Inhibition of Tetrahydrofuran Hydrate Formation in the Presence of Polyol-Modified Glass Surfaces

Glycerol was conjugated to glass test tube surfaces in four configurations by employing two different silane spacers, covalent attachment to glycerol at either the 1- or the 2-position, and with a succinic acid spacer. The resulting surfaces were tested for their ability to inhibit the nucleation of tetrahydrofuran hydrate (THF hydrate) in comparison with polyvinylpyrrolidone (PVP), a known polymeric inhibitor of THF hydrate formation. Contact angle measurements were used as an indication of surface modification throughout the glass derivatization steps. Of the four final surfaces modified with glycerol, only the coating with (3-aminopropyl)triethoxysilane (APTES) and glycerol coupled at the 1-position (leaving a free 1,2-diol) showed significant inhibition of the formation of THF hydrate. The corresponding N-[3-(trimethoxysilyl)propyl]-ethylenediamine (AEAPTMS) coating with glycerol coupled at the 1-position did not show a significant difference over the untreated test tubes. Attachment of glycerol at the 2-position yielded a coating with no benefit over the untreated test tubes regardless of the silane used, and a surface modified with APTES and succinic acid alone enhanced the formation of THF hydrate. The ability to inhibit THF hydrate formation using a polyol-modified surface is a first step in the development of a coating that, alone or in combination with known gas hydrate inhibitors, could be used to prevent gas hydrates from plugging pipelines in field applications.