Abstract: The basic physical properties of hydrocarbon molecules are essential data for refining process development, catalyst research, process simulation and control optimization. Through construction of the database for sulfur-containing compounds in petroleum, the influence of molecular structure of sulfur-containing compound on its basic physical properties and the correlation between them were investigated systematically. The results show that the density, boiling point and refractive index of sulfur-containing compounds are higher than that of the hydrocarbons with similar molecular skeleton structures. The basic physical properties are quite different for varied structure types of sulfur-containing compounds. With the increase of cyclic structure in the sulfur molecule, its density, boiling point and refractive index increase. For the same type of sulfur-containing compounds and isomers, their basic physical properties are further affected by the carbon number of alkyl group, the degree of isomerization, and even the position of sulfur atoms in the molecular structure. Specifically, with the increase of alkyl carbon number, both the density and refractive index increase for sulfides or thiols, while they decrease for cyclic sulfur-containing compounds. The boiling points of acyclic and cyclic sulfur-containing compounds all increase with the increase of alkyl carbon number in the molecule. Moreover, these alkyl and cyclic sulfur-containing compounds have a convergence in the properties with the alkyl carbon increased to some extent. In addition, it was observed that the isomerization of alkyl group and the position of sulfur atom have great influence on the boiling point, but they haveless effect on the density and refractive index. For sulfur isomers, the boiling points decrease with increasing isomerization in their alkyl group. Besides, the isomers with sulfur atom at the external site have relatively higher boiling points.

Key words: sulfur-containing compound, basic physical properties, molecular structure, carbon number, isomer