Interrelation between the spatial structure of unsaturated hydrocarbon molecules and heats of their adsorption

The total area (s ^m) of Voronoi-Dirichlet polyhedron faces corresponding to all intermolecular contacts of one molecule in the structure of crystals and the total volume of pyramids (V ^m) built on such faces and containing the nuclei of atoms participating in intermolecular contacts in their vertices were determined for 19 unsaturated hydrocarbons. The differential molar heat of adsorption of the hydrocarbons on graphitized thermal carbon black was found to be linearly related to the s ^m or V ^m integral parameters of their Voronoi-Dirichlet polyhedra. Aromatic hydrocarbons on the one hand and saturated hydrocarbons, olefins, and acetylene on the other are characterized by different dependences because of the special shapes of their molecular Voronoi-Dirichlet polyhedra.