Measurement of the Hydrate Phase via Raman and NMR Spectroscopy

科罗拉多矿业学院的CTS-9634899项目摘要通过拉曼光谱和核磁共振光谱测量水合物的相结构和组成，提出了一种用于水合物实验的新的最先进的原型。在这项工作中，我们建议做以下六件事：1.用核磁共振测量硅水合物中~(129)Xe和~(13)C(甲烷)的相对笼子占有率，以便与Ripmeester和我们的拉曼工作进行校准；2.用核磁共振和拉曼方法测量的水化数和空穴占有率来评估van der Waals和Platteeuw统计理论；3.用我们现有的400 MHz核磁共振和新的拉曼仪来确定水合物结构(如Si到Sh)之间的固相转变动力学，4.设计、制造、并测试一种将拉曼设备(测量固体)与常规宏观相平衡仪器相结合的新型设备，5.评估拉曼光谱用于动力学水合物研究的可行性，以及6.评估光纤拉曼设备作为在线水合物监测器的可行性。这项工作将有三个主要影响：1。水合物的结构实际上从未被测量过，但却被预测过。在许多情况下，预测了错误的水合物结构。对于至少三种常见的水合物结构，不正确的结构(以及相关的形成条件)被预测的频率比通常认识到的更高。拟议的工作将演示如何纠正这个问题。2.水合物的相组成(空腔占有率、客主比和客客比)也是预测的，而不是测量的。然而，这种测量对于修正现有的热力学模型是必要的，因为水合物的形成条件不仅取决于结构，而且还取决于相组成。3.光纤技术的出现使水合物相组成的测量与宏观相平衡的测量同时进行。这项技术不仅有可能改变实验室中水合物的测量方法，而且还有可能用作工艺流程中水合物形成的在线监测仪。到目前为止，工业上只有压力降来确定管道中水合物的起始和增长。我们现在应该在实验室做这项工作，因为：1.我们已经在实验上验证了拉曼测量Si、SiI和Sh水合物结构和客体组成的概念。2.美国国家科学基金会最近提供了一项配套资金设备赠款，提供了一台能够进行固体或液体测量的400兆赫核磁共振仪器。3.我们有专家人员监督工作。Ben Bloys先生(ARCO)将与我们的10家公司组成的财团就该项目进行行业联络。鲍勃·伯鲁斯博士。美国地质勘探局(USGS)将提供拉曼专业技术和仪器供应。约翰·里普米斯特博士将担任兼职教授，监督拟议的核磁共振工作。

CTS-9634899 Sloan, E.D. Colorado School of Mines PROJECT SUMMARY A new state-of-the-art protoype for hydrate experiments is proposed by measurements of the hydrate phase structure and composition, using Raman and NMR spectroscopy. In this work we propose to do the following six things: 1. Measure the relative cage occupancies of 129Xe and 13C (methane) in sI hydrate via NMR, for calibration with data of Ripmeester and our Raman work, 2. Use the hydration numbers and cavity occupation measured via NMR and Raman methods to assess the van der Waals and Platteeuw statistical theory, 3. Determine the kinetics of solid phase transitions between hydrate structures( e.g. sI to sH ) using our existing 400 MHz NMR, and a new Raman instrument, 4. Design, fabricate, and test a new type of apparatus which combines a Raman devices (to measure the solid) with a regular macroscopic phase equilibria instrument, 5. Assess the viability of Raman spectroscopy for kinetic hydrate studies, and 6. Assess the viability of a Fiber Optics Raman device as an in-line hydrate monitor. The work will have three major impacts: 1. The hydrate structure is virtually never measured but predicted. There are multiple instances in which the incorrect hydrate structure has been predicted. With at least three common hydrate structures, the incorrect structure(and associated formation conditions) is predicted more frequently than commonly realized. The proposed work will demonstrate how this problem may be corrected. 2. The hydrate phase composition( cavity occupation, guest-to-host and guest-to-guest ratios) is also predicted rather than measured. However, such measurements are necessary to correct the existing thermodynamic model since hydrate formation conditions depend not only on structure but also on the phase composition. 3. The advent of Fiber Optics technology enables measurement of hydrate phase composition simultaneously with the macroscopic measurements of phase equilbria. This technology not only has the potential to change the method of hydrate measurements in the laboratory, it also has the potential to be used as an in-line monitor for hydrate formation in process streams. To date industry only has pressure drop to determine the initiation and growth of hydrate in a pipeline. The proposed work should be done now in our laboratory because: 1. We have experimentally validated the concept of the Raman measurement of hydrate structure and guest composition for sI, sII, and sH. 2. A recent NSF matching-funds equipment grant has provided a 400 MHz NMR instrument capable of solid or liquid measurements. 3. We have expert personnel available to supervise the work. Mr. Ben Bloys (ARCO) will be industrial liaison with our consortium of 10 companies to the project. Dr. Bob Burruss. (USGS) will provide Raman expertise and apparatus availability. Dr. John Ripmeester will act as an adjunct professor in supervising the proposed NMR work.