Experimental study on the kinetic effect of N-butyl-N-methylpyrrolidinium bromide on CO2 hydrate

The kinetic effects of N-butyl-N-methylpyrrolidinium bromide ([Py14]-Br) on the formation of CO2 gas hydrates were experimentally investigated. Both of the induction time of CO2 hydrates formation and the formation rates were investigated in the aqueous solutions of [Py14]-Br at different concentrations. Pressure and temperature changes versus time during the hydrate formation process were measured under the isochoric conditions. The induction time had a trend to decrease with the increase of initial pressure or subcooling. [Py14]-Br aqueous solution could delay the induction time compared with pure water system at relatively high subcooling, while it appeared to have no inhibition effect at low subcooling, even enhanced the formation of gas hydrates. It was interesting to find that [Py14]-Br at a low mass fraction could slow the formation rate of CO2 gas hydrate, while it had a promotion effect at high mass fraction. The same promotion effect was also found by PVP at the mass fraction of 2.0%. So [Py14]-Br not only acted as kinetic inhibitor but also promoter of CO2 gas hydrate under different situations.