Sustainability of hollow silica matrix for clathrate hydrate recycling

Storage and transportation of greenhouse gases such as methane (CH4) and carbon dioxide (CO2) are of current interest and converting them into hydrates a priori is a workable option. Bottlenecks such as sluggish and inefficient hydrate conversions can be defeated with the help of suitable porous materials. However, reusability of the porous material is a crucial issue. The present study reports the sustainability of low density silica (SiO2), as matrix material, for a number of freezing thawing cycles without significant loss in hydrate fractions. The experiments on CH4 and CO2 hydrates were conducted respectively at 7.3-7.6 MPa and 3.6-3.8 MPa; in the temperature range of 270-300 K. The faster formation kinetics (t(90) < 2 h, where t(90) is the time taken for 90% of total hydrate conversion) and the overall hydrate conversions (similar to 75%) are attractive features. Thus, the hydrate system consisting of SiO2 - H2O - CH4/CO2 is suitable for gas storage and transportation applications; and possesses features such as rapid and high convertibility to hydrate and also high recyclability. (C) 2016 Elsevier B.V. All rights reserved.