Thermodynamic Properties of Hydrogen + Tetra-n-Butyl Ammonium Bromide Semi-Clathrate Hydrate

Abstract

Thermodynamic stability and hydrogen occupancy on the hydrogen + tetra-n-butyl ammonium bromide semi-clathrate hydrate were investigated by means of Raman spectroscopic and phase equilibrium measurements under the three-phase equilibrium condition. The structure of mixed gas hydrates changes from tetragonal to another structure around 95 MPa and 292 K depending on surrounding hydrogen fugacity. The occupied amount of hydrogen in the semi-clathrate hydrate increases significantly associated with the structural transition. Tetra-n-butyl ammonium bromide semi-clathrate hydrates can absorb hydrogen molecules by a pressure-swing without destroying the hydrogen bonds of hydrate cages at 15 MPa or over.

Use of an artificial neural network algorithm to predict hydrate dissociation conditions for hydrogen+water and hydrogen+tetra-n-butyl ammonium bromide+water systems

“…Table 1 lists the experimental hydrate dissociation data reported in the literature for the hydrogen +water and hydrogen+ TBAB+ water systems, as mentioned earlier. We used the experimental data reported by Mao and Mao (Mao and Mao, 2004) for the hydrogen +water system and Hashimoto et al (2006Hashimoto et al ( , 2008Hashimoto et al ( , 2010 and Arjmandi et al (2007) for the hydrogen+ TBAB+ water system to develop our algorithm. These data are shown in Fig.…”

“…Hydrogen can form gas hydrates at low temperatures and extremely high pressures (Sloan and Koh, 2008;Mao and Mao, 2004;Lokshin et al, 2004;Dyadin et al, 1973Dyadin et al, , 1999. It has been shown that the addition of tetra-n-butyl ammonium bromide (TBAB) in aqueous solution can reduce the pressure required for hydrogen hydrate formation (Hashimoto et al, 2006(Hashimoto et al, , 2008(Hashimoto et al, , 2010Arjmandi et al, 2007). TBAB is a quaternary ammonium salt with a bromine counter ion commonly used as a semi-clathrate hydrate promoter.…”

“…TBAB is a quaternary ammonium salt with a bromine counter ion commonly used as a semi-clathrate hydrate promoter. Unlike clathrate hydrates where water molecules form hydrate cages and small guest molecules like methane are trapped inside cages, in TBAB semi-clathrate hydrates, bromide forms cage structures with water molecules, and the tetra-n-butylammonium cation occupies the center of four cages (Hashimoto et al, 2006(Hashimoto et al, , 2008(Hashimoto et al, , 2010Arjmandi et al, 2007). Table 1 summarizes a list of experimental data for the hydrate dissociation conditions in the H 2 + water and H 2 +TBAB +water systems reported in the literature.…”

“…Among various ANNs reported in the literature, the feed-forward (back propagation) neural network (FNN) method with a modified Levenberg-Marquardt optimization algorithm (Marquardt, 1963; Levenberg, 1944) is used, which is known to be effective to represent the non-linear relationships between variables in complex systems (Normandin et al, 1993;Mohammadi and Richon, 2010;Rivollet, 2005;Wilamowski et al, 2001;Chouai et al, 2002;Piazza et al, 2006;Scalabrin et al, 2006;Schmitz et al, 2006). To develop this algorithm, reliable literature data are used Hashimoto et al, 2006Hashimoto et al, , 2008Hashimoto et al, , 2010Arjmandi et al, 2007) (see Table 1). The developed algorithm is then employed to predict independent experimental data (not used in developing this tool).…”

Effect of Impeller Agitation on Preparation of Tetra-n-Butyl Ammonium Bromide Semiclathrate Hydrate Slurries

“…The concentration of aqueous TBAB solutions results in differences of the crystal structure and thermodynamic stability of TBAB hydrate. TBAB semiclathrate hydrates have become the subject of much attention as an attractive medium for not only refrigerant but also H 2 storage [7][8][9].…”