Experimental Study on the Separation of CH₄ and N₂ via Hydrate Formation in TBAB Solution

Abstract

In order to reduce the emission of coal bed methane mixed with air (can be regarded as a CH4 and N2 mixture), which will be helpful to adequately utilize the natural resources and protect environment, the separation of CH4 and N2 via hydrate formation in tetra-n-butylammonium bromide (TBAB) solution was systematically studied in this work. The CH4−N2 hydrate formation conditions were determined in TBAB solution first, and then the separation experiments were carried out in TBAB and TBAB−sodium dodecyl sulfate (SDS) solution, respectively. The experimental results show that CH4 and N2 form a hydrate much easier after adding TBAB to water. The composition of CH4 in the hydrate after single-stage equilibrium separation in TBAB solution can be increased from 46.25 mol % to 67.86 mol %. At the same conditions, the composition of CH4 after separation in TBAB−SDS solution is 68.66 mol % and the reaction time shortens greatly. Besides, the recovery of CH4 is more than 47%, and the gas storage capacity of hydrate is 19−21 m3/m3. Higher composition and recovery of CH4 are expected to be obtained if multistage separation is applied. It indicates that CH4 can be concentrated effectively from CH4 and N2 via hydrate formation in TBAB solution. Since the hydrate separation technology can substantially avoid the explosion problem caused by CH4 and on the basis of the results obtained in this work, we may say that this technology is quite suitable for the separation of coal bed methane mixed with air and has broad prospects for industrial applications.

Concentrating orange juice through CO2 clathrate hydrate technology

“…For the third method, freeze concentration, concentrate quality is satisfactory but it also consumes a lot of energy, especially during the ice nucleation step (Guignon et al, 2012). Recently, hydrate separation technology has attracted scientific interest in the fields of CO 2 capture (Nguyen Hong et al, 2007;Wang et al, 2013;Eslamimanesh et al, 2012;Fan et al, 2009;Li et al, 2009;Tajim et al, 2014;Gholinezhad et al, 2011;Tang et al, 2013), hydrogen or methane recovery (Liu et al, 2014;Zhong and Englezos, 2012;Sun et al, 2011) and desalination (Javanmardi and Moshfeghian, 2003;Park et al, 2011). Hydrates (also called clathrate hydrates) are nonstoichiometric crystalline inclusion compounds form through the combination of water and suitably sized "guest" molecules, typically under low temperature and elevated pressure conditions (Sloan and Koh, 2008).…”

Experimental and modeling study on the phase equilibria for hydrates of gas mixtures in TBAB solution

“…1. The reactor equipped in an air bath is the same as given in our previous work (Sun et al, 2011). The reactor is made by stainless steel with a design pressure of 20 MPa and a volume of 420 mL.…”

“…The concentration of TBAB was held at 0.05 and 0.10 weight fraction which is the common fraction used by researchers in the literatures (Duc et al, 2007;Li et al, 2010a,b;Lu et al, 2009;Sun et al, 2011). The experimental temperature ranged from 278.1 to 286.2 K. The experimental data are listed in Table 7 and shown in Fig.…”

“…The experimental results showed that the presence of TBAB considerably decreases the formation pressure of simple hydrates (CO 2 or N 2 ) and mixed hydrates (CO 2 -N 2 ). Sun et al (2011) systematically studied the separation of CH 4 and N 2 via hydrate formation in a TBAB solution. The recovery of CH 4 is more than 47%.…”

Thermodynamic stability conditions, methane enrichment, and gas uptake of ionic clathrate hydrates of mine ventilation air

“…SCHs have drawn increasing interest for their potential applications in gas storage [18][19] and gas separation [20,21]. Several studies of this kind have addressed coal methane gas with relatively high original methane concentrations (e.g., close to or over 30 mol%) [22][23][24]. For lean methane-containing gas streams such as MVA, Adamova et al [25] used a statistical thermodynamic approach to predict the hydrate formation pressure of the water + MVA containing 0.5 vol% CH 4 system.…”