Experimental study of CO2 hydrate formation kinetics with and without kinetic and thermodynamic promoters

In this work, an experimental study of CO2 hydrate formation kinetics was performed. The effects of the stirring rate and initial pressure on the hydrate formation rate were investigated. The results showed that a stirring rate of 600 rpm was optimum for increasing the CO2hydrate formation rate, especiallyat lower temperatures. The effects of additives on the hydrate formation rate were also investigated. Three surfactants, sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB) and TritonX-100 (TX-100) were tested. DTAB and TX-100 were new surfactants for investigation on CO2 hydrate formation kinetics. SDS and DTAB did not significantly affect the hydrate formation rate at concentrations of 300 and 500 ppm, whereas SDS increased and DTAB insignificantly decreased the hydrate formation rate at 1000 ppm. Furthermore, TX-100 negligibly decreased the hydrate formation rate at 300 and 500 ppm, but significantly decreased the rate at 1000 ppm. In contrast, the application of thermodynamic additives, tetrahydrofuran (THF) and tetra-n-butyl ammonium bromide (TBAB) at low concentrations increased the hydrate formation rate, and these additives affectedthe rate of hydrate formation in a manner similar to kinetic promoters.