Center for Hydrate Research, Colorado School of Mines, Golden, Colorado 80401, USA.
J Phys Chem A. 2009 Mar 5;113(9):1711-6. doi: 10.1021/jp8010603.
The interconversion of methane-ethane hydrate from metastable to stable structures was studied using Raman spectroscopy. sI and sII hydrates were synthesized from methane-ethane gas mixtures of 65% or 93% methane in ethane and water, both with and without the kinetic hydrate inhibitor, poly(N-vinylcaprolactam). The observed faster structural conversion rate in the higher methane concentration atmosphere can be explained in terms of the differences in driving force (difference in chemical potential of water in sI and sII hydrates) and kinetics (mass transfer of gas and water rearrangement). The kinetic hydrate inhibitor increased the conversion rate at 65% methane in ethane (sI is thermodynamically stable) but retards the rate at 93% methane in ethane (sII is thermodynamically stable), implying there is a complex interaction between the polymer, water, and hydrate guests at crystal surfaces.
使用拉曼光谱研究了甲烷-乙烷水合物从亚稳到稳定结构的相互转化。使用甲烷-乙烷气体混合物（甲烷浓度为 65%或 93%，乙烷与水），在没有和有动力学水合物抑制剂聚（N-乙烯基己内酰胺）的情况下，合成了 sI 和 sII 水合物。在甲烷浓度较高的气氛中观察到更快的结构转化速率，可以用驱动力（sI 和 sII 水合物中水的化学势差）和动力学（气体和水重排的传质）的差异来解释。动力学水合物抑制剂提高了甲烷浓度为 65%的乙烷中的转化速率（sI 在热力学上是稳定的），但却降低了甲烷浓度为 93%的乙烷中的速率（sII 在热力学上是稳定的），这表明聚合物、水和水合物客体在晶体表面之间存在复杂的相互作用。
