NMR Relaxometry for Heavy Petroleum Residues: an Analytical Procedure for Customs Purposes

A procedure for determining group composition using low-frequency pulsed NMR relaxometry is developed to support rapid customs control during the export of heavy petroleum products, including fuel oil, gudron, and mixtures of petroleum refining residues. The study presents the results of NMR relaxometry measurements for samples of heavy petroleum residues. These results are compared with data obtained by the method described in Appendix A to Group 27 of the Commodity Nomenclature of Foreign Economic Activity of the Eurasian Economic Union, which relies on adsorption chromatography. The analysis revealed the influence of several factors on the measured results, including the length of alkyl substituents in the aromatic ring, the structure of resinous and asphaltene substances, the degree of paraffin crystallization, and the presence of heteroatom-containing compounds. The developed method enables the rapid determination of the mass fraction of aromatic hydrocarbons in the petroleum products under study. This parameter provides a basis for assigning a petroleum product to a specific tariff heading in the commodity classification.