stable salts (HSS). To diagnose those problems, amine solutions are analysed at different sites. The most modern way of analyzing HSS in amine-containing solutions is the separation of standard and sulfur-containing anions by gradient anion-exchange chromatography.
High-salinity samples, such as formation water, represent the most difficult water matrices in which the concentration of ions extend over several orders of magnitude. The analysis of major components such as chloride, sulfate, and sodium, which are present at extremely high concentrations, is relatively straightforward, requiring onlya dilution before direct injection of very small sample volumes (~ 1 µL) into the ion chromatograph. However, the analysis of trace ionic constituents in samples of high salinity represents a special challenge for ion chromatography and can be carried out only by carefully selecting chromatographic conditions. The use of high-capacity separator columns in combination with suppressed conductivity detection is mandatory for this application. Chloride eluents in combination with low-wavelength UV detection allow the determination of UV-absorbing anions such as bromide, nitrate, and iodide in samples of high salinity without sacrificing chromatographic performance. If UV detection for the analysis of iodide in formation water is not sensitive enough, pulsed amperometry on an iodized platinum working electrode can serve as an alternative. In the field of cation analysis in samples of high salinity, high-capacity cation exchangers in combination with suppressed conductivity detection are typically employed.
A very important petrochemical application is Combustion IC (CIC) for the determination of various halogens and sulfur in petrochemicals. In Combustion IC, samples are pyrolized in an oxidative atmosphere, the resultant vapors are absorbed in an aqueous solution that is then directly introduced in the ion chromatograph for analysis.
Presenter: Joachim Weiss (Technical Director, Thermo Fisher Scientific)
Dr. Joachim Weiss started his professional career in 1982 as an applications chemist at Dionex Corporation in Germany. He currently holds the position of International Technical Director for the chromatography commercial organization at Thermo Fisher Scientific. He is renowned for his exceptional knowledge in separation science and is a recognized authority on Thermo Scientific™ IC and HPLC instrumentation and applications.
