Abstract:

A method for the determination of C₁-C₆ organic acids in the products from syngas to olefins (SGTO) was developed by ion chromatography, which included the optimized separation conditions, the linear ranges and the working curves determined by using standard samples, the precision and accuracy of the method and the alkaline-washing conditions of the pretreatment for the oil phase samples. The SGTO water phase and oil phase samples were analyzed according to the method. The linearity test showed that the correlation coefficients (R²) for all of the C₁-C₆ organic acids in the specific concentration ranges were above 0.99, which means that all the components had good linear correlations. The recoveries of standard solutions were from 95.6% to 104.3%, and the RSDs (n=5) were from 0.4% to 3.6%. The spiked recoveries in SGTO oil phase samples were from 91.1% to 96.8%, and the RSDs (n=5) were from 0.7% to 2.3%. The accuracy of the method can satisfy the requirement for the analysis of SGTO samples. The results showed that there were more C₂-C₄ organic acids in the water phase samples, while there were more C₄-C₆ organic acids in the oil phase samples. This research has great significance for the study of SGTO reaction, the improvements of catalysts and operation conditions, and is helpful for choosing the materials of the equipment.

Key words: C₁~C₆ organic acids, ion chromatography (IC), oil phase products, syngas to olefins(SGTO), water phase products