Calorimetric and Structural Studies of Tetrabutylammonium Bromide Ionic Clathrate Hydrates

Abstract

In the present work, characteristic properties of tetrabutylammonium bromide (TBAB) ionic clathrate hydrates structures were studied by single-crystal X-ray structure analysis. The structures of three different tetragonal TBAB ionic clathrate hydrates that were formed in our experiments were based on the same water lattice of tetragonal structure I (TS-I) differing in the ways of including bromide anions and arranging tetrabutylammonium cations. We demonstrated that (1) Br(-) can be included into the water lattice, replacing two water molecules, (2) the butyl group of the cation can be inserted not only in large T and P cavities but also in small D cavities of the water lattice TS-I, and (3) one of the reasons for polytypism of ionic clathrate hydrates on the basis of TS-I is the occurrence of alternative modes of arrangements of four-compartment cavities in adjacent layers of the water framework. The compositions of three TBAB ionic clathrate hydrates TBAB·38.1H2O, TBAB·32.5H2O, and TBAB·26.4H2O were determined by chemical analysis, and their enthalpies of fusion were measured by differential scanning calorimetry (DSC). From the obtained results, the enthalpies of the TBAB hydrate formation from TBAB and water were calculated thermodynamically.

Design of Ecological CO2 Enrichment System for Greenhouse Production using TBAB + CO2 Semi-Clathrate Hydrate

“…There are also empty pentagonal dodecahedral (5 12 ) cages in the structure of TBAB SC. TBAB·36H 2 O hydrate is isostructural to the orthorhombic hydrate of TBAB·38H 2 O, but tetragonal hydrates of TBAB·32H 2 O and TBAB·26H 2 O have not been refined yet [27,28]. Crystal structures of gas hydrates are comparable with that of SC.…”

Semiclathrate-based CO2 capture from flue gas mixtures: An experimental approach with thermodynamic and Raman spectroscopic analyses

“…Both TBAB (3.7 mol%) (TBABÁ26.0H 2 O) and TBAC (3.3 mol%) (TBACÁ29.7H 2 O) semiclathrates have tetragonal structure-I (TS-I), whereas TBAF (3.4 mol%) (TBAFÁ28.6H 2 O) semiclathrate forms a cubic structure (CS-I) [32][33][34]37,47,56]. For the TBAF (3.4 mol%) semiclathrate, 79.5% of the small cages are partially filled with water molecules [34], which indicates that the TBAF semiclathrate possesses fewer numbers of vacant small cages that are available for capturing CO 2 and N 2 gas molecules compared with the TBAB and TBAC semiclathrates.…”

“…For the TBAF (3.4 mol%) semiclathrate, 79.5% of the small cages are partially filled with water molecules [34], which indicates that the TBAF semiclathrate possesses fewer numbers of vacant small cages that are available for capturing CO 2 and N 2 gas molecules compared with the TBAB and TBAC semiclathrates. Furthermore, the TBAB (3.7 mol%) semiclathrate has a higher extent of filling of the small cages with TBA cations than that of the TBAC (3.3 mol%) semiclathrate [37,47,56], which results in a lower gas storage capacity for the TBAB (3.7 mol%) semiclathrate compared to the TBAC (3.3 mol%) semiclathrate. For these reasons, the TBAC (3.3 mol%) semiclathrate has a larger number of small cages that can be effectively used for capturing CO 2 and N 2 molecules, and therefore, demonstrates a larger gas uptake and steeper changes in the CO 2 concentration than the TBAB and TBAF semiclathrates as shown in Figs.…”

The Search for Hydrogen Stores on a Large Scale; A Straightforward and Automated Open Database Analysis as a First Sweep for Candidate Materials

“…Such borohydride and borate materials could be worthy of study when mixed with light metal hydrides in composite systems, however. Finally, the clathrate tetra-n-butyl ammonium bromide (26.4) hydrate (TBAB·26.4H2O) is worthy of comment as an impressive representative of clathrate structures, which allow the high density storage of gases (in this case water) through the formation of host-guest structures stabilised by Van-der-Waals interactions [30]. …”