Methane Storage in a Hydrated Form as Promoted by Leucines for Possible Application to Natural Gas Transportation and Storage

Abstract

Methane is important in future energy schemes. The main strategies for storing and transporting methane are compression, liquefaction, and physical adsorption in synthetic porous materials. Here, we show that methane can be stored in a hydrated form using natural amino acids such as leucines as effective promoters to form methane hydrate with a high formation rate and a high capacity. In addition, the methane hydrate formed from the L‐leucine solution dissociates without foaming phenomenon. We also showed that the heavier hydrocarbons in natural gas can enhance the promoting effect of L‐leucine.

Clathrate Hydrates of Greenhouse Gases in the Presence of Natural Amino Acids: Storage, Transportation and Separation Applications

“…Liu et al . reported 0.157 mol/molH 2 O (or 140 mg/g) methane gas consumption in l-met (0.5 wt%) system at somewhat higher gas pressure (9.0 MPa) 24 . Further, Cai et al .…”

“…Recently the amino acids are being used to promote the hydrate formation rate, particularly under low concentrations 22 – 24 . The exact nature for its increased gas uptake ratio is still obscure.…”

“…Liu et al . reported that 0.5 wt% AA systems, such as l-met, l-phe and l-tryptophan are good hydrate promoters for CH 4 – H 2 O system, with rapid and higher gas consumption 24 . In contrast, the methane gas uptake in AA systems with l-serline, l-aspartic acid and l-proline is negligibly small in CH 4 – H 2 O system 24 .…”

“…reported that 0.5 wt% AA systems, such as l-met, l-phe and l-tryptophan are good hydrate promoters for CH 4 – H 2 O system, with rapid and higher gas consumption 24 . In contrast, the methane gas uptake in AA systems with l-serline, l-aspartic acid and l-proline is negligibly small in CH 4 – H 2 O system 24 . Sa et al ., have also reported l-alanine as an active inhibitor for CO 2 hydrate system, whereas it has no influence on CH 4 hydrates and they attribute the plausible reasons to nature and length of side chain; the hydrophobicity index and abnormal interactions with water molecules 14 , 17 .…”

“…Further, Liu et al . 24 , found that the leucines, particularly under lower concentrations (0.1 to 1 wt%), are effective promoters for methane gas in hydrated form with a high formation rate and a high capacity. These authors have also reported that l-methionine, l-tryptophan, l-phenylalanine, l-arginine, l-glutamic acid and l-histidine can promote the formation process of methane hydrate, however, to some lesser extent.…”