The effect of urea in the nucleation process of CO2 clathrate hydrates

Abstract

The role of urea in the promotion and stability of CO2 clathrate hydrates in the context of nucleation was investigated through isothermal–isobaric molecular dynamics simulations. A comparison of structural and dynamic properties was made for aqueous solutions of CO2 interstitial to model montmorillonite surfaces in the presence and absence of urea. The results showed that meta-stable amorphous hydrates associated through proximity interact through cross-relaxation of H-bonds. Urea appears to mediate this effect by functioning as a bridge for thermal fluctuations of H-bond networks between nearby CO2 hydrates. The implications have significant bearing in the modification of solution properties for the enhancement of clathrate hydrate formation in geologic and aquatic sediments through the control and stabilization of nucleation using organic matter.