CHARACTERIZATION OF THE (111) GROWTH PLANES OF A TYPE-II GAS HYDRATE AND STUDY OF THE MECHANISM OF KINETIC INHIBITION BY POLY(VINYLPYRROLIDONE)

This work has developed techniques for studying the mechanism by which a hydrate growth inhibitor, i.e. poly(vinylpyrrolidone) (PVP), acts. The topology of a series of {111} faces of the type II clathrate hydra te, the postulated growth plane, have been studied in detail and used to calculate hydrogen-bond energy surfaces. N-Ethylpyrrolidone (NEP), the monomeric unit, has been used to sample adsorption on one of the { 111} surfaces. The adsorption sites were found to be located around th e large partial cavities, at positions determined by the location of t he pendant hydrogens. There is an added van der Waals attraction betwe en the NEP and the hydrate surface which is optimal when the pyrrolido ne occupies the partial large (16-hedra) cavities on the hydrate surfa ce.