^(13)C固体核磁共振测定气体水合物结构实验研究

^(13)C Solid-state Nuclear Magnetic Resonance Investigations of Gas Hydrate Structures

采用高功率1H去偶结合魔角旋转13C固体核磁共振技术,在低温常压条件下对合成的乙烷和丙烷气体水合物进行了测试,获得了两种纯气体水合物的13C核磁共振谱图,初步建立了固体核磁共振波谱法测定天然气水合物的实验方法。实验表明:乙烷水合物的13C核磁共振谱图中仅有一条谱线(δ7.7),结构类型为sⅠ,且乙烷分子仅填充在大笼中(512 62);丙烷气体水合物13 C核磁共振谱图有2条谱线,分别为甲基碳(δ16.7)和亚甲基碳(δ17.5)的共振峰,其结构类型为sⅡ,且丙烷分子只填充在大笼(51264)中。

Solid State NMR spectroscopy has taken a very prominent place in many spectroscopic techniques employed for the characterization of clathrate hydrates.In this work,we have measured the synthesized ethane gas hydrates by 13C NMR with Magic Angle Spinning（MAS） and High Power 1H Decoupling（HPDEC） at 173 K and atmospheric pressure.Furthermore,we have got the 13C NMR spectra of ethane gas hydrates and propane gas hydrates,and preliminary established the testing method of natural gas hydrate by Solid State 13C NMR spectroscopy.The experimental results show that there is only one resonance line（δ 7.7×10-6） for ethane in the hydrate phase obtained from 13C NMR,while ethane molecules are enclathrated in the sⅠhydrates and only contained in the large cages（51262）.The 13C NMR spectra of Propane gas hydrates exhibit tow resonance lines（δ 16.7 and 17.5）,which are assigned to methyl carbons and methylene carbons,respectively.Consequently,the propane gas hydrates are determined to be sⅡ hydrates,and propane molecules are only trapped in the large cages（51264）.