NMR analysis of the Fischer-Tropsch wastewater: Combination of 1D selective gradient TOCSY, 2D DOSY and qNMR.

Affiliation

Shanxi Engineering Research Center of Biorefinery, Institute of Coal Chemistry, University of Chinese Academy of Sciences, 27 South Taoyuan Road, Taiyuan, 030001, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address: [Email]

Abstract

The Fischer-Tropsch (FT) process is a practical approach to convert synthesis gas (CO and H2) into hydrocarbons and oxygenates, and these product mixtures are usually well-characterized. However, the analysis of Fischer-Tropsch waste water (FTW) is still somewhat underdeveloped and the exact composition of FTW remains unclear. Herein, various qualitative NMR techniques, especially diffusion-ordered spectroscopy (DOSY) and one dimension (1D) selective gradient total correlation spectroscopy (SelTOCSY) were strategically applied in the analysis of FTW. The NMR results show that the DOSY technique can pseudo-separate most of components in complex mixtures over the diffusion dimension. The SelTOCSY technique is used as a supporting method in the cases where the DOSY technique cannot clearly distinguish overlapped signals. Moreover, the quantitative 1H NMR (qNMR) was further used to quantify the components of the sample. These routine and advanced qualitative and quantitative NMR technique utilized here provide a fast, effective and feasible method for the identification of complex mixtures in FTW, which might be a powerful and fast alternative to gas chromatography or high performance liquid chromatography for FTW research.

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