(478c) Kinetics and Equilibria of CH4 Storage in Porous Solid Aided Clathrate Hydrates

Storage of (bio)methane in clathrate hydrates (abbr. hydrates) represents an interesting alternative for LNG and CNG given the large volumetric capacity (172 v/v) at mild conditions (e.g. 2.6 MPa; 273 K), low risk of handling and environmentally benign nature [1]. Hydrate nucleation and growth kinetics, however, are severely hampered by gas diffusing through a growing crystalline layer towards the hydrate-water interface. In this work, we demonstrate the promoting effect of confining water and methane in mesopores of silica-based adsorbents on methane hydrate kinetics and equilibria.

Plenty of research has been devoted to identifying optimal hydrate formation promoters. However, quantitative kinetic data of confined hydrate nucleation, growth, dissociation, and re-growth is greatly underrepresented. Two high-pressure experimental devices were developed in-house: (i) a magnetic suspension balance was adapted to directly monitor gas uptake/release kinetics during consecutive hydrate formation/dissociation cycles, (ii) a robust volumetric system was built to mimic the future gas loading/unloading process in a storage vessel.

During the presentation, we will discuss the design of these newly developed instruments and showcase adsorption/methane hydrate formation measurements. The effect of pressure, temperature, water loading and consecutive gas storage/release cycles on the storage kinetics and equilibria of solid aided methane hydrate formation will be discussed. Macroscopic observations are supplemented with X-ray diffraction, NMR spectroscopy and cryo-tomography measurements to gain deeper understanding of the confining spaces promoting hydrate formation. The importance of working capacity and operating conditions in the future implementation of hydrate-based gas storage will be highlighted in the discussion of the results.

[1] Koh, E. Sloan: Natural gas hydrates: Recent advances and challenges in energy and environmental applications. AIChE Journal 53, 1636-1643 (2007).