Normal Alkanes,Multialkane Synthetic Model Mixtures, and Real Petroleum Waxes: Crystallographic Structures, Thermodynamic properties, and Crystalization

摘要

A general review is presented concerning jointly the crystallographic structures and the solid-solid and solid-liquid transition temperatures and enthalpies in the pure normal alkanes, as well as the structural and thermodynamic behavior of their synthetic binary, ternary , and multinary model mixtures and of real peroleum waxes. A major part of the structural and thermodynamic data of the literature, relative to the pure n-alkanes, are listed from methane up to the alkane with carbon atom number equal to 390. Variation relationships of the crystallographic long c-parameter that corresponds to the periodicity of the molecule layer packing along their axis, melting temperatures, and transition enthalpies are given as a function of the carbon atom number.The study of the literature on the n-alkane mixtures highlights the existence of isostructural binary, and multinary intermediate solid solutions which can be likened to a single pseucomponen. This intermediate solid solution is equivalent to a hypothetical pure n-alkane whose carbon atom number is equal to the average carbon atom number of the mixtures . As a result, the solubility of these multinary solid solutions or real multiparaffinic waxes in linear, cyclic, or aromatic light solvents is identical to that of the pre n-alkanes: pseudobinary eutectiv crystallization of the model or real wax as a single pseudocomponent on one hand and the light solvent on the other hand