Nonpolymeric Kinetic Hydrate Inhibitors: Alkylated Ethyleneamine Oxides

Abstract

In this work, we present the results of a rare class of nonpolymeric molecules that show significant performance as stand-alone kinetic gas hydrate inhibitors (KHIs). n-Butylated amine oxides of four nonpolymeric oligoethyleneamines, pentaethylenehexamine (PEHA), tetraethylenepentamine (TEPA), triethylene tetramine (TETA), diethylenetriamine (DETA) (all made from ammonia and ethylene) with molecular weights in the range 103–232 D, as well as four hyperbranched polyethylenimines (HPEIs) (made from aziridine), with molecular weights in the range of 0.3–10.0 kDa, have been synthesized and evaluated for their KHI performance. All the amine oxides were first evaluated by carrying out slow constant cooling experiments (1 °C/h) at 76 bar with a Structure II hydrate-forming gas in steel rocking cells. The butylated hyperbranched polyethylenimine oxides (HPEI-Bu-AOs) showed molecular weight KHI performance dependence. The performance increased with decreasing molecular weight of the polymer with HPEI-Bu-AOs prepar...