Investigating the effects of hydrophobic and hydrophilic multi-wall carbon nanotubes on methane hydrate growth kinetics

Currently, gas hydrates have sparked the interest of many industries for their potential use in natural gas transportation, component separation and carbon dioxide sequestration. In order to optimize the efficiencies of such applications, there has been a pronounced focus on finding techniques and additives that promote hydrate growth. Previous studies have found that the addition of multi-wall carbon nanotubes (MWNTs) to methane hydrate systems greatly enhances production. In this study, the growth rates of methane hydrates were measured in the presence of as-produced (hydrophobic) and plasma functionalized (hydrophilic) MWNTs. For each condition, the effect of MWNT loading in the aqueous phase was determined. At higher concentrations, the hydrophobic MWNTs produced an enhanced growth rate whose effect plateaued with MWNT loading. The hydrophilic MWNTs' effect had an initial local maximum at lower concentrations and then followed to increase almost linearly with an increase in concentration. (C) 2013 Elsevier Ltd. All rights reserved.