The research on hydro-raffinates from the co-hydrogenation process in terms of mono- and diacylglycerols content determination

Abstract

In this work, the possibilities of using the GC-FID gas chromatography technique for determination of mono- and diacylglycerols content in the stream from the co-hydrogenation of rapeseed oil and middle distillates were investigated. Products from this process are planned to be increasingly used in the future as a new biocomponent of fuel for diesel engines. Before introducing new types of fuel components, it is necessary to test them in detail, especially in terms of residues of the fat raw material. The Regulation of the Minister of Climate of June 24, 2020 on the content of biocomponents formed as a result of co-hydrogenation indicates that the level of biomass conversion is determined on the basis of the content of triacylglycerols in the hydro-raffinate. Hence, on the basis of this determination, it is possible to assess the correctness of the co-hydrogenation process. However, other fatty components may be present in the product of this process in the form of unreacted residues. Therefore, it seems justified to carry out studies on other trace components of fatty origin in the hydro-treating material, due to the introduction of various plant materials together with petroleum hydrocarbons into the co-hydrogenation process. Due to the lack of available standardized methodologies for testing this type of products, a review of the literature was made regarding the possibility of using analytical techniques including gas and liquid chromatography to determine content of the so-called mono- and dicylglycerols, being residues of the fatty raw material, in various types of matrices, including vegetable oils and fatty acid methyl esters. In the case of examining the content of mono- and diacylglycerols in the product from the co-hydrogenation process, it was necessary to use the technique of liquid chromatography for the first-step concentration of the substances of interest. This technique made it possible to separate the sample matrix and concentrate the components to be determined prior to gas chromatographic analysis. Due to the complicated matrix of samples and the low required level of quantification, it was necessary to select appropriate conditions for removing the matrix using the classical liquid chromatography technique. A proprietary methodology for testing the content of mono- and diacylglycerols in the hydro-raffinate was developed, which was used to test selected samples of real hydro-raffinates from the co-HVO and HVO co-hydrogenation process. The ability to detect these trace fat components at a low level was indicated – as low as 2 mg/kg. The obtained sensitivity of the method allowed for additional qualitative assessment of this type of co-hydrogenation products, which are gradually gaining importance on the European market of liquid fuels.