Abstract:

Surfactants is one of the effective methods to promote hydrate formation. The influence of Sodium dodecyl sulfate (SDS) on the formation of hydrate was studied in an autoclave. The microscopic properties for SDS hydrate samples were detected with Raman spectroscopy and powder X-ray diffraction. It was found that the presence of SDS decreased the induction time and enhanced the hydrate growth rate. The microcosmic results showed that the presence of SDS did not change the sI-type hydrate lattice structure and had less impact (a few thousandths) on the crystal spacing compared with ideal sI-type structure and pure methane hydrate. The Raman shift of C-H stretching mode from CH₄ encapsulated in large and small cages are all 2904 and 2915 cm^-1, which illustrate SDS did not change the large and small cages structure. SDS improved the absolute small cages occupancy (q_L) as the absolute large cages occupancy (q_S) approached saturation, and this is also demonstrated that SDS can reduce hydration number and increase storage capacity.

Key words: hydrate, surfactants, storage capacity, kinetics, absolute occupancy

摘要：

表面活性剂是促进水合物生成的有效手段之一。在高压反应釜中研究了十二烷基硫酸钠（SDS）对水合物生成过程的动力学影响，利用XRD和拉曼光谱探究了SDS存在条件下水合物的微观结构。宏观结果表明SDS缩短了诱导时间，加快了水合物生长速率。微观结果表明SDS没有影响sI型水合物的晶型结构，晶面间距与理想sI型水合物及纯水甲烷对比误差在千分之几。水合物中甲烷在大笼小笼中的拉曼位移分别为2904和2915 cm^-1，SDS没有改变大笼小笼结构。大笼绝对占有率（q_L）接近饱和时，SDS可以进一步提高小笼绝对占有率（q_S），从微观角度证明了SDS可以减少水合数，提高储气率。

关键词: 水合物, 表面活性剂, 储气率, 动力学, 绝对占有率